Portable Terminal Window Member Mold Design for Uniform Resin Density
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Solution Overview
Problem
The existing methods for fabricating window members for portable terminals using injection-molded products often result in non-uniform density and thickness distribution, leading to distortion and increased defect rates due to insufficient pressure delivery during the molding process, especially at the end portions away from the melt-resin gate.
Innovation Solution
A window member is fabricated using a mold design where the far end portion is inclined and has a comparable thickness to the central region, allowing uniform injection pressure across the molding space, and an ITO film is laminated onto the inner surface to form a touchscreen, while the outer surface is curved to enhance user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single melt-resin gate is used in injection molding to minimize burrs, then burr formation is reduced, but injection pressure is insufficient at far end portions causing non-uniform density and shrinkage
Solution Approach 1:
The patent divides the single gate into multiple gates (first melt-resin gate and second melt-resin gate) positioned at different locations. This segmentation allows injection pressure to be delivered uniformly across the entire molding space, preventing the density non-uniformity and shrinkage that occur with a single gate, while still controlling burr formation at each gate location.
Solution Approach 2:
The patent applies different gate configurations to different regions of the mold. By positioning gates strategically (including at least one gate at the far end portion), the injection pressure distribution is optimized for each local region, ensuring uniform density throughout the window member while maintaining control over burr formation in specific areas.
2Manufacturing precision
If gate is positioned at center of mold, then injection pressure distribution is improved, but screen distortion occurs
Solution Approach 1:
The patent positions gates at specific locations rather than centrally, with at least one gate positioned at the far end portion of the molding space. This localized gate positioning delivers injection pressure uniformly across different regions without causing the screen distortion that occurs with central gate positioning, achieving both good pressure distribution and shape accuracy.
3Strength
If reinforced glass is used for window member, then surface hardness is sufficient, but manufacturing cost and processing time increase
Solution Approach 1:
The patent uses non-reinforced glass or resin materials that are cheaper and easier to manufacture than reinforced glass. By optimizing the injection molding process with multiple gates to ensure uniform density and eliminate defects, the patent achieves sufficient durability without the need for expensive reinforced materials, thereby reducing manufacturing cost and simplifying the production process.
4Ease of manufacture
If injection molding is used to form curved surface window, then manufacturing cost is reduced, but burr formation and density non-uniformity occur
Solution Approach 1:
The patent maintains the cost-effective injection molding process for forming curved surface windows but addresses the density non-uniformity and burr formation by segmenting the single gate into multiple gates. This allows uniform pressure distribution throughout the molding space while controlling burr formation, preserving both the manufacturing cost advantage and the manufacturing precision.
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 ensures a uniformly dense window member with reduced shrinkage and defect rates, preventing screen distortion and allowing for the use of non-reinforced materials, thereby minimizing manufacturing costs and enhancing user experience.
Implementation Method 1
delivering uniform injection pressure to a molding space with the melt resin
Implementation Method 2
an ITO film is laminated onto the inner surface to form a touchscreen
Data Source
AI summary
Provided are a window member for a display device of a portable terminal and a method for fabricating the window member. An inner surface of the window member is formed as a flat surface from a first end portion to a position adjacent to a second end portion, and an inner surface of the second end portion is formed inclined with respect to the flat surface in a direction toward an outer surface. According to the window member and the method for fabricating the same, shrinkage is minimized during hardening of melt resin by sufficiently delivering injection pressure for the melt resin over the entire molding space of a mold, thereby improving a product defect rate.