Backlit Metal Keycap Character Cavity Fill Method
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Solution Overview
Problem
Existing methods for producing keycaps in portable electronic devices, such as those used in smartphones and PDAs, face challenges in effectively backlighting metal keycaps to display characters in low light conditions, as they often rely on plastic-filled cutouts which can lead to light leakage and air pockets in the fill material.
Innovation Solution
A method involving removing material from the backside of a keycap body to form a cavity in the shape of a character, filling it with a fill material, and then removing material from the front side to expose the fill material, creating a design that does not extend through the body and uses bore holes to prevent air pockets, while undercutting sidewalls to retain the fill material and eliminate bridging elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If plastic-filled cutouts are used in metal keycaps for backlighting, then character visibility is improved, but light leakage and air pockets occur in the fill material
Solution Approach 1:
The method performs preliminary actions by first forming the cavity in the keycap body, then filling it with material, and only after that removing material from the front side. This sequence ensures the fill material is already in place before final shaping, preventing air pockets and ensuring complete filling of the character spaces for optimal backlighting without light leakage.
Solution Approach 2:
The invention applies different material properties to different regions: the keycap body maintains its original material (metal or plastic), while the character cutout regions are filled with a different material that has superior optical properties for backlighting. This local differentiation allows the filled regions to transmit light effectively while the rest of the keycap maintains its structural integrity and aesthetic appearance.
2Illumination intensity
If material is removed from both sides of the keycap body, then character display is improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct sequential operations: first removing material from the backside to form the cavity, then filling the cavity, and finally removing material from the front side to expose the filled character regions. This segmentation allows each operation to be optimized independently and simplifies process control compared to attempting to create the final shape in a single operation.
Solution Approach 2:
The cavity formation and material filling are performed as preliminary actions before the final front-side material removal. This ensures that the fill material is already positioned correctly within the keycap body before the final shaping step, reducing the need for complex post-processing and multiple iterations.
3Illumination intensity
If fill material is used to replace cutout material, then transmittance is improved, but air pockets may form in the fill material
Solution Approach 1:
The fill material is introduced into the cavity before the final front-side material removal step. This preliminary filling ensures that the material has time to settle and conform to the cavity shape completely, reducing the formation of air pockets. The sequence of operations allows the fill material to be properly positioned before the keycap is finalized.
Solution Approach 2:
The invention changes the material parameters by selecting a fill material with appropriate viscosity and optical properties that allow it to flow into and completely fill the character cavities. The material properties are chosen to ensure complete filling without trapping air, while maintaining the desired light transmittance characteristics for effective backlighting.
Data Source
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AI summary
A method for producing a keycap of a keyboard of a portable electronic device that includes removing material from the backside of a body of the keycap to form a cavity in a shape associated with a character, filling the cavity with fill material, and removing material from the front side of the body to expose the fill material on the front surface of the keycap.