Touch Sensor Embedding in Plastic Input Device
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Solution Overview
Problem
Conventional input devices with touch sensors embedded in plastic parts have reduced sensitivity due to increased distance from the outer face of the base and poor yield rates caused by ribbed parts interfering with sensor fixation.
Innovation Solution
Embedding the touch sensor in the plastic part reduces the distance to the outer face, omitting the need for separate fixation, and using a spacer to optimize sensitivity, while also reducing plastic material usage and maintaining strength through strategic openings in the plastic part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the touch sensor is fixed to the back face of the plastic part, then the assembly process is simplified, but the distance from the outer face of the base to the touch sensor increases, reducing sensitivity
Solution Approach 1:
The touch sensor is embedded within the plastic part, with the plastic material surrounding and encapsulating the sensor. This nesting approach allows the sensor to be positioned closer to the base's outer face while the plastic part provides structural support and integration, resolving the contradiction between assembly simplicity and sensitivity.
Solution Approach 2:
The invention uses a single-shot molding process to integrate the touch sensor and plastic part in one manufacturing step, eliminating separate assembly operations. This approach prioritizes manufacturing efficiency and cost-effectiveness while achieving the required sensitivity through optimized sensor positioning within the molded structure.
2Strength
If ribbed parts are added to the back face of the plastic part for attachment, then the attachment strength is improved, but the ribbed parts interfere with fixing the touch sensor, reducing yield rate
Solution Approach 1:
The invention divides the plastic part into functionally distinct regions: a first region on the front face for embedding the touch sensor, and a second region on the back face with ribbed parts for attachment. This segmentation allows each region to optimize its function without interfering with the other, resolving the contradiction between attachment strength and sensor fixation.
Solution Approach 2:
The plastic part is designed with non-uniform local properties: the front face region provides a smooth, accessible surface for sensor embedding, while the back face region features ribbed structures for enhanced attachment. This local differentiation enables both strong attachment and easy sensor fixation without mutual interference.
3Loss of substance
If the plastic part is made thinner to reduce material usage and cost, then material costs are reduced, but the strength of the plastic part decreases
Solution Approach 1:
The invention introduces curved or rounded features into the plastic part structure, such as arches or domes, that provide structural strength through geometric shape. These curved elements distribute stress more effectively, allowing the part to maintain required strength with reduced material thickness, thus resolving the contradiction between material reduction and strength maintenance.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
The invention is provides an improved input device in terms of the sensitivity of a touch sensor and the yield rate. The input device includes a base 100, a plastic part 300 provided on the base 100, a touch sensor 400, and a connecting part 500 connected to the touch sensor 400. The touch sensor 400 is embedded in the plastic part 300 such that the distance between the touch sensor 400 and the touch sensing surface of the base 100 is generally constant.