PCB Relief Cut for Touchscreen Light Guide Alignment
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Solution Overview
Problem
The alignment and mechanical interference issues between printed circuit boards (PCBs) and touchscreen light guides can cause misalignment of LEDs and photodiodes, leading to degraded signal integrity and performance in touchscreen systems, particularly due to variations in the X-Y position and Z-direction alignment, which may result in torsional bending and warping of the PCB or light guide, disrupting the optical system and requiring costly corrections.
Innovation Solution
A relief cut is created on the edge of the printed circuit board to receive the touchscreen light guide assembly, allowing the lens to extend into the board and eliminating mechanical interference, thereby optimizing the alignment of optical centers and preventing warping, using a milled channel that provides clearance for the light guide lenses to protrude without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the touchscreen light guide assembly is mounted directly on the printed circuit board without relief cuts, then the structural integrity of the PCB is maintained, but mechanical interference occurs causing misalignment of LEDs and photodiodes and warping of the PCB
Solution Approach 1:
The PCB edge is segmented by creating relief cuts that separate the mounting area from the main board structure. This allows the light guide assembly to be positioned independently without causing warping or misalignment of other PCB components.
Solution Approach 2:
The relief cuts create nested structures where the light guide assembly fits into recesses formed by the relief cuts. This nesting allows the lens to extend into the relief cut area, eliminating mechanical interference while maintaining precise alignment.
2Reliability
If relief cuts are created on the PCB edge to accommodate the light guide assembly, then mechanical interference is eliminated and alignment is improved, but the PCB manufacturing process becomes more complex
Solution Approach 1:
The relief cuts are created during the PCB manufacturing process before final assembly. This preliminary action ensures that the PCB is pre-configured to accommodate the light guide assembly, preventing alignment issues and signal integrity problems during subsequent assembly steps.
3Ease of manufacture
If the light guide assembly is mounted without relief cuts, then the manufacturing process is simpler, but torsional bending and warping occur disrupting the optical system
Solution Approach 1:
The relief cuts are applied locally at specific edges of the PCB where the light guide assembly needs to be mounted. This localized modification maintains the overall structural integrity and shape stability of the PCB while providing the necessary accommodation for the light guide assembly at critical locations.
Data Source
AI summary
According to an example, a device may comprise a touchscreen light guide assembly, a lens disposed on the touchscreen light guide assembly, and a printed circuit board including a relief cut on an edge of the printed circuit board. The relief cut may be to receive the touchscreen light guide assembly and to allow the lens to extend into the printed circuit board relief cut.