Backlight Module Folded Flexible Circuit Board EMI Reduction
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Solution Overview
Problem
Conventional backlight modules interfere with the sensing operation of electromagnetic touch panels due to metal wires in flexible circuit boards, impairing sensing accuracy.
Innovation Solution
A backlight module design featuring a light guide plate and a flexible circuit board strip with a light source section and a signal transmission section, where the signal transmission section is disposed vertically and minimized in area to reduce interference, and the flexible circuit board is folded to be perpendicular to the light guide plate, minimizing the projected area on the electromagnetic touch panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flexible circuit board is disposed with metal wires to connect the light source structure to the signal source, then the electrical connection is established, but the metal wires interfere with the touch sensing operation of the electromagnetic touch panel and impair sensing accuracy
Solution Approach 1:
The flexible circuit board is folded to form a first fold, changing its spatial arrangement from a flat planar configuration to a three-dimensional structure. This dimensional change allows the circuit board to route signals away from the electromagnetic touch panel sensing area, reducing interference while maintaining electrical connectivity.
Solution Approach 2:
The flexible circuit board is divided into distinct sections: a light source section extending along the light entrance edge, a connection section with folds, and a signal transmission section extending along the side edge. This segmentation allows each section to be optimized for its specific function and positioned to minimize interference with the touch panel.
2Object-affected harmful factors
If the flexible circuit board is folded to be perpendicular to the light guide plate to minimize projected area, then the interference with the electromagnetic touch panel is reduced, but the structural complexity increases
Solution Approach 1:
The flexible circuit board incorporates folds that allow it to change its spatial configuration dynamically. The first fold creates a perpendicular orientation relative to the light guide plate, and the second fold allows adjustment of the signal transmission section's position and orientation, enabling the structure to adapt to minimize interference.
Solution Approach 2:
The connection section with its first and second folds effectively nests portions of the circuit board within the space between the light guide plate and the electromagnetic touch panel, utilizing available three-dimensional space to route signals away from the sensing area.
3Area of stationary object
If the signal transmission section is extended along the side edge of the light guide plate perpendicular to the light source section, then the wiring area is minimized, but the manufacturing precision requirements increase
Solution Approach 1:
The flexible circuit board is pre-formed with specific fold geometries and orientations during manufacturing. The first fold is configured to create a perpendicular relationship with the light guide plate, and the second fold is pre-shaped to direct the signal transmission section along the side edge, ensuring proper alignment before assembly.
Solution Approach 2:
Different sections of the flexible circuit board have different local geometries and orientations optimized for their specific functions. The light source section extends along the light entrance edge, the connection section has specific fold configurations, and the signal transmission section extends along the side edge, with each local region optimized for minimal interference and proper signal transmission.
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 design minimizes the influence of signal wiring on the sensing operation of the electromagnetic touch panel, reducing interference and maintaining the module's overall width and area, thereby enhancing touch sensing performance.
Implementation Method 1
The backlight module includes a light guide plate and a light source module
Data Source
AI summary
A display device includes a display panel, an electromagnetic touch panel, and a backlight module overlapping one another. The backlight module has a light guide plate and a light source module consisting of a flexible circuit board strip. The flexible circuit board strip includes a light source section and a signal transmission section extending along a light entrance edge and a side edge adjacent to the light entrance edge of the light guide plate, respectively. Two ends of a connection section are connected to the light source section and the signal transmission section, respectively. The connection section includes at least one first fold making the light source disposing plane of the light source section and the wiring disposing plane of the signal transmission section be non-coplanar and also makes the wiring disposing plane be parallel to the plane of the side edge of the light guide plate.