Flexible PCB Thickness Reduction for Sidelight Illumination
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Solution Overview
Problem
Conventional sidelight-type spread illuminating apparatuses face issues with light leakage and misassembly due to the deterioration of fixing means for flexible printed circuit boards, leading to hot spots and reduced brightness uniformity, especially in thin designs where environmental factors cause peeling off and displacement of LEDs relative to the light guiding plate.
Innovation Solution
The apparatus incorporates a flexible printed circuit board with a bent portion that includes a thickness-reduced section at the front end, which is fixed to an inclined face on the light guiding plate, reducing the reaction force of bending and preventing peeling off, while also ensuring the optical sheets overlap the thickness-reduced portion to inhibit hot spots and improve assembly by reducing the likelihood of optical sheet displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the flexible printed circuit board is bent to place the bent portion along the inclined face of the light guiding plate, then light leakage from the inclined face is inhibited, but the fixing means deteriorates due to environmental factors causing peeling off through reaction force of bending
Solution Approach 1:
The flexible printed circuit board is designed with a thickness-reduced portion at the bent portion, creating local structural differentiation. This allows the bent portion to have reduced reaction force while maintaining the light-blocking function along the inclined face, preventing both light leakage and peeling off
2Object-generated harmful factors
If the ends of optical sheets are layered on the bent portion of the flexible printed circuit board, then hot spots are inhibited, but misassembly occurs as the optical sheets override the housing frame
Solution Approach 1:
The thickness-reduced portion of the flexible printed circuit board creates a localized low-profile area that allows optical sheets to be positioned correctly. The reduced thickness prevents the optical sheets from overriding the housing frame while maintaining sufficient coverage to inhibit hot spots
3Length of moving object
If the light guiding plate has an inclined face to reduce thickness, then the apparatus becomes thinner, but the bent portion of the flexible printed circuit board causes displacement of LED relative to the light guiding plate
Solution Approach 1:
The thickness-reduced portion is strategically positioned at the bent area of the flexible printed circuit board, providing a stable mounting surface that prevents LED displacement while allowing the overall apparatus to maintain a thin profile through the inclined face design
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 configuration stabilizes the fixation of the flexible printed circuit board, prevents light leakage and hot spots, maintains brightness uniformity, and simplifies assembly by reducing the risk of optical sheet override on the housing frame, thereby achieving excellent luminance properties and ease of assembly in slim designs.
Implementation Method 1
a light guiding plate (11) for planarly outputting light emitted from the LEDs (22)
Implementation Method 2
the light guiding plate has an inclined portion (31) between the light incident face and the light output portion, the inclined portion having an inclined face (16)
Implementation Method 3
a diffusing sheet (17) and a prism sheet (18, 19) placed on the light output face (12) of the light guiding plate (11)
Implementation Method 4
prism sheet (18, 19) placed on the light output face (12) of the light guiding plate (11)
Data Source
AI summary
A spread illuminating apparatus includes a light source, a flexible printed circuit board, and a light guiding plate. The light guiding plate has a light incident face, and a light output portion planarly outputting light. The light guiding plate has an inclined portion between the light incident face and the light output portion, the inclined portion having an inclined face gradually reducing in thickness from the light incident face toward the light output portion; the flexible printed circuit board is placed on the light guiding plate from the side of the inclined face, and has a mounting portion mounting the light source, and a bent portion bent to the mounting portion and fixed to the inclined face of the inclined portion, and the bent portion includes a thickness reduced portion having a thickness less than the mounting portion.