Annular Lighting Device with Reflection Sheet to Block Light Leakage
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Solution Overview
Problem
Conventional circular liquid crystal display devices experience luminance unevenness due to light leakage through exit holes in the casing, leading to dark portions in the display.
Innovation Solution
A lighting device design featuring a light source board with a substantially annular shape and an extended portion that minimizes light leakage by positioning the trace for power supply internally, with a reflection sheet to redirect light and prevent leakage through the exit hole, and a flexible printed circuit board for efficient light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an exit hole is formed in the casing for electrical connection, then power supply to LEDs is enabled, but light leaks through the exit hole causing dark portions in the display
Solution Approach 1:
A light-reflecting member (reflection sheet) is introduced as an intermediary substance to fill and reflect light in the exit hole region. This mediator prevents light leakage while maintaining the electrical connection function, resolving the contradiction between ease of operation and illumination uniformity
Solution Approach 2:
The exit hole, which originally causes harmful light leakage, is converted into a beneficial structure by filling it with a light-reflecting member. The same opening that caused the problem now serves to reflect light back into the light guide plate, improving luminance uniformity while maintaining electrical access
2Illumination intensity
If LEDs are arranged in an annular shape around the light guide plate, then light distribution is improved, but trace routing becomes complex requiring extended board portions
Solution Approach 1:
The trace pattern extends from the two-dimensional annular region into the third dimension by routing traces through the thickness of the light guide plate. This dimensional transition allows complex electrical connections to be achieved without compromising the annular LED arrangement and light distribution
Solution Approach 2:
The board structure is segmented into multiple regions: an annular region for LED mounting, a central region for trace routing, and extended portions for electrical connections. This segmentation allows each region to optimize its function independently, simplifying the overall trace routing complexity
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
The solution effectively reduces luminance unevenness by minimizing light leakage and ensuring consistent light distribution across the display, preventing dark portions and enhancing overall display quality.
Implementation Method 1
a light guide plate 14 having a substantially circular plan view shape and arranged inside the light sources that are arranged in the substantially annular shape
Implementation Method 2
a reflection sheet to redirect light and prevent leakage through the exit hole
Data Source
AI summary
A lighting device includes light sources, a light source board, and a casing. The light source board includes a board body portion having a substantially circular outer edge where the light sources are arranged at intervals in a substantially annular shape such that each light source emits light toward a center, an extended portion extending inward from the board body portion, and a trace portion electrically connected to each light source. The casing includes a tubular-shaped side wall portion surrounding the light sources, and a bottom portion disposed opposite the board body portion and having an exit hole therethrough through which the extended portion is inserted and the distal end of the extended portion is extended outside.