Round Light Guide Plate Vibration Stability
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Solution Overview
Problem
The round lighting device experiences uneven brightness due to rotation of the light guide plate caused by vibration, leading to a mismatch in the positional relationship between the reflection pattern and LEDs, resulting in significant differences in brightness.
Innovation Solution
The lighting device incorporates an annular light source with a round light guide plate and a case that restricts rotation through circumferentially aligned portions with parallel or sloped contact surfaces, ensuring the light guide plate remains aligned with the LEDs, reducing impact and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the light guide plate is made round to match the display device shape, then flexibility in design and aesthetic appearance are improved, but the light guide plate becomes susceptible to rotation due to vibration, causing uneven brightness
Solution Approach 1:
The periphery of the light guide plate is segmented into alternating high-density and low-density reflection areas, which are positioned at specific angular intervals (e.g., 0°, 120°, 240°) to create a stable configuration that resists rotation while maintaining uniform light distribution
Solution Approach 2:
Different regions of the light guide plate back surface are given different reflection densities - high-density reflection areas are positioned opposite to LED light entering portions, while low-density areas are positioned between them, creating a non-uniform local structure that achieves global stability
2Illumination intensity
If a reflection pattern is formed on the back surface of the light guide plate to correct brightness unevenness, then light distribution uniformity is improved, but rotation of the light guide plate causes mismatch between the reflection pattern and LEDs, resulting in significant brightness differences
Solution Approach 1:
The reflection pattern intentionally uses asymmetric density distribution - high-density and low-density areas are alternately arranged at specific angular positions rather than being uniformly distributed, creating a configuration that is stable against rotational displacement
Solution Approach 2:
The reflection pattern is pre-configured with high-density areas positioned exactly opposite to where LED light enters the light guide plate, and low-density areas positioned between them, so that the optimal brightness distribution is achieved before any vibration occurs
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 maintains even brightness by preventing rotation of the light guide plate, reducing damage to the LEDs and ensuring consistent light distribution.
Implementation Method 1
The light travels through the light guide plate and exits the light guide plate through a plate surface of the light guide plate facing the liquid crystal panel
Implementation Method 2
a reflection pattern may be formed on a back surface of the light guide plate
Data Source
AI summary
A lighting device includes an annular light source including light sources arranged in a circular pattern, a light guide plate having a round shape in a plan view, and a case holding the annular light source and the light guide plate. The light guide plate is disposed inside the annular light source. The light guide plate includes light entering portions, circumferentially aligned portions, and a light emitting portion. The light entering portions are opposed to the light sources. Each circumferentially aligned portion is between the adjacent light entering portions. A dimension of the circumferentially aligned portion in the radial direction is larger than a dimension of the light entering portion in the radial direction. The circumferentially aligned portions are aligned with the light sources in the circumferential direction and configured to contact the light sources when the light guide plate is rotated in the circumferential direction.