Curved Reflection Member for Uniform LED Illumination
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Solution Overview
Problem
The surface light source device described in existing technologies often forms a bright line at the central portion of the light emitting area due to non-optimized reflection member shapes, leading to luminance unevenness.
Innovation Solution
The surface light source device features a cavity with a reflection member that has a curved surface including a ridge line, where the distance and emission angle relationships of light beams are carefully managed to prevent sudden changes in illuminance, ensuring uniform light distribution across the light-emitting planar member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional reflection member with non-optimized shape is used, then the device structure is simple, but a bright line is formed at the central portion of the light emitting area causing luminance unevenness
Solution Approach 1:
The reflection member is designed with a curved surface instead of a flat or simple inclined surface. The curved surface includes a ridge line that extends in the row direction, creating a three-dimensional reflective geometry that distributes light more uniformly across the light emitting area, preventing bright line formation at the center.
Solution Approach 2:
Different regions of the reflection member have different reflective properties. The ridge line portion and the side portions are designed with specific curvature radii to control light reflection angles locally, ensuring that light from LEDs is distributed uniformly across the entire light emitting area rather than concentrating at the center.
2Illumination intensity
If the reflection member has a curved surface with ridge line, then luminance uniformity is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention specifies particular ranges for curvature radii (R1 for the ridge line, R2 for the side surfaces) to optimize both optical performance and manufacturability. By defining specific parameter ranges rather than complex free-form surfaces, the design balances optical performance with ease of manufacturing using conventional molding or machining techniques.
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 effectively prevents the formation of bright lines and reduces luminance unevenness, achieving more uniform illumination compared to conventional devices.
Implementation Method 1
light flux controlling member that controls a distribution of light emitted from the light emitting element
Implementation Method 2
light emitted from the light emitting device is reflected toward the light emitting area
Implementation Method 3
a distance between a position where a light beam having been emitted from the light emitting device at emission angle θ and having been specularly reflected once at the reflection member reached the light-emitting planar member
Implementation Method 4
a light-emitting planar member that has a light diffusing property and optical transparency and forms the light emitting area
Data Source
AI summary
This surface light source device has; a case; multiple light-emitting devices arranged on the inner surfaces of a pair of side walls within the case; a reflecting member that protrudes from the base surface of the case, and that reflects light emitted from the light-emitting devices toward an aperture part of the case; and a light-emitting surface member that has a light-diffusing property and a light-transmitting property, and that covers the aperture part. The light-emitting devices are arranged on the side walls such that the light axis of the light-emitting elements is parallel to the base surface of the case. The light-reflecting member has a ridge line that is parallel to the side surfaces and the ceiling surface of the case, and the light-reflecting member is formed with a curved surface, with the ridge line being contained in the apex thereof.