Backlight Device Lens and Reflection Sheet Angle Optimization
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Solution Overview
Problem
Conventional backlight devices for large-sized liquid crystal displays using light emitting diodes (LEDs) face challenges in achieving uniform brightness while maintaining low costs, as they require a large number of LEDs, increasing costs and complexity.
Innovation Solution
A backlight device design featuring a light source element with a plurality of LEDs and a lens system that spreads light, housed in a diffuser plate and reflection sheet configuration, where the LEDs are arrayed in one or multiple rows at the central zone, with a lens incident surface and exit surface optimized to ensure light distribution within a specific angle range (60°≦θm≦80°) to achieve uniform brightness across the liquid crystal display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitting diodes are arranged to achieve uniform brightness, then brightness uniformity is improved, but device complexity and cost increase
Solution Approach 1:
Multiple LEDs are combined into a single integrated light source element with a unified lens structure. The light source element includes multiple LEDs arranged in one or more rows at the central zone, with a single lens having an incident surface and an exit surface that spreads light from all LEDs together, achieving uniform brightness while reducing component count and complexity
Solution Approach 2:
A diffuser plate is introduced as an intermediary component between the light source element and the liquid crystal display panel. The diffuser plate receives light from the integrated light source element and distributes it uniformly across the display area, achieving brightness uniformity without requiring multiple separate LED sources
2Device complexity
If the output of individual light emitting diodes is increased to reduce the number of LEDs, then device complexity is reduced, but light distribution uniformity deteriorates
Solution Approach 1:
The lens structure is designed with different surface characteristics at different locations. The incident surface receives light from multiple LEDs at the central zone, while the exit surface is configured to spread light uniformly across the entire display area. The diffuser plate also has localized properties that enhance light distribution uniformity, compensating for the higher output of individual LEDs
Solution Approach 2:
The optical parameters of the lens are optimized to achieve uniform light distribution. The lens has a specific angle range (60°≦θm≦80°) for light emission from the exit surface, and the distances between LEDs and lens surfaces are carefully controlled. These parameter adjustments ensure that even with increased individual LED output, the overall light distribution remains uniform
3Illumination intensity
If a large number of light emitting diodes are used, then brightness uniformity is improved, but manufacturing cost increases
Solution Approach 1:
Multiple LEDs are merged into a single integrated light source element with a unified lens structure, reducing the total number of components that need to be manufactured and assembled. This integration simplifies the manufacturing process and reduces costs while maintaining brightness uniformity through the coordinated design of the light source element and diffuser plate
Solution Approach 2:
The light source element serves multiple functions: it houses multiple LEDs, provides a unified lens structure for light collimation, and integrates with the diffuser plate for uniform light distribution. This multi-functionality reduces the need for separate components, simplifying manufacturing and reducing overall system cost
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 allows for a simple, cost-effective backlight device and liquid crystal display apparatus that secures sufficient brightness with a reduced number of LEDs, providing uniform light distribution and minimizing luminance unevenness.
Implementation Method 1
a lens which has an incident surface, which light from the light emitting diodes enters, and an exit surface, from which the light goes out having been spread
Implementation Method 2
a reflection sheet which is configured to reflect light emitted from the light source element, toward the diffuser plate
Implementation Method 3
a diffuser plate which is provided so as to cover an opening in the housing
Data Source
AI summary
Provided is a backlight device having: a light source element having LEDs and a lens expanding light from the LEDs; a housing containing the light source element; a diffuser plate covering an opening portion of the housing; and a reflection sheet reflecting light emitted from the light source element, toward the diffuser plate. The LEDs are arranged in one or more rows, at a central zone. The lens has an incident surface receiving light from the LEDs, and an exit surface from which the light goes out, being expanded. The reflection sheet is configured such that the angle between the optical axis of the lens of the light source element, and a line connecting a light emitting surface of each LED of the light source element and an end portion of the backlight device on the long side thereof is within a range of 60°≦θm≦80°.