Edge Light Surface Source Local Dimming via Segmented Guide
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Solution Overview
Problem
Conventional edge light type surface light source devices with local dimming functions tend to become thicker and more complex, while direct light type devices are costly and difficult to make thinner, due to the need for multiple LEDs and complex structures to achieve local dimming.
Innovation Solution
A surface light source device of an edge light type with a simple structure, featuring a light guide with linear convexes and minim convex/concave shapes on its surfaces, paired with linear LED light sources divided into groups for independent light control, a reflective sheet, a prism sheet, and a diffusing sheet, allowing for efficient light distribution and reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LEDs are used in direct light type to achieve local dimming, then local dimming function is improved, but device cost increases and thickness increases
Solution Approach 1:
The light guide plate is divided into multiple light guide regions with different thicknesses, where each region corresponds to a local domain. This segmentation allows different light intensities to be emitted from different regions, achieving local dimming without requiring multiple separate LED light sources.
Solution Approach 2:
The invention transitions from controlling light intensity through multiple discrete LED sources (one-dimensional approach) to controlling light intensity through varying the thickness dimension of the light guide plate itself. By making the light guide plate thickness variable in the vertical dimension, local dimming is achieved more simply.
2Adaptability or versatility
If multiple LEDs are used in direct light type to achieve local dimming, then local dimming function is improved, but device structure becomes complex
Solution Approach 1:
The invention merges the local dimming control function directly into the light guide plate structure itself, rather than requiring separate control systems for multiple LEDs. The variable thickness of the light guide plate integrates both light guidance and intensity control functions into a single component.
Solution Approach 2:
The light guide plate serves multiple functions: it guides light from the LED source, distributes light across the display area, and simultaneously controls the intensity distribution through its variable thickness. This multi-functionality eliminates the need for separate components to achieve local dimming.
3Adaptability or versatility
If space is provided between LCD and LEDs in direct light type, then local dimming is achieved, but device thickness increases
Solution Approach 1:
The light guide plate is segmented into regions of different thicknesses, allowing the structure to achieve local dimming functionality without requiring additional space between the LCD and light source. The thickness variation is achieved within the light guide plate itself.
Solution Approach 2:
The light guide plate is designed as a thin, flexible structure that can vary its thickness locally without requiring significant overall space. This allows the device to maintain a thin profile while still achieving the desired local dimming effect through controlled thickness variations.
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 provides a thin, efficient surface light source with improved visual quality and reduced power consumption, enabling wider angle light emission and reduced overlap in local domains, while maintaining a thin profile and simplifying the structure.
Implementation Method 1
a light guide 2 having a top surface 2s1, a bottom surface 2s2 and a pair of light incident surfaces 2a and 2b
Implementation Method 2
a reflective sheet 3 having a top surface located adjacent the bottom surface 2s2 of the light guide 2
Implementation Method 3
a prism sheet 4 having a top surface 4s1 and a bottom surface 4s2 located adjacent the top surface 2s1 of the light guide 2
Implementation Method 4
a diffusing sheet 5 having a top surface and a bottom surface located adjacent the top surface 4s1 of the prism sheet 4
Data Source
AI summary
A surface light source device having a local dimming function and an LCD unit using the device can include a light guide having a top surface including a plurality of linear convexes and a bottom surface including a plurality of dots. The device can also include a reflective sheet located adjacent the bottom surface, a prism sheet located adjacent the top surface, a diffusing sheet located adjacent the prism sheet, and a pair of LED light sources located adjacent both light incident surfaces of the light guide and divided into a plurality of groups. Each light emitted from the groups can be configured to be emitted independently from a respective one of local domains on a light-emitting surface of the device. Therefore, the disclosed subject matter can provide a surface light source device having a local dimming function with a simple structure as with a conventional edge light type device.