Wide-Angle Lens LED Light-Emitting Device for Thin Backlight Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The direct under type light-emitting device for large-sized liquid crystal displays, when applied to medium/small-sized displays, results in an increased number of LEDs and thickness, similar to or exceeding that of side edge type light-emitting devices.
Innovation Solution
A light-emitting device design incorporating a wide-angle lens and a TIR Fresnel lens, where the wide-angle lens converts Lambertian light into a wide-angle distribution, allowing for increased LED pitch and reduced number, and the TIR Fresnel lens controls directivity, thereby reducing the device's thickness and LED count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a directly under type light-emitting device is applied to medium/small-sized liquid crystal displays, then the light emission area is sufficient, but the number of LEDs increases and the thickness becomes greater than that of side edge type light-emitting devices
Solution Approach 1:
The patent changes the optical parameters by introducing a wide-angle lens with a half-value angle of 60 degrees or more, transforming the light distribution pattern from conventional narrow-angle to wide-angle, thereby reducing the number of LEDs needed while maintaining sufficient light emission area
Solution Approach 2:
The patent introduces a wide-angle lens as an intermediary optical element between the LED and the display panel, which mediates the light propagation by expanding the light angle and improving light utilization efficiency, thus resolving the contradiction between emission area and thickness
2Area of stationary object
If a directly under type light-emitting device is applied to medium/small-sized liquid crystal displays, then the light emission area is sufficient, but the number of LEDs exceeds that of side edge type light-emitting devices
Solution Approach 1:
The patent changes the light distribution parameter by using a wide-angle lens with a half-value angle of 60 degrees or more, which increases the light propagation angle and improves the coverage area per LED, thereby reducing the total number of LEDs required
Solution Approach 2:
The patent applies local quality optimization by positioning the wide-angle lens directly over each LED to create a focused wide-angle light distribution pattern, maximizing the light emission efficiency in the display area while minimizing the number of LEDs needed
3Quantity of substance
If a wide-angle lens is used to convert Lambertian light into wide-angle distribution, then the LED pitch can be increased and number reduced, but the device complexity increases due to additional optical elements
Solution Approach 1:
The patent merges the wide-angle lens function with the existing optical stack by integrating it into the light guide plate structure, combining multiple optical functions into a unified design that reduces overall device complexity despite adding optical elements
Solution Approach 2:
The wide-angle lens serves multiple functions simultaneously: it converts Lambertian light to wide-angle distribution, acts as a light guide, and provides structural support, thereby reducing the need for separate components and minimizing device 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 enables the direct under type light-emitting device to match the thickness and LED count of side edge type devices, even in medium/small-sized displays, while maintaining efficient light distribution and reducing hot spots.
Implementation Method 1
a first reflection surface having a concave shape, arranged above the first incidence surface, and totally reflecting light laterally that enters from the LED via the first incidence surface
Implementation Method 2
a plurality of second reflection surfaces arranged alternately with the plurality of second incidence surfaces and totally reflecting light upward that enters the plurality of second incidence surfaces
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A light-emitting device has an LED, a first optical element placed so as to cover the LED, and a second optical element placed so as to cover the first optical element. The first optical element has: a first incident surface on which light emitted from the LED is made incident; a first reflecting surface having a recessed shape and placed above the first incident surface, the first reflecting surface fully reflecting to the side the light made incident via the first incident surface from the LED; and a first emitting surface placed across the periphery of the first reflecting surface, the first emitting surface emitting the light reflected by the first reflecting surface. The second optical element has: an incident-reflecting surface formed by, placed in concentric circle form, a plurality of second incident surfaces on which light emitted from the first emitting surface is made incident, and a plurality of second reflecting surfaces placed alternately with the plurality of second incident surfaces, that fully reflect upward the light made incident on the plurality of second incident surfaces; and a second emitting surface that is placed above the incident-reflecting surface, and that emits light reflected by the plurality of second light reflecting surfaces.