LED Backlight Light Shielding Pattern for Color Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of LEDs as backlight sources in video display devices leads to color unevenness due to light reflection and re-excitation of phosphors, causing chromaticity changes near the LED, which existing solutions have not adequately addressed.
Innovation Solution
A lighting device configuration using an LED with a light shielding pattern comprising multiple layers of light shielding layers, including white ink and mixed ink of white and blue, and optionally blue and black, to reduce light intensity and chromaticity changes, combined with a prism for improved luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light shielding layer is provided on the optical element to reduce luminance unevenness, then the luminance uniformity is improved, but the chromaticity changes due to light reflection and re-excitation of phosphor cause color unevenness
Solution Approach 1:
The light shielding layer is divided into multiple layers with different optical properties. The first light shielding layer (closer to LED) has high light shielding performance to control chromaticity, while the second light shielding layer (closer to optical element) has lower light shielding performance to maintain luminance uniformity. This segmentation allows each layer to address specific aspects of the problem independently.
Solution Approach 2:
Different regions of the optical element receive different treatments. The light shielding layers are positioned specifically at locations where chromaticity control is most critical (near the LED), while other regions maintain higher light transmission for luminance uniformity. The ink compositions are also varied locally to achieve optimal color control in different zones.
2Object-affected harmful factors
If a light shielding layer is provided to suppress color unevenness, then the chromaticity uniformity is improved, but the light utilization efficiency decreases
Solution Approach 1:
Instead of using a single thick light shielding layer that would block all light, the invention uses multiple thinner layers with progressively decreasing shielding strength. The first layer provides necessary chromaticity control, while subsequent layers provide gradual attenuation, allowing sufficient light to pass through and maintain efficiency while still achieving color uniformity.
Solution Approach 2:
The invention changes the optical parameters of the light shielding layers by using different ink compositions and concentrations. The first layer uses ink with higher light shielding capability for chromaticity control, while subsequent layers use ink with lower shielding capability to allow more light transmission, thus balancing color control with light utilization efficiency.
3Object-affected harmful factors
If multiple light shielding layers are provided with different ink compositions, then the color uniformity is improved, but the device complexity increases
Solution Approach 1:
Multiple light shielding layers with different functions are merged into a single integrated structure on the optical element. The different ink compositions and shielding characteristics are combined in a stacked arrangement, allowing the system to achieve complex color control functionality while maintaining a relatively simple overall structure that can be manufactured as a single component.
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 effectively suppresses color unevenness and improves light utilization efficiency, resulting in enhanced spatial luminance and color uniformity, enabling high-quality image display.
Implementation Method 1
configuring the light shielding layer on the optical element side of the light shielding layers by white ink, and configuring at least one of the other light shielding layers by, for example, mixed ink of white and blue or a mixed ink of white, blue, and black
Implementation Method 2
the light emitted from the LED is reflected on a surface of the light shielding layer, and is made incident again onto the phosphor of the LED
Implementation Method 3
The light emitting diode (LED) that is generally used as a light source of a backlight device emits light having a desired wavelength by exciting a phosphor
Implementation Method 4
in order to further improve the luminance unevenness, a prism may be provided on the LED side of optical element
Data Source
AI summary
A lighting device has a reflection sheet; an LED having an optical element arranged at a predetermined distant position away from the reflection sheet and being used for emitting light in a direction in parallel with a light emitting surface of the lighting device in a space between the reflection sheet and the optical element; and an optical sheet provided on the light emitting surface side of the optical element. A light shielding pattern is provided at a position corresponding to the LED on the light emitting surface side of the optical element, and the light shielding pattern is configured by stacking a plurality of light shielding layers in which the light shielding layer positioned closest to the optical element side is made of a white ink, and in which at least one of the other light shielding layers is made of a mixed color ink.