Backlighting Unit Phosphor Film Structure for Uniform Color Mixing
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Solution Overview
Problem
Conventional back lighting units using light emitting diodes face limitations in providing sufficient phosphor coverage due to the small size of the light guide plate's side surface, leading to inadequate color reproducibility and light distribution for large-sized display devices.
Innovation Solution
A back lighting unit design featuring a light transmitting plate with phosphor films on both surfaces, allowing light to be incident and exit, and utilizing a reflecting portion under the light emitting diode to enhance light distribution, along with multiple phosphor films arranged in specific configurations to achieve uniform color mixing and light diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a phosphor film is placed on the side surface of a light guide plate, then the light emitting diode can be positioned adjacent to the light guide plate, but the area of the phosphor film is limited due to the narrow side surface, resulting in insufficient phosphor quantity for adequate color mixing
Solution Approach 1:
The patent transitions from placing the phosphor film on the side surface (one-dimensional placement) to placing it on the lower or upper surfaces (two-dimensional placement) of the light transmitting plate. This dimensional change allows the phosphor film to utilize the larger surface area of the plate, providing sufficient phosphor quantity for effective color mixing while maintaining ease of LED positioning.
Solution Approach 2:
The patent segments the light transmitting plate into distinct surfaces (lower surface and upper surface) where phosphor films can be independently placed. This segmentation allows different phosphor films to be positioned at different locations, enabling better light distribution and color mixing across the entire plate area.
2Device complexity
If conventional light mixing methods are used with limited space, then the back lighting unit structure is simplified, but both a diffusing sheet and precise design are essentially required to achieve adequate color mixing
Solution Approach 1:
The patent changes the spatial parameters of the system by providing a larger surface area for phosphor film placement on the light transmitting plate. This parameter change allows sufficient phosphor quantity to be distributed across the surface, enabling effective color mixing without requiring additional diffusing sheets or highly precise design configurations.
3Illumination intensity
If the light transmitting plate allows light to be incident on the lower surface and exit from the upper surface, then uniform brightness can be achieved across large-sized display panels, but the plate thickness and light path design become critical parameters
Solution Approach 1:
The patent introduces the light transmitting plate as an intermediary element between the light emitting diode and the display panel. The plate serves as both a structural support and an optical element that guides light from the lower surface to the upper surface, enabling uniform brightness distribution across large display areas while managing the light path length through its thickness.
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 provides a large-sized display panel with uniform brightness and reduced power consumption by allowing for efficient light mixing and diffusion, enabling better color reproducibility and reduced number of light emitting diodes.
Implementation Method 1
a phosphor film structure including a particulate phosphor and formed on at least one of the lower and upper surfaces of the light transmitting plate to convert the wavelength of light
Implementation Method 2
a reflecting portion disposed under the light emitting diode and reflecting light upwards
Data Source
AI summary
A back lighting unit is disclosed in which lower and upper surfaces of a light transmitting plate function as incident and exit surfaces of light, respectively, and a phosphor film structure for wavelength-converting the light is provided at a position which the light is incident on or exits from. The disclosed back lighting unit includes a light emitting means including a light emitting diode disposed to emit light upwards; a light transmitting plate disposed over the light emitting diode, the light transmitting plate having a lower surface allowing light to be incident thereon and an upper surface allowing light to exit therefrom; and a phosphor film structure including a particulate phosphor and formed on at least one of the lower and upper surfaces of the light transmitting plate.