Backlight Film Reflective Layer Uniformity and Durability
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Solution Overview
Problem
The durability of wavelength conversion films in liquid crystal display devices is compromised due to light and heat from LEDs, leading to deterioration of the quantum dot layer, resulting in insufficient durability and potential color unevenness in the backlight unit.
Innovation Solution
A backlight film is designed with a wavelength conversion film sandwiched by a gas barrier film and featuring a reflective layer with a film thickness distribution of ±5% or less, which reduces the impact of light and heat on the quantum dot layer, ensuring high durability and uniform light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LED and wavelength conversion film are disposed near to each other to increase light utilization efficiency, then the brightness of incident light increases, but the temperature increase and deterioration of the wavelength conversion film due to light and heat increases
Solution Approach 1:
A reflective layer is introduced as an intermediary component between the LED and the wavelength conversion film. This reflective layer reflects incident light back onto the wavelength conversion film, increasing light utilization efficiency while preventing direct heat exposure that causes deterioration. The reflective layer acts as a mediator that separates the harmful thermal effect from the useful optical effect.
Solution Approach 2:
The patent converts the harmful reflected light that would otherwise escape uselessly into a beneficial effect by directing it back onto the wavelength conversion film. The reflective layer transforms wasted light into additional excitation source, improving conversion efficiency while the structured arrangement controls heat exposure to prevent deterioration.
2Productivity
If the LED and wavelength conversion film are disposed near to each other to increase light utilization efficiency, then more light is converted, but color unevenness occurs due to non-uniform light distribution
Solution Approach 1:
The reflective layer serves as an intermediary that redistributes light uniformly across the wavelength conversion film. By reflecting light from specific angles and distributing it evenly, the reflective layer ensures uniform excitation of the quantum dots, eliminating color unevenness while maintaining high conversion efficiency.
Solution Approach 2:
The reflective layer is positioned specifically at the bottom of the wavelength conversion film structure, creating localized light reflection precisely where needed. This targeted approach ensures uniform light distribution across the entire film surface, improving color uniformity while maintaining high overall conversion efficiency.
3Device complexity
If the wavelength conversion film is used without a reflective layer to reduce device complexity, then the structure is simpler, but light utilization efficiency decreases and durability is insufficient
Solution Approach 1:
The reflective layer is designed to perform multiple functions simultaneously: it reflects light back onto the wavelength conversion film to improve efficiency, protects the film from heat deterioration to enhance durability, and contributes to uniform light distribution. This multi-functionality justifies the added structural complexity by delivering multiple benefits from a single component.
4Device complexity
If the wavelength conversion film is used without a reflective layer to reduce device complexity, then manufacturing is easier, but the durability and lifespan are insufficient due to light and heat deterioration
Solution Approach 1:
The reflective layer is positioned in advance to protect the wavelength conversion film from heat and light deterioration before damage occurs. By reflecting harmful radiation back onto the film in a controlled manner, the reflective layer prevents cumulative thermal damage and extends the operational lifespan of the wavelength conversion film.
Solution Approach 2:
The reflective layer acts as a protective intermediary between the heat-generating LED and the sensitive wavelength conversion film. It mediates the thermal interaction by reflecting light in a way that reduces heat accumulation in the film, thereby protecting the film structure and extending its service life.
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 prevents deterioration of the wavelength conversion layer, enhancing the durability and lifespan of the backlight film while maintaining uniform light emission without color unevenness, even when used in close proximity to LEDs.
Implementation Method 1
at least one reflective layer provided on one main surface of the wavelength conversion film
Implementation Method 2
the quantum dot exhibits a 'quantum size effect' in which a state density (energy level) of electrons is discrete. According to this quantum size effect, an absorption wavelength and/or an emitting wavelength of light may be controlled by changing the size of quantum dots.
Implementation Method 3
a wavelength conversion film formed of a quantum dot is known... quantum dots converting first wavelength light from the light sources to second wavelength light
Implementation Method 4
a wavelength conversion film having a wavelength conversion layer and a gas barrier film sandwiching the wavelength conversion layer
Data Source
AI summary
An object of the present invention is to provide a backlight film that uses a wavelength conversion film used for a liquid crystal display or the like, has satisfactory durability, and is able to emit light without color unevenness. The object is achieved by including a wavelength conversion film having a wavelength conversion layer and a gas barrier film that sandwich the wavelength conversion layer; and at least one reflective layer provided on one main surface of the wavelength conversion film and causing a film thickness distribution of the reflective layer to be ±5% or less.