Reflective Layer Structure for Blue Light Reduction in Display Panels
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Solution Overview
Problem
Personal immersive devices, such as VR and AR headsets, face challenges in reducing blue light exposure to users, which can cause eye fatigue and other health issues due to the proximity of the display panel to the eyes, while maintaining high resolution and low power operation.
Innovation Solution
A display panel design featuring a light-emitting element with a reflective layer structure that includes an incident-side metal layer, a reflective-side metal layer, and a transparent intermediate layer, where the incident-side metal layer is thinner than the reflective-side metal layer, and the transparent intermediate layer is optimized to absorb blue light, reducing its transmission and enhancing reflectance for other wavelengths, thereby minimizing blue light exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional single-layer metal reflective layer is used, then the device structure is simple and manufacturing is easy, but blue light is not effectively reduced and causes eye fatigue
Solution Approach 1:
The single-layer metal reflective layer is divided into three distinct layers: an incident-side metal layer, a transparent intermediate layer, and a reflective-side metal layer. This segmentation allows each layer to perform a specific function - the incident-side layer partially reflects and absorbs blue light, the intermediate layer provides optical path difference for wavelength-selective interference, and the reflective-side layer provides strong reflection for visible light. Together they achieve blue light reduction while maintaining overall device simplicity.
Solution Approach 2:
The reflective layer uses a composite structure combining multiple materials with different optical properties. The incident-side metal layer (e.g., aluminum or silver) provides initial reflection, the transparent intermediate layer (e.g., silicon oxide or silicon nitride) provides wavelength-selective optical interference, and the reflective-side metal layer (e.g., aluminum) provides strong reflection. This composite material approach enables selective blue light absorption through optical interference while maintaining high reflectance for other wavelengths.
2Object-affected harmful factors
If the incident-side metal layer is made thinner to reduce blue light, then blue light reduction improves, but light reflectance and luminance decrease
Solution Approach 1:
The patent optimizes the thickness parameters of each layer to achieve the desired balance. The incident-side metal layer is set to 50-450 Å (thin enough to allow blue light transmission for interference), the transparent intermediate layer is set to 50-80 nm or 140-160 nm (optimized for blue light wavelength interference), and the reflective-side metal layer is set to 500-2000 Å (thick enough to provide strong reflection). By precisely controlling these thickness parameters, the structure achieves blue light reduction while maintaining sufficient light reflectance for display luminance.
Solution Approach 2:
The transparent intermediate layer acts as an optical intermediary between the incident-side and reflective-side metal layers. It creates the necessary optical path difference to generate wavelength-selective interference that preferentially absorbs blue light. This intermediary layer enables the thin incident-side metal layer to achieve blue light reduction without sacrificing overall light reflectance, as the interference effect compensates for the reduced metal layer thickness.
3Use of energy by moving object
If a thick reflective layer is used to maintain high reflectance, then light loss is reduced, but blue light reduction capability is compromised
Solution Approach 1:
The reflective layer is segmented into three functional zones that work together to resolve this contradiction. The incident-side metal layer (50-450 Å) is thin enough to allow blue light transmission for interference while providing initial reflection. The transparent intermediate layer (50-80 nm or 140-160 nm) provides wavelength-selective optical interference to absorb blue light. The reflective-side metal layer (500-2000 Å) is thick enough to provide strong reflection for visible light. This segmentation allows the overall structure to maintain high reflectance while effectively reducing blue light.
Solution Approach 2:
The composite structure combines materials with complementary optical properties to simultaneously achieve high reflectance and blue light reduction. The metal layers provide strong reflection across the visible spectrum, while the transparent intermediate layer with optimized thickness provides wavelength-selective interference that preferentially absorbs blue light. This composite material approach allows the reflective layer to maintain high overall reflectance while selectively filtering blue light.
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 reduces blue light exposure to the user's eyes without degrading image quality, while also reducing light loss and leakage current, thus enabling low-power operation and preventing degradation of the light-emitting element.
Implementation Method 1
the transparent intermediate layer is optimized to absorb blue light, reducing its transmission and enhancing reflectance for other wavelengths
Implementation Method 2
a reflective-side metal layer from which the light is reflected
Data Source
AI summary
A display panel and a personal immersive device including the same are disclosed. In the display panel, any one of a first electrode and a second electrode of a light-emitting element includes: an incident-side metal layer on which light is incident; a reflective-side metal layer from which the light is reflected; and a transparent intermediate layer interposed between the incident-side metal layer and the reflective-side metal layer.