Porous Layer Optical Insulator for Compact Display Assembly
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Solution Overview
Problem
Conventional backlighting devices for display systems are bulky and difficult to integrate into automated industrial production lines due to the need for air layers between components, which complicates housing and modification, leading to increased costs and complexity.
Innovation Solution
The integration of a porous layer as an optical insulator directly on the light guide's surface with structured light extractors, allowing for a monobloc information display assembly that can be mechanically attached without air layers, using a porous layer with a refractive index lower than typical materials, which slightly reduces light extraction efficiency but provides a mechanical interface for assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air layers are used to separate the light guide from the display device and films, then optical losses are prevented and light propagation is maintained, but the assembly becomes bulky and difficult to integrate into automated production lines
Solution Approach 1:
The patent extracts the air layer function (optical isolation) and replaces it with a porous layer that provides the same optical isolation function while enabling direct mechanical attachment. The porous layer is deposited directly on the light guide surface, removing the need for separate air gaps and multiple discrete components.
Solution Approach 2:
The patent uses a porous layer with controlled porosity (30-70%) and refractive index (1.05-1.25) to achieve optical isolation while providing a mechanical interface for attachment. The porous structure creates an optical gradient that prevents light loss while allowing the layer to serve as a bonding substrate.
2Ease of manufacture
If films are glued directly to the light guide, then the assembly becomes more compact and easier to manufacture, but light is expelled from the guide causing losses in luminous flux
Solution Approach 1:
The porous layer serves as an intermediate substrate that allows films to be attached while maintaining optical isolation. The porous structure with refractive index between air and the light guide material prevents abrupt refractive index changes, thereby preventing light expulsion while enabling mechanical attachment.
Solution Approach 2:
The porous layer acts as an intermediary between the light guide and external films, providing a transition zone that maintains optical properties while enabling mechanical bonding. This intermediary layer prevents direct contact between the light guide and films, avoiding light loss while allowing compact assembly.
3Volume of moving object
If a monobloc assembly is created by removing air layers, then the device becomes less bulky and easier to house, but the mechanical interface for attachment must be provided without compromising optical properties
Solution Approach 1:
The porous layer provides both mechanical attachment capability and optical isolation in a single integrated component. The porous structure allows for bonding while maintaining the refractive index gradient needed for optical isolation, eliminating the need for separate mechanical and optical components.
Solution Approach 2:
The porous layer performs multiple functions simultaneously: it provides optical isolation, serves as a mechanical attachment substrate, and enables compact monobloc assembly. This multi-functional layer eliminates the need for separate components for each function, reducing overall assembly volume and complexity.
4Strength
If the refractive index of the isolation layer is increased to provide better mechanical attachment, then attachment strength improves, but light extraction efficiency decreases due to reduced refractive index contrast
Solution Approach 1:
The patent optimizes the refractive index parameter of the porous layer to be between 1.05 and 1.25, which is higher than air (1.00) for better attachment but lower than typical solid materials for maintained light extraction. The porosity parameter (30-70%) is also optimized to control the effective refractive index while providing mechanical strength.
Solution Approach 2:
The porous structure allows tuning of the effective refractive index by controlling pore size, shape, and distribution. This enables the material to have a refractive index intermediate between air and solid materials, providing both attachment strength and light extraction efficiency simultaneously.
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 approach results in a less bulky, easier-to-handle display assembly that can be integrated into production lines and housed without requiring mold modifications, with the efficiency drop in light extraction compensated by design adjustments and improved light flow, and the porous layer providing a mechanical interface for secure attachment.
Implementation Method 1
a porous layer is obtained from a volume of dielectric material of refractive index N inside which cavities of nanometric dimensions are created so as to obtain an alveolar structure. These cavities are filled with air which has a refractive index n = 1. If the dimension of the cavities is less than the wavelength of the light passing through the porous material, then this porous material will behave with respect to this light as a medium with an average refractive index N1 between the refractive index n of air and refractive index N of dielectric material.
Implementation Method 2
The light inside the guide propagates by total reflection on the inner walls of the guide. The maximum total angle of reflection is the limit angle, with respect to the normal to the surfaces of the guide, beyond which a light ray leaves the guide.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an information display assembly (16) including a transmitting information display device (20) and a backlighting device (18) into which light is fed, the backlighting device (18) being arranged under the information display device (20) relative to a viewer and having an upper surface (24) facing the information display device (20) and a lower surface (38) opposite the upper surface (24), light extractors (22), structured in the upper surface (24) of the backlighting device (18), enabling a portion of the light fed into the backlighting device (18) to be extracted and directing said portion of light toward the information display device (20) so as to illuminate the latter, and a first porous layer (26) being deposited on the upper surface (24) in which the light extractors (22) are structured. The invention also relates to such an information display assembly in which the light extractors are structured in the lower surface of the backlighting device.