Switchable Light Filter for Privacy Viewing Without Brightness Loss
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Solution Overview
Problem
Existing screen technologies struggle with maintaining privacy by limiting viewing angles while minimizing light loss, complexity, and ensuring high brightness and resolution, particularly in devices like LCDs and vehicle displays.
Innovation Solution
A switchable light filter using dichroitic dyes and liquid crystal layers that adjust light transmission based on direction and polarization, allowing modes with different viewing angles through electric field control, reducing light loss and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If microlouver films are used for visual data protection, then viewing angle limitation is achieved, but light loss increases and mechanical attachment/removal is required
Solution Approach 1:
The patent replaces mechanical microlouver films with an electrically controllable liquid crystal system. The liquid crystal layer can be switched between different states (aligned and non-aligned) using electrical fields, eliminating the need for mechanical attachment and removal of physical films while achieving the same viewing angle limitation effect.
Solution Approach 2:
The patent changes the optical parameters of the light guide by introducing scattering particles that can alter light propagation paths. This allows the system to limit viewing angles through optical parameter modification rather than physical film placement, reducing light loss while maintaining privacy protection.
2Object-affected harmful factors
If microlouver films are used for visual protection, then viewing angle is limited, but device complexity increases due to separate transport and manual placement
Solution Approach 1:
The patent integrates the viewing angle control function directly into the light guide structure through embedded scattering particles and liquid crystal layers. This eliminates the need for separate film components that require manual handling, transport, and placement, significantly reducing device complexity while maintaining visual protection functionality.
Solution Approach 2:
The patent merges the privacy protection function with the light guide structure itself. The scattering particles and liquid crystal layer are integrated within the light guide, combining multiple functions (light guidance, scattering, and viewing angle control) into a single unified structure, thereby eliminating separate components and simplifying the overall device.
3Object-affected harmful factors
If complex backlight systems with multiple light guides and optical elements are used, then viewing angle control is achieved, but light loss increases and implementation cost increases
Solution Approach 1:
The patent combines the light guide and scattering functions into a single integrated structure. By embedding scattering particles directly within the light guide material, the system eliminates the need for separate optical elements and multiple light guides, reducing light loss at each interface while maintaining viewing angle control capability.
Solution Approach 2:
The patent modifies the optical parameters of the light guide by controlling the distribution and concentration of scattering particles. This allows precise adjustment of light propagation characteristics and viewing angles through parameter optimization rather than adding complex optical elements, thereby reducing light loss and implementation cost.
4Object-affected harmful factors
If scattering particles in light guide are used for mode switching, then viewing angle limitation is achieved, but light is decoupled in wrong directions reducing brightness
Solution Approach 1:
The patent introduces a liquid crystal layer as an intermediary between the light guide and the viewer. The liquid crystal molecules can be aligned or non-aligned to control light passage. When aligned, they allow light to pass through maintaining brightness; when non-aligned, they limit viewing angles. This intermediary controls the interaction between scattering particles and light to prevent wrong-direction decoupling.
Solution Approach 2:
The patent optimizes the parameters of scattering particles (size, concentration, distribution) to control light scattering angles. By carefully selecting particle parameters, the system achieves viewing angle limitation while minimizing light loss in wrong directions, thereby maintaining brightness when needed.
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
Enables seamless switching between wide and narrow viewing angles with minimal light loss and high brightness, preserving resolution and reducing visual artifacts.
Implementation Method 1
a liquid crystal layer, which is arranged behind or in front of the first optical element in the viewing direction and onto which the first electric field EF1 or the second electric field EF2 acts and which, as a function thereof, influences the polarization state of light passing through it
Implementation Method 2
at least one first optical element, in turn comprising a plurality of light-absorbing transition dipole moments formed by dichroitic dyes, in the case of which the dye mass fraction is more than 1%, arranged in a layer with a thickness of from 0.2 microns to 50 microns
Data Source
AI summary
Switchable light filters are provided and comprise a first optical element, in turn comprising a plurality of light-absorbing transition dipole moments, so that light, which is incident into the first optical element, is transmitted or at least partially absorbed as a function of its direction of incidence with respect to the first optical element and its polarization state, The filters may comprise optional means for generating a first and/or a second electric fields and a liquid crystal layer, onto which the first and/or second electric fields acts, so that the transmission properties of the filters differ between a first operating mode. Lighting devices and screens comprising the filters are also provided.