Switchable Optical Element for Privacy Viewing Without Brightness Loss
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Solution Overview
Problem
Existing display technologies struggle with achieving a wide viewing angle for sharing information while also providing privacy by restricting the view to a narrow angle, often resulting in reduced brightness, complex designs, and limited privacy protection.
Innovation Solution
A planar optical element with alternating first and second regions of different refractive indices, allowing light to be switched between free viewing and privacy modes by controlling the propagation directions of light using layers that are opaque or switchable, ensuring minimal brightness reduction and universal applicability across various screens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microlouver films are used for visual privacy, then privacy protection is improved, but light transmission is reduced and the films require manual installation and removal
Solution Approach 1:
The patent replaces mechanical microlouver films with a light guide plate system that uses optical principles (total internal reflection and refraction) to achieve privacy protection. The light guide plate with structured surfaces redirects light paths based on viewing angles, eliminating the need for manual film installation while maintaining privacy functionality.
Solution Approach 2:
The light guide plate acts as an intermediary optical element between the backlight and display panel. It mediates light distribution by controlling emission angles through its structured surfaces, achieving both privacy protection and high light transmission without requiring additional films.
2Ease of operation
If complex optical elements like microlens elements and prism structures are used to reshape light, then viewing angle control is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the light guide plate into different functional zones with distinct surface structures. The front surface has a first structured region for wide-angle light emission, while the rear surface has a second structured region for controlling light entry angles. This segmentation achieves viewing angle control without requiring multiple separate complex optical elements.
Solution Approach 2:
The patent combines multiple optical functions into a single light guide plate component. The plate simultaneously performs light redistribution, viewing angle control, and privacy protection functions that would traditionally require separate microlens arrays, prism structures, and diffusion films, thereby reducing overall device complexity.
3Ease of operation
If complex light conversion processes are used to achieve wide illumination angle, then viewing angle is improved, but brightness is significantly reduced
Solution Approach 1:
The patent applies preliminary light redistribution at the rear surface of the light guide plate before light enters the main body. The second structured region on the rear surface pre-conditions the light paths, ensuring that light is already optimized for wide-angle emission before undergoing further propagation, thereby minimizing brightness loss while achieving wide viewing angles.
Solution Approach 2:
The patent changes the optical parameters (refractive indices, surface structure geometries) of the light guide plate to optimize light extraction efficiency at different angles. By carefully selecting and tuning these parameters, the system achieves wide viewing angles while maintaining high brightness through minimized optical losses.
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 optical element effectively restricts light propagation directions, maintaining high brightness and resolution in both modes, with a top-hat distribution achieving privacy without significant brightness loss, and can be seamlessly integrated with various display technologies.
Implementation Method 1
Light incident on a first large surface of the optical element enters the optical element exclusively through light-entry surfaces of the first regions and, depending on the angle of incidence, polarization and the ratio of the first to the second refractive index, either a) is propagated unhindered or totally reflected within a first region and is subsequently coupled out again at a light-emitting surface of the corresponding first region, or b) penetrates from the first region into an adjacent second region
Implementation Method 2
depending on the angle of incidence, polarization and the ratio of the first to the second refractive index, either a) is propagated unhindered or totally reflected within a first region and is subsequently coupled out again at a light-emitting surface of the corresponding first region
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2~4
AI summary
The invention relates to an optical element (1) which extends in a planar manner with a light inlet side and a light outlet side. The optical element comprises alternating first and second transparent regions (B1, B2) made of materials with different first and second refractive indices (N1, N2), wherein the first refractive index (N1) is greater than the second refractive index (N2). First and second layers (OB, AB) which are opaque or which can be switched to become opaque are arranged on the light inlet and light outlet surfaces of the second regions (B2). The propagation direction of light passing through the optical element (1) is limited when the layers (OB, AB) are opaque in comparison to when the layers (OB, AB) are switched to be transparent.