Switchable Backlight Front Surface Film Privacy
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Solution Overview
Problem
Switchable backlights with different output modes can result in unwanted visibility of the display from outside their designated viewing cones, particularly in privacy applications, due to lack of sharp cutoffs at the boundaries of the viewing cones.
Innovation Solution
A front surface film with a high haze value, typically above 35%, is used to scatter ambient light, reducing visibility from outside the viewing cone by utilizing the diffusing properties to create scattered reflections that dim the light from outside the current output mode, making it difficult to distinguish whether the backlight is on or off, even in bright ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switchable backlight with narrow and wide output modes is used, then different viewing angles are achieved, but unwanted visibility from outside the viewing cone occurs due to lack of sharp cutoff at boundaries
Solution Approach 1:
The front surface film introduces spatially varying optical properties through its haze characteristic (at least 35%). This local quality variation creates sharp cutoffs at the boundaries of viewing cones by selectively scattering light from different angular regions, thereby eliminating unwanted visibility from outside the designated viewing angles while preserving the switchable backlight's adaptability between narrow and wide output modes.
2Object-affected harmful factors
If the viewing cone boundaries are made sharper to eliminate unwanted visibility, then privacy is improved, but the transition between different output modes becomes less smooth
Solution Approach 1:
The front surface film acts as an intermediary optical element between the switchable backlight and the viewer. It mediates the transition between different output modes by providing gradual scattering effects that smooth out abrupt changes in visibility, while simultaneously maintaining sharp cutoffs at the boundaries of viewing cones through its specific haze characteristics, thus resolving the contradiction between privacy and operational smoothness.
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 high haze front surface film effectively eliminates unwanted visibility by utilizing scattered reflections of ambient light, ensuring that viewers within the designated viewing cone can only see light from the intended output mode, thereby enhancing privacy and readability.
Implementation Method 1
a front surface film with a high haze value, typically above 35%, is used to scatter ambient light, reducing visibility from outside the viewing cone by utilizing the diffusing properties to create scattered reflections
Data Source
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AI summary
Displays (100) including switchable backlight (110, 200) and front surface films (120) are disclosed. Displays with switchable backlights (110) that use a front surface film (120) to reduce the visibility of a display outside an intended viewing area (112, 226) in ambient light are also disclosed. The switchable backlight (110, 200) has two different output modes with different viewing cones (112, 114; 226, 236) to limit visibility to different angular ranges.