Prism-Sheet Backlight Layout for Switchable Privacy Viewing
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Solution Overview
Problem
Existing display devices with wide-viewing angles face issues in maintaining privacy due to the risk of confidential information leakage, and existing anti-peeping solutions do not provide sufficient brightness control or uniform light emission.
Innovation Solution
A backlight module design featuring a first and second light guide plate with non-parallel light incident surfaces and a prism sheet with prism structures arranged at specific intervals, allowing for switching between sharing and anti-peeping modes by controlling light sources, ensuring uniform light distribution and improved privacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light control film is placed in front of the display panel to achieve anti-peeping effect, then privacy protection is improved, but the display brightness and viewing angle are reduced
Solution Approach 1:
The patent divides the backlight system into multiple light guide plates (first and second light guide plates) with different light incident surfaces, each contributing to light distribution in different directions. This segmentation allows the system to maintain brightness while achieving anti-peeping effect through coordinated light control from multiple sources
Solution Approach 2:
The prism sheet is designed with specific prism structures having controlled spacing widths relative to their structure widths (ratio less than 2). This local structural design creates specific light deflection angles that provide anti-peeping effect in certain directions while maintaining brightness in viewing directions, achieving directional light control
2Adaptability or versatility
If an electrically-controlled diffusion sheet or liquid crystal cell is added to achieve switchable anti-peeping display, then viewing angle switching capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses two light sources (first and second light sources) that can be independently controlled to dynamically switch between sharing mode and anti-peeping mode. By adjusting which light source is active, the display can switch viewing angle characteristics without requiring complex electrically-controlled diffusion sheets or liquid crystal cells
Solution Approach 2:
The first and second light guide plates with non-parallel light incident surfaces serve multiple functions: they provide both wide viewing angle display in sharing mode and anti-peeping effect in private mode. This multi-functionality eliminates the need for separate anti-peeping components, reducing device complexity
3Ease of manufacture
If the spacing width between prism structures is increased, then the manufacturing ease is improved, but the light distribution uniformity deteriorates
Solution Approach 1:
The patent specifies that the ratio of spacing width to structure width of the prism structures should be less than 2. This parameter constraint ensures that the prism structures are densely enough arranged to maintain uniform light distribution across the display, preventing gaps in light coverage while still allowing practical manufacturing
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 achieves uniform light emission and enhanced privacy by maintaining continuous light distribution in sharing mode while effectively reducing visibility in anti-peeping mode, improving visual quality and privacy protection.
Implementation Method 1
The first prism structures are disposed on the substrate surface and are arranged at intervals in a normal direction of the second light incident surface
Data Source
AI summary
A backlight module includes first and second light guide plates, first and second light sources, and a first prism sheet disposed on a side of a second light-emitting surface of the second light guide plate. The first and second light sources are disposed on sides of the first and second light guide plates. The second light guide plate is disposed on a side of a first light-emitting surface of the first light guide plate. First prism structures of the first prism sheet are disposed on a substrate surface of a first substrate facing the second light-emitting surface and are arranged at intervals according a spacing width and have a first structure width in a normal direction of a second light incident surface. A ratio of the spacing width to the first structure width is less than 2. A display device including the backlight module is also provided.