Dual Backlight Module for Switchable Privacy Viewing Angles
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Solution Overview
Problem
Existing display devices face challenges in efficiently switching between wide and narrow viewing angles without increasing manufacturing costs or reducing brightness, especially in scenarios requiring privacy protection.
Innovation Solution
A backlight module with dual backlight units, where the upper unit operates in narrow viewing mode when activated alone and wide viewing mode when both units are on, utilizing asymmetric light control structures and prism sheets to manage light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a privacy filter is added on the outermost layer to achieve narrow viewing angle, then privacy mode is achieved, but brightness is noticeably reduced
Solution Approach 1:
The backlight module is divided into two independent backlight units (first and second) that can operate separately or together. By controlling which unit is active, the system switches between narrow and wide viewing angle modes without using traditional privacy filters, thereby avoiding brightness reduction.
Solution Approach 2:
The system dynamically switches between different backlight units based on the required viewing angle mode. The controller activates only the first backlight unit for narrow viewing angle (privacy mode) or both units for wide viewing angle (sharing mode), enabling adaptive viewing angle control without static filters.
2Adaptability or versatility
If an active dedicated display panel is used for each viewing angle mode to achieve viewing angle switching, then viewing angle control is achieved, but manufacturing cost increases
Solution Approach 1:
A single display device is designed to perform multiple functions (narrow viewing angle and wide viewing angle modes) using a shared display panel and controller. The backlight module's dual-unit design enables the same hardware to adapt to different viewing requirements, eliminating the need for multiple dedicated panels.
Solution Approach 2:
The system changes the operational parameters of the backlight module by selectively activating different backlight units. This parameter change (which units are on) achieves viewing angle switching without requiring physical hardware changes or multiple specialized panels, reducing manufacturing complexity.
3Adaptability or versatility
If traditional privacy filters are used to achieve narrow viewing angle, then privacy protection is achieved, but the solution is complex and reduces brightness
Solution Approach 1:
The invention extracts the viewing angle control function from the display panel and relocates it to the backlight module. By placing the viewing angle control mechanism in the backlight unit rather than adding filters to the display stack, the overall system complexity is reduced while maintaining privacy functionality.
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 active switching between narrow and wide viewing angles without additional filters or specialized panels, maintaining brightness and reducing manufacturing costs.
Implementation Method 1
a first prism sheet positioned on a light-exiting side of the upper light guide plate. The first prism sheet includes a plurality of first prisms arranged along a first direction
Implementation Method 2
a plurality of light control structures disposed on the bottom surface. Each of the light control structures having an light receiving surface directed toward the incident surface
Data Source
AI summary
A backlight module comprising an upper backlight unit, and a lower backlight unit positioned beneath the upper backlight unit. The upper backlight unit includes an upper light source, an upper light guide plate for receiving light emitted from the upper light source, and a first prism sheet located on the light-emitting side of the upper light guide plate. The first prism sheet includes multiple first prisms arranged along a first direction, where the first prisms extend along a second direction, and their tips are oriented towards the upper light guide plate. The upper light source includes multiple light-emitting elements arranged along the second direction. When both the upper and lower backlight units are turned on, it operates in a wide viewing mode, and when the upper backlight unit is turned on while the lower backlight unit is turned off, it operates in a narrow viewing mode, thereby providing a switching function between the wide viewing angle mode and the narrow viewing angle mode for the backlight module. The invention also provides a display device including the backlight module.