Mode-Switchable Backlight for Privacy and Public Display Modes
Solution Overview
Problem
Passive displays lack the ability to emit light, limiting their use in practical applications, and often require an external light source to function as active displays.
Innovation Solution
A mode-switchable backlight system that emits narrow-angle light in a privacy mode and broad-angle light in a public mode, achieved by combining narrow-angle emitters and bidirectional emitters, allowing for adjustable illumination zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single backlight system is used, then the display can provide either narrow-angle or broad-angle illumination, but it cannot provide both privacy protection and public visibility simultaneously
Solution Approach 1:
The backlight system is segmented into two independent subsystems: a first directional backlight with narrow-angle emitters for privacy mode, and a second directional backlight with bidirectional emitters for public mode. Each subsystem operates independently and can be controlled separately, allowing the display to switch between privacy-protected and publicly visible modes without requiring a completely complex integrated system.
Solution Approach 2:
The display system achieves multi-functionality by integrating both directional backlight types that can operate in different modes. The same display panel can function as a privacy display when the first backlight is active, and as a public display when the second backlight is active, making the system adaptable to different usage scenarios without requiring separate display devices.
2Object-affected harmful factors
If narrow-angle emitters are used, then privacy protection is achieved with restricted view zone, but broad-angle illumination and public visibility are lost
Solution Approach 1:
The system dynamically adjusts the viewing angle coverage by switching between two backlight configurations. When privacy protection is needed, the narrow-angle emitters provide restricted illumination to specific viewing zones. When public visibility is needed, the bidirectional emitters expand the illumination coverage to broader angles. This dynamic switching allows the system to adapt illumination characteristics to different operational requirements.
3Illumination intensity
If bidirectional emitters are used, then broad-angle illumination is achieved for public visibility, but privacy protection and restricted view zone capability are lost
Solution Approach 1:
The backlight system is divided into separate functional segments: bidirectional emitters for public mode illumination and narrow-angle emitters for privacy mode illumination. This segmentation allows each emitter type to optimize its performance for its intended purpose without compromise, while the system as a whole gains the ability to switch between contrasting functional states.
4Illumination intensity
If an external light source is added to a passive display, then the display can emit light and function as an active display, but the inherent low power consumption advantage of passive displays is reduced
Solution Approach 1:
The system manages power consumption by changing operational parameters - specifically, by selectively activating only the required backlight subsystem based on the desired display mode. When privacy mode is needed, only the first directional backlight with narrow-angle emitters is activated, consuming less power. When public mode is needed, the second directional backlight with bidirectional emitters is activated. This parameter-based control optimizes energy usage according to functional requirements.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4B
AI summary
A mode-switchable backlight and privacy display provide narrow-angle emitted light during a first mode and broad-angle emitted light in a second mode, the broad-angle emitted light being a combination of the narrow-angle emitted light and bidirectional emitted light. The mode-switchable backlight includes a first directional backlight and a second directional backlight. The first directional backlight includes an array of narrow-angle emitters configured to provide the narrow-angle emitted light during both of the first mode and second mode, while the second directional backlight includes an array of bidirectional emitters configured to provide the bidirectional emitted light exclusively during the second mode. The mode-switchable privacy display includes an array of light valves configured to modulate the narrow-angle emitted light during the first mode and to modulate broad-angle emitted light during the second mode.