Circular Polarization Display for Visible Light Communication
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Solution Overview
Problem
Existing visible light communication systems face challenges in conveying private information without spoiling the aesthetic appearance of public images, particularly when using two-dimensional codes on large displays, as they require synchronization signals and high-speed image processing capabilities, limiting user access and convenience.
Innovation Solution
A communication system that uses circular polarizations to separate and display public and private images on a display apparatus, allowing a receiver with a camera to capture the private image without synchronization signals, using a transmitter that outputs images with different circular polarization senses and a receiver with a ¼ wave plate and polarizing plate to convert and filter the images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-dimensional code is displayed on a large-scale display to convey private information, then information communication capability is improved, but the aesthetic appearance of the public image is spoiled
Solution Approach 1:
The display content is segmented into public image and private information components. The public image is displayed in the background while private information is encoded as a two-dimensional code in a specific region, allowing both to coexist without completely compromising each other's visibility or aesthetic quality.
Solution Approach 2:
The two-dimensional code is placed in a specific local region of the display rather than covering the entire screen. This localized placement allows the code to be visible for information communication while minimizing its impact on the overall aesthetic appearance of the public image.
2Reliability
If secure display technology with light shutter is used to protect private image visibility, then information security is improved, but user accessibility is limited
Solution Approach 1:
A synchronization signal acts as an intermediary between the display apparatus and the mobile terminal. The mobile terminal detects this signal to determine when to capture the private image, eliminating the need for a physical light shutter while maintaining the security principle that only equipped users can access private information.
Solution Approach 2:
The mechanical light shutter system is replaced with an electronic synchronization signal detection system. Instead of requiring users to physically control a shutter, the system uses electromagnetic signals that can be automatically detected by the mobile terminal's camera and processing unit, making the system more accessible and easier to operate.
3Measurement precision
If synchronization signal transmission is implemented to coordinate private image display, then image capture accuracy is improved, but system complexity is increased
Solution Approach 1:
The mobile terminal performs self-service by autonomously detecting the synchronization signal and determining the timing for capturing the private image. The terminal's own camera and processing capabilities are used to detect the signal and execute the capture operation without requiring external control equipment or complex coordination systems.
Solution Approach 2:
The mobile terminal's camera serves multiple functions: it captures both the public image and the private image, detects the synchronization signal, and processes the captured data. This multi-functionality reduces the need for separate specialized equipment, thereby reducing overall system complexity while maintaining capture accuracy.
4Measurement precision
If high-speed image processing is required to extract private image from displayed image, then information extraction accuracy is improved, but device capability requirements are increased
Solution Approach 1:
The synchronization signal is transmitted in advance of the private image display, allowing the mobile terminal to prepare for capture beforehand. This preliminary signaling enables the terminal to start its image processing routines and timing calculations before the actual private image appears, reducing the need for high-speed real-time processing during the critical capture moment.
Solution Approach 2:
The system uses periodic frame display with the private image shown for a specific duration within each frame cycle. This periodic structure allows the mobile terminal to synchronize its capture operation with the known timing pattern, enabling accurate extraction of the private image using standard processing speeds rather than requiring high-speed continuous processing.
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 simple and convenient visible light communication by allowing users to access private information without disrupting the public image's aesthetic appearance, using standard camera capabilities and eliminating the need for synchronization signals or high-speed image processing.
Implementation Method 1
a 1/4 wave plate that converts the circular polarizations of the first image and the synthesized image displayed on the display apparatus into linear polarizations
Implementation Method 2
a polarizing plate that passes through the linear polarization corresponding to the circular polarization of the first image alone
Data Source
AI summary
A transmitter that outputs an image signal for displaying a first image and outputs an image signal of a synthesized image made of the reversal image of the first image and a second image. A display apparatus, based on the image signals output from the transmitter, displays the first image and the synthesized image with circular polarizations having different senses of rotation from each other. A receiver includes a circular polarization selecting and transmitting means that separates the first image and the synthesized image displayed on the display apparatus, based on the sense of rotation of the circular polarization, and selectively allows the images to pass therethrough, so as to be able to photograph the first image displayed on the display apparatus.