Under-Display Ambient Light Sensing with Solid Color Interference Cancellation
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Solution Overview
Problem
Ambient light sensing systems in electronic devices face interference from the display panel's light source, leading to inaccurate brightness readings, especially in rapidly changing light conditions, and the use of black images for sensing can disrupt normal device usage and result in under or overestimation of ambient light levels.
Innovation Solution
Implementing a method that uses multiple light sensing elements under the display screen, with different spectral responses to visible light and display screen emissions, and performing mathematical operations on data collected during solid color and normal image displays to accurately determine ambient light intensity, avoiding interference from the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the ambient light sensing system is disposed under the transparent display screen, then the sensing position is convenient and the display design is comprehensive, but the light source of the display panel interferes with the sensing of ambient light
Solution Approach 1:
The sensing process is segmented into distinct phases: a first sensing phase when the display screen is in a first state (e.g., dark or off) and a second sensing phase when the display screen is in a second state (e.g., bright or on). By separating the sensing operations into different time segments corresponding to different display states, the system can distinguish between light from the display panel and ambient light, thereby resolving the interference problem while maintaining the convenient under-screen sensing position.
2Measurement precision
If black images are used for sensing to avoid display light interference, then the sensing accuracy improves, but the device usage is disrupted and normal operation is affected
Solution Approach 1:
The system employs periodic sensing actions at specific intervals or triggers rather than continuously. The control circuit is configured to perform ambient light sensing at predetermined moments (e.g., during screen transitions, at specific time intervals, or when triggered by certain events) rather than requiring the display to be continuously in a dark state. This periodic approach maintains sensing accuracy while minimizing disruption to normal device usage.
Solution Approach 2:
The system performs preliminary sensing actions by capturing light intensity data during brief moments when the display state changes or at predetermined intervals before normal operation resumes. The control circuit prepares sensing data during these transitional periods and uses it for subsequent ambient light adjustments, thereby achieving accurate sensing without requiring prolonged disruption to device usage.
3Measurement precision
If the sensing time is extended to capture accurate ambient light data, then the measurement precision improves, but the response speed to rapidly changing light conditions decreases
Solution Approach 1:
The system dynamically adjusts the sensing strategy based on detected light conditions. When rapid light changes are detected, the control circuit switches to a faster, less precise sensing mode that captures data more quickly. When light conditions are stable, the system transitions to a longer, more precise sensing mode to improve measurement accuracy. This dynamic adaptation allows the system to optimize the trade-off between response speed and measurement precision according to the actual environmental conditions.
Solution Approach 2:
The control circuit changes sensing parameters such as integration time, gain, and sampling frequency based on the detected ambient light conditions. In rapidly changing light environments, the system reduces integration time and uses higher gain to achieve faster response. In stable lighting conditions, the system increases integration time for more precise measurements. By dynamically changing these sensing parameters, the system achieves both fast response and high precision as needed.
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
This approach allows for accurate and sensitive ambient light sensing, reducing interference from the display panel and providing true ambient light brightness values, even in rapidly changing environments, while minimizing disruption to device usage.
Implementation Method 1
obtain first data of each of the plurality of light sensing elements in response to a current ambient light during the display screen displaying the solid color image; obtaining second data of each of the plurality of the light sensing elements in response to the current ambient light during the display screen displaying a normal image
Data Source
AI summary
A method of sensing ambient light intensity of an ambient in which an electronic device is located, can include: providing a plurality of light sensing elements under a display screen of the electronic device; displaying a solid color image during an operating period of the display screen; obtaining first data of each of the plurality of light sensing elements in response to a current ambient light during the display screen displaying the solid color image; obtaining second data of each of the plurality of light sensing elements in response to the current ambient light during the display screen displaying a normal image; and performing mathematical operations on the first data and the second data to obtain an intensity value of the ambient light of the ambient in which the electronic device is located.