Under-Display Ambient Light Sensor Leakage Rejection
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Solution Overview
Problem
Under-display ambient light sensors in electronic devices face noise interference from leakage light emitted by OLED pixels, even during display blanking times, due to capacitance-like discharging effects, which affects the accuracy of ambient light measurements.
Innovation Solution
The implementation of a look-up table and an ambient light calculating formula that accounts for various operating conditions, including refresh rates and display luminosities, to reject leakage light by pre-calculating leakage light ratios and applying them to ambient light calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If under-display ambient light sensors are used to measure ambient light, then the device integration is improved and screen real estate is maximized, but measurement precision deteriorates due to noise interference from OLED pixel leakage light
Solution Approach 1:
The patent segments the ambient light measurement process into two distinct phases: a first measurement taken when pixels are in a first state (emitting light) and a second measurement taken when pixels are in a second state (not emitting light). By separating the measurements based on pixel states and subsequently processing them to eliminate leakage light effects, the system achieves both integrated display design and precise ambient light sensing.
2Measurement precision
If display blanking time is used to reduce leakage light interference, then measurement precision is improved, but productivity deteriorates due to additional processing requirements
Solution Approach 1:
The patent performs preliminary actions by taking a first ambient light measurement during a blanking time when pixels are not emitting light, before the display normally becomes active. This preliminary measurement captures the baseline leakage light level, which is then used to correct subsequent measurements taken when pixels are actively emitting light, thereby improving precision without significantly impacting overall processing efficiency.
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 effectively minimizes noise in ambient light measurements by accurately distinguishing and rejecting leakage light, thereby enhancing the precision of ambient light sensing and improving the overall performance of under-display sensors.
Implementation Method 1
each of the pixel circuits include an organic light-emitting diode (OLED) configured to illuminate
Data Source
AI summary
This document describes systems and directed at rejecting display leakage light in under-display sensors. In aspects, an ambient light sensor of an electronic device rejects leakage light originating from pixels in a display using a look-up table and an ambient light calculating formula. In implementations, the look-up table is developed based on a variety of operating conditions that the electronic device may experience, including variable refresh rates and display luminosities. The look-up table includes pre-calculated values of a leakage light ratio, for given operating conditions, that can be used to reject leakage light originating from displays by computing the ambient light calculating formula.