Light Sensor Measurement Using Display Synchronization Signals
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Solution Overview
Problem
The use of OLED displays in smartphones interferes with light measurements by ambient and proximity sensors, leading to inaccurate readings due to emitted light interference.
Innovation Solution
A method involving periodic synchronization signals from the display to generate timing signals, tracking these signals with a counter, and accumulating light sensor output signals during display blank times to generate a composite output signal, thereby minimizing interference and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If OLED display is used to maximize display size, then display area is improved, but light sensor measurement accuracy deteriorates due to emitted light interference
Solution Approach 1:
The system uses periodic synchronization signals from the display controller to generate timing signals that periodically activate the light sensor during display blanking intervals. This periodic action allows the sensor to measure ambient light only when the display is not emitting light, resolving the interference issue while maintaining the full-area OLED display
Solution Approach 2:
The system performs preliminary synchronization by receiving periodic synchronization signals from the display controller before activating the light sensor. This preliminary action ensures the sensor is activated at the precise moment when the display enters blanking mode, preventing light interference before it can occur
2Measurement precision
If light sensor is activated continuously to improve measurement accuracy, then measurement precision is improved, but interference from OLED display emissions worsens
Solution Approach 1:
Instead of continuous activation, the light sensor is activated periodically only during display blanking intervals. This periodic activation maintains measurement accuracy by capturing ambient light exclusively when the display is dark, while eliminating the harmful interference that would occur during display emission periods
Solution Approach 2:
The system extracts and isolates the measurement function to specific time intervals (blanking periods) when the display is not emitting light. By separating the measurement action from the display emission periods, the system eliminates interference while maintaining measurement capability
3Measurement precision
If light sensor output is accumulated over multiple timing signals to improve accuracy, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The system accumulates light sensor outputs continuously over multiple timing signals during successive display blanking intervals. This continuous accumulation of useful measurement data improves the signal-to-noise ratio and measurement precision while utilizing otherwise wasted blanking periods
Solution Approach 2:
The system performs partial measurements during each blanking interval and accumulates these partial results over multiple intervals. By performing repeated partial measurements rather than a single excessive measurement, the system achieves higher precision without requiring an unacceptably long total measurement time
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 measurement of light sensor output by isolating light sensor readings from OLED display emissions, enhancing the precision of ambient and proximity sensor measurements.
Implementation Method 1
The method includes receiving, via a sensor circuit, periodic synchronization signals from a display of a device
Implementation Method 2
OLED displays include an organic compound that emits light when an electrical current is applied
Data Source
AI summary
A method, an electronic device, and a computer program product for measuring light sensor output in an electronic device. The method includes receiving periodic synchronization signals from a display and generating one or more timing signals based on the received periodic synchronization signals. The method further includes tracking a number of timing signals and in response to each timing signal, recording output signals from a light sensor. The output signals correspond to a light level detected by the light sensor. The method further includes accumulating the recorded output signals over a threshold number of timing signals, The method includes determining if a value of the counter is at least equal to or greater than the threshold number. In response to determining that the value of the counter is at least equal to or greater than the threshold number, generating a composite output signal based on the accumulated recorded output signals.