Ambient Light Sensor Synchronization With Display Refresh Cycles
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Solution Overview
Problem
Conventional ambient light sensing systems beneath displays, such as in smartphones, face inaccuracies due to light emitted by the display being incident on the sensor, which interferes with ambient light measurements.
Innovation Solution
An ambient light sensing system that utilizes an integrator with values periodically written into memory, synchronized with the display's synchronization signal, alternating between pixel off and pixel on values to isolate and measure ambient light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ambient light sensor is located beneath the display, then the device structure is simplified and the sensor is protected, but the display light interferes with the ambient light measurements causing inaccurate readings
Solution Approach 1:
The patent applies periodic action by synchronizing the sensor integration periods with the display refresh cycles. The sensor integrates light during specific time windows that correspond to when display pixels are turned off, allowing periodic measurement of ambient light without continuous interference from display emission. This temporal synchronization enables accurate ambient light detection while maintaining the simplified beneath-display structure.
Solution Approach 2:
The patent uses preliminary action by pre-synchronizing the sensor integration timing with the display refresh signal. Before actual ambient light measurement begins, the system establishes a synchronized timing relationship where the sensor knows exactly when the display will be off, allowing it to prepare and integrate during those predetermined intervals. This advance timing coordination eliminates measurement errors from display light interference.
2Speed
If the sensor continuously integrates light to capture ambient light variations, then the measurement responsiveness is improved, but the display light contamination increases the measurement error
Solution Approach 1:
The sensor performs continuous periodic integration synchronized with display refresh cycles, integrating during each off-period of the display. This maintains high responsiveness by continuously sampling ambient light at regular intervals while ensuring each integration period occurs only when the display is off, thereby maintaining measurement precision despite continuous operation.
Solution Approach 2:
The system maintains continuous useful action by continuously synchronizing sensor integration with display refresh signals. Rather than intermittently measuring, the sensor continuously integrates ambient light during each display off-period, ensuring uninterrupted ambient light monitoring while the synchronization mechanism continuously eliminates display light contamination from measurements.
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 efficient ambient light measurements by distinguishing between ambient light and light emitted by the display, improving the accuracy of light intensity readings.
Implementation Method 1
an optical detector located beneath a display and detector electronics
Data Source
AI summary
The present disclosure provides an ambient light sensing system including an optical detector located beneath a display and a detector electronics. The detector electronics includes an integrator configured to integrate an output from the detector, at least one counter which is connected to the integrator, and a memory which is connected to the integrator. The at least one counter is synchronized to a synchronization signal of the display. The at least one counter causes values to be periodically written from the integrator into the memory.