Ambient Light Sensor Charge Pump Control for Under-Display Measurement
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Solution Overview
Problem
Existing electronic devices with ambient light sensors face challenges in accurately distinguishing between ambient light and screen-emitted light when the sensor is positioned under the screen without a dedicated opening, leading to difficulties in precise light measurement.
Innovation Solution
The method involves controlling the screen to alternate between light-emitting and non-emitting phases, with a charge pump precharging the ambient light sensor, specifically a Single Photon Avalanche Diode (SPAD), during the light-emitting phases to enable accurate measurement during the non-emitting phases, using a control circuit to manage the charge pump and sensor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ambient light sensor is positioned under the screen without a dedicated opening, then the device structure is simplified and the screen can be fully protective, but the sensor cannot distinguish with precision between ambient light and screen-emitted light
Solution Approach 1:
The screen is controlled to alternate periodically between a first phase (light emission) and a second phase (no light emission). The ambient light sensor measures ambient light during the second phase when the screen is not emitting light, eliminating interference from screen light and enabling precise measurements without dedicated sensor openings.
Solution Approach 2:
The charge pump is precharged during the first phase (screen light emission phase) before the second phase begins. This preliminary charging ensures the sensor is ready for immediate operation during the measurement phase, eliminating measurement delays and ensuring accurate readings start immediately when the screen turns off.
2Reliability
If the charge pump is continuously active to power the SPAD sensor, then the sensor is always ready for measurement, but energy consumption increases
Solution Approach 1:
The charge pump operates periodically, charging during the first phase (screen light emission) and remaining active during the second phase (measurement phase). This periodic operation pattern ensures the sensor is charged and ready for measurement while minimizing continuous energy consumption compared to constant operation.
Solution Approach 2:
The charge pump performs preliminary charging during the first phase before the measurement phase begins. This ensures the sensor has sufficient charge for immediate operation during the second phase without requiring continuous pumping, reducing overall energy consumption while maintaining sensor readiness.
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 precise measurement of ambient light during the screen's non-emitting phases, enabling accurate light power adjustment and energy savings, while allowing the sensor to be placed under the screen without a dedicated opening, enhancing the device's functionality and battery life.
Implementation Method 1
an ambient light sensor, comprising at least a SPAD powered by a charge pump
Implementation Method 2
Single Photon Avalanche Diode (SPAD)
Implementation Method 3
precharging a charge pump of an ambient light sensor during the first phases
Data Source
AI summary
An embodiment method of command of an electronic device comprises controlling a screen to alternate periodically between a first phase in which the screen emits light and a second phase in which no light is emitted by the screen, and precharging a charge pump of an ambient light sensor during the first phases, the ambient light sensor comprising at least a single photon avalanche diode powered by the charge pump.