Proximity Sensor Sliced Integration Time Ambient Light Cancellation
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Solution Overview
Problem
Conventional proximity sensors in cell phones often inaccurately detect the proximity of a user's face due to ambient light interference, leading to unexpected touch screen activations and power consumption issues.
Innovation Solution
A proximity sensor with a sliced integration time sensing mechanism, where the integration time is divided into multiple phase times, allowing the light transmitter to emit sensing light during certain phases and ambient light to be received during others, enabling phase cancellation to isolate the brightness of the sensing light and correct for ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the proximity sensor continuously receives light signals to detect distance, then the detection accuracy is improved, but ambient light interference causes measurement errors
Solution Approach 1:
The integration time is divided into multiple phases (first phase, second phase, third phase) where different operations occur. During the first and third phases, the sensor receives both sensing light and ambient light. During the second phase, only ambient light is received. This temporal segmentation allows the system to separate and eliminate ambient light interference through phase cancellation, thereby improving distance detection accuracy while maintaining continuous monitoring capability.
2Speed
If the light transmitter continuously emits sensing light to maintain detection capability, then the response speed is improved, but energy consumption increases
Solution Approach 1:
The light transmitter operates periodically rather than continuously, emitting sensing light during the first and third phases while remaining inactive during the second phase. This periodic operation maintains detection capability by ensuring sensing light is emitted at regular intervals, enabling the sensor to respond to proximity changes while significantly reducing overall power consumption compared to continuous emission.
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 distance detection between the electronic device and the user's face, preventing unintended touch screen activations and optimizing power usage by effectively eliminating ambient light interference.
Implementation Method 1
The light receiver is disposed in a path along which the sensing light is reflected by the detected object. The light receiver is configured to receive a first light signal formed by the sensing light reflected by the detected object
Implementation Method 2
A first brightness of the first light signal is integrated over the first phase time to form a first integrated brightness value. A second brightness of the second light signal is integrated over the second phase time to form a second integrated brightness value
Implementation Method 3
The light receiver is configured to subtract the second integrated brightness value from the first integrated brightness value to obtain a first integrated brightness correction value by phase cancellation
Data Source
AI summary
A proximity sensor with a sliced integration time sensing mechanism and a sensing method thereof are provided. A light transmitter emits a sensing light toward a detected object during a first phase time. A light receiver receives a first light signal formed by the sensing light reflected by the detected object and an ambient light during the first phase time, and receives a second light signal of the ambient light during a second phase time. A first brightness of the first light signal is integrated over the first phase time to form a first integrated brightness value. A second brightness of the second light signal is integrated over the second phase time to form a second integrated brightness value. The light receiver subtracts the second integrated brightness value from the first integrated brightness value to obtain a first integrated brightness correction value by phase cancellation.