ToF Sensor Diaphragm Structure for Cross-Talk Noise Reduction
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Solution Overview
Problem
Time-of-flight (ToF) sensors in electronic devices experience noise interference due to light reflection from components like cover glass and shielding layers, which degrades their sensitivity and accuracy in measuring distances to external objects.
Innovation Solution
Incorporating a diaphragm structure between the light emitting and receiving parts of the sensor module, which includes a first region to block light reflected from the shielding layer and a second region to block light reflected from the cover glass, thereby reducing noise and improving detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hole size for the ToF sensor is reduced, then the device structure is improved and compactness is enhanced, but the amount of light reflected from components like cover glass and shielding layers increases, causing more noise and deteriorating sensor sensitivity
Solution Approach 1:
A diaphragm structure is introduced as an intermediary component between the light emitting part and receiving part of the ToF sensor. This diaphragm selectively blocks reflected light from components (cover glass, shielding layer) while allowing light reflected from external objects to reach the receiving part, thus resolving the noise problem without requiring a larger hole size
Solution Approach 2:
The diaphragm structure is divided into multiple regions (first region and second region) that separately block light reflected from different components (shielding layer and cover glass). This segmentation allows precise control of light paths from different sources while maintaining a compact hole structure
2Volume of moving object
If the hole size for the ToF sensor is reduced, then the device structure is improved and compactness is enhanced, but the sensitivity of the ToF sensor deteriorates due to increased noise
Solution Approach 1:
The diaphragm acts as a mediator that improves sensor reliability by filtering out noise signals from reflected light while maintaining the compact hole structure. This allows the sensor to maintain high sensitivity despite the reduced hole size
Solution Approach 2:
The diaphragm structure extracts and blocks only the harmful reflected light components from specific sources (shielding layer and cover glass) while allowing the useful light from external objects to pass through, thus maintaining sensor sensitivity in a compact configuration
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
The diaphragm structure effectively blocks unwanted reflected light, enhancing the sensitivity and accuracy of distance measurements by ensuring that most of the light received is from the external object, thus reducing noise and improving detection performance.
Implementation Method 1
part of the light output from the light emitting part may be input to the receiving part after being reflected by a component (e.g., cover glass or shielding layer) other than the external object
Implementation Method 2
a diaphragm structure disposed between the light emitting part and the receiving part and including a first region blocking first reflected light reflected from the shielding layer among the emitted light, and a second region blocking second reflected light reflected from the cover glass among the emitted light
Implementation Method 3
a light emitting part that emits light based on a signal received from the processor
Implementation Method 4
a receiving part to receive the emitted light after being reflected from the external object and returning back
Data Source
AI summary
An electronic device for reducing noise occurring in measuring a distance to an external object is provided. The electronic device includes a cover glass, a rear cover facing the cover glass, a display disposed between the cover glass and the rear cover and having a hole formed in a specified area, a shielding layer disposed between the display and the rear cover and having the hole formed in an area corresponding to the specified area, a sensor module disposed in the hole to measure a distance between the electronic device and an external object, a printed circuit board (PCB) disposed between the shielding layer and the rear cover, and at least one processor disposed on the printed circuit board and operatively connected to the sensor module, wherein the sensor module may include a light emitting part that emits light based on a signal received from the processor, and a receiving part to receive the emitted light after being reflected from the external object and returning back, and a diaphragm structure disposed between the light emitting part and the receiving part and including a first region blocking first reflected light reflected from the shielding layer among the emitted light and a second region blocking second reflected light reflected from the cover glass among the emitted light.