TOF Image Sensor Pixel Layout With Peripheral Noise Blocking
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Solution Overview
Problem
Image sensing devices face challenges in accurately capturing three-dimensional images due to noise interference in the substrate, which affects the precision of distance measurement using the Time of Flight (TOF) method.
Innovation Solution
The implementation of an image sensing device with a pixel array structure that includes noise blocking structures over the peripheral region of the substrate, allowing incident light to reach the sensing region while shielding noise components, and utilizing a Current-Assisted Photonic Demodulator (CAPD) pixel structure to enhance signal detection and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the substrate area is increased to improve light sensing capability, then the sensing performance is improved, but noise interference from peripheral regions increases
Solution Approach 1:
The substrate is segmented into a central sensing region and peripheral regions. The noise blocking structures are selectively positioned in the peripheral regions to block noise while allowing the central sensing region to maintain full light sensing capability. This segmentation allows the device to benefit from a larger substrate area while preventing noise from peripheral areas from degrading measurement precision.
Solution Approach 2:
Different regions of the substrate are given different functional qualities: the central region maintains high light transmission for sensing, while the peripheral regions incorporate noise blocking structures to filter out noise. This local differentiation in quality allows the substrate to simultaneously achieve large area coverage and low noise levels, improving depth measurement accuracy without sacrificing sensing capability.
2Object-affected harmful factors
If noise blocking structures are added to shield peripheral regions, then noise interference is reduced, but light transmission to the sensing region may be blocked
Solution Approach 1:
The noise blocking function is extracted and isolated to specific peripheral regions of the substrate, separate from the central sensing region. By positioning noise blocking structures only in areas where they will not interfere with light paths to the sensing region, the design achieves noise reduction while preserving full light transmission capability to the active sensing area.
Solution Approach 2:
The noise blocking structures act as intermediary elements positioned between the peripheral regions and the sensing region. These structures selectively block noise signals while allowing light to pass through to the sensing region, serving as a mediator that filters harmful noise without interfering with the useful light transmission needed for imaging.
3Area of stationary object
If the substrate area is increased to improve sensing coverage, then the field of view is expanded, but signal-to-noise ratio deteriorates
Solution Approach 1:
The substrate area is segmented into functional zones: a central sensing region that captures light signals and peripheral regions where noise blocking structures are positioned. This segmentation enables the device to maintain a large overall substrate area for expanded field of view while preventing noise from peripheral areas from degrading the signal-to-noise ratio in the central sensing region.
Solution Approach 2:
Different local regions of the substrate are assigned different functional qualities: the central region optimizes for light reception with high transmission, while peripheral regions incorporate noise blocking features. This local quality differentiation allows the substrate to simultaneously achieve large sensing coverage and high signal-to-noise ratio by treating different areas with different functional characteristics.
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 design improves the accuracy of data sensing by effectively blocking noise and minimizing interference, leading to enhanced precision in capturing depth information and three-dimensional images.
Implementation Method 1
a substrate structured to include a sensing region that generates charge carriers in response to incident light
Implementation Method 2
a lens layer disposed over the substrate to direct incident light toward the substrate in the unit pixel
Implementation Method 3
noise blocking structures being structured to leave space above the sensing region open to allow the incident light from the lens layer to reach the sensing region while shielding a peripheral region of the sensing region in the substrate from the incident light
Data Source
AI summary
An image sensing device is provided to include a pixel array including unit pixels. Each unit pixel includes a substrate including a sensing region that generates charge carriers in response to incident light, first and second signal detectors configured to receive control signals for generating a charge current in the sensing region of the substrate and capture the charge carriers moving by the charge current, a lens layer disposed to direct incident light toward the substrate in the unit pixel, and a noise blocking structures disposed over a peripheral region of the sensing region and underneath the lens and structured to leave space above the sensing region open to allow the incident light from the lens layer to reach the sensing region while shield a peripheral region of the sensing region in the substrate from the incident light.