Single Gate Pixel Architecture for High-Resolution Depth Imaging
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Solution Overview
Problem
Current image sensors struggle to obtain high-resolution and high-definition depth images using a single pixel, as they require separate methods for color and depth information, and existing technologies are inefficient in combining these for a unified image representation.
Innovation Solution
A single gate pixel architecture is introduced, comprising a first transfer unit, a second transfer unit, a connection unit, and a reset unit, with an accumulation node configured as a pinned photodiode and a floating diffusion node, allowing for charge transfer and voltage resetting to achieve both color and depth image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pixel is used to capture both color and depth information, then device complexity is reduced, but image quality and resolution deteriorate
Solution Approach 1:
The pixel is segmented into distinct functional regions: a light detector element for depth information and a color filter array for color information. The charge accumulation node separates depth-related charges from color-related charges, allowing independent processing of each type of information without interference, thereby maintaining high depth image quality while using a single pixel structure.
Solution Approach 2:
The accumulation node acts as an intermediary that receives and separates charges from different sources. It selectively accumulates charges from the light detector element (for depth) while excluding charges from the color filter path, enabling the single pixel to simultaneously capture both depth and color information with high precision.
2Measurement precision
If charge accumulation is performed during active time period, then depth image sensitivity is improved, but charge leakage and noise increase
Solution Approach 1:
The pixel employs dynamic control of the accumulation node potential through a reset signal that adjusts the potential based on the operational phase. During the active accumulation period, the potential is optimized for charge collection; during inactive periods, the potential is adjusted to prevent leakage, thereby maintaining high sensitivity while minimizing harmful charge leakage effects.
Solution Approach 2:
The accumulation node operates in periodic cycles: accumulating charges from the light detector during active time periods when depth information is needed, and resetting or holding charges during inactive periods. This periodic operation allows sensitive charge accumulation only when necessary, reducing the window for charge leakage and noise accumulation.
3Productivity
If electric field is applied to transfer charge from light detector to accumulation node, then charge transfer efficiency is improved, but risk of charge loss at node boundaries increases
Solution Approach 1:
The accumulation node is designed with equipotential regions at its boundaries that match the potential of adjacent regions. This equipotential design eliminates potential barriers at node boundaries, allowing charges to transfer smoothly from the light detector to the accumulation node without reflection or loss, thereby maintaining both high transfer efficiency and reliable charge retention.
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 architecture enables the capture of high-resolution and high-definition depth images by efficiently transferring charges and resetting voltages, enhancing the sensitivity and accuracy of depth image acquisition while maintaining a high fill factor.
Implementation Method 1
a light detector element to generate a charge
Data Source
AI summary
A single gate pixel of an image sensor, architecture of the single gate pixel, and an operation method of the single gate pixel may be provided. The single gate pixel includes a first transfer unit to transfer a charge, generated by a light detector element, to an accumulation (ACC) node, a second transfer unit to transfer the charge, accumulated in the ACC node, to a Floating Diffusion (FD) node, a connection unit to connect the light detector element to a driving voltage, and a reset unit to reset a voltage of the FD node based on a reset control signal.