ToF Imaging Element Wiring Layout for Lower Parasitic Capacitance
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Solution Overview
Problem
Existing techniques do not effectively address the reduction of cyclic errors and dispersion of drive current in Time-of-Flight (ToF) sensors, which are crucial for accurate distance measurement.
Innovation Solution
The proposed solution involves an imaging element with specific wiring configurations that connect transistors in adjacent pixels to vias, allowing for the connection to wiring in another layer, and includes redundant wiring to manage parasitic capacity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of pixels are driven at the same time, then the imaging element can capture more light and improve signal strength, but the drive current concentrates causing strong charging and discharged currents that may cause an IR drop
Solution Approach 1:
The patent divides the pixel array into multiple groups, where each group shares common transfer units and charge accumulation units. This segmentation allows pixels to be driven in a dispersed manner rather than all simultaneously, reducing peak drive current while maintaining overall imaging capability. The grouping structure enables sequential or staggered driving of different pixel groups, preventing current concentration.
2Measurement precision
If phase shifting is applied to reduce cyclic error, then measurement accuracy improves, but the wiring structure becomes more complex requiring additional connections
Solution Approach 1:
The patent designs the wiring structure so that the same transfer units and charge accumulation units serve multiple pixel groups simultaneously. This multi-functional design enables phase shifting for cyclic error reduction without requiring separate dedicated wiring for each pixel, as the shared units handle phase-shifted signals from multiple groups through their common connection paths.
Solution Approach 2:
The patent merges the wiring resources by having multiple pixel groups share common transfer units and charge accumulation units. This consolidation reduces the overall wiring complexity compared to having dedicated wiring for each pixel, while still supporting the phase shifting required for cyclic error reduction in the ToF measurement process.
3Power
If pixels are dispersed to prevent IR drop, then drive current is reduced, but the wiring structure becomes more complex
Solution Approach 1:
The patent segments pixels into groups that share common wiring resources, enabling dispersed driving of individual pixels while maintaining simplified group-level wiring. This segmentation allows current dispersion at the pixel level without proportionally increasing wiring complexity, as shared units serve multiple pixels within each group.
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 reduces cyclic errors and disperses drive current, enhancing the accuracy and reliability of distance measurements in ToF sensors.
Implementation Method 1
a photoelectric conversion unit that performs photoelectric conversion
Data Source
AI summary
The present technique relates to an imaging element and a distance measurement module capable of reducing parasitic capacity. A distance measurement module includes: a first wiring that connects predetermined transistors in first adjacent pixels to a via formed in one of first adjacent pixels and connected to a wiring formed in another layer; and a second wiring that connects predetermined transistors in second adjacent pixels to a via formed in a pixel that is adjacent to one of second adjacent pixels and connected to a wiring formed in another layer, in which the first wiring is connected to a redundant wiring. The present technique can be applied to a distance measurement sensor that performs distance measurement, for example.