Indirect ToF Pixel Array Layout for S/N and Readout Speed
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Solution Overview
Problem
As the number of pixels in distance measuring sensors increases to improve resolution, the signal amount per pixel decreases, leading to a concern about a decrease in distance measurement accuracy due to insufficient Signal-to-Noise (S/N) ratio.
Innovation Solution
The implementation of a light receiving device with a back-illuminated current assisted photonic demodulator (CAPD) sensor configuration, which includes a pixel array unit with two taps per pixel for enhanced light reception and signal processing, along with a specific wiring arrangement of vertical signal lines to improve S/N ratio and reading speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to improve resolution, then the resolution is improved, but the signal amount per pixel decreases leading to insufficient S/N ratio
Solution Approach 1:
The patent combines signals from multiple pixels by connecting multiple first taps to a single second tap, merging their outputs to a common vertical signal line. This signal merging increases the total signal amount while maintaining high pixel count for resolution, thereby improving the S/N ratio without sacrificing measurement precision
Solution Approach 2:
The patent makes the second tap and vertical signal line serve multiple functions by having them shared among multiple pixels. A single second tap processes signals from multiple first taps, and a single vertical signal line carries combined signals from multiple pixels, enabling the system to maintain both high resolution and adequate signal strength
2Measurement precision
If the number of pixels is increased to improve resolution, then the resolution is improved, but the reading speed decreases due to increased complexity
Solution Approach 1:
The patent merges the reading operations of multiple pixels by having multiple first taps connected to a shared second tap and vertical signal line. This consolidation reduces the total number of reading paths and simplifies the output structure, thereby maintaining high reading speed despite the increased number of pixels for improved resolution
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 configuration effectively curbs the decrease in distance measurement accuracy by ensuring a sufficient S/N ratio even with an increased number of pixels, thereby maintaining high resolution and accuracy in distance measurement.
Implementation Method 1
signal charges obtained by receiving light reflected by a measurement object are distributed to two charge accumulation regions
Data Source
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AI summary
The present technology relates to a light receiving device and a distance measuring module capable of curbing a decrease in distance measurement accuracy due to an increase in the number of pixels. A light receiving device includes a pixel array unit in which pixels each having a first tap detecting charge photoelectrically converted by a photoelectric conversion unit and a second tap detecting charge photoelectrically converted by the photoelectric conversion unit are two-dimensionally arranged in a matrix. In the pixel array unit, four vertical signal lines for outputting a detection signal detected by any one of the first tap and the second tap to the outside of the pixel array unit are arranged for one pixel column. The present technology can be applied to a distance measuring sensor or the like of the indirect ToF scheme, for example.