SPAD Photoelectric Conversion Device Photon Incidence Weighting
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Solution Overview
Problem
Existing ranging technologies using the TOF method with SPAD elements fail to accurately reflect the incidence mode of photons on pixels, leading to inadequate distance measurement accuracy.
Innovation Solution
A photoelectric conversion device that generates weight values based on the incidence frequency of photons, using time count values and pulse widths to improve ranging accuracy by determining appropriate signal outputs and distance information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If weight is determined only by the number of reactions of light receiving element, then processing is simple, but distance measurement accuracy cannot be improved when photons incident in different modes
Solution Approach 1:
The patent segments the weight determination process into two distinct components: (1) weight based on the number of reactions of light receiving elements, and (2) weight based on the pulse width of detection signals. This segmentation allows each component to capture different aspects of photon incidence characteristics, thereby improving distance measurement accuracy while maintaining manageable processing complexity through modular computation.
Solution Approach 2:
The patent introduces pulse width as an additional dimension for weight determination beyond the traditional single metric of reaction count. By incorporating pulse width information, the system captures temporal characteristics of photon incidence, transforming a one-dimensional measurement (count only) into a two-dimensional measurement (count + pulse width), which resolves the limitation of inadequate accuracy for different photon incidence modes.
2Measurement precision
If only count value of time from light emission to photon incidence is used, then processing is simple, but appropriate weight cannot be reflected for different photon incidence modes
Solution Approach 1:
The patent performs preliminary action by determining weights for different photon incidence modes before actual distance measurement processing. By pre-establishing weight values based on pulse width characteristics and reaction counts, the system prepares a comprehensive weighting framework that preserves photon incidence mode information, preventing information loss during subsequent measurement operations.
Solution Approach 2:
The patent implements feedback by using the determined weights (based on both reaction counts and pulse widths) to adjust and refine distance measurement results. This feedback mechanism ensures that photons incident in different modes contribute appropriately to the final measurement, preserving the nuanced information about incidence modes rather than losing it through simple counting alone.
3Measurement precision
If weight is determined without considering pulse width, then processing is fast, but distance measurement accuracy is insufficient
Solution Approach 1:
The patent maintains continuity of useful action by seamlessly integrating pulse width measurement into the existing time-of-flight measurement framework. The pulse width determination occurs continuously alongside the time-of-flight measurement without requiring separate processing stages, ensuring that the additional accuracy gained from pulse width information does not come at the cost of significant processing time delays.
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
Enhances ranging accuracy by accurately reflecting photon incidence frequency, reducing errors from ambient light and noise, and improving distance measurement precision.
Implementation Method 1
a light receiving unit configured to generate a light reception pulse signal in response to incidence of light
Data Source
AI summary
A photoelectric conversion device includes a light receiving unit configured to generate a light reception pulse signal in response to incidence of light, a time information acquisition unit configured to acquire, for each periodic light emission of a light emitting unit, a first time count value indicating an elapsed time from a light emission of the light emitting unit to an input of the light reception pulse signal, and a second time count value indicating a pulse width of the light reception pulse signal, and a weight determination unit configured to generate a weight value corresponding to the second time count value as a signal used to generate information indicating a relationship between each of the first time count values and a light reception frequency.