SPAD Optical Controller with Delayed-Light Sampling for Ranging
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Solution Overview
Problem
Existing optical sensors using Single Photon Avalanche Diode (SPAD) pixels for distance detection face limitations in accuracy and frame rate due to two-stage sampling, which restricts the final distance detection resolution.
Innovation Solution
A controller is employed to control the emission of reference and multiple types of delayed lights in detection intervals, with each type delayed by a specific interval, allowing for one-stage sampling and accumulation of response outputs to determine time distribution, thereby improving distance detection accuracy and frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-stage sampling is used for distance detection with SPAD pixels, then the detection process can be completed, but the distance detection resolution and frame rate are limited
Solution Approach 1:
The patent divides the sampling process into multiple parallel one-stage sampling operations by emitting multiple types of light (reference light and delayed lights) with different delay intervals. Each sampling operation processes a specific time window, effectively segmenting the detection process to achieve both high resolution and high frame rate without requiring sequential two-stage sampling
Solution Approach 2:
The patent applies preliminary action by emitting delayed lights with predetermined delay intervals before the actual detection. These delayed lights are emitted in advance with specific timing offsets, allowing the system to capture time distribution information at multiple points simultaneously through one-stage sampling, thereby improving both resolution and frame rate
2Measurement precision
If multiple types of delayed lights are emitted with different delay intervals, then time distribution information can be obtained more accurately, but the light emission complexity increases
Solution Approach 1:
The patent changes the timing parameter of light emission by introducing multiple delay intervals (e.g., 0 ns, 500 ps, 1 ns) for different types of lights. This parameter variation allows the system to capture different portions of the time distribution of reflected light, improving measurement precision while maintaining a systematic and controllable emission pattern that manages device complexity
3Productivity
If one-stage sampling is used instead of two-stage sampling, then the frame rate can be improved, but the distance detection resolution may be compromised
Solution Approach 1:
The patent adds a temporal dimension to the sampling process by introducing multiple delay intervals for different light types. Instead of using a single one-stage sampling operation that would limit resolution, the system uses multiple one-stage sampling operations at different time offsets, effectively transforming a one-dimensional sampling approach into a multi-dimensional temporal sampling strategy that achieves both high frame rate and high 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 approach enables high distance resolution and high frame rate, achieving improved distance detection accuracy by utilizing the time distribution of output accumulated values to specify a specific divided period for distance output, overcoming the limitations of two-stage sampling.
Implementation Method 1
detect a distance to a target by receiving reflected lights from the target with a SPAD pixel
Implementation Method 2
The irradiation lights include reference light and multiple types of delayed lights for each detection frame. The reference light is emitted at a start timing of a detection interval. The multiple types of delayed lights are emitted with delays from start timings of detection intervals and different in delay by a delay interval from each other
Implementation Method 3
Each detection frame is a duration for obtaining time distribution of an output accumulated value. The time distribution of an output accumulated value is created by accumulating the response output for detection intervals
Data Source
AI summary
A controller for an optical sensor including a SPAD pixel includes a processor. The processor controls irradiation lights to be emitted respectively in each of detection intervals. The irradiation lights including reference light and multiple types of delayed lights for each detection frame. The reference light is emitted at a start timing of a detection interval, and the multiple types of delayed lights are emitted with delays from start timings of detection intervals and different in delay by a delay interval from each other. Response output of the SPAD pixel is repeatedly sampled at sampling intervals during each detection interval, and accumulated for detection intervals to obtain time distribution of an output accumulated value. The processor outputs data of a distance to a target according to a specific divided period, which is specified based on the time distribution of the output accumulated value.