Reconfigurable ToF Sensor Logic for Lens Misalignment Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional time of flight ranging systems face manufacturing defects such as lens misalignment, leading to incomplete light detection by SPAD arrays, resulting in inaccurate distance measurements and reduced manufacturing yield.
Innovation Solution
The implementation of reconfigurable OR logic circuitry within macropixels, allowing for selective signal passing and combination between neighboring photodetection blocks, enabling adjustment for misalignment and reconfiguration of the active detection area to compensate for manufacturing irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fixed SPAD arrays are used, then device structure is simple, but manufacturing yield is reduced due to lens misalignment
Solution Approach 1:
The patent implements reconfigurable OR logic circuitry that allows the detector to dynamically reconfigure which SPAD pixels are active and how they are grouped into macropixels. This dynamic reconfiguration capability enables the system to adapt to lens misalignment by shifting the active detection area, thereby resolving the contradiction between maintaining simple structure and achieving high manufacturing precision.
Solution Approach 2:
The system changes the operational parameters of the detector by allowing variable configuration of OR logic combinations across SPAD pixels. Through control signals, the system can alter which pixels contribute to each macropixel output, effectively changing the detection geometry to compensate for manufacturing tolerances without requiring physical repositioning of components.
2Measurement precision
If lens positioning is made more precise, then light detection accuracy improves, but manufacturing cost increases
Solution Approach 1:
The patent converts the harmful effect of lens misalignment into a beneficial feature by using the misalignment information to reconfigure the OR logic circuitry. Instead of requiring expensive precision manufacturing, the system deliberately designs in reconfigurability that allows it to exploit the actual (imperfect) lens position to achieve accurate measurements, thereby improving ease of manufacture while maintaining measurement precision.
Solution Approach 2:
The system performs preliminary characterization of the lens position relative to the SPAD array during manufacturing or initial operation. Based on this preliminary information, the OR logic circuitry is pre-configured or dynamically configured to compensate for the specific misalignment, allowing accurate measurements without requiring high-precision manufacturing in the first place.
3Adaptability or versatility
If reconfigurable OR logic is implemented, then compensation for misalignment is enabled, but device complexity increases
Solution Approach 1:
The patent segments the SPAD array into multiple macropixels, where each macropixel is formed by OR-combining signals from a specific subset of SPAD pixels. This segmentation allows independent configuration of each macropixel's contributing pixels through control signals, enabling adaptability while keeping the logic circuitry structured and manageable through modular design.
Solution Approach 2:
The reconfigurable OR logic circuitry serves multiple functions: it can compensate for lens misalignment, it can optimize detection sensitivity for different target positions, and it can adapt to varying operational conditions. This multi-functionality justifies the added complexity by providing versatile adaptation capabilities that benefit overall system performance across multiple scenarios.
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 solution enhances the accuracy of distance measurements by ensuring complete light detection and improving manufacturing yield by allowing for adjustments in the active detection area, effectively addressing the issue of lens misalignment.
Implementation Method 1
some of the light reflects off the target surface and returns to the time of flight ranging system where it is detected by a reflected light detector
Data Source
AI summary
An electronic device includes a time-of-flight unit with a laser emitting ranging light toward a scene, and a detector detecting ranging light reflected from the scene. The detector includes photodetection regions of macropixels. Each macropixel includes photodiodes, and OR logic circuitry receiving outputs of photodiodes as input and generating a detection signal. Each macropixel has output combining logic, and selection circuitry selectively passing the detection signal to the output combining logic or to output combining logic of a neighboring macropixel. The output combining logic has inputs coupled to the selection circuitry and the selection circuitry of the neighboring macropixel, and generates an output signal by logically combining outputs of the selection circuitry and the selection circuitry of the neighboring macropixel. Timing circuitry determines distances to points of the scene from elapsed time between emitting the ranging light and detecting of ranging light reflected from the scene by the photodetection regions.