Dynamic SPAD Array Configuration for dTOF Angular Resolution
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Solution Overview
Problem
Existing Time-of-Flight (ToF) ranging systems with fixed-focus lenses or zoom lenses face challenges in maintaining sufficient angular resolution, leading to reduced depth pixel resolution and inadequate depth information, especially when the focal length increases.
Innovation Solution
A dTOF ranging method and system that dynamically adjust the angular resolution by activating specific Single Photon Avalanche Diodes (SPADs) based on user-input, using different modes to change the number of SPADs per pixel and the block size of the SPAD array, without increasing the photosensitive area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the focal length of the RGB lens is increased to enlarge the field of view, then the coverage area is improved, but the angular resolution remains unchanged and depth pixel resolution decreases
Solution Approach 1:
The patent implements dynamic switching between multiple SPAD array configurations (first configuration with larger block size and more SPADs per pixel, second configuration with smaller block size and fewer SPADs per pixel) based on the current focal length. When focal length increases and field of view enlarges, the system switches to the first configuration to maintain angular resolution. This dynamic adaptation resolves the contradiction by making the system's resolution characteristics changeable rather than fixed.
Solution Approach 2:
The patent changes the operational parameters of the SPAD array by switching between different configurations with different block sizes and different numbers of SPADs per pixel. This parameter change allows the system to adapt to different focal lengths and field of view requirements, maintaining measurement precision across varying operational conditions without requiring physical modification of the sensor array.
2Measurement precision
If the number of pixels in the ToF device is increased to improve angular resolution, then the depth information precision is improved, but the photosensitive area must be enlarged which increases chip cost and reduces spatial efficiency
Solution Approach 1:
The patent segments the SPAD array into multiple configurable blocks and implements different configurations that can be switched based on operational requirements. Instead of using a single large array with high pixel count, the system divides the array into manageable segments (blocks) that can be reconfigured to achieve the desired angular resolution for different focal lengths, thereby maintaining precision without requiring a continuously enlarged photosensitive area.
Solution Approach 2:
The patent makes the SPAD array multi-functional by enabling it to operate in different configurations (first configuration for long focal length, second configuration for short focal length) using the same physical hardware. This universality allows a single photosensitive area to serve multiple resolution requirements, eliminating the need to enlarge the chip for different angular resolution needs.
3Productivity
If the block size of the SPAD array is increased to reduce the number of pixels, then the spatial efficiency is improved, but the angular resolution decreases
Solution Approach 1:
The patent implements dynamic switching between different block size configurations. The system can switch to a larger block size configuration when spatial efficiency is prioritized (shorter focal length) and switch to a smaller block size configuration when angular resolution is prioritized (longer focal length). This dynamic approach resolves the contradiction by making block size adjustable rather than fixed.
Solution Approach 2:
The patent changes the block size parameter of the SPAD array based on operational requirements. By switching between different block size configurations, the system can optimize the balance between spatial efficiency and angular resolution for different focal lengths and field of view requirements, rather than being constrained to a single fixed block size.
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 allows for efficient and cost-effective adjustment of angular resolution, improving depth information precision without the need for increased pixel count or photosensitive area, thus enhancing the accuracy of target identification.
Implementation Method 1
selected SPADs (Single Photon Avalanche Diodes) are activated based on first area position information
Implementation Method 2
pixel data is output through a TDC (Time-to-Digital Converter) array according to a number of SPADs in each pixel
Data Source
AI summary
The invention discloses a dTOF ranging method and a dTOF ranging system, which are applied to the field of optical measurement technology. The method includes setting a first mode and a second mode; wherein the first mode activates the corresponding SPADs according to the first area position information, and outputs the data of each pixel through the TDC array according to the number of components in the first pixel; the second mode activates the corresponding SPADs according to the second area position information, and outputs the data of each pixel through the TDC array according to the number of components in the second pixel. The position information of each area includes the block size of the corresponding area of the SPAD array and the position of the SPAD. The method also includes switching between the first mode and the second mode according to user-input command.