TOF Sensor Clock Synchronization for Stable Depth Measurement
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Solution Overview
Problem
Time-of-flight (TOF) sensors face accuracy degradation due to variations in temperature, voltage, or manufacturing processes affecting the phase relationship between light pulse transmission and sampling, leading to inconsistent depth information in 3D imaging applications.
Innovation Solution
A TOF distance measuring system with a clock signal generation circuit, replicated transmission circuit, and delay locked loop ensures a fixed phase difference between light pulse transmission and sampling, using identical layouts for the transmission and replicated transmission circuits to maintain consistency across temperature, voltage, and manufacturing changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional image sensors are used for 3D imaging, then device complexity is reduced, but measurement precision degrades due to inability to accurately capture depth information
Solution Approach 1:
The patent combines the light emitting module and TOF sensor array into an integrated sensor system, merging multiple functions (light emission, light detection, depth calculation) into a single unified device. This integration maintains measurement precision while reducing overall system complexity compared to separate components.
Solution Approach 2:
The TOF sensor system performs multiple functions: emitting light pulses, detecting reflected light, calculating time-of-flight, and generating depth maps. This multi-functionality eliminates the need for separate depth sensing devices, improving measurement precision without proportionally increasing device complexity.
2Measurement precision
If phase relationship between transmission and sampling is not synchronized, then device operation is simpler, but measurement precision degrades due to inaccurate depth information
Solution Approach 1:
The system uses a delay locked loop (DLL) that continuously monitors and adjusts the phase relationship between transmission and sampling clocks. The DLL provides feedback control to maintain synchronized timing, ensuring measurement precision without requiring complex manual synchronization mechanisms.
Solution Approach 2:
The clock signal generation system dynamically adjusts phase relationships in real-time to maintain synchronization between light pulse transmission and sampling operations. This dynamic adaptation ensures accurate depth measurement while keeping the synchronization system relatively simple through automated adjustment.
3Reliability
If temperature, voltage, or manufacturing variations occur, then device adaptability improves, but measurement precision degrades due to phase relationship shifts
Solution Approach 1:
The delay locked loop continuously monitors phase relationships and automatically compensates for drift caused by temperature, voltage, or manufacturing variations. This feedback mechanism maintains reliable phase synchronization across varying environmental conditions without requiring the system to be overly sensitive or adaptive to each specific condition.
Solution Approach 2:
The system adjusts clock signal parameters (phase, timing) in real-time to compensate for environmental variations. By dynamically changing these parameters through the DLL, the system maintains measurement reliability while avoiding the need for complex adaptive mechanisms for each specific environmental condition.
4Manufacturing precision
If replicated transmission circuit with identical layout is used, then manufacturing precision is improved, but device complexity increases due to additional circuit requirements
Solution Approach 1:
The patent implements a replicated transmission circuit that copies the reference clock signal path with identical layout and structure. This copying approach ensures manufacturing precision and consistency in phase relationships, while the replication itself provides a straightforward method to achieve the desired precision without overly complex design procedures.
Data Source
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AI summary
The present application discloses a time-of-flight (TOF) sensor and a related chip, electronic device, and distance measuring system. The TOF sensor includes: a clock signal generation circuit, configured to generate a first clock signal and a second clock signal; a transmission circuit, configured to generate a third clock signal based on the first clock signal, wherein the third clock signal is outputted to the light-emitting module; a replicated transmission circuit, configured to simulate the transmission circuit, and generate a fourth clock signal based on the second clock signal; a delay locked loop, configured to generate a fifth clock signal based on one of a plurality of sixth clock signals and the fourth clock signal; a clock tree, configured to generate the plurality of sixth clock signals based on the fifth clock signal; a pixel array, having a plurality of pixel columns respectively sampling the reflected light pulse based on the plurality of sixth clock signals to generate a sampling result; and a depth determination unit, configured to obtain a depth information based on the sampling result.