I/Q Counter Circuit for Time-of-Flight Sensor Depth Sensing
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Solution Overview
Problem
Current time-of-flight image sensors face challenges in efficiently determining distance and depth due to the complexity of signal processing and shared components among numerous photoelectric conversion devices, which can lead to noise and inefficiencies in data processing.
Innovation Solution
The proposed solution involves a time-of-flight sensor system with a pixel array and processing circuitry that includes multiple photodiodes and a counter capable of switching between up and down count modes, utilizing a comparator to compare signal voltages with a reference signal, and a counter to perform counts based on comparison results, enabling improved depth sensing and imaging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple photoelectric conversion devices share common signal processing components (such as ADC or S/H circuit), then device complexity is reduced, but measurement precision deteriorates due to noise and inefficiencies in data processing
Solution Approach 1:
The patent divides the pixel array into multiple independent blocks, where each block contains photoelectric conversion devices and dedicated signal processing components. This segmentation allows each block to process signals independently, preventing noise propagation across the entire array while maintaining modular complexity management.
Solution Approach 2:
The patent introduces intermediate storage nodes and buffering mechanisms between photoelectric conversion devices and shared signal processing components. These intermediaries isolate noise from the conversion process, allowing multiple devices to share components without compromising measurement precision.
2Reliability
If a counter circuit resets the count value when overflow occurs, then reliability is improved, but loss of information occurs because the count value before overflow cannot be recovered
Solution Approach 1:
The patent implements feedback mechanisms where the counter circuit monitors its own count value and provides feedback signals when approaching overflow conditions. This allows the system to take corrective action (such as scaling down measurements or alerting the control unit) before information is lost, maintaining both reliability and information integrity.
Solution Approach 2:
The counter circuit performs preliminary actions by detecting potential overflow conditions before they occur. When the count value approaches the maximum threshold, the circuit preemptively triggers scaling operations or alternative processing paths, preventing information loss while maintaining reliable counting operations.
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 enhances depth sensing and imaging by simplifying signal processing, reducing noise, and improving output bandwidth, making it more efficient and effective in determining distance and depth in wave-based sensors.
Implementation Method 1
charge is collected in a photoelectric conversion device of the pixel circuit as a result of the impingement of light
Data Source
AI summary
A time-of-flight device comprises a pixel array including a plurality of pixel circuits arranged in an array, respective ones of the plurality of pixel circuits including a first photodiode configured to selectively output two analog signals respectively via two paths, and including a second photodiode configured to selectively output two analog signals respectively via two paths; a signal line coupled to the first photodiode and a second photodiode; and processing circuitry including: a comparator configured to compare a voltage of the signal line with a reference signal and to output a comparison result, and a counter configured to perform a count based on the comparison result in response to a count control signal, wherein the count control signal is configured to switch the counter between an up count mode and a down count mode while a count value is held in the counter.