Ranging Device Pixel Charge Segmentation for Moving Object Accuracy
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Solution Overview
Problem
Existing ranging devices face challenges in accurately measuring distances, especially when objects move, due to the need for long charge accumulation periods and scanning times, which can lead to movement distortion and inaccurate readings.
Innovation Solution
A ranging device with a selecting unit that directs signal and unnecessary charge transfer signals to specific regions of pixels, allowing signal charges to be collected in designated areas while discharging unnecessary charges, thereby improving distance calculation accuracy by isolating ambient light effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reset operation is carried out each time charges are accumulated to remove ambient light interference, then ambient light components are prevented from being reflected in the signal, but a relatively long charge accumulation period is required to ensure sufficient signal quantity
Solution Approach 1:
The pixel is divided into multiple independent charge storage regions (first charge storage region, second charge storage region, third charge storage region) that can be independently controlled. This segmentation allows different regions to accumulate charges during different time periods, enabling the system to collect sufficient signal charges across multiple accumulation cycles without being constrained by a single long accumulation period, thus resolving the contradiction between measurement precision and time loss.
Solution Approach 2:
The patent implements preliminary discharge of unnecessary charges (generated by ambient light) from the first charge storage region before signal charge accumulation begins. By clearing unwanted charges in advance and using the third charge storage region to collect and discharge ambient light charges during signal accumulation, the system ensures that signal accumulation is not contaminated by ambient light interference, maintaining measurement precision without requiring excessively long accumulation periods.
2Quantity of substance
If a relatively long charge accumulation period is set to ensure sufficient signal quantity, then signal quantity is ensured, but the scanning period also needs to be set to a long period, making it difficult to appropriately measure distance when the object moves
Solution Approach 1:
The patent enables continuous charge accumulation across multiple time periods by utilizing multiple charge storage regions. While the first charge storage region is being discharged of ambient light charges, the second and third regions continue accumulating signal charges. This continuous accumulation process ensures sufficient signal quantity without requiring the scanning system to slow down, thereby maintaining fast scanning speed while ensuring adequate signal quantity for accurate ranging of moving objects.
Solution Approach 2:
The patent implements dynamic control of charge transfer timing, allowing the system to flexibly manage when charges are transferred between different storage regions based on the scanning phase and light source emission timing. This dynamic charge management enables the system to optimize both signal quantity accumulation and scanning speed adaptively, resolving the contradiction between ensuring sufficient signal and maintaining fast scanning for moving objects.
3Measurement precision
If multiple charge storage regions and transfer electrodes are used to separate signal charges from ambient light charges, then distance calculation accuracy is improved, but device complexity increases
Solution Approach 1:
The third charge storage region serves multiple functions: it accumulates ambient light-generated charges during signal accumulation periods, acts as a temporary storage for discharge, and enables the first charge storage region to be cleared of ambient light charges before signal accumulation. This multi-functional design achieves high distance calculation accuracy through effective charge separation without proportionally increasing device complexity, as a single third region performs multiple critical functions.
Solution Approach 2:
The patent implements a self-service mechanism where the pixel structure uses its own third charge storage region to collect and hold ambient light charges that would otherwise contaminate signal measurements. By having the pixel autonomously manage its own charge separation and discharge operations through internally controlled transfer electrodes, the system achieves high measurement precision without requiring complex external intervention or additional complex structures beyond the three charge storage regions and their associated transfer electrodes.
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 accurate and stable distance measurement even with moving objects by isolating signal and unnecessary charges, reducing the impact of ambient light and improving the device's ability to handle moving targets.
Implementation Method 1
Each of the plurality of pixels includes a charge-generating region generating charges in accordance with incident light
Data Source
AI summary
In accordance with an irradiation position of pulsed light, a selecting unit outputs a first transfer signal to a first transfer electrodes and outputs a second transfer signal to a second transfer electrodes, to allow signal charges to flow into first and second signal charge-collecting regions of a pixel corresponding to the irradiation position, and outputs a third transfer signal to a third transfer electrodes to allow unnecessary charges to flow into an unnecessary charge-discharging regions of a pixel other than the pixel corresponding to the irradiation position. An arithmetic unit reads out signals corresponding to respective quantities of signal charges collected in the first and second signal charge-collecting regions of the pixel selected by the selecting unit, and calculates a distance to an object based on a ratio between a quantity of signal charges collected in the first signal charge-collecting regions and a quantity of signal charges collected in the second signal charge-collecting regions.