Multi-Tap ToF Sensor Pixel Charge Accumulation
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Solution Overview
Problem
Existing multi-tap Time of Flight (ToF) sensors require complex processing to determine which charge accumulation units accumulate reflected light, making it difficult to calculate distances efficiently when using multiple time windows (TWs).
Innovation Solution
A distance image capturing device and method that includes a light source unit, a light receiving unit with a distance image sensor having pixels with multiple charge accumulation units, and a pixel driving circuit that synchronizes charge accumulation with light emission. The device calculates distance using the same equation regardless of which charge accumulation units accumulate the reflected light, simplifying the processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple time windows (TWs) are used for distance measurement, then measurement accuracy and measurable distance are improved, but processing complexity increases due to the need for case division and determination of which charge accumulation units contain reflected light
Solution Approach 1:
The pixel is divided into multiple charge accumulation units (first, second, third charge accumulation units) that can independently accumulate electric charges from reflected light during different time windows. This segmentation allows simultaneous measurement of distances at different time ranges without requiring complex case-by-case processing, as each unit operates independently to capture photons arriving at different times.
Solution Approach 2:
The patent performs preliminary action by pre-configuring multiple charge accumulation units to accumulate electric charges during specific time windows before the actual distance calculation. This allows the system to have all necessary charge data ready in advance, eliminating the need for complex determination processes during the calculation phase and enabling direct distance computation for multiple time windows.
2Length of stationary object
If multiple charge accumulation units are used to extend measurable distance, then measurement range is improved, but the complexity of determining which units contain reflected light increases
Solution Approach 1:
The pixel is divided into multiple charge accumulation units (first, second, third charge accumulation units) that can independently accumulate electric charges from reflected light during different time windows. This segmentation allows simultaneous measurement of distances at different time ranges without requiring complex case-by-case processing, as each unit operates independently to capture photons arriving at different times.
3Measurement precision
If case division processing is performed to determine which charge accumulation units accumulate reflected light, then distance calculation accuracy is maintained, but processing time and complexity increase
Solution Approach 1:
The patent performs preliminary action by pre-configuring multiple charge accumulation units to accumulate electric charges during specific time windows before the actual distance calculation. This allows the system to have all necessary charge data ready in advance, eliminating the need for complex determination processes during the calculation phase and enabling direct distance computation for multiple time windows.
Solution Approach 2:
The distance calculation unit is designed with universal functionality to calculate distances based on electric charge amounts from any combination of charge accumulation units using the same calculation equation. This multi-functional design eliminates the need for different calculation methods for different cases, allowing the system to maintain accuracy while reducing processing time by applying a unified calculation approach.
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
Enables easy and efficient processing of distance calculations when using multiple TWs, reducing complexity and improving measurement accuracy without the need for case-specific calculation equations.
Implementation Method 1
a distance image sensor in which a plurality of pixels, each having a photoelectric conversion element that generates electric charges according to incident light
Implementation Method 2
measures a distance between a measurement instrument and a target object based on a flight time of light in a space
Data Source
AI summary
A light source unit, a light receiving unit including a distance image sensor in which a plurality of pixels are arranged and a pixel driving circuit, and a distance calculation unit calculating a distance to a subject based on electric charge amount accumulated in each of the charge accumulation units are provided, and a relationship between the emission timing and the accumulation timing is set such that electric charges corresponding to reflected light of the optical pulse reflected from the subject is accumulated in any of the three or more charge accumulation units provided in the pixels, and the distance calculation unit calculates the distance to the subject by using the same calculation equation regardless of which two charge accumulation units, in which electric charges are successively accumulated, among the three or more charge accumulation units provided in the pixels accumulate the electric charges corresponding to the reflected light.