TOF Sensor AD Converter Noise Reduction via Pixel Signal Difference

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Solution Overview

Problem

Noise in pixel signals from solid-state imaging elements used in TOF sensors reduces the accuracy of distance measurements in distance measuring devices.

Innovation Solution

A distance measuring device with a light receiving section that includes multiple pixels, where adjacent pixel signals are AD-converted by the same AD converting section, allowing for the calculation of a difference between these signals to reduce noise and improve measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If multiple AD converting sections are used to process pixel signals from multiple pixels simultaneously, then processing speed is improved, but noise increases due to variations between different AD converting sections

Engineering Contradiction:

Improvesignal processing speedVSAvoiddistance measurement accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The pixel array is divided into multiple regions, with each region processed by a dedicated AD converting section. This segmentation allows parallel processing of multiple pixel signals simultaneously, improving processing speed while maintaining consistency within each segment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces offset correction to compensate for parameter variations between different AD converting sections. By detecting and correcting offset differences, the system maintains measurement precision across multiple parallel processing channels.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a single AD converting section is used to process pixel signals sequentially, then noise is reduced through consistent conversion, but processing speed decreases

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidsignal processing speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

Offset correction is performed preliminarily for each AD converting section before actual distance measurement. This preliminary calibration ensures that subsequent parallel processing maintains high precision without requiring sequential verification.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates multiple copies of the AD converting section, each dedicated to processing signals from specific pixel regions. This allows simultaneous processing while maintaining the consistent conversion characteristics of individual sections through offset correction.

Inventive Principle:

Principle #26Copying

3Measurement precision

If offset correction is performed for all AD converting sections, then measurement accuracy is improved, but processing time and complexity increase

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Offset correction is performed selectively rather than universally for all AD converting sections. The system applies correction only where necessary based on detected variations, reducing overall processing time while maintaining accuracy where needed.

Inventive Principle:

Principle #16Partial or excessive action

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 effectively inhibits noise in pixel signals, thereby maintaining and enhancing the accuracy of distance measurements.

Implementation Method 1

a light receiving section emitting irradiation light, a light receiving section including a plurality of pixels and receiving reflected light corresponding to the irradiation light reflected at an object

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

The light receiving section includes a plurality of AD converting sections AD-converting pixel signals read from the pixels

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Data Source

PatentUS11513200B2Distance measuring device and distance measuring method

Publication Date: 2022.11.29 SONY SEMICON SOLUTIONS CORP

AI summary

The present technology relates to a distance measuring device and a distance measuring method that inhibit possible noise in a pixel signal based on reflected light from an object to allow accuracy of distance measurement to be maintained. A distance measuring device according to an aspect of the present technology includes a light emitting section emitting irradiation light, a light receiving section receiving reflected light corresponding to the irradiation light reflected at an object, a calculation section calculating a distance to the object on the basis of a time from emission of the irradiation light until reception of the reflected light, and a control section controlling emission of the irradiation light. The light receiving section includes a plurality of AD converting section AD-converting pixel signals read from the pixels. A first pixel signal and a second pixel signal respectively read from a first pixel and a second pixel of the plurality of pixels forming the light receiving section are AD-converted by an identical AD converting section of the plurality of AD converting sections, the first and second pixels being adjacent to each other. During a process of calculating the time, the calculation section calculates a difference between the first pixel signal and the second pixel signal AD-converted by the identical AD converting section.