ToF Camera Pulse Duty Selection for Cyclic Error Suppression

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Solution Overview

Problem

In Time-of-Flight (ToF) camera systems using the indirect distance measurement method, cyclic errors occur when light is emitted with a 50% pulse duty, affecting the accuracy of distance measurement.

Innovation Solution

A signal generation apparatus is introduced, comprising a first pulse generator for the light source and a second pulse generator for the pixel, with a signal selection section that outputs a duty signal from either a first duty or a second duty, different from the first, to reduce cyclic errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If light is emitted with a 50% pulse duty in a ToF camera system using the indirect measurement method, then the light source output efficiency is improved, but cyclic errors occur in distance measurement

Engineering Contradiction:

Improvelight source output efficiencyVSAvoiddistance measurement accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent changes the pulse duty parameter from the conventional 50% to alternative values (first duty or second duty, both different from 50%). This parameter change eliminates the cyclic error in distance measurement while maintaining effective light source output. The signal selection section selects between different duty values to optimize both measurement accuracy and energy efficiency.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a signal selection section is added to choose between different duty values, then cyclic error suppression is achieved, but device complexity increases

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidsignal generation apparatus complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the signal generation function into separate components: a first pulse generator for light source control, a second pulse generator for pixel control, and a signal selection section. This segmentation allows independent optimization of each component and simplifies the overall design by assigning specific functions to dedicated modules.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The signal selection section serves multiple functions: it selects between different duty values to suppress cyclic errors, maintains synchronization between light source and pixel signals, and adapts to different measurement conditions. This multi-functionality reduces the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11894851B2Signal generation apparatus for time-of-flight camera with suppressed cyclic error

Publication Date: 2024.02.06 SONY SEMICON SOLUTIONS CORP

AI summary

A signal generation apparatus is used in a ToF camera system especially adopting the indirect system and suppresses occurrence of a cyclic error. The signal generation apparatus includes a first pulse generator configured to generate a pulse to be supplied to a light source that irradiates light upon a distance measurement target, a second pulse generator configured to generate a pulse to be supplied to a pixel that receives the light reflected by the distance measurement target, and a signal selection section configured to select and output a duty cycle of a signal to be outputted from the first pulse generator from between a first duty cycle and a second duty cycle different from the first duty cycle.