ToF Autofocusing Camera Using Phase Difference Distance Measurement

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Solution Overview

Problem

Current autofocusing methods in camera modules, such as phase AF and contrast AF, are inefficient due to the need for specialized sensors and complex algorithms, resulting in high computational load and battery consumption.

Innovation Solution

A method utilizing a time-of-flight (ToF) camera to extract distance information and perform autofocusing for an RGB camera, which includes an illumination unit and a sensor unit to calculate distance using phase differences, allowing for rapid autofocusing through actuator control and lens movement based on pre-stored correlations and calibration data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phase AF or contrast AF is used, then autofocusing function is achieved, but computational load and battery consumption increase

Engineering Contradiction:

Improveautofocusing functionVSAvoidbattery consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces complex computational algorithms (software-based contrast AF and phase AF) with a hardware-based time-of-flight measurement system. The ToF camera directly measures distance using light flight time, substituting mechanical/optical measurement for computational processing, thereby reducing battery consumption while maintaining reliable autofocusing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a ToF camera as an intermediary device between the object and the RGB camera. This intermediary directly provides distance information, eliminating the need for complex image processing algorithms to infer focus distance, thus reducing computational load and energy consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If contrast AF with complex software algorithm is used, then autofocusing is achieved, but processing time increases

Engineering Contradiction:

Improveautofocusing functionVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces time-consuming software algorithms with direct hardware measurement. The ToF camera provides instantaneous distance measurements through optical flight time detection, eliminating the iterative processing required by contrast AF algorithms and significantly reducing focus adjustment time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs preliminary distance measurement using the ToF camera before the RGB camera needs to adjust focus. This advance acquisition of distance information allows the autofocus system to be prepared in advance, reducing the overall time required for focus adjustment when needed.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If phase AF with special sensor is used, then autofocusing is achieved, but sensor versatility is reduced

Engineering Contradiction:

Improveautofocusing functionVSAvoidsensor freedom

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a multi-functional camera system where the ToF camera serves as a dedicated distance measurement sensor while the RGB camera maintains its universal imaging capability. This allows the system to use standard, versatile RGB sensors without requiring specialized phase detection sensors, thereby maintaining sensor freedom and adaptability while achieving reliable autofocusing.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 fast and efficient autofocusing with reduced computational load and battery consumption, allowing for direct lens movement and digital processing.

Implementation Method 1

a method of performing autofocusing through a simple computation within a short time is required

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Implementation Method 2

the sensor unit receives pieces of information about the light having a plurality of phases reflected by the object based on an output of the light, and the ToF camera extracts the distance information using the pieces of information

Methodology Applied

Scientific EffectPhase difference:

Data Source

PatentUS11539873B2Camera apparatus and autofocusing method therefor

Publication Date: 2022.12.27 LG INNOTEK CO LTD

AI summary

An auto-focusing method of a camera apparatus according to an embodiment of the present invention comprises the steps of: extracting distance information of an object by using a ToF camera; and performing auto-focusing on an RGB camera by using auto-focusing information according to the distance information, wherein the ToF camera includes an illumination unit for outputting light to the object and a sensor unit for receiving information about light reflected from the object, the sensor unit receives a plurality of pieces of information about the light reflected from the object at a plurality of phases on the basis of the output of the light, and the ToF camera extracts the distance information by using the plurality of pieces of information.