Direction Aware Autofocus Lens Control

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Solution Overview

Problem

Existing autofocus systems in imaging devices often take longer to achieve focus due to searching in both directions, leading to delayed and sometimes incorrect focus, resulting in a higher failure rate and undesirable user experience.

Innovation Solution

A method and apparatus that determine the initial direction to move the lens by tracking changes in a reference parameter, such as object size, across multiple frames, allowing for quicker and sharper focus by initiating the focus operation in the correct direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the imaging device searches in both directions for optimal focus, then the focus coverage is complete, but the search time increases and focus accuracy decreases

Engineering Contradiction:

Improvefocus accuracyVSAvoidautofocus search time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by capturing multiple preview frames and analyzing object motion direction before initiating the autofocus search. This preliminary analysis of reference parameters (object size changes) allows the system to predict the optimal search direction, avoiding unnecessary bidirectional searching and reducing overall search time while maintaining focus accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of searching bidirectionally from the current lens position, the system inverts the conventional approach by determining the optimal search direction first through motion analysis of preview frames. The lens then searches unidirectionally in the predetermined direction, reversing the traditional search pattern to achieve faster and more accurate focusing.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the lens moves in the incorrect direction, then the system may eventually find focus, but the user experiences increasing defocus and delayed focus

Engineering Contradiction:

Improvefocus success rateVSAvoidtime to achieve focus

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of object motion direction using reference parameters from multiple preview frames before initiating the autofocus search. This preliminary determination of the optimal search direction ensures the lens moves toward focus from the outset, preventing the harmful effect of initial defocus and ensuring immediate focus success.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies preliminary anti-action by counteracting the potential harmful effect of searching in the wrong direction. Through motion analysis of preview frames, the system predicts the optimal search direction in advance and initiates the lens movement in that direction, preventing the occurrence of initial defocus and the need for corrective reverse searching.

Inventive Principle:

Principle #9Preliminary anti-action

3Adaptability or versatility

If the system searches in both directions, then all possible focus positions are covered, but the user experiences increasing defocus during the search

Engineering Contradiction:

Improvefocus search coverageVSAvoiduser experience during search

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary analysis of object motion direction using reference parameters from multiple preview frames before initiating the autofocus search. This preliminary determination ensures the lens moves in the optimal direction from the start, maintaining focus coverage while preventing the harmful effect of increasing defocus during the search process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system inverts the conventional bidirectional search approach by first determining the optimal search direction through motion analysis and then performing unidirectional searching. This inversion maintains the versatility of comprehensive focus coverage while eliminating the harmful user experience of increasing defocus during the search.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3218756B1Direction aware autofocus

Publication Date: 2020.10.07 QUALCOMM INC

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AI summary

Methods and imaging devices are disclosed for determining a first direction to move a lens in an autofocus operation. For example, one method includes capturing a plurality of frames depicting a scene, selecting a portion of at least one frame that corresponds to an object in a displayed frame, and tracking the object in the plurality of frames, where tracking the object provides a reference parameter of the object for each of the plurality of frames. The method may further include detecting a change in the reference parameter between at least a first frame and a second frame of the plurality of frames, determining a focus direction based on the change in the reference parameter, and initiating a focus operation by moving a lens of the imaging device based on the determined focus direction.