Digital Camera Autofocus Lens Speed Control

Solution Overview

Problem

Conventional digital cameras with automatic-focusing functions based on contrast detection type face challenges in timing the shutter release accurately and suffer from time lag between focusing and capturing, as they require image data processing and lens position adjustment, leading to delayed image capture and potential misalignment.

Innovation Solution

An image capture device with automatic-focusing capabilities that compares contrast values of images captured while moving the focus lens, allowing for faster and more accurate focusing by switching between low-speed and high-speed focusing modes based on the shutter button's half-pressed and full-pressed states, enabling immediate and precise image capture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional contrast detection automatic focusing is used, then focusing accuracy is achieved, but time lag occurs between shutter release and image capture

Engineering Contradiction:

Improvefocusing accuracyVSAvoidtime lag

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary focusing adjustment during the half-pressed state of the shutter button, completing the focusing process before the actual capture moment. This preliminary action eliminates the time lag that would otherwise occur between shutter release and focused image capture.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamic focusing speed adjustment based on shutter button state. During half-press, the focus lens moves at a first speed for precise adjustment. When the shutter is fully pressed, the system switches to a second speed to rapidly complete focusing, thereby reducing time lag while maintaining accuracy.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If focusing adjustment is performed before capture, then focusing accuracy is improved, but shutter release timing is delayed

Engineering Contradiction:

Improvefocusing accuracyVSAvoidshutter release timing

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The system performs preliminary focusing adjustment during the half-pressed state of the shutter button, completing the focusing process before the actual capture moment. This preliminary action eliminates the time lag that would otherwise occur between shutter release and focused image capture.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamic focusing speed adjustment based on shutter button state. During half-press, the focus lens moves at a first speed for precise adjustment. When the shutter is fully pressed, the system switches to a second speed to rapidly complete focusing, thereby reducing time lag while maintaining accuracy.

Inventive Principle:

Principle #15Dynamics

3Loss of time

If fast focusing is implemented, then time lag is reduced, but focusing precision deteriorates

Engineering Contradiction:

Improvetime lagVSAvoidfocusing accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The patent implements dynamic focusing speed adjustment based on shutter button state. During half-press, the focus lens moves at a first speed for precise adjustment. When the shutter is fully pressed, the system switches to a second speed to rapidly complete focusing, thereby reducing time lag while maintaining accuracy.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The focusing process is segmented into two distinct phases: a first phase during half-press with slower, more precise focusing, and a second phase during full press with faster focusing. This segmentation allows the system to optimize for both precision and speed at different stages of the capture process.

Inventive Principle:

Principle #1Segmentation

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

The solution ensures accurate focusing and timely shutter release, reducing time lag and improving the quality of captured images by optimizing focusing speed and precision during the image capture process.

Implementation Method 1

image capture element, by which an image of a subject is captured

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

focus lens, which can be moved along an optical axis of the objective lens to adjust a focus position

Methodology Applied

Scientific EffectMechanical displacement for optical focusing:

Implementation Method 3

objective lens, a subject image of a subject is formed by the objective lens on the image capture element

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS7515820B2Image capture device with automatic focusing function

Publication Date: 2009.04.07 CASIO COMPUTER CO LTD

AI summary

In a digital camera, a focus lens is moved at a low speed between a timing at which a shutter key is half pressed and a timing at which the shutter key is fully pressed to detect a focused position. When the shutter key is fully pressed by a user before the focus lens reaches a focused position, the focus lens is moved at a higher speed than that of a case in which the shutter key is half pressed, and a focused position is detected. Thereby, even when the shutter key is fully pressed by a user before the focus lens reaches the focused position, the digital camera can realize focusing with less delay in capturing.