Digital Camera Autofocus Speed via Dynamic Lens Control
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Solution Overview
Problem
Conventional focus adjustment methods in digital photographic instruments, especially in portable devices like cellular phones and PDAs, are insufficiently quick for single-action mode photography, leading to potential out-of-focus shots and unsatisfactory operational experience due to longer focusing times.
Innovation Solution
A digital photographic instrument with an edge enhancing section that determines focus validity by adjusting the degree of edge enhancement based on focus evaluation values, allowing for faster focusing by varying the lens movement distance and complementing autofocusing with edge enhancement processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lens position is moved gradually to determine focus evaluation values at multiple positions, then the focus precision is improved, but the focusing time increases
Solution Approach 1:
The patent applies dynamics by making the lens movement speed variable rather than constant. The control section adjusts the lens movement speed dynamically based on the focus evaluation value: when the evaluation value indicates good focus, the lens moves faster; when the evaluation value indicates poor focus, the lens moves slower. This dynamic speed adjustment allows the system to maintain high focus precision through multiple evaluation points while reducing overall focusing time by spending less time moving between positions where precise evaluation is less critical.
2Measurement precision
If the lens movement step width is reduced to narrow the distance between positions, then the focus precision is improved, but the focusing time increases
Solution Approach 1:
The patent implements dynamic adjustment of lens movement parameters. The control section varies both the movement speed and step width based on focus evaluation results. When approaching a position with good focus evaluation, the system reduces step width to maintain precision but increases movement speed to cover the reduced distance quickly. This dynamic coordination of step width and speed allows narrow positioning for precision while minimizing the time penalty.
3Productivity
If the lens is moved quickly to shorten focusing time, then the focusing speed is improved, but the focus precision deteriorates
Solution Approach 1:
The patent uses dynamic speed adjustment to resolve the contradiction between focusing speed and precision. The control section monitors focus evaluation values during lens movement and adjusts speed accordingly: faster movement when evaluation values suggest the focus point is distant, slower movement when approaching the optimal focus position. This ensures high focusing speed overall while maintaining precision at critical evaluation points.
Solution Approach 2:
The patent implements feedback control where focus evaluation values obtained during lens movement are fed back to the control section. The control section uses this feedback information to adjust subsequent lens movement speed and positioning. This closed-loop feedback mechanism allows the system to achieve high focusing speed by making informed decisions about where to move quickly and where to move slowly based on real-time focus evaluation, thereby maintaining precision without sacrificing overall speed.
Data Source
AI summary
There is provided a digital photographic instrument comprising an edge enhancing section which enhances the edge of image data. The instrument determines whether a focus is good or bad and adjusts the degree of edge enhancement in the edge enhancing section according to the result of the determination, thereby giving a sharp photograph. The instrument also shortens time required for focusing by complementing an autofocusing mechanism.