Auto-focus Apparatus Using Frequency Response Analysis
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Solution Overview
Problem
Existing auto-focus methods face challenges in achieving accurate focusing, especially under conditions of poor texture contrast and weak ambient light, leading to degraded imaging performance.
Innovation Solution
An auto-focus apparatus and method that utilizes a lens, a lens driving component, and a focus control module to obtain frequency response results from multiple original images, calculating a desired frequency response result to determine the focusing position, with a filter unit adjusting parameters based on historical images to improve focusing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active auto-focus method is used, then auto-focusing can be achieved by measuring distance, but infrared light or ultrasonic waves may be reflected in various directions or not reach the target object, degrading auto-focusing performance
Solution Approach 1:
The patent replaces the active emission system (infrared generator or ultrasound generator) with a passive optical system. Instead of actively sending out infrared light or ultrasonic waves and measuring their reflection, the system uses the existing ambient light reflected from the target object. This substitution eliminates the problems of light scattering and directional reflection while maintaining distance measurement capability through optical focusing.
2Measurement precision
If active auto-focus method is used, then distance measurement is possible, but low contrast between actively sent light and received light makes auto-focusing difficult under weak ambient light
Solution Approach 1:
The patent substitutes the active light emission system with passive ambient light utilization. By removing the infrared generator and relying on natural or environmental light reflected from the target object, the system achieves better contrast under weak ambient light conditions. The imaging sensor directly captures the reflected ambient light without the interference of actively emitted light, solving the low contrast problem.
3Use of energy by moving object
If passive auto-focus method is used, then power consumption and device size are reduced, but focusing performance degrades when target object has poor texture contrast or weak ambient light
Solution Approach 1:
The patent applies preliminary action by performing multiple image captures at different focal positions before determining the final focus. The imaging sensor captures images at multiple predetermined focal positions, and the processor analyzes these preliminary images to identify the optimal focus position. This preliminary sampling approach enables accurate focusing even under poor texture contrast or weak ambient light conditions, while maintaining low power consumption since no active emission system is used.
4Volume of moving object
If passive auto-focus method is used, then device size is reduced, but false focusing occurs and focusing time increases when target object is in narrow strip form with weak texture
Solution Approach 1:
The patent uses preliminary action by capturing images at multiple predetermined focal positions before determining the final focus. This preliminary sampling at different focal planes allows the system to accurately identify the correct focus position even for narrow strip objects with weak texture, preventing false focusing and reducing the time needed to achieve accurate focus while maintaining a compact device size.
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
This approach enhances focusing accuracy and speed, particularly in low-light conditions, and reduces the time required to achieve focus, while minimizing image noise and improving overall imaging performance.
Implementation Method 1
the lens is configured to guide light transmitted from a target object, where original images are formed based on the light guided by the lens at multiple positions
Implementation Method 2
light reflected by a target object (i.e. an object being photographed) is caught by an imaging sensor (such as, a CCD sensor, a CMOS sensor, etc.)
Data Source
AI summary
An auto-focus apparatus and an auto-focus method are provided. The auto-focus apparatus includes: a lens, a lens driving component, and a focus control module; wherein the lens is configured to guide light transmitted from a target object; wherein the lens driving component is configured to drive the lens to move to the multiple positions to obtain the original images, and drive the lens to a focusing position obtained by the focus control module; and wherein the focus control module is configured to obtain frequency respond results each of which corresponds to interested pixels in one of the original images, calculate a desired frequency respond result based on the obtained frequency respond results and take a first position of the lens corresponding to the desired frequency respond result as the focusing position. Accordingly, focus accuracy and focus speed under conditions of poor contrast texture and weak light are improved.