Camera Auto-Focusing Using Encoder and Distance Sensor
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Solution Overview
Problem
Conventional auto-focusing methods in cameras, whether passive or active, face challenges such as prolonged auto-focusing time, difficulty in successive focusing during moving pictures, and increased manufacturing costs due to the need for individual algorithms and suboptimal driving current applications across different driving units.
Innovation Solution
An apparatus and method utilizing a distance measuring sensor and an encoder-type driving unit, allowing for fast and successive auto-focusing by determining the displacement of the focus lens irrespective of the driving unit characteristics, using a unified algorithm and initial encoder values to optimize focus positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If passive auto-focusing method is used to obtain edge values and move focus lens step by step, then manufacturing cost is reduced and device size is small, but auto-focusing time is prolonged and successive focusing during moving pictures is difficult
Solution Approach 1:
The encoder detects the initial position of the focus lens before auto-focusing begins, and the distance measuring sensor pre-measures the distance to the subject. This preliminary detection of position and distance parameters enables the system to calculate and execute the precise lens displacement needed, rather than moving step-by-step to search for focus. This preliminary action significantly reduces auto-focusing time and enables successive focusing during moving pictures.
2Speed
If active auto-focusing method with distance measuring sensor is used, then auto-focusing speed is improved, but device complexity and manufacturing cost increase due to additional hardware and need for individual algorithms
Solution Approach 1:
The encoder serves multiple functions: it detects the initial position of the focus lens, monitors lens displacement during auto-focusing, and provides feedback for focus verification. This multi-functional use of a single component simplifies the overall device structure compared to using separate components for each function, thereby reducing device complexity while maintaining fast auto-focusing speed.
Solution Approach 2:
The encoder provides real-time feedback on the focus lens position during auto-focusing. The image signal processor compares the detected lens position with the target position calculated from distance measurements, and adjusts the driving current accordingly. This feedback mechanism enables precise focus control without requiring complex individual algorithms for each driving unit, as the system self-corrects based on actual position feedback.
3Ease of manufacture
If common driving current is applied to all driving units to increase manufacturing yield, then manufacturing cost is reduced, but auto-focusing accuracy deteriorates due to characteristic variations of individual driving units
Solution Approach 1:
Each driving unit serves itself by using the encoder to detect its own initial position and the image signal processor to calculate its specific displacement requirement based on distance measurements and lens characteristics. The system determines the precise driving current needed for each individual unit based on real-time feedback, eliminating the need for manual calibration or individualized algorithm programming during manufacturing. This self-service approach maintains high manufacturing yield while achieving accurate focus positioning.
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 quick and successive auto-focusing within one frame, reducing the time required for focusing and simplifying manufacturing by eliminating the need for individual algorithms and optimizing driving current applications.
Implementation Method 1
the light emitted from the distance measuring sensor is an infrared ray
Implementation Method 2
an encoder operative to detect an initial position of the lens system
Implementation Method 3
An image sensor detects the images formed by the lens system and converts them to electrical signals
Data Source
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AI summary
Disclosed is an apparatus and method for auto-focusing a camera, which includes the steps of detecting an initial value of an encoder by measuring an initial position of a lens system, matching the measured initial value of the encoder with the initial position value of the lens system to be moved, measuring a distance value of a subject through a distance measuring sensor, determining a displacement that a focus lens has to be moved with respect to the measured distance value, and adjusting a position of the focus lens such that a position value of the focus lens actually moved is the same as the displacement value.