Ranging Apparatus N-Order Correction Function
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Solution Overview
Problem
Recent digital cameras with optical image stabilizers face challenges in accurately correcting light quantity balance between A-image and B-image for focus detection, leading to decreased ranging accuracy and increased computational costs due to production errors and noise effects.
Innovation Solution
A ranging apparatus that calculates a correction function approximating the output ratio data using an N-order function to correct the light quantity balance between A-image and B-image, allowing for high-accuracy ranging with reduced computational volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If template matching is used to calculate image shift amount with a large search region size, then ranging accuracy is improved, but computational volume increases
Solution Approach 1:
The patent applies preliminary action by calculating and storing correction coefficients for light quantity balance collapse before actual ranging operations. The correction function is pre-computed based on pupil region characteristics, allowing the main template matching process to use smaller search regions while maintaining accuracy through pre-applied corrections to the picture image data.
2Measurement precision
If correction coefficient is calculated after assembling lens and imaging sensor, then production error effects are reduced, but manufacturing complexity increases
Solution Approach 1:
The correction coefficients are calculated as a preliminary step during the manufacturing process, specifically after assembling the lens and imaging sensor. This preliminary calculation captures the actual light quantity balance characteristics of the assembled components, allowing production errors to be compensated without requiring complex post-assembly adjustments or recalibrations.
3Measurement precision
If uniform irradiation method is used to correct light quantity balance, then light quantity ratio accuracy is improved, but noise effects increase
Solution Approach 1:
The patent applies local quality by calculating separate correction coefficients for different pupil regions (first pupil region and second pupil region) rather than using a single uniform correction factor. This allows the correction to account for local variations in light quantity balance across the pupil, reducing the need for excessive uniform irradiation that would amplify noise while still achieving accurate light quantity balance correction.
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 enables high-accuracy ranging with a small computational volume, reducing errors caused by light quantity balance collapse and noise, while minimizing production adjustments and costs.
Implementation Method 1
pixels having a ranging function are arranged in the entire imaging sensor or part thereof, and the distance to an object is detected by a phase difference method. The ranging pixels are equipped with a plurality of photoelectric conversion units and configured such that light fluxes that have passed through different regions on a lens pupil are guided to different photoelectric conversion units.
Data Source
AI summary
A ranging apparatus includes: an output ratio data calculation unit for calculating an output ratio data of first and second image data; a correction function calculation unit for calculating a correction function approximating the output ratio data by an N-order function (N being an integer equal to or greater than 1) having a pixel position as a variable; a correction unit for correcting at least one of the first and second image data on the basis of the correction function; and a ranging unit for calculating the defocus amount by using the picture image data corrected by the correction unit.