Focus Detection Pixel Pairs for Dark Subject Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing focus state detection methods in digital cameras face challenges in accuracy due to misalignment between photoelectric converters and microlenses, leading to noise and reduced contrast, especially when capturing dark subjects or those with low contrast, resulting in suboptimal focus state detection.
Innovation Solution
The optical device employs a combination of first and second focus state detection pixel pairs that receive light fluxes from different pupil areas of the photographing lens, with a detection unit that adjusts its method based on the subject's brightness and contrast, either averaging signals or selecting between detection states to enhance focus state detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photoelectric converter is divided into two sections to receive light beams from different pupil areas for focus state detection, then focus state detection capability is enabled, but misalignment between photoelectric converters and microlenses occurs during manufacturing, leading to noise and reduced detection accuracy
Solution Approach 1:
The photoelectric converter is divided into two distinct sections (first and second photoelectric converters) that respectively receive light beams from different pupil areas (first and second pupil areas). This segmentation enables the system to perform focus state detection by comparing signals from these separated regions, allowing accurate focus detection while managing the complexity of alignment through functional separation.
Solution Approach 2:
The patent combines multiple pixel pairs (both first and second focus state detection pixel pairs) to generate composite first and second images. By merging the signals from multiple pixel pairs, the system improves signal-to-noise ratio and maintains detection reliability even when individual pixels suffer from misalignment issues during manufacturing.
2Measurement precision
If multiple focus state detection pixel pairs are used to improve signal strength, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The first and second focus state detection pixel pairs serve multiple functions: they enable focus state detection through pupil division, provide redundant signals for improved accuracy, and can be integrated into the existing image sensor array without requiring completely separate detection hardware. This multi-functionality approach improves precision while managing device complexity.
Solution Approach 2:
The patent utilizes the pupil area dimension (spatial distribution of light entry points) to create distinct first and second pupil areas that map to different photoelectric converter sections. This dimensional approach allows focus detection to be performed using existing sensor structures, avoiding the need for additional complex detection hardware while maintaining measurement precision.
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 reduces noise and improves focus state detection accuracy by adapting to varying subject conditions, ensuring precise focus control even in challenging lighting scenarios.
Implementation Method 1
a first focus state detection pixel pair, which receives a pair of light fluxes having transmitted different pupil areas of the photographing lens
Data Source
AI summary
An optical device comprises an image sensor having plural pixels and a detection unit configured to detect a focus state. The pixels include first focus state detection pixel pairs that respectively receive a pair of light fluxes having transmitted different pupil areas of the photographing lens, and second focus state detection pixel pairs that respectively receive a pair of light fluxes having transmitted pupil areas shifted by a predetermined amount from the pupil areas where the pair of light fluxes received by the first focus state detection pixel pairs have transmitted. The detection unit detects the focus state based on signal pairs obtained by adding the signals output from the first and second focus state detection pixel pairs, respectively, if a subject to be photographed is darker than a predetermined brightness, otherwise the detection unit detects the focus state based on signal pairs output from the first and second focus state detection pixel pairs, respectively.