Image Pickup Element Phase-Difference Detection via Micro-Lens Edge Alignment
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Solution Overview
Problem
Existing image pickup elements with phase-difference detecting functions face challenges in accurately performing focus detection due to reduced light sensitivity and manufacturing difficulties as pixels become miniaturized, particularly due to the need for transistors and small light-blocking mask openings.
Innovation Solution
An image pickup element with a matrix arrangement of photoelectric conversion portions and micro-lenses, where a pair of photoelectric conversion portions optically receive light beams through segmental regions in the exit pupil, with micro-lenses aligned to extend through the edges of the conversion portions, allowing for accurate focus detection and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transistor is installed near each half-sized photoelectric conversion portion to convert output signals, then photoelectric conversion portions can be miniaturized, but the photoelectric conversion portion size is reduced further and light reception sensitivity is lowered
Solution Approach 1:
The photoelectric conversion portion is divided into two independent half-sized photoelectric conversion portions, each capable of receiving light from different pupil segments. This segmentation allows for reduced pixel size while maintaining sufficient light reception area for accurate phase-difference detection.
Solution Approach 2:
A light-blocking mask with specifically designed opening patterns is introduced as an intermediary element to control and direct light beams to the appropriate photoelectric conversion portions. This mask enables proper light routing despite the miniaturized structure, maintaining detection accuracy.
2Manufacturing precision
If small openings are formed in the light-blocking mask to limit photographic-subject light, then pupil segmentation is achieved, but manufacturing difficulty increases as pixels are miniaturized
Solution Approach 1:
The design parameters of the light-blocking mask openings are optimized to achieve effective pupil segmentation while maintaining manufacturability. The opening dimensions and patterns are carefully calculated to provide sufficient light control without requiring excessively small or complex structures that would be difficult to manufacture.
3Productivity
If photoelectric conversion portions are reduced in size for pixel miniaturization, then more pixels can be packed, but the amount of light received is reduced and sensitivity is lowered
Solution Approach 1:
By segmenting each pixel into two specialized photoelectric conversion portions, each portion can be optimized for specific light reception tasks. This segmentation allows for efficient use of the reduced pixel area while maintaining adequate light reception capability for phase-difference detection.
Solution Approach 2:
The patent replaces traditional mechanical light control mechanisms with an optically optimized structure where micro-lenses and light-blocking masks work together to direct light efficiently to the miniaturized photoelectric conversion portions, compensating for their reduced 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
The solution enables accurate phase-difference focus detection with improved light sensitivity and manufacturing feasibility even as pixels are miniaturized, minimizing blockage of necessary light and reducing ghost flare occurrences.
Implementation Method 1
a pair of photoelectric conversion portions that optically receive, via a pair of micro-lenses, photographic-subject light beams passing through a pair of segmental regions
Implementation Method 2
photoelectric conversion portions (photodiodes) that generate pixel signals by optically receiving photographic-subject light beams
Data Source
AI summary
An image pickup element includes a light-receiving portion having a matrix arrangement formed by disposing first-direction arrays, each having photoelectric conversion portions arranged in a first direction with a predetermined gap maintained therebetween, in a second direction orthogonal to the first direction, and micro-lenses provided above the light-receiving portion. A certain first-direction array in the matrix arrangement is provided with a pair of photoelectric conversion portions that optically receive, via a pair of micro-lenses, photographic-subject light beams passing through a pair of segmental regions in an exit pupil of a photographic optical system, the pair of segmental regions being disposed biasedly in opposite directions from each other in the first direction. The pair of micro-lenses is disposed such that light axes thereof extend through vicinities of edges of the pair of photoelectric conversion portions, the edges being the farthest edges from each other in the first direction.