Phase-Detection Pixel Light-Blocking Layout for Sensitivity Uniformity
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Solution Overview
Problem
Existing imaging units with image-plane phase-difference detection pixels face variations in detection sensitivity, which affect their phase-difference detection characteristics.
Innovation Solution
The imaging unit incorporates two or more image-plane phase-difference detection pixels with a semiconductor layer, photoelectric converter, charge holding section, first and second light-blocking films, where the second light-blocking films are strategically positioned in specific regions to minimize sensitivity variation by controlling light exposure through an opening in the first light-blocking film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If second light-blocking films are provided in both first regions and second regions of phase-difference detection pixels, then light blocking capability is improved, but detection sensitivity variation increases
Solution Approach 1:
The patent applies local quality by providing second light-blocking films only in first regions (overlapping regions) of phase-difference detection pixels, while omitting them from second regions. This localized approach blocks light only where needed (in overlapping regions) while maintaining uniform detection sensitivity across all pixels by avoiding additional light blocking in non-overlapping regions.
2Measurement precision
If second light-blocking films are added to block light in overlapping regions, then phase-difference detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the pixel region into first regions (overlapping regions) and second regions (non-overlapping regions), and selectively places second light-blocking films only in the first regions. This segmentation approach improves phase-difference detection accuracy by blocking light only where overlapping occurs, while avoiding unnecessary structural complexity by not adding light-blocking films to the entire pixel area.
3Object-affected harmful factors
If second light-blocking films are provided in all pixel regions, then light blocking is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent extracts the second light-blocking films from the entire pixel region and places them only in the first regions (overlapping regions). This extraction approach enhances light blocking effectiveness where needed while reducing manufacturing precision requirements, as fewer films need to be positioned with high precision compared to covering the entire pixel area.
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 configuration reduces variation in detection sensitivity between phase-difference detection pixels, enhancing the phase-difference detection characteristic and achieving superior imaging performance.
Implementation Method 1
The photoelectric converter is provided in the semiconductor layer, and is configured to generate electric charge corresponding to a light reception amount by photoelectric conversion
Data Source
AI summary
An imaging unit having a superior phase-difference detection characteristic is provided. The imaging unit includes two or more image-plane phase-difference detection pixels each including a semiconductor layer, a photoelectric converter, a charge holding section, a first light-blocking film, and a second light-blocking film. The semiconductor layer includes a front surface and a back surface on an opposite side to the front surface. The photoelectric converter is provided in the semiconductor layer, and is configured to generate electric charge corresponding to a light reception amount by photoelectric conversion. The charge holding section is provided between the front surface and the photoelectric converter in the semiconductor layer, and is configured to hold the electric charge. The first light-blocking film is positioned between the photoelectric converter and the charge holding section, and has an opening through which the electric charge is allowed to pass. The second light-blocking film is positioned on an opposite side to the first light-blocking film as viewed from the photoelectric converter. Here, all of the second light-blocking films of the two or more respective image-plane phase-difference detection pixels are provided in respective first regions, or are provided in respective second regions. The first regions each include an overlapping region that is a region overlapping the opening in a pixel region occupied by the photoelectric converter. The second regions are each a region other than the first region in the pixel region.