Phase Difference Pixel Arrangement for Light Leakage Control

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Solution Overview

Problem

In color image capturing elements, light leakage from image capturing pixel cells to phase difference detection pixel cells causes color mixture, leading to degraded accuracy in phase difference detection, which is further influenced by the color of the photographic subject and difficult to correct.

Innovation Solution

A solid state image capturing element with pixel cells arranged in a two-dimensional array, each equipped with a color filter separating light into three colors, includes specific patterns of phase difference detecting pixel cells to minimize light interference, using correlation operations between different types of phase difference detecting pixel cells to calculate phase difference information and control focusing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pixel cells for phase difference detection are arranged adjacent to pixel cells for image capturing, then phase difference detection can be performed, but light leaks from image capturing pixel cells to phase difference detecting pixel cells causing color mixture which degrades detection accuracy

Engineering Contradiction:

Improvephase difference detection accuracyVSAvoidlight leakage and color mixture

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A light shielding structure (black matrix or light blocking wall) is introduced as an intermediary element between the image capturing pixel cells and phase difference detecting pixel cells. This intermediary blocks the leaked light from reaching the phase difference detecting pixel cells, thereby preventing color mixture while allowing the compact adjacent arrangement to be maintained.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The pixel array is segmented into distinct functional regions with clear spatial separation. Phase difference detecting pixel cells are grouped in specific patterns (such as alternating rows or columns) rather than being randomly distributed, creating discrete zones that reduce cross-contamination from leaked light while maintaining detection functionality.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If pixel cells for phase difference detection and image capturing are mixed in a two-dimensional arrangement, then device complexity is reduced, but color mixture occurs which degrades measurement precision

Engineering Contradiction:

Improvepixel arrangement complexityVSAvoidphase difference detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The pixel arrangement uses an asymmetric pattern where phase difference detecting pixel cells are positioned in specific non-uniform locations (such as alternating rows or columns rather than a regular grid). This asymmetric arrangement reduces the symmetry of light leakage paths and minimizes color mixture effects while maintaining a relatively simple overall two-dimensional structure.

Inventive Principle:

Principle #4Asymmetry

3Ease of manufacture

If the arrangement pattern of pixel cells is simplified, then manufacturing becomes easier, but light leakage causes color mixture which affects detection accuracy

Engineering Contradiction:

Improvepixel array fabricationVSAvoidphase difference detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The light shielding structures are applied locally only at the boundaries between image capturing pixel cells and phase difference detecting pixel cells, rather than uniformly across the entire pixel array. This localized approach prevents color mixture at critical interfaces while maintaining manufacturing simplicity for the majority of the pixel array.

Inventive Principle:

Principle #3Local quality

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 prevents accuracy degradation in phase difference detection due to color mixture, enabling precise focus control by minimizing the influence of color interference in phase difference information calculation.

Implementation Method 1

each of the plurality of pixel cells has a color filter which is formed above the photoelectric converting unit, and light which is transmitted through the color filters and is separated to at least three different colors

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a plurality of pixel cells each including a photoelectric converting unit

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS9172925B2Solid state image capturing element, image capturing apparatus, and focusing control method

Publication Date: 2015.10.27 FUJIFILM CORP

AI summary

An image capturing element 5 has a phase difference detecting region 50a in a light receiving region 50 in which pixel cells are arranged, in the region 50a, some of pixel cells mounted with G filters, among the pixel cells which are arranged in a Bayer pattern, serve as phase difference detecting pixel cells 51R and 51L, the pixel cell 51L and the pixel cell 51R receive light which passes through different pupil areas of the image capturing lens 1, the pixel cell 51L includes two types of pixel cells (3) and (4) having different arrangement patterns of the adjacent pixel cells 51 and the pixel cell 51R includes two types of pixel cells (1) and (2) having different arrangement patterns of the adjacent pixel cells 51.