Image Sensor Focus Detection Pixel Arrangement

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Solution Overview

Problem

Image signal calculation for focus detection pixels in image-capturing apparatuses often requires interpolation from distant imaging pixels, leading to poorer image quality, especially when blue edges are detected, as existing technologies rely on significant distances for pixel signal generation.

Innovation Solution

Focus detection pixels are alternately disposed with blue and green pixels in image sensor arrays, allowing for more accurate pixel signal interpolation using nearby imaging pixels, reducing interpolation errors and improving image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If focus detection pixels are disposed in a standard Bayer array position, then the image sensor can maintain a regular pixel structure, but pixel signals for focus detection pixels must be interpolated from distant imaging pixels, resulting in significant interpolation errors and poorer image quality

Engineering Contradiction:
Improvepixel signal accuracyVSAvoidpixel array structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating a specialized pixel arrangement where focus detection pixels are surrounded by a dedicated ring of auxiliary imaging pixels at adjacent positions. This local restructuring ensures that each focus detection pixel has nearby reference pixels for accurate interpolation, while the rest of the image sensor maintains the standard Bayer array structure. The auxiliary pixels are specifically positioned to provide color information from all three color channels (red, green, blue) at adjacent locations, enabling accurate signal generation without significant interpolation errors.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If pixel interpolation is performed using distant imaging pixels, then focus detection pixels can be positioned in standard array locations, but the interpolation error increases significantly, especially for blue edges and fine details

Engineering Contradiction:
Improvefocus detection capabilityVSAvoidimage signal accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-arranging auxiliary imaging pixels in specific positions around each focus detection pixel before the actual focus detection process. These auxiliary pixels are positioned in advance to ensure they are adjacent to the focus detection pixels, creating a ready-made interpolation framework. This preliminary structural arrangement ensures that when focus detection is performed, the required pixel signals can be immediately obtained from nearby auxiliary pixels without needing to perform long-distance interpolation, thereby ensuring high signal accuracy for focus detection.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2076025B1Image sensor, focus detection device, focus adjustment device and image-capturing apparatus
Publication Date: 2013.03.20 NIKON CORP
  • EP2076025B1 patent drawingFigure 1
  • EP2076025B1 patent drawingFigure 2
  • EP2076025B1 patent drawingFigure 3

AI summary

An image sensor includes: a plurality of imaging pixel rows, which include a plurality of types of imaging pixels with varying spectral sensitivity characteristic that are arrayed two-dimensionally based upon a first spectral sensitivity characteristics array pattern; and at least one non-imaging pixel row, which includes a plurality of non-imaging pixels that are disposed in place of some of the pluralityof types of imagingpixels in the plurality of imaging pixel rows. The plurality of imaging pixel rows include adj acent imaging pixel rows made up with the plurality of types of imaging pixels and set adjacent to the non-imaging pixel row; and the adjacent imaging pixel rows assume a second spectral sensitivity characteristics array pattern different from the first spectral sensitivity characteristics array pattern, so that spectral sensitivity characteristics different from spectral sensitivity characteristics achieved in conformance to the first spectral sensitivity characteristics array pattern are achieved via specific imaging pixels making up part of the adjacent imaging pixel rows.