Micro-Lens Array Position Compensation for Focus Detection

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Solution Overview

Problem

The challenge lies in accurately aligning the micro-lens array and the area sensor in focus detection devices, which hinders precise focus detection due to instability in their positional relationship, making it difficult to achieve high-accuracy focus detection.

Innovation Solution

A light receiving device with a micro-lens array and a storage unit that stores position-related information about the relative positional relationship between the micro-lens array and the light receiving element array, allowing for precise calculation of pupil image positions and normalization of light receiving element outputs to detect focusing conditions accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the micro-lens array and area sensor are layered during manufacturing, then the device structure is simplified and ease of manufacture is improved, but the alignment accuracy between micro-lens centers and light receiving element centers deteriorates

Engineering Contradiction:

Improveease of manufactureVSAvoidalignment accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-storing position-related information about the relative positional relationship between the micro-lens array and light receiving element array during the manufacturing process. This information is saved in a storage unit, allowing the system to compensate for alignment deviations later during operation, thus resolving the contradiction between ease of manufacture and manufacturing precision.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the micro-lens array and area sensor are layered during manufacturing, then the device complexity is reduced, but the reliability of focus detection deteriorates due to unstable positional relationship

Engineering Contradiction:

Improvedevice complexityVSAvoidreliability of focus detection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback by using the stored position-related information to calculate and compensate for the actual positional relationship between the micro-lens array and light receiving element array during operation. This feedback mechanism ensures reliable focus detection despite the simplified layered structure, resolving the contradiction between device complexity and reliability.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If high alignment accuracy is required between micro-lens centers and light receiving element centers, then focus detection precision is improved, but manufacturing difficulty increases and ease of manufacture deteriorates

Engineering Contradiction:

Improvefocus detection precisionVSAvoidease of manufacture

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by capturing and storing the actual positional relationship data during manufacturing, then using this pre-acquired information to enable precise focus detection without requiring difficult high-precision alignment during assembly, thus resolving the contradiction between measurement precision and ease of manufacture.

Inventive Principle:

Principle #10Preliminary action

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 solution enables high-accuracy focus detection without requiring exacting precision in the alignment of the micro-lens array and the area sensor, improving the reliability of focus detection in imaging devices.

Implementation Method 1

a micro-lens array disposed between the image forming optical system and the light receiving element array, which includes a plurality of micro-lenses arrayed in correspondence to the plurality of light receiving elements

Methodology Applied

Scientific EffectLight focusing: Lens

Data Source

PatentUS8680451B2Light receiving device, focus detection device and imaging device

Publication Date: 2014.03.25 NIKON CORP

AI summary

A light receiving device that receives light having passed through an image forming optical system and outputs a light reception signal includes: a light receiving element array formed by arraying a plurality of light receiving elements; a micro-lens array disposed between the image forming optical system and the light receiving element array, which includes a plurality of micro-lenses arrayed in correspondence to the plurality of light receiving elements; and a storage unit that stores position-related information pertaining to a relative positional relationship assumed by the micro-lens array and the light receiving element array with respect to a plane perpendicular to optical axes of the micro-lenses.