Lens Optical Axis Alignment Using Pre-Recorded Tracking Codes

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Solution Overview

Problem

Existing methods for aligning lens assemblies with digital image sensors in portable devices are limited by mechanical uncertainties, resulting in positional errors and slow assembly rates, as mechanical alignment is faster but less accurate than active alignment.

Innovation Solution

An enhanced assembly method using a tracking code on the lens housing, which includes a micro-barcode for precise optical characterization and alignment, allowing for high-speed and accurate positioning of lenses with respect to the image sensor by utilizing a bonding head with multiple axes of motion and pre-recorded optical characterization data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If mechanical alignment is used to position lenses with respect to the image sensor, then assembly rate is improved (1600 units per hour or more), but manufacturing precision deteriorates (positional uncertainties are introduced)

Engineering Contradiction:

Improveassembly rateVSAvoidpositioning accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-characterizing the optical properties of lens assemblies before assembly. Optical axes and back focal distances are measured and stored in a database prior to the assembly process. During assembly, this pre-recorded data is retrieved and used to guide rapid positioning, eliminating the need for slow active alignment while maintaining high precision. The bonding head positions the lens housing based on pre-fetched optical data, achieving both high speed and accuracy.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If active alignment is used to position the lens housing on the base plate, then manufacturing precision is improved (accurate positioning is achieved), but productivity deteriorates (assembly rate is limited to 200 units per hour or less)

Engineering Contradiction:

Improvepositioning accuracyVSAvoidassembly rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the mechanical active alignment system with an optical data-driven system. Instead of using mechanical feedback and image processing to guide positioning in real-time, the invention uses pre-measured optical characterization data stored in a database. The bonding head retrieves this data and positions components based on the stored optical axes and focal distances, substituting complex real-time mechanical alignment with rapid data retrieval and execution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If multiple positional uncertainties are introduced through mechanical alignment of lens housing to base plate, then ease of manufacture is improved (simple mechanical process), but manufacturing precision deteriorates (accuracy of lens position with respect to image sensor is limited)

Engineering Contradiction:

Improveprocess simplicityVSAvoidlens positioning accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical alignment system with an optical data-driven positioning system. Instead of relying on mechanical fixtures and manual alignment procedures that introduce cumulative errors, the invention uses a bonding head equipped with optical sensors and a database of pre-measured optical characteristics. The system retrieves optical axis and focal distance data, then positions the lens housing and image sensor accordingly, eliminating multiple sources of mechanical positional uncertainty while maintaining process simplicity through automation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10171713B1Method of aligning lens optical axis to image sensor plane without active alignment

Publication Date: 2019.01.01 APPLE INC

AI summary

A tracking code is applied to a lens housing that holds one more lenses. A back focus distance and a tilt of an optical axis with respect to a datum of the lens housing is electronically recorded. A position of an image sensor surface of an image sensor mounted on a substrate is measured. The lens housing is positioned such that the optical axis is perpendicular to the image sensor surface using the measured position of the image sensor surface and the electronically recorded optical data for the lens housing. The lens housing is positioned along the optical axis such that the lenses are separated from the image sensor surface using the measured position of the image sensor surface and the electronically recorded back focus distance for the tracking code of the lens housing. The lens housing is joined to the substrate with an adhesive.