Vehicular Camera Focus Drift Mitigation via MEMS Imager Adjustment

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Solution Overview

Problem

Vehicle camera systems face misalignment issues due to plastic housing shrinkage over time, leading to degraded image quality as the imager and lens become misaligned, which existing technologies fail to dynamically compensate for effectively.

Innovation Solution

A micro-electro-mechanical system (MEMS) based control system using capacitive comb drives adjusts the imager's position relative to the PCB to maintain optimal focus, employing electrostatic actuation and thermal actuation to correct focus shifts caused by material shrinkage and thermal expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plastic housing is used in camera module, then manufacturing cost is reduced, but focus alignment drifts over time due to shrinkage

Engineering Contradiction:

Improvemanufacturing costVSAvoidfocus alignment stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent implements a dynamic focus adjustment mechanism that continuously or periodically adjusts the imager position to compensate for drift caused by plastic housing shrinkage. The system transitions from a static fixed-focus design to a dynamic adaptive-focus design, allowing the camera to maintain optimal focus despite material degradation over time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs a feedback control system where the ECU monitors image focus quality and automatically adjusts the imager position accordingly. This closed-loop feedback mechanism detects focus drift caused by plastic shrinkage and compensates in real-time, resolving the reliability issue while maintaining the cost benefits of plastic housing.

Inventive Principle:

Principle #23Feedback

2Device complexity

If imager position is fixed on PCB, then device complexity is reduced, but image quality degrades due to misalignment

Engineering Contradiction:

Improvecamera structure complexityVSAvoidimager-lens alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces a movable imager mechanism that can adjust its position relative to the lens along the optical axis. This dynamic positioning capability allows the system to compensate for alignment drift without requiring complex precision manufacturing, as the adjustment mechanism corrects minor misalignments after assembly.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent separates the imager from the main PCB structure, allowing it to be positioned and adjusted independently. This segmentation enables focused adjustment of the imager-lens alignment without affecting other camera components, reducing overall device complexity while improving alignment precision.

Inventive Principle:

Principle #1Segmentation

3Productivity

If standard camera design is used, then productivity is maintained, but focus drift requires expensive materials and lenses

Engineering Contradiction:

Improvecamera production efficiencyVSAvoidfocus stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a self-correcting focus system where the camera automatically compensates for its own drift issues through the ECU-controlled imager adjustment. This self-service capability eliminates the need for expensive drift-resistant materials and precision lenses, allowing standard components to be used while maintaining focus stability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the operational parameters of the camera system by introducing active focus adjustment capability. This allows the system to adapt to drift conditions dynamically, maintaining image quality with standard components rather than requiring expensive materials designed to prevent drift in the first place.

Inventive Principle:

Principle #35Parameter changes

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

The system dynamically compensates for focus shifts, enhancing image quality and camera lifespan by allowing the use of less expensive materials and lenses, reducing design complexities and costs, while minimizing the impact of vibrations and temperature changes.

Implementation Method 1

Methodology Applied

Scientific EffectElectrostatic actuation: Electrostatics

Implementation Method 2

employing electrostatic actuation and thermal actuation to correct focus shifts caused by material shrinkage and thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11800222B2Vehicular camera with focus drift mitigation system

Publication Date: 2023.10.24 MAGNA ELECTRONICS INC

AI summary

A vehicular camera system includes a camera module disposed at a vehicle that captures image data. The camera module includes a printed circuit board (PCB) having an imager disposed thereat that includes an imaging array having at least one million photosensors arranged in rows and columns. The camera module includes a lens aligned with the imager. The system includes an electronic control unit (ECU) with electronic circuitry and associated software. With the camera module disposed at the vehicle, and responsive to images imaged at the imager not being focused, the vehicular camera system adjusts position of the imager relative to the PCB to bring images imaged at the imager into focus.