Lens Drive Position Sensor Placement for Compact Optical Modules

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Solution Overview

Problem

Conventional lens drive devices face challenges in downsizing while maintaining position detection accuracy and accommodating larger lens diameters, due to limited space for position sensor arrangements.

Innovation Solution

The lens drive device features a position sensor arranged between wire connection positions and a coil, overlapping with the sides of a four-sided polygon, allowing for undivided coil placement and precise position control, with a circuit board design that reduces noise interference and stress on the position sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the position sensor is arranged in the middle part of a side (conventional arrangement), then the coil can be divided into two portions with the sensor in between, but the arrangement region for the position sensor becomes limited and it becomes hard to maintain position detection accuracy

Engineering Contradiction:

Improvecoil arrangementVSAvoidposition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

Instead of placing the position sensor in the middle of a coil side (conventional approach), the patent inverts the arrangement by placing the sensor between the wire connection position and the coil. This reversal of the conventional arrangement allows the coil to remain undivided while providing adequate space for the position sensor, thereby maintaining position detection accuracy without requiring coil segmentation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Area of moving object

If the lens diameter is increased while maintaining the outer diameter size of the lens drive device, then the device achieves better imaging performance, but the space for position sensor arrangement becomes even more limited

Engineering Contradiction:

Improvelens diameterVSAvoidposition sensor arrangement space

Core Design Contradiction:

Area of moving objectVSArea of stationary object

Solution Approach 1:

The patent utilizes the radial dimension by positioning the position sensor between the wire connection position (at the outer periphery) and the coil (closer to the center). This radial arrangement optimizes the use of available space in the limited area, allowing for larger lens diameters while maintaining adequate space for the position sensor without increasing the overall device outer diameter.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If the position sensor is arranged near the wire connection position, then there is sufficient space for the sensor and its wiring, but the coil needs to be positioned accordingly which may affect drive force generation

Engineering Contradiction:

Improveposition sensor arrangement spaceVSAvoidelectromagnetic drive force

Core Design Contradiction:

Area of stationary objectVSForce

Solution Approach 1:

The patent applies local quality by creating distinct functional zones: the position sensor is positioned in the region between the wire connection and the coil where local space availability is optimal, while the coil maintains its integrity and positioning in the region most favorable for generating electromagnetic drive force. This localized optimization of different functional requirements resolves the conflict between space availability and drive force generation.

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 configuration enables downsizing of the device, allows for larger lens diameters, and maintains precise position detection accuracy by preventing position detection errors and noise interference.

Implementation Method 1

the movable portion can move relatively to the fixed portion in a vertical direction to the light axis direction by an electromagnetic force generated in the magnet and the coil

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

the hole element can detect a magnetic force by a magnet constituting the drive means and can detect a position of the blur correction movable portion

Methodology Applied

Scientific EffectMagnetic force detection: Magnetic Field

Data Source

PatentUS10444531B2Lens drive device having position sensor and circuit board

Publication Date: 2019.10.15 ACTUTEK CORP

AI summary

A lens drive device includes a movable portion, a fixed portion, and four suspension wires. The movable portion has a lens holder holding a lens and a magnet arranged at a position that does not overlap with the lens when viewed from a light axis direction. The fixed portion has a coil and a position sensor arranged to oppose against the magnet in the light axis direction and a circuit board having multiple wirings. The wires are arranged around the lens at approximately equal intervals in the light axis direction. The sensor and the coil are arranged to overlap with four sides of a four-sided polygon formed by connecting four wire connection positions where the wires are connected with the fixed portion. The sensor is arranged between the wire connection position closest to the sensor and the coil closest thereto.