Lens Drive Unit Capacitor Filtering for Position-Sensor Noise

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Solution Overview

Problem

Existing camera modules for compact electronic devices face challenges in low power consumption and stability due to noise from crosstalk with coils and inadequate feedback closed-loop performance of position sensors.

Innovation Solution

A lens drive unit is designed with a bobbin, first coil, first magnet, and first position sensor, incorporating a capacitor connected in parallel to the circuit board to eliminate noise and improve feedback performance, along with a resistor and elastic members for stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a voice coil motor (VCM) is used for autofocus in a general camera module, then autofocus functionality is achieved, but power consumption is high and cannot be applied to subminiature camera modules

Engineering Contradiction:

Improvepower consumptionVSAvoidapplicability to subminiature camera modules

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The patent extracts the essential feedback control function from the traditional VCM system and implements it using a simplified coil-magnet-elastic member mechanism. The position sensor feedback is separated and processed independently, enabling the system to achieve autofocus functionality with significantly reduced power consumption suitable for subminiature camera modules.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the operating parameters by using a different drive mechanism (coil-magnet interaction instead of VCM) and adjusting the feedback loop parameters through the position sensor. This allows the system to maintain autofocus capability while operating at lower power levels appropriate for portable devices.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If additional destabilization inhibiting means is installed in the camera module, then stability during photographing is improved, but device complexity increases

Engineering Contradiction:

Improvestability during photographingVSAvoiddevice complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the autofocus mechanism and image stabilization functionality into a single integrated system. The coil-magnet assembly serves dual purposes: driving autofocus while the position sensor feedback loop simultaneously provides stabilization. This consolidation achieves destabilization inhibition without proportionally increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The position sensor and feedback circuitry serve multiple functions: they provide feedback for autofocus control while simultaneously enabling image stabilization. This multi-functionality allows the system to address both autofocus and stabilization requirements through a single integrated mechanism rather than separate dedicated systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If a capacitor is connected in parallel to the circuit board to eliminate noise, then feedback closed-loop performance is improved, but device complexity increases

Engineering Contradiction:

Improvefeedback closed-loop performanceVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent converts the harmful electromagnetic interference and noise from the coil-magnet interaction into a beneficial signal processing opportunity. By adding the capacitor in parallel to create an RC filter network, the system transforms the noisy feedback signal into a cleaned, more accurate position signal, thereby improving closed-loop performance. The resistor-capacitor combination converts the harmful high-frequency noise into a useful filtering mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Noise due to crosstalk is eliminated, and feedback closed-loop performance of the position sensor is enhanced, ensuring improved stability and reduced power consumption.

Implementation Method 1

a capacitor connected in parallel to the first and second terminals of the circuit board to eliminate noise from an output of the first position sensor

Methodology Applied

Scientific EffectElectromagnetic filtering: Filter (electronic)

Implementation Method 2

a first coil disposed on an outer circumference of the bobbin, a first magnet disposed on a lateral portion of the housing so as to correspond to the first coil

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS12436360B2Lens driving device, and camera module and optical instrument comprising same

Publication Date: 2025.10.07 LG INNOTEK CO LTD

AI summary

An embodiment comprises: a housing a bobbin disposed inside the housing, and having a lens disposed thereon; a first coil disposed at the outer circumferential surface of the bobbin; a first magnet disposed at a size part of the housing in correspondence to the first coil; a first position sensor disposed in the bobbin, and including first and second input terminals and first and second output terminals; a circuit board including first and second terminals electrically connected to the first and second output terminals of the first position sensor; and a capacitor connected in parallel to the first and second terminals of the circuit board so as to remove noise from the output of the first position sensor.