Piezo Actuator Deflection Control for Crystal Pulling

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Solution Overview

Problem

Existing crystal pulling devices face challenges in reducing pendulum deflections during the crystal pulling process, which can lead to orbiting and restrictions in process parameters, requiring complex structural and control designs like a displaceable XY table.

Innovation Solution

A pendulum deflection reduction device using two piezo element units and a control unit is integrated with the crystal pulling device, allowing for targeted control of the deflection pulley to counteract pendulum deflections, thereby reducing or damping subsequent pendulum deflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a displaceable XY table is provided below the cable rotating head to counteract pendulum deflections, then pendulum deflections are reduced, but the device becomes complex and requires heavy stable structure with complex motor drive

Engineering Contradiction:

Improvependulum deflection reductionVSAvoidstructural and control design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of pendulum deflection compensation from the complex XY table system and implements it through a simplified device comprising only a deflection pulley and two piezo element units. This extraction maintains the core functionality while eliminating unnecessary structural complexity and heavy components.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical XY table displacement system with piezoelectric actuators that directly adjust the deflection pulley position. This substitution uses piezoelectric effect-based micro-positioning instead of heavy mechanical movement, achieving the same pendulum deflection compensation with a compact, low-inertia design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a heavy and stable XY table is designed to absorb inertial forces during movement, then pendulum deflection counteraction is effective, but the device complexity and mass increase

Engineering Contradiction:

Improvependulum deflection counteraction effectivenessVSAvoidXY table mass

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the heavy mechanical XY table with lightweight piezoelectric element units that act directly on the deflection pulley. This substitution eliminates the need for heavy inertial mass while maintaining effective pendulum deflection counteraction through precise, rapid piezoelectric actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs piezoelectric elements that can rapidly change their state and provide dynamic adjustment of the deflection pulley position. This dynamic response capability allows effective pendulum deflection compensation without requiring heavy stable structure, as the piezoelectric elements can quickly adapt to changing pendulum motions.

Inventive Principle:

Principle #15Dynamics

3Speed

If the XY table is designed for rapid movement to counteract pendulum deflections, then deflection reduction is effective, but the motor drive becomes complex

Engineering Contradiction:

Improvedeflection counteraction speedVSAvoidmotor drive complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent replaces complex motor drive systems with piezoelectric element units that inherently provide rapid response without complex control electronics. The piezoelectric effect enables direct, high-speed position adjustment of the deflection pulley with simple voltage control, eliminating the need for complex motor drives.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The piezoelectric elements provide self-contained actuation capability, converting electrical signals directly to mechanical displacement without requiring external motor drives or complex transmission systems. This self-service characteristic enables rapid deflection counteraction while minimizing device complexity.

Inventive Principle:

Principle #25Self-service

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 solution effectively reduces pendulum deflections without the need for a displaceable XY table, minimizing mass movement and allowing for rapid deflection reduction, thus enabling crystal pulling within the system's resonant frequency range.

Implementation Method 1

using the piezo effect for the targeted adjustment of a movement section of the deflection pulley

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP4570967A1Device for reducing pendulum deflections during a crystal pulling process

Publication Date: 2025.06.18 SILTRONIC AG

Figure 1A~1B

AI summary

The invention relates to a pendulum deflection reduction device (200) comprising two piezo element units (201, 202) and a control unit, which are designed and interact with a deflection roller (10) of a cable rotating head of a crystal pulling device during a pulling process in such a way that a current pendulum deflection of the crystal rod section growing essentially continuously into a crystal rod is counteracted by means of a targeted, communicating control of the piezo element units (201, 202) via the control unit, using the piezo effect to specifically adjust a movement section of the deflection roller (10).