Dental Handpiece Control for Dynamic Rotation Angle Adjustment

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Solution Overview

Problem

Existing dental handpiece control methods for reciprocating rotations in root canal cutting often result in file breakage due to fixed rotation angles, causing the file to bite into the tooth even under increased loads.

Innovation Solution

A dental handpiece control apparatus that dynamically adjusts the forward and backward rotation angles based on load torque, reducing the likelihood of file biting by setting smaller forward rotation angles and larger backward rotation angles as load torque increases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If fixed preset rotation angles are used for forward and backward rotations, then the control system is simple and easy to operate, but the file continues to rotate up to the set angle even when load increases, causing the file to bite into the root canal and potentially break

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of rotation angles based on real-time load torque detection. The control system continuously monitors load torque and modifies forward and backward rotation angles accordingly, transitioning from fixed preset values to variable values that adapt to changing operational conditions, thereby preventing file breakage while maintaining ease of use through automated control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates a load torque detection unit that provides real-time feedback to the control system. This feedback mechanism enables the system to monitor load conditions and automatically adjust rotation angles to prevent excessive force application, resolving the contradiction between simple operation and reliable operation by automating the adjustment process

Inventive Principle:
Principle #23Feedback

2Productivity

If the first rotation angle is made larger than the second rotation angle to eject cut debris upwardly, then debris ejection is improved, but the file may bite into the root canal when load increases, causing breakage

Engineering Contradiction:
ImproveproductivityVSAvoidreliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent dynamically adjusts the relationship between forward and backward rotation angles based on load torque. When load torque is low, the forward rotation angle exceeds the backward rotation angle to optimize debris ejection. When load torque increases, the system reduces the forward rotation angle or increases the backward rotation angle to prevent file biting, thereby maintaining both productivity and reliability through adaptive control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the rotation angle parameters in response to load torque variations. By modifying these parameters dynamically, the system optimizes debris ejection efficiency under normal conditions while preventing file breakage under high load conditions, thus resolving the contradiction between productivity and reliability

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2805687B1Device for controlling a dental handpiece
Publication Date: 2018.08.29 NAKANISHI INC
  • EP2805687B1 patent drawingFigure 1
  • EP2805687B1 patent drawingFigure 2
  • EP2805687B1 patent drawingFigure 3

AI summary

A dental handpiece control apparatus including: a relay 17 that switches a polarity of a voltage applied to a motor 20, and thereby switches a rotation direction of the motor 20 to forward rotation and backward rotation, the motor 20 being incorporated in the dental handpiece to rotate a cutting tool (a file) mounted to the dental handpiece; and a control section 11 that controls the switching of the voltage polarity by the relay 17 based on a rotation angle θF for forward rotation and a rotation angle θR for backward rotation of the motor 20, the rotation angle θF and the rotation angle θR being associated with state information of the file.