Spectacle Frame Contour Scanning with Dynamic Stylus Speed Control

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Solution Overview

Problem

Existing methods for scanning the contour of spectacle frame openings for peripheral grinding of lenses are inefficient, requiring high equipment and control effort, and often result in deformation or stylus dislodgment from lightweight frames, especially with angular or heavily shelled designs.

Innovation Solution

A method where the rotational speed of the stylus is adjusted based on radial speed and Z-axis acceleration to maintain constant, low force contact, preventing deformation and stylus dislodgment, achieved by programming the evaluation and control unit to regulate rotational speed in real-time according to radial and Z-axis position data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the stylus scans the contour of spectacle frame openings at high speed, then scanning efficiency is improved, but the stylus may lift up or fall out of the frame groove

Engineering Contradiction:
Improvescanning speedVSAvoidstylus contact stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies dynamics by making the rotational speed of the stylus variable rather than constant. The control unit continuously adjusts the rotational speed based on real-time feedback from position sensors, allowing the stylus to maintain stable contact with the frame groove while achieving high scanning efficiency. This dynamic speed adjustment resolves the contradiction between scanning speed and contact stability.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the stylus exerts larger force to maintain contact with the frame groove, then scanning reliability is improved, but the spectacle frame may deform

Engineering Contradiction:
Improvestylus contact stabilityVSAvoidframe shape accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements feedback control where position sensors continuously monitor the stylus position and frame response, and the control unit adjusts the rotational speed accordingly. This feedback mechanism ensures the stylus maintains adequate contact force for reliable scanning while preventing excessive force that would deform the frame, thus resolving the contradiction between contact stability and frame accuracy.

Inventive Principle:
Principle #23Feedback

3Reliability

If complex sequence control is implemented to regulate stylus movement, then scanning reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvescanning process reliabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the operational parameter of rotational speed from a fixed value to a dynamically adjustable parameter controlled by a simple control unit. This approach achieves reliable scanning through parameter optimization without requiring complex sequence control mechanisms, thereby resolving the contradiction between scanning reliability and device simplicity.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If the stylus rotational speed is increased to improve productivity, then scanning efficiency is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvescanning speedVSAvoidcontour scanning accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by continuously adjusting the rotational speed based on the specific scanning conditions and frame geometry. The control unit optimizes the rotational speed in real-time to maintain measurement precision while achieving high scanning efficiency, resolving the contradiction between productivity and measurement accuracy.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP1974854B1Method for scanning the contours of openings in a spectacles frame and device for scanning the contours of openings in a spectacles frame for the peripheral grinding of spectacles lenses
Publication Date: 2010.09.01 BUCHMANN DEUTSCHLAND GMBH
  • EP1974854B1 patent drawingFigure 1~4

AI summary

The method involves controlling the rotating speed of a tracing pin (24) relative to a spectacle frame opening (23) depending on the radial velocity or radial acceleration and the speed or acceleration by an evaluation and control unit (33) in direction of the Z-axis of the tracing pin. The radial velocity or radial acceleration and the speed or acceleration is remained within the predetermined limits in the direction of the Z-axis of the tracing pin. An independent claim is also included for an application of a device for scanning the contour of a spectacle frame opening.