Method for improving the centering of stamping matrices

Abstract

Abstract THE CARE AND ACCURACY OF CENTERING THE NEGATIVE, E.G. OF THE MASTER OR STAMPING MATRIX, USED IN THE PRODUCTION OF SOUND AND VIDEO RECORD DISCS IS IMPROVED BY PREPARING THE ORIGINAL LACQUER FOIL RECORD SO THAT THE NEGATIVE WILL HAVE A PROFILE WHICH EXTENDS CENTRICALLY TO THE RECORD GROOVE SPIRAL. THIS IS ACCOMPLISHED BY, PRIOR TO THE CUTTING OF THE SPIRAL GROOVE CONTAINING THE RECORDED INFORMATION INTO THE LACQUER FOIL, INSERTING A CENTERING CORE, WHICH HAS A CENTRAL BORE OF A DIAMETER SUFFICIENT TO ACCEPT THE SPINDLE OF THE RECORDER TURNATABLE AND HAS A LATERALLY EXTENDING ANNULAR FLANGE DEFINING A GALVANICALLY REPRODUCIBLE CENTERING EDGE, INTO A CENTERING HOLE IN THE FOIL AND THEN, AFTER PLACING THE LACQUER FOIL WITH THE CENTERING CORE ON THE RECORDER TURNTABLE, PLACING A CENTERING SLEEVE WITH TWO CONCENTRIC BORES OVER THE SPINDLE OF THE RECORDER TURNTABLE TO ENGAGE THE CENTERING EDGE OF THE CORE WITH ONE BORE AND TO ENGAGE THE SPINDLE WITH THE OTHER BORE SO AS TO CENTRICALLY POSITION THE LACQUER FOIL ABOUT THE SPINDLE. WHEN HIGH CUTTING DISC SPEEDS ARE EMPLOYED, THE SLEEVE IS PREFERABLY FASTENED TO THE SPINDLE. THE SLEEVE MAY BE FORMED BY CONVENTIONAL MACHINING METHODS OR BY GALVANIC ACTION.

Inventors

• 👤 K Roeschmann
• 👤 A Wuehle

Bibliographic Details