Percussion instrument

US4499906A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Juergen Wohlgemuth · Darmstadt, DE
• Eugen Hohmann · Bensheim, DE

Key dates

• Filing date: Apr 11, 1983
• Grant date: Feb 19, 1985
• Expiry date: Apr 11, 2003

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2203/0623
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A percussion instrument suitable for use in dental practice for determining the degree of looseness of teeth has a movably seated ram which is accelerated to a defined velocity by an electromagnetic drive means and is subsequently moved toward a test subject (such as a tooth) in free flight. The electromagnetic means also controls return of the ram to a rest position. The ram is comprised of a non-magnetic section and a section of low magnetic retentivity passing through a magnetic coil. Control electronics supplies current pulses to the coil. The velocity of the ram is detected by a measuring and evaluation unit and is maintained at a constant value after a comparison of a rated value with the actual velocity value. The current feed to the coil is discontinued when the rated velocity is reached.