US 4,499,906 AGranted

Percussion instrument

AssigneeSiemens Aktiengesellschaft

InventorsJuergen Wohlgemuth, Eugen Hohmann

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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.

Claims18

Dependent claims

A percussion instrument comprising:

a housing;
a ram displacably seated in said housing consisting of at least a section of non-magnetic material and a section of low magnetic retentive material;
a drive means for accelerating said ram from an initial position to free flight at a constant velocity toward an object to be tested by the reactive rebound of said ram there against and for returning said ram to said initial position, said drive means including at least one drive coil surrounding a portion of said ram and into which said low magnetic retentive section of said ram extends up to approximately one-half of the length of said coil when said ram is in said initial position;
a control means connected through a switch to said drive means for supplying periodic current pulses to said drive coil;
and
an evaluator means including a measuring means for measuring the velocity of said ram, a comparator for comparing the actual value of said ram with a rated velocity value, and a switch control means for interrupting the connection between said drive means and said control means when said actual velocity equals said rated velocity during acceleration of said ram.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/483,881Filed 11 Apr 1983
Priority: DE 321553026 Apr 1982
Granted: 19 Feb 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

A61B 9/005
Instruments for examination by percussion; Pleximeters: electric apparatus for detecting reflex action, e.g. monitoring depth of anaesthesia
A61B 5/1104
Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb: induced by stimuli or drugs
A61B 9/00
Instruments for examination by percussion
G01N 3/303
By applying a single impulsive force, e.g. by falling weight: generated only by free-falling weight