Detection system for power equipment
AssigneeSd3, LLC
InventorsStephen F. Gass, J. David Fulmer
Life of this patent
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Abstract
A machine is disclosed having a detection subsystem adapted to detect contact between a person and a specified portion of the machine, and to distinguish that contact from contact with other materials. The detection subsystem imparts an electrical signal to a specified portion of the machine, and distinguishes that contact based on a predetermined frequency response of the electrical signal. A reaction subsystem then causes a predetermined action to take place. The machine may be a power saw designed to minimize injury in the event a person accidentally contacts the blade.
Claims4
A method of detecting contact between a human body material and a specified portion of a woodworking machine, and of distinguishing that contact from contact between at least one other material and the machine, the method comprising:
- imparting an electrical signal on the specified portion of the machine, where the electrical signal includes at least two different frequency components;
- measuring a characteristic of the electrical signal as a function of frequency when the specified portion is in contact with the human body material to obtain a first frequency response;
- measuring the characteristic of the electrical signal as a function of frequency when the specified portion is in contact with the other material to obtain a second frequency response;
- comparing the first and second frequency responses;
- and
- setting frequency measurement parameters to distinguish human body material contact from contact by the other material.
A method of detecting contact between a human body material and a specified portion of a woodworking machine, and of distinguishing that contact from contact between at least one other material and the machine, the method comprising:
- imparting an electrical signal on the specified portion of the machine, where the electrical signal includes at least two different frequency components;
- where the frequency components include a first frequency component having a period equal to or greater than the RC-time constant of a nominal human body and a second frequency component having a period less than the period of the first frequency component;
- measuring a characteristic of the electrical signal as a function of frequency when the specified portion is in contact with the human body material to obtain a first frequency response;
- measuring the characteristic of the electrical signal as a function of frequency when the specified portion is in contact with the other material to obtain a second frequency response;
- comparing the first and second frequency responses;
- and setting frequency measurement parameters to distinguish human body contact from contact by the other material.
Dependencies are inferred from the claim text.