Discrete proximity detection system

• US 20030002942A1
• Filed: 07/02/2002
• Published: 01/02/2003
• Est. Priority Date: 07/02/2001
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Gass, Stephen f., Fulmer, J. David
• Granted Patent: US 7,171,879 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23Q 5/58 Safety devices protecting the operator B23Q11/0089
• CPC Class Codes: B27G 21/00 Safety guards or devices specially designed for other wood-working machines auxiliary devices facilitating proper operation of said wood-working machines
• CPC Class Codes: F16P 3/12 with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine F16P3/08 takes precedence
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 408/96 Miscellaneous
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/707 By endless band or chain knife
• CPC Class Codes: Y10T 83/7726 By movement of the tool
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]
• CPC Class Codes: Y10T 83/7788 Tool carrier oscillated or rotated

Abstract

A machine is described having at least one dangerous portion. The machine also includes a safety system to detect dangerous proximity between a person and the dangerous portion and perform a predetermined action to limit or prevent injury to the person from the dangerous portion.

Claims

1. A woodworking machine comprising:

at least one dangerous portion;

a detection system configured to detect when any portion of a person'"'"'s body is at a distance from the dangerous portion that is within a predetermined range of distances; and

a reaction system configured to perform one or more predetermined actions in the event the detection system detects that a portion of a person'"'"'s body is at a distance from the dangerous portion that is within the predetermined range of distances.

2. The woodworking machine of claim 1, where the dangerous portion is a cutting tool adapted to cut wood.

3. The woodworking machine of claim 2, where the predetermined range of distances is from approximately 0.1 millimeter to approximately 20 millimeters.

4. The woodworking machine of claim 2, where the predetermined range of distances is from approximately 1 millimeter to approximately 4 millimeters.

5. The woodworking machine of claim 2, where the detection system includes a high voltage generation subsystem configured to generate a high voltage, and a connection configured to couple, directly or indirectly, the high voltage to the cutting tool.

6. The woodworking machine of claim 5, where the high voltage generation subsystem includes a belt movable to generate static charge.

7. The woodworking machine of claim 6, where the detection system includes a charge dissipation element configured to limit static charge buildup on the cutting tool.

8. The woodworking machine of claim 5, where the high voltage generation subsystem includes a high voltage power supply.

9. The woodworking machine of claim 5, further comprising an arbor configured to support the cutting tool, and where the connection is configured to couple the high voltage to the cutting tool through the arbor.

10. The woodworking machine of claim 5, further comprising a static discharge detection subsystem configured to detect a static discharge between the cutting tool and a person'"'"'s body.

11. For use on power equipment having at least one dangerous portion, a method of detecting dangerous proximity between a person and the dangerous element, the method comprising:

generating a high voltage;

applying the high voltage to the dangerous portion, where the high voltage is sufficient to cause an electrical discharge between the dangerous portion and the person'"'"'s body when any portion of the person'"'"'s body comes within a predetermined distance from the dangerous portion; and

detecting when an electrical discharge between the dangerous portion and the person'"'"'s body occurs.

12. The method of claim 11, where the power equipment is a woodworking machine and the dangerous portion is a cutting tool.

13. The method of claim 11, where the step of generating a high voltage includes generating a DC voltage.

14. The method of claim 13, where the step of generating a high voltage includes generating an intermittent DC voltage.

15. The method of claim 11, where the step of generating a high voltage includes generating an AC voltage.

16. The method of claim 11, where the predetermined distance is at least approximately 0.1 millimeter and less than approximately 20 millimeters.

17. The method of claim 11, where the predetermined distance is at least approximately 1 millimeter and less than approximately 4 millimeters.

19. The woodworking machine of claim 18, where the high voltage generation means includes a Van De Graf generator.

20. The woodworking machine of claim 18, where the detection means includes means for detecting an electrical discharge between the cutting means and a person'"'"'s body when the person'"'"'s body is spaced-apart from the cutting means.

18. A woodworking machine comprising:

cutting means for cutting wood;

high voltage generation means;

connection means for coupling, directly or indirectly, the high voltage generation means to the cutting means; and

detection means for detecting an electrical discharge between the cutting means and a person'"'"'s body.