Contact detection system for power equipment

• US 20020069734A1
• Filed: 01/16/2002
• Published: 06/13/2002
• Est. Priority Date: 09/29/2000
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Gass, Stephen F., Fulmer, J. David
• Granted Patent: US 7,377,199 B2
• Time in Patent Office: Days
• US Class Current: 83/13
• CPC Class Codes: B23D 45/06 with a circular saw blade arranged underneath a stationary work-table
• CPC Class Codes: B23D 47/08 of devices for bringing the circular saw blade to the workpiece or removing same therefrom
• CPC Class Codes: B23D 55/08 of devices for guiding or feeding strap saw blades
• CPC Class Codes: B23D 59/001 Measuring or control devices, e.g. for automatic control of work feed pressure on band saw blade measuring in general G01; controlling in general G05
• CPC Class Codes: B27B 13/14 Braking devices specially designed for band sawing machines, e.g. acting after damage of the band saw blade
• CPC Class Codes: B27B 5/38 Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing B23D47/005 takes precedence
• CPC Class Codes: B27G 19/00 Safety guards or devices specially adapted for wood saws; Auxiliary devices facilitating proper operation of wood saws
• CPC Class Codes: B27G 19/02 for circular saws
• 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 83/04 Processes
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/088 Responsive to tool detector or work-feed-means detector
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/613 Work guard
• CPC Class Codes: Y10T 83/7693 Tool moved relative to work-support during cutting
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]
• CPC Class Codes: Y10T 83/7763 Tool carrier reciprocable rectilinearly
• CPC Class Codes: Y10T 83/7788 Tool carrier oscillated or rotated
• CPC Class Codes: Y10T 83/8773 : Bevel or miter cut

Abstract

A woodworking machine having one or more dangerous portions of the machine is disclosed. The machine also includes a safety system configured to detect accidental contact between a person and at least one of the dangerous portions by electrically coupling a signal to the person'"'"'s body, and detecting if the signal becomes coupled to the dangerous portion.

Claims

1. A method for detecting accidental contact between a person and a dangerous portion of a woodworking machine, the method comprising:

providing a first electrode electrically coupled to the person;

providing a second electrode electrically coupled to the dangerous portion;

transmitting a signal by one of the first or second electrodes; and

identifying contact if the transmitted signal is received by the other of the first or second electrodes.

2. The method of claim 1, where the step of transmitting includes transmitting the signal by the first electrode through the person.

3. The method of claim 1, where the step of transmitting includes transmitting the signal by the second electrode through the dangerous portion.

4. The method of claim 1, where the woodworking machine includes at least one cutting tool, and where the step of providing a second electrode includes providing a second electrode electrically coupled to the at least one cutting tool.

5. The method of claim 1, where the woodworking machine includes at least one guard, and where the step of providing a second electrode includes providing a second electrode electrically coupled to the at least one guard.

6. The method of claim 1, where the step of transmitting includes transmitting an alternating electrical signal.

7. The method of claim 6, where the alternating electrical signal has a particular frequency, and where the step of identifying includes identifying contact if an electrical signal having the particular frequency is received.

8. The method of claim 1, where the step of transmitting includes transmitting a ground electrical signal.

9. A woodworking machine comprising:

a support structure;

a cutting tool supported by the support structure and configured to cut workpieces;

a motor configured to drive the cutting tool; and

a safety system configured to detect accidental contact between a person and the cutting tool and take one or more predetermined actions in the event such contact is detected;

where the safety system includes a first electrode configured to electrically couple to the person'"'"'s body, and a second electrode configured to electrically couple to the cutting tool; and

where the safety system is configured to apply an electrical signal to one of the first or second electrodes and to detect whether a corresponding signal is transmitted to the other one of the first or second electrodes through the person'"'"'s body.

10. The woodworking machine of claim 9, where the support structure includes at least one contact region configured to contact a person during operation of the woodworking machine, and where the first electrode is configured to electrically couple to the person'"'"'s body via the at least one contact region.

11. The woodworking machine of claim 9, where the support structure includes at least one handle configured to be contacted by a person during operation of the woodworking machine, and where the first electrode is configured to electrically couple to the person'"'"'s body via the at least one handle.

12. The woodworking machine of claim 9, where the support structure includes at least one guard configured to contact a portion of a person'"'"'s body if the portion of the user'"'"'s body is placed proximate the cutting tool, and where the first electrode is configured to electrically couple to the person'"'"'s body via the at least guard.

13. The woodworking machine of claim 9, further comprising a switch configured to be actuated by a person to control the motor, and where the first electrode is configured to electrically couple to the person'"'"'s body via the switch.

15. The machine of claim 14, further comprising cutting means configured to cut workpieces, and where the at least one dangerous portion is the cutting means.

16. The machine of claim 14, further comprising cutting means for cutting workpieces, and guard means for at least partially shielding the cutting means, and where the at least one dangerous portion is the guard means.

17. The machine of claim 14, further comprising means for coupling a detection signal onto the at least one dangerous portion.

18. The machine of claim 17, where the means for detecting includes means for detecting if the detection signal coupled onto the at least one dangerous portion changes due to the coupling of the electrical signal onto the at least one dangerous portion.

19. The machine of claim 14, where the electrical signal is a ground signal.

20. The machines of claim 14, where the electrical signal is an alternating signal.

14. A woodworking machine having one or more dangerous portions comprising:

means for coupling an electrical signal onto the person;

means for monitoring at least one of the dangerous portions for the presence of electrical signals; and

means for detecting if the electrical signal coupled onto the person becomes coupled onto the at least one dangerous portion.