Detection system for power equipment

• US 7,210,383 B2
• Filed: 08/13/2001
• Issued: 05/01/2007
• Est. Priority Date: 08/14/2000
• Status: Expired due to Term

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Jensen, Joel F., Gass, Stephen F., Schramm, Benjamin B., Chamberlain, Robert L., Betts-LaCroix, Jonathan N.
• Primary Examiner(s): PRONE, JASON D
• Application Number:
  US09/929,426
• Publication Number:
  US 20020017176A1
• Time in Patent Office: 2,087 Days
• Field of Search: 83D/IG.1, 83/58, 83D/IG.2, 83/621, 83/62, 83/72, 83/767, 837/88, 835/81, 834/712, 834/771, 833/971, 835/221.2, 835/26, 83/63, 340/660, 340/686.6, 340/696.6, 144/154.5, 144/356, 144/384, 144/391, 144/427, 144/286.5, 324/550, 324/424, 56/109, 56/113, 192/192.A, 192/129.R, 192/130, 241/32.5, 318/362, 335/242, 335/1, 335/132, 411/2, 411/39, 411/390, 403/2, 403/28, 74/2, 169/57, 169/59, 169/42, 188/5, 188/6, 137/68.12, 137/72, 137/76, 89/15.6, 102/202.7, 451/409, 337/239, 337/148, 337/1, 337/5, 337/10, 337/17, 337/140, 337/170, 337/190, 337/237, 337/401, 337/290, 337/404, 337/405, 218/2, 218/154, 280/806, 297/480, 307/639, 307/328, 307/115, 307/326, 307/142, 307/117, 307/126, 307/131, 408/5
• US Class Current: 83/58
• CPC Class Codes: B23D 47/025 of tables
• 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 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: B26D 7/24 arranged to disable the operating means for the cutting member
• 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 vibration-damping of sawing machines or devices working with circular saw blades B23D47/005
• 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: B27G 19/06 for band or strap 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 3/14 the means being photocells or other devices sensitive without mechanical contact
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: G05B 9/02 electric
• 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 83/091 Responsive to work sensing means
• CPC Class Codes: Y10T 83/141 With means to monitor and control operation [e.g., self-regulating means]
• CPC Class Codes: Y10T 83/162 : With control means responsive to replaceable or selectable information program
• CPC Class Codes: Y10T 83/175 : With condition sensor
• CPC Class Codes: Y10T 83/178 : Responsive to work
• CPC Class Codes: Y10T 83/541 : Actuation of tool controlled in response to work-sensing means
• 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 83/7697 : Tool angularly adjustable relative to work-support
• CPC Class Codes: Y10T 83/7726 : By movement of the tool
• CPC Class Codes: Y10T 83/7734 : With guard for tool
• CPC Class Codes: Y10T 83/7788 : Tool carrier oscillated or rotated
• CPC Class Codes: Y10T 83/85 : Signal; e.g., alarm
• CPC Class Codes: Y10T 83/8773 : Bevel or miter cut

Abstract

Woodworking machines including conductive cutters adapted to cut workpieces, and motors adapted to drive the cutters are disclosed. The machines also include a contact detection system adapted to detect contact between a person and the cutter, and to distinguish contact between the person and the cutter from contact between the workpiece and the cutter. The machines further include a reaction system adapted to cause a predetermined action to take place upon detection of contact between the person and the cutter by the contact detection system.

Claims

1. A woodworking machine comprising:

a conductive cutter adapted to cut a workpiece;

a motor adapted to drive the cutter;

a contact detection system electrically coupled to the cutter to impart an electrical signal thereto, where the electrical signal has a voltage amplitude, where the voltage amplitude is changed when a person contacts the cutter, where the contact detection system is adapted to identify contact between a person and the cutter as a reduction in the voltage amplitude of the signal on the cutter of at least 5% within 100 microseconds, and where the contact detection system is adapted to distinguish contact between the person and the cutter from at least one other event generating a comparable amount of change in the voltage amplitude based on the time during which the change in the voltage amplitude occurs; and

a reaction system adapted to cause a predetermined action to take place upon detection of contact between the person and the cutter by the contact detection system.

3. The machine of claim 1, where the at least one property is the voltage amplitude of the electrical signal.

2. A woodworking machine comprising:

a conductive cutter adapted to cut a workpiece;

a motor adapted to drive the cutter;

a contact detection system electrically coupled to the cutter to impart an electrical signal thereto, where the electricai signal has at least one property, and where the at least one property is changed when a person contacts the cutter, and where the contact detection system is adapted to distinguish contact between the cutter and the person from at least one other event generating a comparable amount of change in the at least one property based on the time during which the change in the at least one property occurs; and

a reaction system adapted to cause a predetermined action to take place upon detection of contact between the person and the cutter by the contact detection system.

4. The machine of claim 2, where the time during which the change in the at least one property occurs is less than one millisecond.

5. The machine of claim 2, where the time during which the change in the at least one property occurs is less than one hundred microseconds.

6. The machine of claim 2, where the at least one other event is contact between the cutter and green wood.

7. The machine of claim 2, where the predetermined action includes stopping movement of the cutter.