Power cutting tool comprising a radar sensing system

• US 7,421,932 B1
• Filed: 07/06/2006
• Issued: 09/09/2008
• Est. Priority Date: 05/19/2005
• Status: Active Grant

• Current Assignee: Power Tool Institute
• Original Assignee: Power Tool Institute
• Inventors: Shafer, David C., Heinzmann, Fred J.
• Primary Examiner(s): Choi; Stephen
• Application Number:
  US11/481,539
• Time in Patent Office: 796 Days
• Field of Search: 83/58, 83/62, 83/63, 83/72, 83/761, 83 766- 769, 833/70, 834/772, 83D/IG.1, 342/90, 342109-112, 192/129.R, 192/125.R, 192/116.5, 318/362, 700/253, 700/255
• US Class Current: 83/58
• 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: B23Q 11/0082 by determining whether the operator is in a dangerous position B23Q17/2438 takes precedence
• CPC Class Codes: B23Q 17/24 using optics or electromagnetic waves
• CPC Class Codes: B23Q 17/2438 of an operator or a part thereof
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/162 With control means responsive to replaceable or selectable information program
• CPC Class Codes: Y10T 83/541 Actuation of tool controlled in response to work-sensing means
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]

Abstract

A power cutting tool having a movable blade, such as a table saw, comprising a radar sensing system for movement of an object in a region near the blade is disclosed. The radar sensing system emits a radio frequency wave and receives wave energy reflected by the object. The system measures the Doppler shift of the received wave energy to detect the presence of a fast moving object in a zone near the blade. When such a condition is detected, a reaction system can be activated to mitigate the condition.

Claims

1. A power cutting tool comprising:

a platform having a cutting surface;

a movable blade for cutting an object on the cutting surface; and

at least one radar sensing system comprising;

an open-ended waveguide having a longitudinal axis parallel to the plane of the blade and perpendicular to the cutting surface, the open-ended waveguide having an open end at the cutting surface of the platform and adjacent to the blade;

an antenna element positioned below the cutting surface, wherein the antenna element is inserted into the open-ended waveguide, and wherein the antenna element is perpendicular to the longitudinal axis of the open-ended waveguide; and

circuitry connected to the antenna element for producing an output related to the velocity of an object in a velocity range in a region near the blade and above the cutting surface.

2. The power cutting tool of claim 1, wherein the radar sensing system detects a direction of movement of the object.

3. The power cutting tool of claim 1, wherein the radar sensing system comprises a continuous wave radar sensing system.

4. The power cutting tool of claim 1, wherein the radar sensing system comprises a range-gated radar sensing system.

5. The power cutting tool of claim 1, further comprising a dielectric plug positioned in the open-end of the waveguide.

6. The power cutting tool of claim 5, wherein the antenna is aligned along the axis of rotation of the movable blade.

7. The power cutting tool of claim 1, wherein the antenna is aligned along the axis of rotation of the movable blade.

8. A table saw comprising:

a table having a cutting surface;

a rotatable blade disposed in an opening defined by the table such that at least a portion of the rotatable blade extends above the cutting surface; and

at least one radar sensing system comprising;

an open-ended waveguide having a longitudinal axis parallel to the plane of the blade and perpendicular to the cutting surface, the open-ended waveguide having an open end at the cutting surface of the platform and adjacent to the blade;

an antenna element positioned below the cutting surface, wherein the antenna element is inserted into the open-ended waveguide, and wherein the antenna element is perpendicular to the longitudinal axis of the open-ended waveguide; and

circuitry connected to the antenna element for producing an output related to the velocity of an object in a velocity range in a region near the blade and above the cutting surface.

9. The table saw of claim 8, wherein the radar sensing system detects a direction of movement of the object.

10. The table saw of claim 8, wherein the radar sensing system comprises a continuous wave radar sensing system.

11. The table saw of claim 8, wherein the radar sensing system comprises a range-gated radar sensing system.

12. The table saw of claim 8, further comprising a dielectric plug positioned in the open-end of the waveguide.

13. The table saw of claim 12, wherein the antenna is aligned along the axis of rotation of the rotatable blade.

14. The table saw of claim 8, wherein the antenna is aligned along the axis of rotation of the rotatable blade.

15. A table saw comprising:

a table having a cutting surface;

a rotatable blade disposed in an opening defined by the table such that at least a portion of the rotatable blade extends above the cutting surface, the blade having first and second lateral sides; and

a radar sensing system comprising;

a first open-ended waveguide having a longitudinal axis parallel to the plane of the blade and perpendicular to the cutting surface, the first open-ended waveguide having an open end at the cutting surface of the platform and adjacent to the first lateral side of the blade;

a first antenna element positioned below the cutting surface, wherein the first antenna element is inserted into the first open-ended waveguide, and wherein the first antenna element is perpendicular to the longitudinal axis of the first open-ended waveguide;

a second open-ended waveguide having a longitudinal axis parallel to the plane of the blade and perpendicular to the cutting surface, the second open-ended waveguide having an open end at the cutting surface of the platform and adjacent to the second lateral side of the blade;

a second antenna element positioned below the cutting surface, wherein the second antenna element is inserted into the second open-ended waveguide, and wherein the second antenna element is perpendicular to the longitudinal axis of the second open-ended waveguide;

circuitry connected to the first and second antenna elements for producing an output related to the velocity of an object in a velocity range in a region near the blade and above the cutting surface.