	US 7,538,281 B2
	Load cells for use in high precision load measuring system
James R. Pottebaum, Woodinville, Wash. (US); and Amar Inalsingh, San Francisco, Calif. (US)
Assigned to The AIS Group, Inc., San Francisco, Calif. (US)
Filed on Nov. 10, 2005, as Appl. No. 11/271,685.
Application 11/271685 is a continuation of application No. 10/437337, filed on May 13, 2003, granted, now 7,009,118.
Prior Publication US 2006/0064264 A1, Mar. 23, 2006
Int. Cl. G01G 3/13 (2006.01)

U.S. Cl. 177—211 [177/229; 73/862.627]

20 Claims

1. A load cell for use in a high precision system for measuring a load, the load cell generally defining a six sided horizontally elongated block comprising:

a. a top surface, a bottom surface, a front face, a rear face, a first end and a second end;

i. one of said top surface or said bottom surface having a first force contact area located between the first end and the second end of the load cell, the other of said top surface or said bottom surface having a second force contact area laterally displaced from the first force contact area between the first force contact area and the first end of the load cell and a third force contact area laterally displaced from the first force contact area between the first force contact area and the second end of the load cell;

b. first and second front shear measurement areas on a planar surface of the load cell parallel with a plane defined by the front face, the first front shear measurement area having a first Wheatstone bridge strain gauge attached thereto located laterally from the first force contact area between the first force contact area the second force contact area and the second front shear measurement area having a second Wheatstone bridge strain gauge attached thereto located laterally from the first force contact area between the first force contact area and the third force contact area;

c. first and second rear shear measurement areas on a planar surface of the load cell parallel with a plane defined by the rear face, the first rear shear measurement area having a third Wheatstone bridge strain gauge attached thereto located laterally from the first force contact area between the first force contact area the second force contact area and the second rear shear measurement area having a fourth Wheatstone bridge strain gauge attached thereto located laterally from the first force contact area between the first force contact area and the third force contact area; and

i. one or two load separation prevention elements attaching the load to either the first force contact area or the second and third force contact areas, the load separation prevention element preventing excessive separation of the load from the load cell.