Rolf P Haggstrom

6888074, May 3, 2005

Jun 10, 2003

10/457551

Rolf P. Haggstrom - Sudbury MA, US

The Flintec Group, Ltd. - Wan Chai

G01G023/01
G01L001/22

177211, 73 115, 73862622, 73862627, 73862631

Simple and inexpensive electrical compensation for off-axis and off-center loading sensitivity is possible in compression column load cells comprising a pair of compensation strain gages in series with each of the main strain gages in the load cell. The compensation gages are arranged crosswise to each associated main strain gage, and connected in series with their associated main strain gage. Each set of one main strain gage and two series connected compensation gages form one bridge arm in a strain gage bridge. Two compensation gages meet at each bridge corner, and are shunted by a common trimming resistor. The loading sensitivity compensation works for both conventional fixed axis load cells and Rocker Pin load cells.

7342185, Mar 11, 2008

Feb 28, 2005

11/066531

Rolf P. Haggstrom - Berlin MA, US

The Flintec Group, Ltd. - Wan Chai

G01G 3/142

177211, 73862627

Simple and inexpensive electrical compensation for off-axis and off-center loading sensitivity is possible in compression column load cells having a pair of compensation strain gages in series with each of the main strain gages in the load cell. The compensation gages are connected in series with their associated main strain gage. Each set of one main strain gage and two series connected compensation gages form one bridge arm in a strain gage bridge. Two compensation gages meet at each bridge corner, and are shunted by a common trimming resistor. The loading sensitivity compensation works for both conventional fixed axis load cells and Rocker Pin load cells.

50054295, Apr 9, 1991

Sep 21, 1989

7/410301

Rolf P. Haggstrom - East Walpole MA

BLH Electronics, Inc. - Canton MA

G01L 122

7386265

A new strain gage transducer comprises a support bar for measuring a load force. A base supports one end of the support bar in cantilever fashion in an orientation generally orthogonal to the direction in which the load force is to be applied. A load portion receives the load force and transmits it to the support bar, forcing it to flex. The amount of flexure is measured thereby allowing the amount of the load force to be determined. The base support includes a receiving portion mount on the base.

50868560, Feb 11, 1992

Nov 20, 1990

7/616073

Rolf P. Haggstrom - East Walpole MA

Flintab AB - Vaster.ang.s

G01G 2300

177161

A weighing method for a wheel supported load, such as a hospital bed, uses a weighing device having a base with a flat bottom surface, and a track surface for a wheel arranged parallel to the bottom surface. The track surface is supported on an arrangement for sensing weight which includes a pair of cantilever bending beams with strain gages, and one end of the track surface extends beyond the end of the flat bottom surface. To start weighing, the weighing device is first tilted, so the track surface can be wedged between a wheel and the floor. In this position the track surface acts as a ramp for the wheel. The wheel is next rolled up onto the track surface until it is above the front edge of the flat bottom surface. At this point the weighing device will flip over by gravity to rest on the flat bottom surface, and the weighing of the load can be done without risk for force shunting to the floor. A weighing device suitable for use with the method is also disclosed.

51350629, Aug 4, 1992

Mar 15, 1991

7/670397

Harry E. Lockery - Sudbury MA
Rolf P. Haggstrom - East Walpole MA

Flintab AB - Vaster.ang.s

G01G 314
G01L 122

177211

A strain gage transducer system, such as a load cell based weighing system, is protected against moisture related errors by an electrically conducting guard circuit for terminals and other parts subject to wet or humid conditions. The guard circuit is connected to an electrical potential close to a potential of signal terminals in a strain gage bridge, for instance to a center tap in a power supply for the strain gage bridge.

48541796, Aug 8, 1989

Oct 2, 1987

7/104797

Rolf P. Haggstrom - East Walpole MA

BLH Electronics, Inc. - Canton MA

G01L 122

7386266

An electrical strain-gaged load cell whose central and peripheral load-transmitting portions are coaxial with one another about an axis of applied loading includes intermediate interconnections formed by several planar-surfaced elongated shear-sensing beam elements whose opposite ends are integral with the coaxial portions and whose directions of elongation are essentially those of chords across the substantially annular spacing between the coaxial portions. Even in cells of small size, the relatively large chordal lengths of the beams, and the relatively sizable access spaces which may be accommodated alongside them, allow for convenient and facile installation of strain gages which will electrically characterize shear strains induced in the beams as they share transmission of the applied loading. Relatively massive end connections by which the beams connect with the coaxial portions are cantilevered radially inwardly and outwardly of the coaxial portions, angularly between the sites of the beams, to provide sturdy supports which will avoid undesirable end effects and, at the same time, will enable overall size and bulk of the cell to be minimized in designs rated for various capacities.

50458272, Sep 3, 1991

Nov 15, 1990

7/614158

Rolf P. Haggstrom - East Walpole MA

BLH Electronics, Inc. - Canton MA

G01L 122
G01B 716

338 2

A low level strain gage transducer including housing which supports a strain member having a fixed end member and a free end member in the form of a cup, the free end member supported by a folded arm arrangement including one or more arms which permits the element being monitored for strain forces to pivot with respect to the cup so as to to accommodate any mis-alignment forces applied to the cup that would otherwise generate bending forces resulting in erroneous strain measurements.

49585266, Sep 25, 1990

Oct 10, 1989

7/419391

Rolf P. Haggstrom - East Walpole MA

Flintab AB - Vaaster.ang.s

G01L 122
G01L 2500

7386267

A strain gage load cell is adjusted to zero output signal at no load or a fixed tare load on the load cell independent of the load cell temperature by shunting a pair of opposing arms of the strain gage bridge by equal resistors, and connecting a pair of equal resistors between opposite terminals of the power supply for the strain gage bridge and opposite corners of the output terminals of the strain gage bridge. The zero adjustment according to the invention is especially useful with load cell arrangements where individual strain gage elements must have equalized sensitivities.