Abstract: Apparatus for measuring force, useful in a weighing scale for example, includes a parallelogram-like load cell structure that deflects in response to application of the force to be measured, and a pair of force-sensitive crystal resonators, attached to cantilever sensor beams forming part of the structure for sensing the deflection of the load cell structure. The two resonators are attached to the sensor beams such as to be placed in tension and compression, respectively, upon deflection of the structure and thereby cause their vibration frequency to increase and decrease, respectively, with increases in applied force. The difference between the two frequencies, which varies substantially linearly with changes in applied force and is inherently digital in nature, is used as a measure of the force applied to the load cell structure.

Abstract: A vibrating beam resonator is formed with a unitary isolator mass at each end of the vibratory beam. Isolator springs connected to the unitary masses are joined to mounts. Forces applied to the mounts cause the vibrating beam frequency to vary to enable precise force measurements. With this arrangement, fewer cutting operations are required to produce the vibrating beam resonator than were necessary with known resonators. In a preferred embodiment, a side of the vibratory beam is formed by an edge of the crystal blank from which the resonator is cut to further reduce cutting time. This also permits cuts to be made from only one side of the blank.