Load cell having a hollow and a strain gauge formed on a substrate

Abstract

A load cell for use in detecting a load imposed thereon which includes a strain inducing unit (1) having a longitudinal axis and including a strain generating area (6) for generating a strain as a function of the load, and a strain sensor (40) including a substrate (41) having a strain detecting element (43) formed thereon for detecting the strain generated at the strain generating area (6) of the strain inducing unit (1). The strain inducing unit (1) includes a fixed rigid body (2), a movable rigid body (3), first and second beams (4) connecting the fixed rigid body (2) and the movable rigid body (3) together, and an intermediate plate structure (30) fixed to and positioned between the fixed and movable rigid bodies (2 and 3). The intermediate plate structure (30) has a cut space (P) defined therein at a location intermediate between the fixed rigid body (2) and the movable rigid body (3). The strain inducing unit (1) is of a symmetrical profile with respect to a geometric center point (C) of the load cell and having a hollow defined therein and delimited by the fixed rigid body (2), the movable rigid body (3), the first and second beams (4) and the intermediate plate structure (30). The strain sensor (40) is accommodated within the hollow so as to straddle the cut space (P) and positioned substantially in alignment with a mid-center line (OX) extending past the geometric center point (C) and parallel to the longitudinal axis (X) of the strain inducing unit (1).