Acceleration sensor element and acceleration sensor having same

A covered acceleration sensor element including:

• a weight portion, a support frame portion surrounding the weight portion, a plurality of flexible beam portions for connecting the weight portion to the support frame portion, piezoresistance elements provided on the beam portions, and wirings for connecting the piezoresistance elements,
• the covered acceleration sensor element being configured such that an upper cover and a lower cover enclosing a periphery of the weight portion together with the support frame portion are joined to a face and a back of the support frame portion, and
• the covered acceleration sensor element being adapted to detect acceleration in a direction of a first axis as a thickness direction in which the upper cover, the support frame portion, and the lower cover are stacked, and acceleration in a direction of at least one of a second axis in a plane perpendicular to the first axis, or a third axis in the plane and perpendicular to the second axis, from changes in resistances of the piezoresistance elements,
• wherein the support frame portion is separated by separation grooves into an inner frame and an outer frame surrounding a periphery of the inner frame, the upper cover and the lower cover are joined to the outer frame, and the inner frame is connected to and held by the outer frame via a plurality of inner frame support portions having flexibility, and
• the beam portions are connected to both sides of the weight portion along at least one of the second axis or the third axis, and the inner frame support portions are connected to both sides of the inner frame at a predetermined angle from the at least one of the second axis or the third axis,
• wherein individual ones of the inner frame support portions have opposing ends connected to the inner frame and the outer frame, respectively, and both of the opposing ends are disposed at the predetermined angle from the at least one of the second axis or the third axis,
• wherein the beam portions are connected to both sides of the weight portion along both of the second axis and the third axis, and the inner frame support portions are connected to both sides of the inner frame at the predetermined angle from both of the second axis and the third axis, and
• wherein the beam portions are connected to both sides of the weight portion along both of the second axis and the third axis, and the inner frame support portions are connected to both sides of the inner frame 30 to 60 degrees from both of the second axis and the third axis.