Patent ID: 7650787

Claim:
An acceleration sensor comprising: a case that includes: a bottom wall that is made from a predetermined material, the bottom wall having a top side and a bottom side, the top side of the bottom wall having a central region and a peripheral region that surrounds central region; a projection portion that is attached to the top side of the bottom wall and that is located at the central region of the top side of the bottom wall, the projection portion being made of the predetermined material and having a top surface that is disposed higher than the peripheral region of the top side of the bottom wall; and a side wall attached to the bottom wall and extending upward from the bottom wall in a height direction; a semiconductor acceleration sensor chip supported on the projection portion, the sensor chip including: a fixed portion mounted on the top surface of the projection portion; a plummet portion surrounding the fixed portion without contacting the fixed portion, the plummet portion being shaped as an approximately square column and having an approximately square cavity for housing the fixed portion, the plummet portion being disposed outward of the projection portion and above the peripheral region of the top side of the bottom wall; and beam portions extending along diagonals of the cavity of the plummet portion and connecting the fixed portion and the plummet portion, the beam portions having a thickness that is thinner than the thickness of the fixed portion; terminals outside the case; and wiring that electrically connects at least some of the terminals to the sensor chip.