High impact resistant acceleration sensor
AssigneeDai Nippon Printing Co., Ltd.
InventorShinji Maekawa
Life of this patent
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Abstract
An acceleration sensor having a high impact resistance to prevent breakage under excessive acceleration, but can stably exert a sensing performance. The acceleration sensor is formed of an SOI substrate of a three-layered structure including a silicon layer (active layer silicon), a silicon oxide layer, and a silicon layer (substrate silicon). The acceleration sensor includes frame parts, a plurality of beam parts, the beam parts projecting inward from the frame part, and a weight part supported by the beam parts. A strain sensing part is provided on each of the beam parts. A width W of each of the beam parts, a length I of each of the beam parts, and an inner frame length L of the frame part satisfy the following relationships of Expressions (1) and (2). 2<L/I≦2.82 Expression (1) I/W≦3.68 Expression (2)
Claims7
An acceleration sensor formed of an SOI substrate of a three-layered structure including an active silicon layer, a silicon oxide layer, and a silicon substrate, the acceleration sensor comprising:
- a frame part;
- a plurality of beam parts, the beam parts projecting inward from the frame part;
- and
- a weight part supported by the beam parts;
- wherein:
- each of the beam parts is provided with a strain sensing part;
- and
- a width W of each of the beam parts, a length I of each of the beam parts, and an inner frame length L of the frame part satisfy the following relationships of Expressions (1) and (2),
- 2<L/I≦2.82 Expression (1)
- I/W≦3.68 Expression (2),
- wherein the weight part is completely exposed outside on a side of the beam parts so that even when an excessive acceleration up to 10,000 G is applied to the acceleration sensor, the weight part can move without contacting the acceleration sensor,
- wherein the strain sensing part includes piezoresistors, each having a longitudinal direction substantially parallel to the corresponding beam part,
- wherein windows are defined by the frame part and the beam parts, each of the windows being provided with a corner portion farthest away from the center of the acceleration sensor defined by sides arranged perpendicular to one another, and
- wherein the acceleration sensor is a multi-axis sensor capable of sensing strain in an x-axis direction, a y-axis direction and a z-axis direction.
Dependencies are inferred from the claim text.