Pressure sensor having multiple piezoresistive elements

Patent metadata

Field	Value
Publication number	US-9513182-B2
Application number	US-201214397871-A
Country	US
Kind code	B2
Filing date	Jul 24, 2012
Priority date	Jun 29, 2012
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A pressure sensor includes: a sensor section having one fixed end and first to four gauge resistors arranged on a diaphragm; and a support member fixing the sensor section. A first pair to fourth pair of piezoresistive elements are arranged on the diaphragm. Two piezoresistive elements of each pair have opposite resistance value change directions, and distances to the support member are equal to each other. A distances between each piezoresistive element of the third pair and the fourth pair and the support member is longer than a distance between each piezoresistive element of the first pair and the second pair and the support member. Each gauge resistor includes a combined resistance, which is provided by serially connecting two corresponding piezoresistive elements. The two corresponding piezoresistive elements have a same resistance value change direction.

First claim

The invention claimed is:

1. A pressure sensor comprising:
a sensor section having one direction as a longitudinal direction, one end in the longitudinal direction as a fixed end, and the other end as a free end opposite to the one end, and including a thin diaphragm and a plurality of piezoresistive elements that is disposed on the diaphragm to provide a bridge circuit; and
a support member that fixes the one end of the sensor section,
wherein the diaphragm has a shape having a first side of an outer contour line that orthogonally intersects the longitudinal direction,
wherein the first side is disposed on an one end side, and
wherein the plurality of piezoresistive elements are disposed in a predetermined region other than a region around a middle point of the first side of the diaphragm.

2. The pressure sensor according to claim 1 ,
wherein the sensor section includes a silicon substrate and has a rectangular parallelepiped shape,
wherein the diaphragm is formed in the silicon substrate,
wherein the diaphragm has a polygonal shape having the outer contour line including the first side and a second side to a fourth side,
wherein the longitudinal direction is defined as a first direction, and a direction orthogonal to the longitudinal direction is defined as a second direction,
wherein the first side and the third side that face each other are parallel to the second direction, and the second side and the fourth side that face each other are parallel to the first direction, and
wherein the first side is disposed on a fixed end side.

3. The pressure sensor according to claim 2 ,
wherein the silicon substrate has a main surface that is a plane,
wherein the plurality of piezoresistive elements include a first piezoresistive element to a fourth piezoresistive element,
wherein the first piezoresistive element and a third piezoresistive element are formed adjacent to a central portion of the third side of the diaphragm,
wherein the second piezoresistive element is formed adjacent to a central portion of the second side of the diaphragm, and
wherein the fourth piezoresistive element is formed adjacent to a central portion of the fourth side of the diaphragm.

4. The pressure sensor according to claim 2 ,
wherein the silicon substrate has a main surface that is a plane,
wherein the plurality of piezoresistive elements include a first piezoresistive element to a fourth piezoresistive element,
wherein the first piezoresistive element to the fourth piezoresistive element are formed adjacent to the third side of the diaphragm,
wherein the first piezoresistive element and a third piezoresistive element are serially connected to each other through a second piezoresistive element interposed therebetween,
wherein the first piezoresistive element and the third piezoresistive element are serially connected to each other through the fourth piezoresistive element interposed therebetween,
wherein the first piezoresistive element and the third piezoresistive element include a resistance value change portion having a resistance value, which is changed when a pressure is applied to the diaphragm, respectively,
wherein the resistance value change portion of the first piezoresistive element and the resistance value change portion of the third piezoresistive element extend in the first direction,
wherein the second piezoresistive element and the fourth piezoresistive element include a resistance value change portion having a resistance value, which is changed when the pressure is applied to the diaphragm, respectively, and
wherein the resistance value change portion of the second piezoresistive element and the resistance value change portion of the fourth piezoresistive element extend in the second direction.

5. The pressure sensor according to claim 2 ,
wherein the silicon substrate has a main surface that is a plane,
wherein the plurality of piezoresistive elements include a first piezoresistive element to a fourth piezoresistive element,
wherein the first piezoresistive element and a third piezoresistive element are formed in a central portion of the diaphragm, and
wherein a second piezoresistive element and the fourth piezoresistive element are formed adjacent to a central portion of the third side of the diaphragm.

6. The pressure sensor according to claim 2 ,
wherein a ratio of a length of the first side and a length of the second side is defined as an aspect ratio, and
wherein the aspect ratio is equal to or larger than 1.

7. A pressure sensor comprising:
a sensor section having one direction as a longitudinal direction, one end in the longitudinal direction as a fixed end, and the other end as a free end opposite to the one end, and including a thin diaphragm and a plurality of piezoresistive elements that is disposed on the diaphragm to form a bridge circuit; and
a support member that fixes the one end of the sensor section,
wherein the diaphragm has a circular outer contour line,
wherein a straight line, which is parallel to the longitudinal direction and passes through a center of the diaphragm, intersects an outer contour line of the diaphragm at two intersections, and
wherein the plurality of piezoresistive elements is disposed in a predetermined region excluding a region around an intersection positioned on a fixed end side.

8. The pressure sensor according to claim 7 ,
wherein the outer contour line of the diaphragm is an elliptical shape, which has a length in a direction orthogonal to the longitudinal direction is longer than a length in the longitudinal direction.

9. A pressure sensor comprising:
a sensor section having one direction as a longitudinal direction, one end in the longitudinal direction as a fixed end, and the other end as a free end opposite to the one end, and including a thin diaphragm and a plurality of piezoresistive elements that is disposed on the diaphragm to form a bridge circuit; and
a support member that fixes the one end of the sensor section,
wherein the diaphragm has an outer contour line of a triangular shape,
wherein the triangular shape has a vertical angle with a first side to a third side,
wherein the vertical angle is disposed on a one end side, and
wherein the plurality of piezoresistive elements is disposed in a predetermined region excluding a region around the vertical angle.

10. A pressure sensor comprising:
a sensor section having one direction as a longitudinal direction, one end in the longitudinal direction as a fixed end, and the other end as a free end opposite to the one end, and including a thin diaphragm and a first gauge resistor to a fourth gauge resistor that are disposed on the diaphragm to form a bridge circuit; and
a support member that fixes the one end of the sensor section,
wherein a first pair to a fourth pair of piezoresistive elements are disposed on the diaphragm,
wherein each of the piezoresistive elements has a resistance value change direction indicating a direction, in which a resistance value increases or decreases according to an applied force,
wherein two piezoresistive elements of each pair have opposite resistance value change directions,
wherein the first pair includes a first piezoresistive element and a fifth piezoresistive element, the second pair includes a second piezoresistive element and a sixth piezoresistive element, the third pair includes a third piezoresistive element and a seventh piezoresistive element, and the fourth pair includes a fourth piezoresistive element and an eighth piezoresistive element,
wherein distances between piezoresistive elements of the first pair and the second pair and the support member are equal to each other,
wherein distances between piezoresisti

Assignees

• Kakoiyama Naoki
• Denso Corp

Inventors

• Kakoiyama Naoki

Classifications

• G01L19/04

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• G01L9/0052 Primary

  of piezoresistive elements (circuits therefor G01L9/06) · CPC title

• G01L9/0055

  bonded on a diaphragm · CPC title