Z-axis inertial sensor with extended motion stops

Patent metadata

Field	Value
Publication number	US-11499987-B2
Application number	US-202016904182-A
Country	US
Kind code	B2
Filing date	Jun 17, 2020
Priority date	Jun 17, 2020
Publication date	Nov 15, 2022
Grant date	Nov 15, 2022

Abstract

A sensor includes a movable element adapted for rotational motion about a rotational axis due to acceleration along an axis perpendicular to a surface of a substrate. The movable element includes first and second ends, a first section having a first length between the rotational axis and the first end, and a second section having a second length between the rotational axis and the second end that is less than the first length. A motion stop extends from the second end of the second section. The first end of the first section includes a geometric stop region for contacting the surface of the substrate at a first distance away from the rotational axis. The motion stop for contacting the surface of the substrate at a second distance away from the rotational axis. The first and second distances facilitate symmetric stop performance between the geometric stop region and the motion stop.

First claim

What is claimed is:

1. A sensor comprising:
a substrate;
a first movable element positioned in spaced apart relationship away from a surface of the substrate, the first movable element being adapted for rotational motion in a first direction in response to acceleration along an axis perpendicular to the surface of the substrate, the rotational motion occurring about a first rotational axis positioned between first and second ends of the first movable element, the first movable element including:
a first section between the first rotational axis and the first end of the first movable element, the first section being characterized by a first length, a first end of the first section including a first geometric stop region configured to contact the surface of the substrate at a first distance away from the first rotational axis,
a second section between the first rotational axis and the second end of the first movable element, the second section being characterized by a second length that is less than the first length,
a first motion stop extending from a second end of the second section, wherein a first width of the first motion stop is less than a second width of the second section of the first movable element and the first motion stop is coplanar with the second section, the first motion stop is configured to contact the surface of the substrate at a second distance away from the first rotational axis, and wherein the first and second distances are defined to yield substantially symmetric stop performance between the first geometric stop region and the first motion stop, and

a second movable element positioned in spaced apart relationship away from the surface of the substrate, the second movable element being adapted for rotational motion in a second direction in response to the acceleration, the rotational motion occurring about a second rotational axis positioned between third and fourth ends of the second movable element, the second direction being opposite to the first direction, the second movable element including:
a third section between the second rotational axis and the third end of the second movable element, the third section being characterized by a third length, and a third end of the third section including a second geometric stop region configured to contact the surface of the substrate at a third distance away from the second rotational axis,
a fourth section between the second rotational axis and the fourth end of the second movable element, the fourth section being characterized by a fourth length that is less than the third length, and
a second motion stop extending from a fourth end of the fourth section, wherein a third width of the second motion stop is less than a fourth width of the fourth section of the second movable element, the second motion stop configured to contact the surface of the substrate at a fourth distance away from the second rotational axis, wherein the third and fourth distances are defined to yield the substantially symmetric stop performance between the second geometric stop region and the second motion stop;

a first lateral extension section extending from a first side of the first section, the first lateral extension section being located proximate a fourth end of the second movable element, wherein the first lateral extension section includes a first notch sized to receive the second motion stop, wherein the first notch is defined by a first edge along a first notch length of the first notch and a second edge along the first notch length, the first edge being parallel and opposed to the second edge, the second motion stop residing in the first notch and spaced apart from the first edge of the first notch by a first gap distance and spaced apart from the second edge of the first notch by the first gap distance; and
a second lateral extension section extending from a second side of the third section, the second lateral extension section being located proximate the second end of the first movable element, wherein the second lateral extension section includes a second notch sized to receive the first motion stop, wherein the second notch is defined by a third edge along a second notch length of the second notch and a fourth edge along the second notch length, the third edge being parallel and opposed to the fourth edge, the first motion stop residing in the second notch and spaced apart from the third edge of the second notch by a second gap distance and spaced apart from the fourth edge of the second notch by the second gap distance,
wherein the first and second movable elements have a substantially equivalent shape and the second movable element is generally oriented in rotational symmetry relative to the first movable element about a point location on the surface of the substrate such that the first and second movable elements are disposed beside one another along a direction of a common rotational axis, and the first rotational axis and the second rotational axis each extend along the common rotational axis.

2. The sensor of claim 1 wherein the first motion stop is characterized by a stop length, and wherein the second length of the second section summed with the stop length of the first motion stop is at least eighty percent of the first length of the first section.

3. The sensor of claim 1 wherein the second distance at which the first motion stop contacts the surface is within twenty-five percent of the first distance at which the first geometric stop region contacts the surface.

4. The sensor of claim 1 wherein each of the first and second sections and the first motion stop exhibit the same thickness in a direction that is perpendicular to the surface of the substrate.

5. The sensor of claim 1 wherein:
the first motion stop is characterized by a first stop length; and
the sensor further comprises the second motion stop extending from the first end of the first section, the second motion stop defining the first geometric stop region, the second motion stop being characterized by a second length that is less than the first stop length.

6. The sensor of claim 1 wherein the first motion stop is characterized by a first stop length and the second motion stop is characterized by a second stop length that is substantially equivalent to the first stop length.

7. The sensor of claim 1 wherein:
the first length is substantially equivalent to the third length; and
the second length is substantially equivalent to the fourth length.

8. The sensor of claim 1 wherein the second movable element is located in an orientation that is rotated about the point location approximately one hundred eighty degrees relative to the first movable element.

9. The sensor of claim 1 wherein:
the first movable element including the first lateral extension section forms a first L-shaped movable element; and
the second movable element including the second lateral extension section forms a second L-shaped movable element, the first and second L-shaped movable elements being arranged in a nested configuration without contact between the first and second L-shaped movable elements.

10. A sensor comprising:
a substrate;
a first movable element positioned in spaced apart relationship away from a surface of the substrate, the first movable element being adapted for rotational motion about a first rotational axis positioned between first and second ends of the first movable element, the first movable element including:
a first section between the first rotational axis and the first end of the first movable element, the first section being characterized by a first length, a first end of the first section including a first geometric stop region configured to contact the surface of the substra

Assignees

• Nxp Usa Inc

Inventors

• Mcneil Andrew C
• Li Fengyuan

Classifications

• B81B2201/0235

  Accelerometers · CPC title

• G01P15/125 Primary

  by capacitive pick-up · CPC title

• B81B3/0051 Primary

  For defining the movement, i.e. structures that guide or limit the movement of an element (mechanical arrangements for preventing or damping vibration or shock H01H3/60) · CPC title

• G01P2015/0831

  the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration · CPC title

• B81B2201/0228

  Inertial sensors · CPC title