Device and method for a threshold sensor

Patent metadata

Field	Value
Publication number	US-10793424-B2
Application number	US-201916558145-A
Country	US
Kind code	B2
Filing date	Sep 1, 2019
Priority date	Apr 7, 2015
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A device with a first MEMS device and a second MEMS device is disclosed. The first MEMS device is configured to sense at least one external influence. The second MEMS device is responsive to the at least one external influence. The first MEMS device is configured to change a state when the at least one external influence exceeds a threshold value. The first MEMS device is configured to retain the state below the threshold value, wherein the change in state of the first MEMS device is done passively and wherein the state of the first MEMS device is indicative of a status of the second MEMS device. In one example, the first MEMS device further comprises a normally open switch that closes when the external influence exceeds the threshold value.

First claim

What is claimed is:

1. A device, comprising: a first MEMS device, wherein the first MEMS device is configured to sense at least one external influence, and wherein the first MEMS device is configured to change a physical state and store the changed physical state when the at least one external influence exceeds a threshold value, and the first MEMS device is configured to retain the physical state below the threshold value, wherein the change in state of the first MEMS device is done passively, substantially due to an energy from the external influence, wherein the first MEMS device formed on a substrate includes a device layer and a different layer, the device layer including a mass movably coupled to the device layer, the mass including a plunger, wherein the mass including the plunger configured to move normal relative to the device layer; at least a first conductor and a second conductor are formed on the different layer and disposed relative to the plunger, with a gap disposed between the first conductor and the second conductor; wherein, the plunger impacts the first conductor when the at least one external influence exceeds the threshold value and changes the gap between the first conductor and the second conductor; wherein the first conductor comes in contact with the second conductor when the at least one external influence exceeds the threshold value, the first conductor and the second conductor together form a switch and the resistance of the switch determines the physical state of the first MEMS device, wherein a resistance indicates that the external influence exceeded the threshold value and another resistance indicates that the external influence did not exceed the threshold value; and a second MEMS device formed on the substrate along with the first MEMS device, the second MEMS device responsive to the at least one external influence, wherein the stored physical state of the first MEMS device is indicative of a status of the second MEMS device.

2. The device of claim 1 , wherein the at least one external influence is at least one of shock, strain and temperature.

3. The device of claim 1 , wherein the second MEMS device is at least one of a gyroscope, accelerometer, magnetometer, barometer and microphone.

4. The device of claim 1 , wherein the change in physical state of the first MEMS device is irreversible.

5. The device of claim 1 , wherein the physical state is indicative of the direction of the at least one external influence.

6. The device of claim 1 , wherein the physical state of the first MEMS device is detected visually, with a microscope.

7. The device of claim 1 , further including a readout circuit configured to read the state of first MEMS device and output the status of second MEMS device.

8. A device, comprising: a first MEMS device, wherein the first MEMS device is configured to sense at least one external influence, and wherein the first MEMS device is configured to change a physical state and store the changed physical state when the at least one external influence exceeds a threshold value; wherein the first MEMS device formed on a substrate includes a device layer and a different layer, the device layer including a mass movably coupled to the device layer, the mass including a plunger, wherein the mass including the plunger configured to move normal relative to the device layer; at least a first conductor and a second conductor are formed on the different layer and disposed relative to the plunger, with a gap disposed between the first conductor and the second conductor, the first conductor and the second conductor together with the gap form a normally open mechanical switch, wherein the plunger impacts the first conductor when the at least one external influence exceeds the threshold value and closes the gap between the first conductor and the second conductor and closes the normally open mechanical switch, wherein the first conductor comes in contact with the second conductor when the at least one external influence exceeds the threshold value, and the resistance of the mechanical switch determines the physical state of the first MEMS device, wherein a resistance indicates that the external influence exceeded the threshold and another resistance indicates that the external influence did not exceed the threshold value; and the first MEMS device is configured to retain the physical state below the threshold value, wherein the change in state of the first MEMS device is done passively; and a second MEMS device formed on the substrate along with the first MEMS device, the second MEMS device responsive to the at least one external influence, wherein the stored physical state of the first MEMS device is indicative of a status of the second MEMS device.

9. The device of claim 8 , wherein the second MEMS device is at least one of a gyroscope, accelerometer, magnetometer, barometer and microphone.

10. The device of claim 8 , wherein the change in physical state of the first MEMS device is irreversible.

11. The device of claim 8 , wherein the physical state is indicative of the direction of the at least one external influence.

12. The device of claim 8 , wherein the state of the first MEMS device is detected visually, with a microscope.

13. The device of claim 8 , further including a readout circuit configured to read the state of first MEMS device and output the status of second MEMS device.

Assignees

• Invensense Inc

Inventors

• Thompson Matthew Julian
• Lloyd Stephen
• Seeger Joseph

Classifications

• H10P74/277

  Circuits for electrically characterising or monitoring manufacturing processes, e.g. circuits in tested chips or circuits in testing wafers · CPC title

• G01M1/16

  by oscillating or rotating the body to be tested · CPC title

• H03K21/023

  comprising pulse shaping or differentiating circuits · CPC title

• G01N3/02

  Details · CPC title

• G01M17/0078

  Shock-testing of vehicles · CPC title