# US 7,745,746 B2 · Micromachined mechanical switch

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- Number: US 7,745,746 B2
- Document ID: US7745746B2
- Status: Granted
- Kind: B2
- Application number: 12/017,769
- Filed: 2008-01-22
- Published: 2009-07-23
- Granted: 2010-06-29
- Earliest claimed: 2008-01-22
- Assignees: Infineon Technologies Sensonor AS
- Inventors: Markus Lohndorf; Terje Kvisteroey
- Web page: https://patentgrep.com/patent/US7745746B2

## CPC

- H01H 1/0036: {Switches making use of microelectromechanical systems [MEMS] (for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009)}
- B60C 23/0459: {self triggered by motion sensor}
- B60C 23/0488: {Movement sensor, e.g. for sensing angular speed, acceleration or centripetal force}
- H01H 35/14: Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch {(wherein the liquid constitutes a contact of the switch H01H29/002)}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES

## Abstract

A mechanical switch is arranged to electrically connect a power source to an electrical component. The switch includes a resilient structure, a first electrically conductive element connected to the power source and a second conductive element connected to the electrical component. At least one of the conductive elements is attached to the resilient structure. The switch is arranged such that the conductive elements are positioned out of contact with one another in the absence of a force being applied to the switch, and the resilient structure is moveable in response to a force applied thereto, the force being applied upon rotation of a tire to which the switch is connected. Upon the application of a force above a predetermined threshold, the resilient structure moves to bring the conductive elements into contact with one another, the contact electrically connecting the power source to the electrical component.

## Claims

### Claim 1

A tire pressure monitoring system (TPMS) comprising:
a power source;
TPMS circuitry; and
a mechanical switch positioned between the power source and the TPMS circuitry and arranged to electrically connect a power source to an electrical component, the switch comprising:
a resilient structure; and
a first electrically conductive element connected to the power source and a second conductive element connected to the electrical component, at least one of the conductive elements being attached to the resilient structure,
wherein the switch is arranged such that:
the conductive elements are positioned out of contact with one another in the absence of a force being applied to the switch;
the resilient structure is moveable in response to a force applied thereto, the force being applied upon rotation of a tire to which the switch is connected; and
upon application of a force above a predetermined threshold, the resilient structure moves to bring the conductive elements into contact with one another, the contact electrically connecting the power source to the electrical component.

### Claim 2 (depends on 1)

The switch according to claim 1, wherein the electrical component forms part of the tire pressure monitoring system (TPMS).

### Claim 3 (depends on 1)

The switch according to claim 1, wherein the force is applied in a substantially radial direction of the tire.

### Claim 4 (depends on 1)

The switch according to claim 1, wherein the switch is a micro mechanical device.

### Claim 5 (depends on 1)

The switch according to claim 1, wherein the resilient structure is arranged such that the resilient structure is sensitive to an acceleration in the order of between 1 g and 10 g, where g is the gravitational acceleration.

### Claim 6 (depends on 1)

The switch according to claim 1, wherein contact resistance between the electrically conductive elements is less than 100 ohms.

### Claim 7 (depends on 1)

The switch according to claim 1, wherein at least one of the electrically conductive elements comprise gold.

### Claim 8 (depends on 1)

The switch according to claim 1, wherein at least one of the electrically conductive elements comprise ruthenium.

### Claim 9 (depends on 1)

The TPMS according to claim 1, wherein the system is arranged to determine a footprint of a tire in which the TPMS is provided.

### Claim 10 (depends on 9)

The TPMS according to claim 9, wherein the system is arranged to determine vertical load of a vehicle comprising the tire in which the TPMS is provided.