MEMS MICROPHONE ELEMENT AND DEVICE INCLUDING SUCH AN MEMS MICROPHONE ELEMENT

• US 20150156591A1
• Filed: 12/03/2014
• Published: 06/04/2015
• Est. Priority Date: 12/03/2013
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: SCHELLING, Christoph, SCHEBEN, Rolf, EHRENPFORDT, Ricardo
• Granted Patent: US 9,571,938 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0221 Variable capacitors
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0285 Vibration sensors
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 29/004 for microphones H04R29/007 takes precedence

Abstract

A capacitive MEMS microphone element is described which may be used optionally for detecting acoustic signals (microphone mode) or for detecting ultrasound signals in a defined frequency range (ultrasound mode). In the layered structure of the MEMS microphone element, at least two carrier elements for the two electrode sides of a capacitor system are formed one above the other and at a distance from one another for signal detection. At least one of the two carrier elements is sound pressure-sensitive and at least one of the two electrode sides includes at least two electrode segments which are electrically contactable independent of one another, which together with the at least one electrode of the other electrode side form partial capacitances which are independent of one another.

Claims

1. An MEMS microphone element, comprising:

at least two carrier elements for two electrode sides of a capacitor system, the carrier elements being formed one above another and at a distance from one another in its layered structure for signal detection, wherein;

at least one of the carrier elements is sound pressure-sensitive,

at least one of the electrode sides includes at least two electrode segments that are electrically contactable independent of one another,

the electrode segments together with the at least one electrode of the other electrode side form partial capacitances which are independent of one another, and

a shape and extension of the electrode segments across a surface are determined by a position and extension of vibration antinodes of a sound pressure-sensitive carrier element when the carrier element is excited to higher mode vibrations using ultrasound of a defined frequency.

2. The MEMS microphone element as recited in claim 1, further comprising:

a fixed, acoustically permeable counter-element as another carrier element, wherein;

the electrode segments have a layout tuned to a defined ultrasound frequency,

the electrode segments are formed on the fixed counter-element , and

the sound pressure-sensitive carrier element includes a diaphragm.

3. The MEMS microphone element as recited in claim 1, further comprising:

a fixed, acoustically permeable counter-element as another carrier element, wherein;

the electrode segments have a layout tuned to a defined ultrasound frequency,

the sound pressure-sensitive carrier element includes a diaphragm, and

the electrode segments are formed on the diaphragm.

4. A device, comprising:

at least two carrier elements for two electrode sides of a capacitor system, the carrier elements being formed one above another and at a distance from one another in its layered structure for signal detection, wherein;

at least one of the carrier elements is sound pressure-sensitive,

at least one of the electrode sides includes at least two electrode segments that are electrically contactable independent of one another,

the electrode segments together with the at least one electrode of the other electrode side form partial capacitances which are independent of one another, and

a shape and extension of the electrode segments across a surface are determined by a position and extension of vibration antinodes of a sound pressure-sensitive carrier element when the carrier element is excited to higher mode vibrations using ultrasound of a defined frequency;

at least one optionally activatable ultrasound transmitter that transmits ultrasound signals of a defined frequency and to which a layout of the electrode segments of the MEMS microphone element is tuned; and

an arrangement for signal evaluation optionally appropriate to one of a microphone mode and an ultrasound mode.

5. The device as recited in claim 4, wherein the optionally activatable ultrasound sensor transmits ultrasound signals of a higher mode of a resonance frequency of the sound pressure-sensitive carrier element of the MEMS microphone element.

6. The device as recited in claim 4, wherein the arrangement for signal evaluation is designed in such a way that the signal evaluation in the microphone mode is based on at least one partial capacitance, and that in the ultrasound mode, partial capacitances, which correspond to antinodes in phase opposition of the diaphragm, are added up phase shifted by 180°

.

7. The device as recited in claim 4, wherein the arrangement for signal evaluation is designed in such a way that the partial capacitances in the microphone mode are added up as a function of a signal level of an acoustic signal.

8. The device as recited in claim 4, wherein the arrangement for signal evaluation is designed in such a way that the ultrasound mode is used at least one of for localizing an object and for motion detection.