MEMS Microphone System with Low Pressure Gap and Back Volume

• US 20190007759A1
• Filed: 02/07/2018
• Published: 01/03/2019
• Est. Priority Date: 06/28/2017
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Akustica Incorporated, Robert Bosch GmbH
• Inventors: Meisel, Daniel, Doller, Andrew
• Granted Patent: US 10,448,132 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/0163 Spring holders
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0061 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: H04R 1/04 Structural association of microphone with electric circuitry therefor in deaf-aid sets H04R25/00
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005

Abstract

A MEMS microphone system comprises a transducer die having a pierce-less diaphragm and a motion sensor suspended from the diaphragm. The system further comprises a housing and the diaphragm divided a volume inside the housing into a front volume and a back volume. The motion sensor suspended from the diaphragm is located in the back volume having a gas pressure that is substantially equal or lower than an ambient pressure.

Claims

1. A microphone system comprising:

a housing;

a volume formed within the housing;

a movable member divided the volume into a front volume and a back volume; and

a sensor located in the back volume, the sensor is suspended from the movable member;

wherein the sensor configured to detect frequency and amplitude of the movable member in motion and converts both the frequency and the amplitude into an electrical signal for further processing.

2. The microphone system of claim 1 wherein the movable member is a pierce-less diaphragm.

3. The microphone system of claim 2 wherein the sensor is an electrode assembly, the electrode assembly comprising:

a first electrode and a first support member formed part of the first electrode;

a second electrode and a second support member formed part of the second electrode; and

a gap formed between the first and second electrodes;

wherein the first and second electrodes are parallel to each other, the first and second support members coupled the first and second electrodes to the movable member.

4. The microphone system of claim 3 wherein the first support member has a length different from a length of the second support member.

5. The microphone system of claim 4 wherein the second support member comprises a tubular shape body with a hollow portion for receiving the first support member.

6. The microphone system of claim 2 wherein the microphone system further comprises a second sensor suspended from the movable diaphragm, each of the sensor comprising:

an electrode having a spring element; and

an insulator configured to support the electrode.

7. The microphone system of claim 6 wherein the sensor is selected from a group consisting of a motion sensor, a capacitive transducer, a piezoelectric transducer, a piezoresistive transducer, a one-channel acceleration sensor, a two-channel acceleration sensor, a three-channel acceleration sensor, a pure dynamic motion sensor, a velocity sensor, a rotational-rate sensor, a rotational accelerator sensor, a laser-doppler, an interferometer, an optical sensor, a light sensor, and a magnetic sensor.

8. The microphone system of claim 1 wherein the back volume is having a gas pressure that is substantially equal or lower than an ambient pressure.