# US 10,118,817 B2 · MEMS devices with membrane having venting flaps hingedly attached to one another > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,118,817 B2 - Document ID: US10118817B2 - Status: Granted - Kind: B2 - Application number: 15/608,011 - Filed: 2017-05-30 - Published: 2017-09-14 - Granted: 2018-11-06 - Earliest claimed: 2014-12-19 - Assignees: Cirrus Logic, Inc. - Applicants: Cirrus Logic International Semiconductor Ltd. - Inventors: Scott Lyall Cargill; Marek Sebastian Piechocinski - Web page: https://patentgrep.com/patent/US10118817B2 ## CPC - B81B 7/0061: {suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound} - H04R 19/005: {using semiconductor materials} - H04R 19/04: Microphones (H04R19/01 takes precedence) - B81B 2201/0257: Microphones or microspeakers - B81B 2201/0264: Pressure sensors - 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 - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract This application relates to MEMS transducer having a membrane layer (101) and at least one variable vent structure (301). The variable vent structure has a vent hole for venting fluid so as to reduce a pressure differential across the membrane layer and a moveable vent cover (302a, 302b) which, at an equilibrium position, at least partly blocks the vent hole. The vent cover is moveable from its equilibrium position in response to a pressure differential across the vent cover so as to vary the size of a flow path through the vent hole. In various embodiments the vent cover comprises at least a first flap section (302a) and a second flap section (302b), the first flap section being hingedly coupled to the side of the vent hole and the second flap section being hingedly coupled to the first flap section so as to be moveable with respect to the first flap section. In some embodiments the second flap section (302b) may be configured so that it deflects away from the first section (302a) more readily than the first section deflects away from its equilibrium position. ## Claims ### Claim 1 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the variable vent structure is configured such that the extent to which the first flap section deflects away from an equilibrium position for a given pressure differential is different to the extent to which the second flap section deflects away from the first flap section for the same pressure differential. ### Claim 2 (depends on 1) A MEMS transducer as claimed in claim 1 wherein the second flap section is coupled to the membrane layer only via the first flap section. ### Claim 3 (depends on 1) A MEMS transducer as claimed in claim 1 wherein the variable vent structure is configured such that the second flap section deflects away from the first flap section more readily than the first flap section deflects away from equilibrium position. ### Claim 4 (depends on 1) A MEMS transducer as claimed in claim 1 wherein the variable vent structure is configured such that, in use, for at least one pressure differential the amount of deflection of the second flap section with respect to the first flap section will be greater than the amount of deflection of the first flap section from equilibrium. ### Claim 5 (depends on 1) A MEMS transducer as claimed in claim 1 wherein the variable vent structure is configured to provide a flow path size that varies, in use, with pressure within the normal expected operating range of the MEMS transducer so as to provide a variable sensitivity. ### Claim 6 (depends on 1) A MEMS transducer as claimed in claim 1 wherein the variable vent structure is formed in a first layer of material and the variable vent structure is formed from the same material as said first layer wherein the variable vent structure is configured such that, at an equilibrium position, said first flap section and said second flap section lie substantially with the plane of the first layer. ### Claim 7 (depends on 6) A MEMS transducer as claimed in claim 6 wherein the first layer is the membrane layer. ### Claim 8 (depends on 1) A MEMS transducer as claimed in claim 1 wherein said device is at least one of: a portable device; a battery powered device; an audio device; a computing device; a communications device; a personal media player; a mobile telephone; a games device; a wearable device; and a voice controlled device. ### Claim 9 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the first flap section is coupled to the membrane layer via a first connection and the second flap section is coupled to the first flap section by a second connection. ### Claim 10 (depends on 9) A MEMS transducer as claimed in claim 9 wherein the dimensions and/or geometry of the first connection and second connection are different from one another. ### Claim 11 (depends on 9) A MEMS transducer as claimed in claim 9 wherein at least one of the first and second connections comprises a beam structure. ### Claim 12 (depends on 9) A MEMS transducer as claimed in claim 9 wherein at least one of the first and second connections comprises a plurality of connecting regions spaced apart along a hinging axis. ### Claim 13 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the first flap section is coupled to the membrane layer for movement substantially about a first hinging axis and the second flap section is coupled to the first flap section for movement with respect to the first flap section substantially about a second hinging axis, wherein the first and second hinging axes are parallel to one another. ### Claim 14 (depends on 13) A MEMS transducer as claimed in claim 13 wherein the first flap section is coupled for movement about the first hinging axis in a rotational direction and the second flap section is coupled for movement about the second hinging axis in the same rotational direction. ### Claim 15 (depends on 13) A MEMS transducer as claimed in claim 13 wherein the first flap section is coupled for movement about the first hinging axis in a rotational direction and the second flap section is coupled for movement about the second hinging axis in the opposite rotational direction. ### Claim 16 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the second flap section is within the perimeter of the first flap section. ### Claim 17 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the variable vent structure is configured such that, in use, at least the first flap section is not substantially deflected from an equilibrium position at pressure differentials below a first pressure threshold and is substantially deflected from equilibrium position at pressure differentials above a second pressure threshold for the first section. ### Claim 18 (depends on 17) A MEMS transducer as claimed in claim 17 wherein the variable vent structure is configured such that, in use, the second flap section is substantially deflected from equilibrium position at pressure differentials above a second pressure threshold for the second section. ### Claim 19 A MEMS transducer comprising: a membrane layer; and at least one variable vent structure; wherein said variable vent structure provides a flow path having a size that varies with pressure differential across the membrane layer; wherein the variable vent structure comprises at least a first flap section and a second flap section, the first flap section being coupled via at least one hinge to the membrane layer, and the second flap section being coupled via at least one hinge to the first flap section; and wherein the variable vent structure comprises at least one additional flap section, wherein the or each additional flap section is coupled via at least one hinge to one of the first flap section or the second flap section or an intermediate additional flap section.