# US 2014/0196546 A1 · Pressure Sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196546 A1 - Document ID: US20140196546A1 - Status: Published application - Kind: A1 - Application number: 13/742,047 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Transducers Direct LLC - Applicants: Transducers Direct LLC - Inventors: David Allen Topmiller - Web page: https://patentgrep.com/patent/US20140196546A1 ## CPC - G01L 9/06: of piezo-resistive devices - G01L 9/0055: {bonded on a diaphragm} - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract A pressure sensor is claimed for measuring the pressure of a fluid. The pressure sensor comprises two or more half bridges, an analog-to-digital converter, a microcontroller, an output generator, and one or more redundancy circuits. Each half bridge comprises two resistive pressure sensing elements (RSPE) electrically coupled to the analog-to-digital converter. Each redundancy circuit comprises a switch and resistor electrically in series. A redundancy circuit may be disposed electrically in parallel with any or all of the RSPEs of the half bridges such that when an RSPE fails open, its corresponding redundancy circuit may be activated in order to permit the resistor of the redundancy circuit to take the place of the RSPE. This permits the analog-to-digital converter to continue to operate normally, even with a failed RSPE. The pressure sensor may then base its calculated pressure on the remaining half bridges which do not have a failed RSPE. ## Claims ### Claim 1 A pressure sensor for measuring the pressure of a fluid, the pressure sensor comprising two or more half bridges, an analog-to-digital converter, a microcontroller, an output generator, and one or more redundancy circuits, wherein: the two or more half bridges are mechanically coupled to the fluid; each of the two or more half bridges comprises a first resistive pressure sensing element (RPSE) and a second RPSE, such that the resistance of the first RPSE increases when the pressure of the fluid increases, and the resistance of the second RPSE decreases when the pressure of the fluid increases; the analog-to-digital converter is electrically coupled to the two or more half bridges and is operable to measure the resistance of the first and second RPSEs of the two or more half bridges such that the analog-to-digital converter is operable to produce a first digital number corresponding to the pressure of the fluid based on the measured resistance of the first and second RPSEs of at least one of the two or more half bridges; the microcontroller is electrically coupled to the analog-to-digital converter and the output generator, such that the microcontroller is operable to read the first digital number from the analog-to-digital converter, generate a second digital number corresponding to the pressure of the fluid, and write the second digital number to the output generator; the output generator is operable to receive the second digital number from the microcontroller and produce an electrical output signal based on the second digital number such that the electrical output signal corresponds to the pressure of the fluid; and the one or more redundancy circuits are electrically coupled to the one or more of the first RPSEs or one or more of the second RPSEs of the two or more half bridges, and the redundancy circuit comprises a resistor and a switch in series, wherein: the switch is electrically coupled to the microcontroller and comprises an open position and a closed position such that the microcontroller determines whether the switch is in the open position or the closed position; and when the switch is in the open position, the resistor has little or no effect on the resistance of the one or more first RPSEs or the one or more second RPSEs with which the redundancy circuit is electrically in parallel; and when the switch is in the closed position, the resistor is electrically in parallel with the one or more first RPSEs or the one or more second RPSEs with which the redundancy circuit is electrically in parallel. ### Claim 2 (depends on 1) The pressure sensor of claim 1 comprising two half bridges. ### Claim 3 (depends on 2) The pressure sensor of claim 2 comprising two redundancy circuits electrically in parallel with the first RPSE and the second RPSE of one of the two half bridges. ### Claim 4 (depends on 1) The pressure sensor of claim 1, wherein the analog-to-digital converter comprises a time-to-digital converter operable to measure the resistance or the ratio of the resistance of the first and/or second RPSEs of the two or more half bridges by measuring a voltage discharge time of a capacitor charged to a substantially fixed voltage through the first and/or second RPSEs. ### Claim 5 (depends on 4) The pressure sensor of claim 4, wherein the analog-to-digital converter comprises a PS09 time-to-digital converter. ### Claim 6 (depends on 1) The pressure sensor of claim 1, wherein the first and second RPSEs of the two or more half bridges comprise piezoresitive devices. ### Claim 7 (depends on 1) The pressure sensor of claim 1, wherein the output generator comprises a digital-to-analog converter operable to produce the electrical output signal comprising an analog voltage or an analog current. ### Claim 8 (depends on 7) The pressure sensor of claim 7, wherein the electrical output signal comprises an analog voltage of approximately 0 to 10 Volts corresponding to the pressure of the fluid. ### Claim 9 (depends on 7) The pressure sensor of claim 7, wherein the electrical output signal comprises an analog current of approximately 4 mA to 20 mA corresponding to the pressure of the fluid. ### Claim 10 (depends on 1) The pressure sensor of claim 1, wherein the output generator comprises a digital switch operable to produce the electrical output signal comprising a digital voltage corresponding to the pressure of the fluid. ### Claim 11 A method for operating a pressure sensor for measuring the pressure of a fluid, wherein the pressure sensor comprises two or more half bridges, an analog-to-digital converter, a microcontroller, an output generator, and one or more redundancy circuits, wherein: the two or more half bridges are mechanically coupled to the fluid; each of the two or more half bridges comprises a first resistive pressure sensing element (RPSE) and a second RPSE, such that the resistance of the first RPSE increases when the pressure of the fluid increases, and the resistance of the second RPSE decreases when the pressure of the fluid increases; the analog-to-digital converter is electrically coupled to the two or more half bridges and is operable to measure the resistance of the first and second RPSEs of the two or more half bridges such that the analog-to-digital converter is operable to produce a first digital number corresponding to the pressure of the fluid based on the measured resistance of the first and second RPSEs of at least one of the two or more half bridges; the microcontroller is electrically coupled to the analog-to-digital converter and the output generator, such that the microcontroller is operable to read the first digital number from the analog-to-digital converter, generate a second digital number corresponding to the pressure of the fluid, and write the second digital number to the output generator; the output generator is operable to receive the second digital number from the microcontroller and produce an electrical output signal based on the second digital number such that the electrical output signal corresponds to the pressure of the fluid; and the one or more redundancy circuits are electrically coupled to the one or more of the first RPSEs or one or more of the second RPSEs of the two or more half bridges, and the redundancy circuit comprises a resistor and a switch in series, wherein: the switch is electrically coupled to the microcontroller and comprises an open position and a closed position such that the microcontroller determines whether the switch is in the open position or the closed position; and when the switch is in the open position, the resistor has little or no effect on the resistance of the one or more first RPSEs or the one or more second RPSEs with which the redundancy circuit is electrically in parallel; and when the switch is in the closed position, the resistor is electrically in parallel with the one or more first RPSEs or the one or more second RPSEs with which the redundancy circuit is electrically in parallel, and the method comprises: determining that one or more of the first or second RPSEs has malfunctioned; setting to the closed position the switch of the redundancy circuit electrically in parallel with the malfunctioned first or second RPSE; and basing the measured pressure on the resistance of the one or more half bridges which do not have a malfunctioned first or second RPSE. ### Claim 12 (depends on 11) The method of claim 11, wherein the pressure sensor comprises two half bridges. ### Claim 13 (depends on 12) The method of claim 12, wherein the pressure sensor comprises two redundancy circuits electrically in parallel with the first RPSE and the second RPSE of one of the two half bridges. ### Claim 14 (depends on 11) The method of claim 11, wherein the analog-to-digital converter comprises a time-to-digital converter operable to measure the resistance or the ratio of the resistance of the first and/or second RPSEs of the two or more half bridges by measuring a voltage discharge time of a capacitor charged to a substantially fixed voltage through the first and/or second RPSEs. ### Claim 15 (depends on 14) The method of claim 14, wherein the analog-to-digital converter comprises a PS09 time-to-digital converter. ### Claim 16 (depends on 11) The method of claim 11, wherein the first and second RPSEs of the two or more half bridges comprise piezoresitive devices. ### Claim 17 (depends on 11) The method of claim 11, wherein the output generator comprises a digital-to-analog converter operable to produce the electrical output signal comprising an analog voltage or an analog current. ### Claim 18 (depends on 17) The method of claim 17, wherein the electrical output signal comprises an analog voltage of approximately 0 to 10 Volts corresponding to the pressure of the fluid. ### Claim 19 (depends on 17) The method sensor of claim 17, wherein the electrical output signal comprises an analog current of approximately 4 mA to 20 mA corresponding to the pressure of the fluid. ### Claim 20 (depends on 11) The method sensor of claim 11, wherein the output generator comprises a digital switch operable to produce the electrical output signal comprising a digital voltage corresponding to the pressure of the fluid.