# US 11,029,175 B2 · Method for processing a measurement signal from a pressure measurement cell, and a measurement cell arrangement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,175 B2 - Document ID: US11029175B2 - Status: Granted - Kind: B2 - Application number: 15/571,160 - Filed: 2016-02-10 - Published: 2018-09-13 - Granted: 2021-06-08 - Earliest claimed: 2016-02-10 - Assignees: Inficon GmbH - Applicants: Inficon AG - Inventors: Felix Mullis - Web page: https://patentgrep.com/patent/US11029175B2 ## CPC - G01D 3/036: on measuring arrangements themselves - G01L 19/083: {electrical} - G01L 19/12: Alarms or signals - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract Method for determining a pressure in a pressure cell, the method consisting in determining a measuring signal (x) that is at least proportional to a measured pressure in the pressure cell, generating an output signal (y) from the measuring signal (x) using a filter unit (10) comprising a transfer function by at least reducing, preferably eliminating, a noise signal contained in the measuring signal determining a change over time of the measuring signal (x), and setting the transfer function as a function of the change over time of the measuring signal (x). A measuring cell arrangement is also specified. ## Claims ### Claim 1 A method of determining a pressure in a process chamber having a membrane pressure cell therein, in accordance with a specification of a vacuum process, wherein the method comprises: determining, in a signal processor a measuring signal that is at least proportional to a measured pressure in the membrane pressure cell, generating an output signal using a filter unit comprising a transfer function derived from the measuring signal by at least reducing a noise signal contained in the measuring signal, wherein the transfer function is defined by the formula yn=αxn+(1−α)yn-1 wherein yn is a time-discrete output signal, xn is a time-discrete measuring signal, α is a variable whose value depends on the change over time of the measuring signal, and n is a time-dependent index, determining a change over time of the measuring signal, and processing, in the signal processor, the measuring signal in a fast path for generating an output pulse, wherein the output pulse of the fast path is active for at least as long as the determined change over time of the measuring signal over three sampling intervals is greater than the noise signal acquired in the same time period, which noise signal is contained in the measuring signal or in a measuring signal change acquired in the same time period, wherein the output pulse is provided by a control unit to a valve actuator, to control the pressure in the process chamber. ### Claim 2 (depends on 1) The method according to claim 1, further comprising adjusting the pressure in the membrane pressure cell at least proportional to the output signal. ### Claim 3 (depends on 1) The method according to claim 1, characterized in that the transfer function has at least a first order low pass characteristic, and further comprises adjusting its time constant as a function of the change of the measuring signal. ### Claim 4 (depends on 1) The method according to claim 1, further comprising: determining an average value of the measuring signal, determining a difference signal by calculating the difference between the measuring signal and the average value of the measuring signal, and deriving the change over time of the measuring signal at least from the difference signal. ### Claim 5 (depends on 4) The method according to claim 4 further comprising determining the average value of the measuring signal using an exponential average filter, which is defined for a time-discrete measuring signal by fn=β1·xn+(1−β1)·fn-1 wherein fn is the time-discrete average of the measuring signal, β1 is a variable, xn is the time-discrete measuring signal, and n is a time-dependent index, wherein the variable β1 has a value between 1 and 0. ### Claim 6 (depends on 4) The method according to claim 4, further comprising determining the change over time of the measuring signal by formation of an average of the difference signal. ### Claim 7 (depends on 4) The method according to claim 4, further comprising determining the change of the measuring signal using an exponential average filter, which is defined for a time-discrete difference signal by ΔXn=β2en+(1−β2) Δxn-1 where Δxn is the time-discrete time change of the measuring signal, β2 is a variable, en is the time-discrete difference signal and n is a time-discrete index, wherein the variable β2 has a value between 1 and 0. ### Claim 8 (depends on 1) The method according to claim 1, further comprising processing the measuring signal in a slow path for generating a switching signal, the switching signal (SC) of the slow path being active at least as long as the determined change over time of the measuring signal, measured longer than 2*TS, is greater than the noise in the measuring signal measured in the same time period or in the measuring signal change, wherein TS is a predefined minimal pulse width of the output pulse and that the variable α obtains a value depending on an OR operation between the output pulse and the switching signal. ### Claim 9 (depends on 1) The method according to claim 1, comprising assigning either a value α1 or a value α2 to the variable α at least after a predetermined transition time after a switching process, wherein the value α1 lies in the range of 0.01 to 0.9 and wherein the value α2 lies in the range of 0.0001 to 0.01. ### Claim 10 (depends on 9) The method according to claim 9, comprising switching from the value α1 to the value α2 taking place over a finite timespan Fin. ### Claim 11 (depends on 9) The method according to claim 9, comprising switching from the value α2 to the value α1 taking place over a finite timespan Fout. ### Claim 12 A measuring signal arrangement comprising a membrane pressure measuring cell operatively connected to a process chamber, the membrane pressure measuring cell comprising a filter unit generating a pressure-dependent measuring signal, which is applied to the filter unit and generating an output signal, wherein a change of the measuring signal is determined, and wherein the transfer function is adjusted as a function of the change over time of the measuring signal, the transfer function being defined by the formula: yn=αxn+(1−α)yn-1 wherein yn is the time-discrete output signal, xn is the time-discrete measuring signal, α is a variable whose value depends on the change over time of the measuring signal, and n is a time-dependent index, wherein the measuring signal is applied to a fast path to generate an output pulse, the output pulse of the fast path being active at least as long as the determined change of the measuring signal during at least three sampling intervals is greater than the noise signal acquired in the same time period, which noise signal is contained in the measuring signal or in a measuring signal change acquired in the same time period. ### Claim 13 (depends on 12) The measuring signal arrangement according to claim 12, wherein the output signal is used for adjusting the pressure in the membrane pressure measuring cell. ### Claim 14 (depends on 12) The measuring signal arrangement according to claim 12, wherein the transfer function comprises a low pass characteristic of at least first order, the time constant of which is adjustable as a function of the change over time of the measuring signal. ### Claim 15 (depends on 14) The measuring signal arrangement according to claim 14, wherein an average of the measuring signal is determined by calculating the difference between the measuring signal and the average value of the measuring signal, and wherein the change over time of the measuring signal is derived at least from the difference signal. ### Claim 16 (depends on 15) The measuring signal arrangement according to claim 15, wherein the average of the measuring signal is determined using an exponential average filter, which is defined for a time-discrete measuring signal by fn=β1·xn+(1−β1)·fn-1 wherein fn is the time-discrete average of the measuring signal, β1 is a variable, xn is the time-discrete measuring signal, and n is a time-dependent index, wherein the variable β1 has a value between 1 and 0. ### Claim 17 (depends on 16) The measuring signal arrangement according to claim 16, wherein the change over time of the measuring signal is determined by formation of an average of the difference signal. ### Claim 18 (depends on 15) The measuring signal arrangement according to claim 15, wherein the change over time of the measuring signal is determined using an exponential average filter, which is defined as a time-discrete difference signal by Δxn=β2en+(1−β2) Δxn-1 wherein Δx is the time-discrete change over time of the measuring signal, β2 is a variable, en is the time-discrete difference signal and n is a time-dependent index, wherein the variable β2 has a value between 1 and 0. ### Claim 19 (depends on 12) The measuring signal arrangement according to claim 12, wherein the measuring signal is further applied to a slow path for generating a switching signal, the switching signal of the slow path being active at least as long as the determined change over time of the measuring signal, measured longer than 2*TS, is greater than the noise in the measuring signal during the same time period or in the measuring signal change, wherein TS is a predefined minimal pulse width of the output pulse, and that the variable α obtains a value depending on an OR operation between the output pulse and the switching signal. ### Claim 20 (depends on 12) The measuring signal arrangement according to claim 12, wherein either a value α1 or a value α2 is assigned to the variable α at least after a predetermined transition time after a switching process, wherein the value α1 lies in the range of 0.01 to 0.9, and wherein the value α2 lies in the range of 0.0001 to 0.01. ### Claim 21 (depends on 12) The measuring signal arrangement according to claim 12, further comprising a transition unit associated with the filter unit seen in a direction given by a signal flow path, the transition unit switching from a value α1 to a value α2 during a finite timespan Fin and/or switching from a value α2 to a value at during a finite timespan Fout.