# US 10,478,078 B2 · Device and method for determining vital signs of a subject > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,478,078 B2 - Document ID: US10478078B2 - Status: Granted - Kind: B2 - Application number: 15/102,649 - Filed: 2014-11-28 - Published: 2016-10-20 - Granted: 2019-11-19 - Earliest claimed: 2013-12-12 - Assignees: Koninklijke Philips N.V. - Applicants: Koninklijke Philips N.V. - Inventors: Gerard De Haan - Web page: https://patentgrep.com/patent/US10478078B2 ## CPC - A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)} - A61B 5/0077: {Devices for viewing the surface of the body, e.g. camera, magnifying lens} - A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters - A61B 5/7203: {for noise prevention, reduction or removal} - A61B 5/725: {using specific filters therefor, e.g. Kalman or adaptive filters (specific diagnostics methods using using bioelectric or biomagnetic signals A61B5/316)} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract The present invention relates to a Device for determining vital signs of a subject comprising an interface (22) for receiving a periodic photoplethysmographic, PPG, signal obtained from a subject (14) by a PPG measurement, a signal partitioning unit (24) for partitioning the PPG signal in time into a plurality of PPG sub-signals covering a half period or an integer multiple of a half period, a normalizing unit (26) for normalizing the PPG signal in advance of the partitioning and/or the PPG sub-signals in time and/or amplitude, a signal combination unit (28) for combining a number of normalized PPG sub-signals to obtain a combined PPG sub-signal, and a vital sign processor (30) for deriving a desired vital sign from the PPG signal, one or more combined PPG sub-signals or an enhanced PPG signal obtained by consecutively arranging a number of combined PPG sub-signals. ## Claims ### Claim 1 A device for determining vital signs of a subject comprising: a controller with a memory that stores instructions; a processor that executes the instructions, wherein, when executed by processor, the instructions cause the controller to execute a process comprising: receiving a periodic photoplethysmographic (PPG) signal obtained from a subject by a PPG measurement; partitioning the PPG signal in time into a plurality of PPG sub-signals respectively covering a half period of the PPG signal; normalizing in time and/or amplitude the PPG signal in advance of the partitioning and/or the PPG sub-signals to obtain normalized PPG sub-signals; combining the normalized PPG sub-signals to obtain one or more combined PPG sub-signals; and deriving a desired vital sign of the subject from the one or more combined PPG sub-signals or an enhanced PPG signal obtained by consecutively arranging a plurality of the combined PPG sub-signals. ### Claim 2 (depends on 1) The device as claimed in claim 1, wherein said combining further comprises consecutively arranging the combined PPG sub-signals according to a chronological order of the normalized PPG sub-signals, from which they have been obtained. ### Claim 3 (depends on 1) The device as claimed in claim 1, wherein said combining further comprises combining a predetermined number of consecutive normalized PPG sub-signals arranged within a time window to obtain a combined PPG sub-signal, wherein the time window is shifted in time for each combined PPG sub-signal. ### Claim 4 (depends on 1) The device as claimed in claim 1, wherein the partitioning further comprises detecting zero-crossings and/or extrema of the PPG signal, and using the detected zero-crossings and/or extrema for partitioning the PPG signal. ### Claim 5 (depends on 1) The device as claimed in claim 1, wherein said normalizing the PPG signal in advance of the partitioning further comprises: detecting extrema of the PPG signal, fitting a first curve through detected peaks and a second curve through detected valleys; subtracting a momentary average value of the first and second curves from a momentary signal value of the PPG signal; and dividing a momentary resulting value by a momentary difference value of the first and second curves to obtain a normalized signal value of the PPG signal. ### Claim 6 (depends on 1) The device as claimed in claim 1, wherein said normalizing further comprises repeating the normalizing until a stop condition is met or normalized signal value obtained from the normalizations converge. ### Claim 7 (depends on 1) The device as claimed in claim 1, wherein said combining further comprises generating an average, a weighted average or a trimmed mean of two or more normalized PPG sub-signals. ### Claim 8 (depends on 1) The device as claimed in claim 1, wherein said combining further comprises generating a weighted average or a trimmed mean of two or more normalized PPG sub-signals, wherein the weight for weighting normalized PPG sub-signals decreases with a time-distance to a current time interval. ### Claim 9 (depends on 1) The device as claimed in claim 1, further comprising a filter for low-pass or band-pass filtering the received PPG signal, wherein the filtered PPG signal is used for subsequent processing. ### Claim 10 (depends on 1) The device as claimed in claim 1, wherein said combining further comprises scaling the period of the combined PPG sub-signals in time to match the period of a current time interval and to consecutively arrange a number of the scaled combined PPG sub-signals to obtain the enhanced PPG signal. ### Claim 11 (depends on 1) The device as claimed in claim 1, further comprising a high frequency (HF) boosting filter for boosting of high-frequency harmonics in the PPG sub-signals and/or the enhanced PPG signal, wherein said filtered PPG signal is used for subsequent processing. ### Claim 12 (depends on 1) The device as claimed in claim 1, further comprising an imaging unit for acquiring image frames of a subject, and the process further comprises: deriving a PPG signal from a skin portion of the subject shown in the image frames and for providing the PPG signals to an interface. ### Claim 13 (depends on 1) The device as claimed in claim 1, further comprising a PPG sensor for acquiring PPG signals from a PPG measurement at a skin portion of the subject and for providing the PPG signals to a interface. ### Claim 14 A method for determining vital signs of a subject, the method comprising: receiving a periodic photoplethysmographic (PPG) signal obtained from the subject by a PPG measurement; partitioning the PPG signal in time into a plurality of PPG sub-signals respectively covering a half period of the PPG signal; normalizing in time and/or amplitude the PPG signal in advance of the partitioning and/or the PPG sub-signals to obtain normalized PPG sub-signals; combining the normalized PPG sub-signals to obtain one or more combined PPG sub-signal; and deriving a desired vital sign from the one or more combined PPG sub-signals or an enhanced PPG signal obtained by consecutively arranging a plurality of the combined PPG sub-signals. ### Claim 15 (depends on 14) A non-transitory computer-readable medium storing a computer program executable on a computer processor, which when executed by the computer processor cause a computer to carry out the steps of the method as claimed in claim 14.