Photoplethysmography apparatus

Patent metadata

Field	Value
Publication number	US-2018014737-A1
Application number	US-201615546344-A
Country	US
Kind code	A1
Filing date	Jan 26, 2016
Priority date	Jan 30, 2015
Publication date	Jan 18, 2018
Grant date	—

Abstract

The invention relates to a photoplethysmography (PPG) apparatus ( 100 ), comprising at least one light source ( 110 ) configured to generate a beam of source light ( 114 ) having a source beam angle ( 118 ) and at least one controllable beam angle adapter ( 120 ) configured to receive a beam-angle control signal ( 170 ) indicative of a modified beam angle ( 124 ) to be set, the beam angle adapter ( 120 ) being further configured to provide the beam of source light ( 114 ) with a modified beam angle ( 124 ) to an external object ( 130 ). The PPG apparatus ( 100 ) comprises at least one PPG sensor( 140 )configured to provide a sensor signal ( 145 ) indicative of source light ( 150 ) scattered by the external object ( 130 ), and a PPG evaluation and control unit ( 160 ) configured to receive the sensor signal ( 145 ), to provide the beam-angle control signal ( 170 ) and to provide at its output ( 180 ) an AC signal component of the sensor signal ( 145 ).

First claim

1 . A photoplethysmography apparatus, hereinafter PPG apparatus, comprising:
at least one light source configured to generate a beam of source light having having a source beam angle directed towards an external object; at least one controllable beam angle adapter arranged between the light source and the external object and configured to receive a beam-angle control signal indicative of a modified beam angle to be set, which differs from the source beam angle, the beam angle adapter being further configured to receive the beam of source light having the source beam angle and to provide the beam of source light with the modified beam angle to the external object; at least one PPG sensor which is arranged and configured to provide a sensor signal indicative of scattered source light, which has been scattered by the external object and detected by the PPG sensor, and which comprises an AC signal component indicative of a change of an amount of blood and air in a body part and allowing to determine vital sign information of the external object; and a PPG evaluation and control unit, which is configured to receive the sensor signal, to determine and provide the beam-angle control signal in dependence on the AC signal component of the sensor signal or in dependence on the AC signal component of the sensor signal and a DC signal component of the sensor signal and to determine and selectively provide at its output the AC signal component.

2 . The PPG apparatus of claim 1 , wherein the beam angle adapter comprises a liquid crystal lens with an adjustable focal length.

3 . The PPG apparatus of claim 1 , wherein the PPG evaluation and control unit is configured to determine a ratio difference between a ratio of the AC signal component of the sensor signal and the DC signal component of the sensor signal) and a predetermined reference ratio thereof, and to provide the beam-angle control signal in dependence on the ratio difference.

4 . The PPG apparatus of claim 1 , further comprising a distance sensor, which is configured to provide a distance signal which is indicative of a distance between the light source and the external object, wherein the PPG evaluation and control unit is configured to receive the distance signal and to determine and provide the beam-angle control signal in dependence on the received distance signal.

5 . The PPG apparatus of claim 1 , further comprising a pressure sensor, which is configured to provide a pressure signal which is indicative of a pressure exerted by the PPG apparatus on the external object, wherein the PPG evaluation and control unit is configured to receive the pressure signal and to determine and provide the beam-angle control signal in dependence on the received pressure signal.

6 . The PPG apparatus of claim 1 , wherein the PPG evaluation and control unit is further configured to receive beam-angle control information as a user input via a user input interface of the PPG apparatus and to determine and provide the beam-angle control signal in dependence on the beam-angle control information.

7 . The PPG apparatus of claim 1 , wherein the PPG evaluation and control unit is configured to control performance of a calibration measurement by the PPG apparatus to provide a calibration of the PPG apparatus, the calibration providing an allocation of
a) the DC signal component of the sensor signal or b) a signal-component ratio of the AC signal component of the sensor signal and the DC signal component of the sensor signal, to an object type by a predetermined object-type classification of external objects, the object-type classification allocating different amounts of the DC signal component or of the signal-component ratio to different object types.

8 . The PPG apparatus of claim 7 , wherein the PPG evaluation and control unit is configured to determine an object type based on the sensor signal and the calibration, and to determine the beam-angle control signal in dependence on the object type determined in the calibration.

9 . The PPG apparatus of claim 1 , wherein the PPG evaluation and control unit is further configured to determine at least one motion parameter indicative of a motion of the external object as a whole relative to the light source, and to determine the beam-angle control signal in dependence on the motion parameter.

10 . A method for operating a photoplethysmography apparatus, hereinafter PPG apparatus, the method comprising:
providing at least one beam of source light having a source beam angle directed towards an external object; determining and providing a beam-angle control signal indicative of a modified beam angle to be set, which differs from the source beam angle of the at least one beam of source light; adapting the at least one beam of source light in dependence on the beam-angle control signal to set the modified beam angle by means of at least one beam angle adapter; providing a sensor signal indicative of scattered source light, which has been scattered by the external object, and which comprises and AC component indicative of a change of an amount of blood or air in a body part and allowing to determine vital sign information of the external object; and determining and selectively providing the AC signal component of the sensor signal; wherein determining and providing the beam-angle control signal is performed in dependence on the AC signal component of the sensor signal or in dependence on the AC signal component of the sensor signal and a DC signal component of the sensor signal.

11 . The method of claim 10 , further comprising:
providing a distance signal which is indicative of a distance between a light source and the external object or a pressure signal which is indicative of a pressure exerted by the PPG apparatus on the external object; receiving the distance signal or the pressure signal and determining and providing the beam-angle control signal in dependence on the received distance signal or pressure signal.

12 . The method of claim 10 , further comprising:
providing an allocation of a) the DC signal component of the sensor signal or b) a signal-component ratio of the AC signal component of the sensor signal and the DC signal component of the sensor signal, to an object type by a predetermined object-type classification of external objects, the object-type classification allocating different amounts of the DC signal component or of the signal-component ratio to different object types; and determining the beam-angle control signal in dependence on the object type determined by the allocation.

13 . The method of claim 10 , further comprising:
determining from a sequence of at least two beam-angle control signals taken at different former points in time at least one motion parameter indicative of a motion of the external object as a whole relative to the light source; and determining the beam-angle control signal in dependence on the motion parameter.

14 . A computer program for operating a photoplethysmography apparatus comprising program code means for causing a computer to carry out a method according to claim 10 .

Assignees

• Koninklijke Philips Nv

Inventors

• Paulussen Elvira Johanna Maria
• Presura Cristian Nicolae
• Van Gool Edgar Martinus

Classifications

• A61B5/02416

  using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence) · CPC title

• A61B5/14551

  for measuring blood gases · CPC title

• A61B5/14552

  Details of sensors specially adapted therefor · CPC title

• A61B5/02427 Primary

  Details of sensor · CPC title

• A61B5/0037 Primary

  Performing a preliminary scan, e.g. a prescan for identifying a region of interest · CPC title