Optical device for measuring a heart rate of a user

• US 9,681,812 B2
• Filed: 01/22/2015
• Issued: 06/20/2017
• Est. Priority Date: 02/04/2014
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Presura, Cristian Nicolae
• Primary Examiner(s): Luong, Peter
• Application Number:
  US15/110,121
• Publication Number:
  US 20160331251A1
• Time in Patent Office: 880 Days
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 2560/0242 adapted to measure environmental factors, e.g. temperature, pollution
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths

Abstract

The invention relates to an optical device for measuring a heart rate of a user. Said optical device comprises: —two light sources (1,2) for emitting light into the skin of the user, —a sensor (3) for sensing the light signals emitted by each of the two light sources and reflected through the skin of the user so as to determine the heart rate of the user. The two light sources (1,2) are situated at different distances from the sensor such that the light signals received from each of the two light sources have a different penetration depth into the skin.

Claims

1. Optical device for measuring a heart rate of a user, said device comprising:

two light sources for emitting light into the skin of the user,

a sensor for receiving light signals from the light emitted by each of the two light sources and reflected through the skin of the user so as to determine the heart rate of the user, wherein the two light sources are situated at different distances from the sensor such that the light signals received from each of the two light sources have a different penetration depth into the skin,

wherein the device further comprises a temperature sensor for measuring an ambient temperature and a control unit which is configured to select the light source which is farthest from the sensor when the ambient temperature measured by the temperature sensor is below a predetermined threshold.

2. Optical device as claimed in claim 1, wherein the control unit is further configured to select the light source which is the closest to the sensor in power save mode.

3. Optical device as claimed in claim 1, wherein the light signals emitted by two light sources have an identical or similar wavelength.

4. Optical device as claimed in claim 3, wherein the color of the light emitted by the two light sources is green.

5. Optical device as claimed in claim 1, wherein the light signals emitted by two light sources have different wavelengths.

6. Optical device as claimed in claim 5, wherein the color of the light emitted by one light source is green and the color of the light emitted by the other light source is blue and wherein the green light source is placed at a larger distance from the sensor than the blue light source.

7. Optical device as claimed in claim 1, wherein one light source is lift up with respect to the surface of the skin of the user.

8. Optical device as claimed in claim 1, where the light sources are light emitting diodes.

9. Optical device as claimed in claim 1, where the sensor is a photo-detector diode.

10. Optical device as claimed in claim 1, arranged for being worn at the wrist.

11. Optical device as claimed in claim 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the light signals emitted by the light sources are pulsed at different times and synchronized with the sensor.