Photoplethysmography sensor apparatus and method
First Claim
Patent Images
1. A photoplethysmography sensor apparatus comprising:
- a light source unit configured to generate a first light signal;
a photodetector unit configured to observe a second light signal, where said second light signal is indicative of an absorption of said first light signal in a target, wherein said photodetector unit is further configured to output a photodetector output signal in response to observing said second light signal; and
an ambient light compensating feedback loop comprising a track-and-hold unit configured to receive said photodetector output signal;
wherein said photoplethysmography sensor apparatus is configured to compare an output signal of said track-and-hold unit to a reference signal (VR), and wherein said ambient light compensating feedback loop comprises a first amplifying unit configured to provide a compensation current based on said comparison to the track-and-hold unit.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention relates to a photoplethysmography sensor apparatus (200, 300), a photoplethysmography sensor method (400), and a photoplethysmography sensor computer program product. It is proposed to measure a photoplethysmographic signal without ambient light interference. Ambient light signals are rejected by subtraction of a compensation current at the input of a transimpedance amplifier (240, 340). The compensation current is controlled via a closed loop, without interfering with the low duty cycle operation of a photoplethysmography LED (210, 310).
-
Citations
14 Claims
-
1. A photoplethysmography sensor apparatus comprising:
-
a light source unit configured to generate a first light signal; a photodetector unit configured to observe a second light signal, where said second light signal is indicative of an absorption of said first light signal in a target, wherein said photodetector unit is further configured to output a photodetector output signal in response to observing said second light signal; and an ambient light compensating feedback loop comprising a track-and-hold unit configured to receive said photodetector output signal; wherein said photoplethysmography sensor apparatus is configured to compare an output signal of said track-and-hold unit to a reference signal (VR), and wherein said ambient light compensating feedback loop comprises a first amplifying unit configured to provide a compensation current based on said comparison to the track-and-hold unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A photoplethysmography sensor method comprising the steps of:
-
generating a first light signal by a light source unit; observing a second light signal by a photodetector unit, wherein said second light signal is indicative of an absorption of said first light signal in a target; receiving, in response to observing said second light signal, a photodetector output signal by an ambient light compensating feedback loop comprising a track-and-hold unit and an amplifying unit; comparing an output signal of the track-and-hold unit to a reference signal (VR), wherein said output signal of said track-and-hold unit is based on said photodetector output signal; and providing a compensation current by the amplifying unit to the track-and-hold unit based on said comparison.
-
-
14. A photoplethysmography sensor computer program product comprising a computer readable memory storing computer program code means for causing a photoplethysmography sensor apparatus to carry out the following steps, when the program is run on a computer controlling the photoplethysmography sensor apparatus:
-
generate a first light signal by a light source unit; observe a second light signal by a photodetector unit, wherein said second light signal is indicative of an absorption of said first light signal in a target; receive, in response to observing said second light signal, a photodetector output signal by an ambient light compensating feedback loop comprising a track-and-hold unit and an amplifying unit; compare an output signal of the track-and-hold unit to a reference signal (VR), wherein said output signal of said track-and-hold unit is based on said photodetector output signal; and provide a compensation current by the amplifying unit to the track-and-hold unit based on said comparison.
-
Specification