Multiple light paths architecture and obscuration methods for signal and perfusion index optimization

• US 10,215,698 B2
• Filed: 12/12/2014
• Issued: 02/26/2019
• Est. Priority Date: 09/02/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Han, Chin San, Block, Ueyn, Land, Brian R., Kestelli, Nevzat Akin, Isikman, Serhan, Wang, Albert, Shi, Justin
• Primary Examiner(s): Gillman, Amelie R
• Application Number:
  US14/569,235
• Publication Number:
  US 20160058312A1
• Time in Patent Office: 1,537 Days
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6898 Portable consumer electronic devices, e.g. music players, telephones, tablet computers
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 2201/0638 Refractive parts
• CPC Class Codes: G01N 2201/068 Optics, miscellaneous

Abstract

A photoplethysmographic (PPG) device is disclosed. The PPG device can include one or more light emitters and one or more light sensors to generate the multiple light paths for measuring a PPG signal and perfusion indices of a user. The multiple light paths between each pair of light emitters and light detectors can include different separation distances to generate both an accurate PPG signal and a perfusion index value to accommodate a variety of users and usage conditions. In some examples, the multiple light paths can include the same separation distances for noise cancellation due to artifacts resulting from, for example, tilt and/or pull of the device, a user'"'"'s hair, a user'"'"'s skin pigmentation, and/or motion. The PPG device can further include one or more lenses and/or reflectors to increase the signal strength and/or and to obscure the optical components and associated wiring from being visible to a user'"'"'s eye.

Claims

1. An electronic device comprising:

a first light emitter configured to generate a first light to travel a first light path and a second light to travel a second light path, wherein the first light path is in a different direction than the second light path;

a first window overlaying the first light emitter;

a second light emitter configured to generate a third light to travel a third light path and a fourth light to travel a fourth light path, wherein the third light path is in a different direction than the fourth light path;

a second window overlaying the second light emitter, the second window laterally spaced from the first window;

a first light sensor located a first separation distance from the first light emitter and a second separation distance from the second light emitter, the first separation distance being different from the second separation distance, wherein the first light sensor is configured to detect the first light and generate a first signal indicative of the detected first light, and detect the fourth light and generate a fourth signal indicative of the detected fourth light;

a third window overlaying the first light sensor;

a second light sensor located the second separation distance from the first light emitter and the first separation distance from the second light emitter, wherein the second light sensor is configured to detect the second light and generate a second signal indicative of the detected second light, and detect the third light and generate a third signal indicative of the detected third light;

a fourth window overlaying the second light sensor, the fourth window laterally spaced from the third window; and

a processor coupled to the first light sensor and the second light sensor, the processor configured to determine a physiological signal from the first signal and the third signal.

2. The electronic device of claim 1, wherein the processor is further configured to generate photoplethysmography (PPG) signals from the physiological signal.

3. The electronic device of claim 1, wherein the processor is further configured to use the second signal and the fourth signal to reduce noise in the first signal and the third signal.

4. The electronic device of claim 1, further comprising a lens, wherein the lens is a Fresnel lens or an image displacement film.

5. The electronic device of claim 1, further comprising a lens, wherein the lens includes an optical center placed in substantially a same location as the first light from the first light emitter.

6. The electronic device of claim 1, further comprising a lens located between the first window and the first light emitter, wherein the lens is an image displacement film, a brightness enhancement film, or a Fresnel lens.

7. The electronic device of claim 1, further comprising:

an optical isolation disposed between the first light emitter and the first light sensor; and

a reflector disposed on the optical isolation.

8. The electronic device of claim 1, wherein the first light sensor is partitioned into a plurality of sensing regions.

9. The electronic device of claim 1, wherein the first light emitter and the second light emitter emit light at different wavelengths.

10. The electronic device of claim 1, wherein the first light emitter is a green light emitting diode and the second light emitter is an infrared light emitting diode.

11. The electronic device of claim 1, further comprising a diffusing agent covering the first light emitter.

12. The electronic device of claim 11, wherein the diffusing agent is made of white TiO₂.

13. The electronic device of claim 1, wherein the processor is further configured to generate perfusion index signals from the second signal and the fourth signal.

14. A method for determining a physiological signal from an electronic device, the electronic device including:

a first light emitter, a second light emitter, a first light sensor, a second light sensor, a first window, a second window, a third window, a fourth window, and a processor, the method comprising;

emitting first light from the first light emitter through the first window, the first light traveling a first light path, the first window overlaying the first light emitter;

emitting second light from the first light emitter through the first window, the second light traveling a second light path, wherein the first light path is in a different direction than the second light path;

emitting third light from the second light emitter through the second window, the third light traveling a third light path, the second window overlaying the second light emitter, wherein the second window is laterally spaced from the first window;

emitting fourth light from the second light emitter through the second window, the fourth light traveling a fourth light path, wherein the third light path is in a direction different than the fourth light path;

detecting the first light through the third window using the first light sensor and generating a first signal indicative of the detected first light, the third window overlaying the first light sensor;

detecting the fourth light through the third window using the first light sensor and generating a fourth signal indicative of the detected fourth light,

wherein the first light sensor is located a first separation distance from the first light emitter and a second separation distance from the second light emitter, the first separation distance being different from the second separation distance;

detecting the second light through the fourth window using the second light sensor and generating a second signal indicative of the detected second light, the fourth window overlaying the second light sensor, wherein the fourth window is laterally spaced from the third window;

detecting the third light through the fourth window using the second light sensor and generating a third signal indicative of the detected third light,

wherein the second light sensor is located the second separation distance from the first light emitter and the first separation distance from the second light emitter; and

determining the physiological signal from the first signal and the third signal.

15. The method of claim 14, further comprising dynamically selecting the second signal, the fourth signal, or both to include in the determination of the physiological signal, wherein the dynamic selection is based on at least one of a user characteristic and a usage condition.

16. The method of claim 14, the method further comprising canceling or reducing a noise from the first signal and the third signal.

17. The method of claim 14, wherein the physiological signal is a first physiological signal, the method further comprising:

determining a second physiological signal from the second signal.

18. The method of claim 17, wherein the first physiological signal is indicative of a first photoplethysmographic signal with a first associated perfusion index, and the second physiological signal is indicative of a second photoplethysmographic signal with a second associated perfusion index.

19. The method of claim 14, the method further comprising:

dynamically activating the first light emitter; and

dynamically deactivating the second light emitter.