# US 11,076,771 B2 · Systems and methods for determining physiological signals using ambient light

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- Number: US 11,076,771 B2
- Document ID: US11076771B2
- Status: Granted
- Kind: B2
- Application number: 15/713,022
- Filed: 2017-09-22
- Published: 2018-03-22
- Granted: 2021-08-03
- Earliest claimed: 2016-09-22
- Assignees: Apple Inc.
- Applicants: Apple Inc.
- Inventors: Nicholas Paul Joseph Allec; Joel S. Armstrong-Muntner; Chau V. H. Nguyen
- Web page: https://patentgrep.com/patent/US11076771B2

## CPC

- A61B 5/0261: {using optical means, e.g. infrared light}
- A61B 5/0059: {using light, e.g. diagnosis by transillumination, diascopy, fluorescence (photoacoustic A61B5/0093; optical measurement of heart rate A61B5/02416; optical measurement of blood flow A61B5/0261; optical measurement of analytes A61B5/1455)}
- A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)}
- A61B 5/02438: {with portable devices, e.g. worn by the patient}
- A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters
- A61B 5/6801: {specially adapted to be attached to or worn on the body surface}
- A61B 5/6802: {Sensor mounted on worn items}
- A61B 5/681: {Wristwatch-type devices}
- A61B 5/6898: {Portable consumer electronic devices, e.g. music players, telephones, tablet computers}
- A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)}
- A61B 2560/0242: adapted to measure environmental factors, e.g. temperature, pollution
- A61B 2562/0233: Special features of optical sensors or probes classified in A61B5/00
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

This relates to systems and methods for determining one or more physiological signals of a user using ambient light. The systems and methods can include one or more light sensors configured to measure light that has interacted with a user and one or more light sensors configured to measure ambient light. The gain of the one or more light sensors can be adjusted based on the levels of measured ambient light. For example, the gain of the one or more light sensors can be increased when ambient light levels are low (e.g., a low light environment), or the gain of the one or more light sensors can be decreased when ambient light levels are high (e.g., a bright light environment). In some examples, the systems can include a variable opacity element whose transmission properties (e.g., opacity and/or selected one or more wavelengths to pass through) can be varied.

## Claims

### Claim 1

A device comprising:
a light emitter configured to emit first light;
one or more first light sensors configured to measure second light that has interacted with a user and generate a first signal indicative of the measured second light;
one or more second light sensors configured to measure ambient light and generate a second signal indicative of the measured ambient light;
a variable opacity element optically coupled to the one or more first light sensors and configured to receive the second light; and
a controller configured to:
determine, based on the second signal, whether a light level of the measured ambient light is greater than or equal to a predetermined threshold;
transmit a third signal to the variable opacity element, the third signal indicative of an opacity of the variable opacity element; and
perform a measurement of physiological information based on the first signal, wherein:
in accordance with a first determination that the light level of the measured ambient light is greater than or equal to the predetermined threshold, the second light is measured while the light emitter is not emitting light and the variable opacity element has a first opacity; and
in accordance with a second determination that the light level of the measured ambient light is less than the predetermined threshold, the second light is measured while the light emitter is emitting the first light and the variable opacity element has a second opacity less than the first opacity.

### Claim 2 (depends on 1)

The device of claim 1, further comprising:
a display configured to display one or more images from a first surface of the device, wherein the one or more second light sensors are located at the first surface and the one or more first sensors are located at a second surface, opposite the first surface, of the device.

### Claim 3 (depends on 1)

The device of claim 1, wherein the one or more first light sensors and the one or more second light sensors are located on a same side of the device.

### Claim 4 (depends on 1)

The device of claim 1, wherein the one or more first light sensors are located on a bottom of the device and the one or more second light sensors are located on a sidewall of the device.

### Claim 5 (depends on 1)

The device of claim 1, wherein the variable opacity element includes a plurality of regions, wherein the plurality of regions have different transmission properties.

### Claim 6 (depends on 1)

The device of claim 1, wherein:
the variable opacity element is capable of moving in and out of a light path of the one or more first light sensors, the one or more second light sensors, or both; and
a motion system operatively coupled to the variable opacity element and the controller, wherein the controller is further configured to:
transmit a fourth signal to the motion system, the fourth signal indicative of a motion state of the variable opacity element.

### Claim 7 (depends on 1)

The device of claim 1, further comprising:
at least one angular acceptance element,
wherein the controller is further configured to determine which of the one or more first or second lights sensors are activated.

### Claim 8 (depends on 7)

The device of claim 7, wherein:
the variable opacity element and the at least one angular acceptance element are integrated;
the at least one angular acceptance element is capable of being electrically controlled,
wherein the controller is further configured to adjust an acceptance angle of the at least one angular acceptance element based on which of the one or more first light sensors or the one or more second light sensors are activated.

### Claim 9 (depends on 1)

The device of claim 1, wherein at least one of the one or more first light sensors or the one or more second light sensors includes a plurality of detector pixels, the device further comprising:
a color filter array including a plurality of color filter units, wherein each color filter unit is associated to one of the plurality of detector pixels.

### Claim 10 (depends on 1)

The device of claim 1, wherein the one or more first light sensors are configured with a first measurement frequency, and the one or more second light sensors are configured with a second measurement frequency, different from the first measurement frequency.

### Claim 11 (depends on 1)

The device of claim 1, wherein the variable opacity element is adapted to be positioned between the user and the one or more first light sensors.

### Claim 12 (depends on 1)

The device of claim 1, wherein:
the variable opacity element is a first variable opacity element; and
the device further comprises a second variable opacity element optically coupled to the one or more second light sensors.

### Claim 13 (depends on 12)

The device of claim 12, wherein the second variable opacity element is further optically coupled to the one or more first light sensors.

### Claim 14

A method comprising:
utilizing a device including a variable opacity element coupled to one or more first light sensors, wherein the variable opacity element is configured to receive light that has interacted with a user and is controlled by a controller configured to transmit a first signal to the variable opacity element, the first signal indicative of an opacity of the variable opacity element;
detecting ambient light using one or more second light sensors;
generating a second signal indicative of the detected ambient light;
determining, based on the second signal, whether a light level of the ambient light is greater than or equal to a predetermined threshold;
in accordance with a first determination that the light level of the ambient light is greater than or equal to the predetermined threshold, detecting, while a light emitter is not emitting light and the variable opacity element has a first opacity, first light that has interacted with the user using the one or more first light sensors;
in accordance with a second determination that the light level of the ambient light is less than the predetermined threshold:
emitting second light using the light emitter; and
detecting the first light while the light emitter is emitting the second light and the variable opacity element has a second opacity less than the first opacity;
generating a first light signal indicative of the detected first light; and
performing a measurement of physiological information based on the first light signal indicative of the detected first light.

### Claim 15 (depends on 14)

The method of claim 14, further comprising:
adjusting the first or second opacity of the variable opacity element based on the detected ambient light.