Self-mixing optical proximity sensors for electronic devices
An electronic device may have optical sensors. Control circuitry may use sensor measurements in controlling adjustable components and taking other actions. The optical sensors may be self-mixing sensors such as incoherent self-mixing sensors. One or more sensors may be used in gathering sensor measurements. In configurations in which an electronic device contain multiple self-mixing sensors, multi-wavelength measurements can be gathered using incoherent light sources in the sensors that operate a set of different wavelengths. The light source of each incoherent self-mixing sensor may be a superluminescent light-emitting diode, a resonant cavity light-emitting diode, or other amplified or non-amplified spontaneous emission source. Optical systems such as lenses in a housing for an electronic device may be aligned with the self-mixing sensors. Self-mixing sensors may serve as proximity sensors, sensors for detecting touch input, sensors for measuring spectrums associated with targets of unknown materials, displacement sensors, or other sensors.
1. An electronic device, comprising:
a housing;
an adjustable component in the housing;
an incoherent self-mixing sensor in the housing; and
control circuitry in the housing that is configured to gather a sensor measurement with the incoherent self-mixing sensor and that is configured to adjust the adjustable component using the sensor measurement.
2. The electronic device defined in claim 1 wherein the adjustable component comprises a touch screen display and wherein control circuitry is configured to deactivate a touch sensor in the touch screen display in response to the sensor measurement.
3. The electronic device defined in claim 1 wherein the adjustable component comprises a display and wherein the control circuitry is configured to display information on the display in response to the sensor measurement.
4. The electronic device defined in claim 1 wherein the adjustable component comprises a motor and wherein the control circuitry is configured to adjust the motor in response to the sensor measurement.
5. The electronic device defined in claim 1 wherein the incoherent self-mixing sensor comprises a light source selected from the group consisting of:
a resonant-cavity light-emitting diode, a superluminescent diode, an edge-emitting light-emitting diode, a surface-emitting light-emitting diode, a spontaneous emission source, and a non-amplified spontaneous emission source.
6. The electronic device defined in claim 5 wherein the light source is configured to emit infrared light having a wavelength of at least 1.5 microns.
7. The electronic device defined in claim 6 further comprising an optical system in the housing, wherein the light source is configured to emit the infrared light through the optical system.
8. The electronic device defined in claim 7 wherein the optical system includes a lens.
9. The electronic device defined in claim 1 wherein the adjustable component comprises a speaker.
10. The electronic device defined in claim 1 wherein the adjustable component comprises a component selected from the group consisting of: a display, a touch sensor, a speaker, a haptic output device, and a motor.
11. The electronic device defined in claim 1 wherein the incoherent self-mixing sensor comprises a light-emitting diode that does not lase and does not form a laser.
12. An electronic device, comprising:
incoherent self-mixing sensors each having a respective light source configured to emit light at a different respective wavelength;
an adjustable component; and
control circuitry configured to adjust the adjustable component using sensor data from the incoherent self-mixing sensors.
13. The electronic device defined in claim 12 wherein each of the incoherent light sources is configured to emit infrared light.
14. The electronic device defined in claim 13 wherein at least one of the incoherent light sources is configured to emit infrared light having a wavelength of at least 2 microns.
15. The electronic device defined in claim 14 further comprising:
a housing containing the incoherent self-mixing sensors; and
a lens in the housing, wherein the incoherent self-mixing sensors are configured to receive light through the lens.
16. An electronic device comprising:
an adjustable component with a movable member;
an incoherent self-mixing sensor having a diode configured to emit light that illuminates the movable member; and
control circuitry configured to adjust the adjustable component using a sensor measurement from the incoherent self-mixing sensor.
17. The electronic device defined in claim 16 wherein the adjustable component comprises a speaker and wherein the movable member comprises a speaker diaphragm.
18. The electronic device defined in claim 17 wherein the diode is configured to receive a portion of the emitted light that has been redirected toward the diode from the speaker diaphragm.
19. The electronic device defined in claim 18 further comprising a housing structure, wherein the control circuitry is configured to prevent contact between the speaker diaphragm and the housing structure by monitoring displacement of the speaker diaphragm using the sensor measurement.
20. The electronic device defined in claim 18 wherein the control circuitry is configured to manage distortion in the speaker by monitoring displacement of the speaker diaphragm using the sensor measurement.