Infrared Sensors for Electronic Devices

• US 20140197317A1
• Filed: 01/11/2013
• Published: 07/17/2014
• Est. Priority Date: 01/11/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yang, Henry H., Last, Matthew E.
• Granted Patent: US 8,981,302 B2
• Time in Patent Office: Days
• US Class Current: 250/341.8
• CPC Class Codes: G06F 1/1684 Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H04M 1/32 Locking setting devices during transmission to prevent interference by user
• CPC Class Codes: H04M 1/724631 by limiting the access to the user interface, e.g. locking a touch-screen or a keypad
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10
• CPC Class Codes: H04M 2250/22 including a touch pad, a touch sensor or a touch detector digitizers for touch screens G06F3/041
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

An electronic device may be provided with proximity sensor capabilities for monitoring for the presence of nearby external objects. The electronic device may make temperature measurements such as measurements involving the monitoring of nearby objects for emitted blackbody light indicative of whether or not the external object is a heat-emitting object such as a human body part. The same sensor that is used in gathering temperature readings may be used in gathering proximity sensor data or separate temperature sensor and proximity sensor detector structures may be used. Motion sensor capabilities may be provided using sensor structures having an array of heat sensing elements. Signals from the array of heat sensing elements may be used in making temperature measurements and in gathering proximity sensor readings. Sensor structures may operate at wavelengths longer than 3 microns such as wavelengths from 3-5 microns or 10-15 microns.

Claims

1. An electronic device, comprising:

a light source operable at wavelengths longer than 3 microns;

a light detector operable at wavelengths longer than 3 microns; and

control circuitry that modulates the light source to produce modulated light at wavelengths longer than 3 microns that reflects from external objects and is detected by the light detector to produce a proximity sensor signal.

2. The electronic device defined in claim 1 wherein the external object is a human body part that emits blackbody light and wherein the control circuitry is configured to use the light detector to detect the blackbody light.

3. The electronic device defined in claim 1 wherein the light source comprises a microelectromechanical systems light source.

4. The electronic device defined in claim 3 wherein the light source is configured to emit light at a wavelength of 10-15 microns.

5. The electronic device defined in claim 1 wherein the light source comprises a semiconductor device.

6. The electronic device defined in claim 5 wherein the light source is configured to emit light at a wavelength of 3-5 microns.

7. The electronic device defined in claim 1 wherein the light detector is configured to detect light at a wavelength of 3-5 microns.

8. The electronic device defined in claim 1 wherein the light detector is configured to detect light at a wavelength of 10-15 microns.

9. The electronic device defined in claim 8 wherein the light detector comprises a bolometer.

10. The electronic device defined in claim 9 wherein the light detector comprises an array of multiple heat sensing elements.

11. The electronic device defined in claim 1 wherein the light detector comprises an array of multiple heat sensing elements and wherein the control circuitry is configured to gather signals from a subset of the multiple heat sensing elements to make a temperature measurement indicative of whether the external object is a human body part.

12. The electronic device defined in claim 1 wherein the light detector comprises an array of multiple heat sensing elements and wherein the control circuitry is configured to detect motion of the external object by processing signals from the multiple heat sensing elements.

13. The electronic device defined in claim 12 further comprising a silicon lens that gathers light for the light detector.

14. The electronic device defined in claim 1 further comprising a display, wherein the control circuitry is configured to inhibit touch screen functionality in the display based on the proximity sensor signal.

15. An electronic device, comprising:

a housing;

a display mounted in the housing;

a light sensor that is mounted under an inactive area in the display and that is configured to detect light at a wavelength longer than 3 microns; and

control circuitry configured to measure blackbody light signals at wavelengths longer than 3 microns using the light sensor.

16. The electronic device defined in claim 15 further comprising a sensor window in the inactive area, wherein the light sensor is aligned with the sensor window and receives the light through the sensor window.

17. The electronic device defined in claim 15 further comprising a light-based proximity sensor having a near infrared light source that is modulated by the control circuitry and a corresponding near infrared light detector.

18. The electronic device defined in claim 15 further comprising:

a visible light ambient light detector; and

a light source that is modulated by the control circuitry to produce a light signal having a wavelength longer than 3 microns.

19. The electronic device defined in claim 15 wherein the light sensor is configured to measure light at wavelengths of 10-15 microns.

20. The electronic device defined in claim 19 wherein the light sensor comprises a bolometer.

21. A method of monitoring for external objects within the vicinity of an electronic device, comprising:

modulating a light source in the electronic device to emit modulated light; and

monitoring for reflections of the emitted modulated light using a mid-infrared light detector.

22. The method defined in claim 21 wherein the mid-infrared light detector comprises a light sensor configured to detect signals at a wavelength of 10-15 microns and wherein monitoring for reflections of the emitted modulated light comprises demodulating signals detected with the light detector to produce proximity sensor data.

23. The method defined in claim 22 wherein the mid-infrared light detector comprises a bolometer having an array of heat sensing elements, the method further comprising:

detecting motion in the external objects using the array of heat sensing elements.