Infrared and capacitance based sensing for proximity detection

• US 9,042,833 B1
• Filed: 12/21/2011
• Issued: 05/26/2015
• Est. Priority Date: 12/21/2011
• Status: Expired due to Fees

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Jayaraj, Nagendra Bage, Obeidat, Khaled Ahmad, Williams, Marshall, Lee, Michael M.
• Primary Examiner(s): GESESSE, TILAHUN
• Application Number:
  US13/333,576
• Time in Patent Office: 1,252 Days
• Field of Search: 455/41.1, 455/41.2, 340/539.22, 340/12.51, 340/10.1
• US Class Current: 455/66.1
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use

Abstract

A proximity detection module determines, using an infrared (IR) sensor of a user device, a distance between an object and the user device. The proximity detection module compares the distance to a distance threshold. If the distance is below the predefined distance threshold, the proximity detection module determines, using a capacitance sensor of the user device, a capacitance value associated with the object. The proximity detection module compares the capacitance value to a predefined presence threshold, and if the capacitance value meets or exceeds the predefined presence threshold, determines that the object comprises a body part of a user.

Claims

1. A method comprising:

determining, using an infrared (IR) sensor of a user device, a distance between an object and the user device;

comparing the distance to a distance threshold;

determining that the distance is below the distance threshold;

determining, using a capacitance sensor of the user device, a capacitance value associated with the object;

comparing the capacitance value to a presence threshold;

determining that the capacitance value meets or exceeds the presence threshold;

determining, using a metal detection circuit, whether the object comprises a metal object or whether the object does not comprise a metal object; and

in response to the object not comprising a metal object, determining, by a processing device, that the object comprises a body part of a user.

2. The method of claim 1, wherein the distance threshold is ten millimeters.

3. The method of claim 1, wherein the capacitance value comprises a difference between a measured capacitance value and a baseline value of the capacitance sensor.

4. The method of claim 1, further comprising:

in response to the capacitance value not meeting or exceeding the presence threshold, maintaining a current transmission power of the user device.

5. The method of claim 1, further comprising:

in response to the object not comprising a metal object, reducing a transmission power of the user device.

6. The method of claim 1, further comprising:

in response to the object comprising a metal object, determining that the user is not in proximity to the user device.

7. A non-transitory computer-readable storage medium storing instructions which, when executed, cause a processing device to perform operations comprising:

determining a distance between an object and a user device;

comparing the distance to a distance threshold;

determining a capacitance value of the object;

comparing the capacitance value to a presence threshold for the body part;

determining, using a metal detection circuit, whether the object comprises a metal object or whether the object does not comprise a metal object; and

in response to the distance being below the distance threshold, the capacitance value meeting or exceeding the presence threshold, and the object not comprising a metal object, determining that the object comprises the body part of the user.

8. The non-transitory computer-readable storage medium of claim 7, wherein determining if the object comprises a body part of the user comprises comparing the capacitance value to an expected capacitance value for the body part at the distance.

9. The non-transitory computer-readable storage medium of claim 7, wherein the capacitance value comprises a difference between a measured capacitance value and a baseline value of a capacitance sensor.

10. The non-transitory computer-readable storage medium of claim 7, wherein the operations further comprise:

determining if the object comprises a metal object.

11. The non-transitory computer-readable storage medium of claim 10, wherein determining if the object comprises a metal object comprises:

determining a resonant frequency of a metal detection circuit;

comparing a change in the resonant frequency of the metal detection circuit to a metal threshold; and

in response to the change in the resonant frequency meeting or exceeding the metal threshold, determining that the object comprises a metal object.

12. The non-transitory computer-readable storage medium of claim 10, wherein the operations further comprise:

in response to the object not comprising a metal object, reducing a transmission power of the user device.

13. The non-transitory computer-readable storage medium of claim 10, wherein the operations further comprise:

in response to the object comprising a metal object, maintaining a current transmission power of the user device.

14. A user device, comprising:

a processor;

a distance sensor;

a capacitance sensor;

a metal detection circuit; and

a memory operatively coupled to the processor, the memory storing a proximity detection module, executable by the processor and the memory, the proximity detection module configured to;

determine a distance between an object and a user device;

compare the distance to a distance threshold;

determine a capacitance value of the object;

compare the capacitance value to a presence threshold for the body part;

determine, using the metal detection circuit, whether the object comprises a metal object or whether the object does not comprise a metal object; and

in response to the distance being below the distance threshold, the capacitance value meeting or exceeding the presence threshold, and the object not comprising a metal object, determine that the object comprises the body part of the user.

15. The user device of claim 14, wherein determining if the object comprises a body part of the user comprises comparing the capacitance value to an expected capacitance value for the body part at the distance.

16. The user device of claim 14, wherein the capacitance value comprises a difference between a measured capacitance value and a baseline value of a capacitance sensor.

17. The user device of claim 14, wherein the proximity detection module is further configured to:

in response to the object not comprising a metal object, reduce a transmission power of the user device.

18. The user device of claim 14, wherein the proximity detection module is further configured to:

in response to the object comprising a metal object, maintain a current transmission power of the user device.

19. A method comprising:

detecting, by a processing device, a presence of an object in proximity to a user device;

compare a distance between the object and the user device to a distance threshold;

comparing a capacitance value of the object to a presence threshold;

determining, by the processing device using a metal detection circuit, whether the object comprises a metal object or whether the object does not comprise a metal object; and

in response to the distance being below the distance threshold, the capacitance value meeting or exceeding the presence threshold, and the object not comprising a metal object, determining that the object comprises the body part of the user.

20. The method of claim 19, wherein detecting the presence of the object comprises:

determining if the capacitance value meets or exceeds the presence threshold.

21. The method of claim 19, wherein determining whether the object comprises a metal object comprises:

determining a resonant frequency of a metal detection circuit;

comparing a change in the resonant frequency of the metal detection circuit to a metal threshold; and

in response to the change in the resonant frequency meeting or exceeding the metal threshold, determining that the object comprises a metal object.

22. The method of claim 21, further comprising:

maintaining a current transmission power of the user device.

23. The method of claim 21, further comprising:

in response to the change in the resonant frequency not meeting or exceeding the metal threshold, determining that the object does not comprise a mental object; and

reducing a transmission power of the user device.