ELECTRONIC DEVICES WITH CAPACITIVE PROXIMITY SENSORS FOR PROXIMITY-BASED RADIO-FREQUENCY POWER CONTROL

• US 20130241780A1
• Filed: 04/26/2013
• Published: 09/19/2013
• Est. Priority Date: 07/17/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Amm, David T., Schlub, Robert W., Leung, Omar S., Li, Qingxiang, Ayala Vazquez, Enrique, Gomez Angulo, Rodney A., Jiang, Yi, Caballero, Ruben, King, Brian M.
• Granted Patent: US 8,947,305 B2
• Time in Patent Office: Days
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/24 with receiving set
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/44 using equipment having another main function to serve additionally as an antenna , e.g. means for giving an antenna an aesthetic aspectH01Q1/27 - H01Q1/34 take precedence
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

An electronic device may have a housing in which an antenna is mounted. An antenna window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. Near-field radiation limits may be satisfied by reducing transmit power when an external object is detected in the vicinity of the dielectric antenna window and the antenna. A capacitive proximity sensor may be used in detecting external objects in the vicinity of the antenna. The proximity sensor may have conductive layers separated by a dielectric. A capacitance-to-digital converter may be coupled to the proximity sensor by inductors. The capacitive proximity sensor may be interposed between an antenna resonating element and the antenna window. The capacitive proximity sensor may serve as a parasitic antenna resonating element and may be coupled to the housing by a capacitor.

Claims

1. An electronic device comprising:

a housing;

an antenna window in the housing; and

metal structures that serve as an antenna resonating element and a capacitive proximity sensor electrode, wherein the metal structures are configured to transmit radio-frequency signals through the antenna window.

2. The electronic device defined in claim 1, further comprising:

a capacitance-to-digital converter coupled to the metal structures.

3. The electronic device defined in claim 2, further comprising:

a plurality of radio-frequency choke inductors coupled between the metal structures and the capacitance-to-digital converter.

4. The electronic device defined in claim 3, wherein the capacitance-to-digital converter has first and second inputs, wherein a first radio-frequency choke inductor of the plurality of radio-frequency choke inductors is coupled between the metal structures and the first input, and wherein a second radio-frequency choke inductor of the plurality of radio-frequency choke inductors is coupled between the metal structures and the second input.

5. The electronic device defined in claim 1, further comprising:

radio-frequency transceiver circuitry coupled to the metal structures that transmits the radio-frequency signals at an output power; and

circuitry coupled to the metal structures that limits the output power when an external object is detected within a given distance of the metal structures.

6. The electronic device defined in claim 1, wherein the housing comprises a conductive housing and wherein the antenna window comprises a dielectric antenna window in the conductive housing.

7. The electronic device defined in claim 6, wherein the metal structures include a portion that serves as a parasitic antenna resonating element.

8. The electronic device defined in claim 6, further comprising:

radio-frequency transceiver circuitry;

a positive antenna feed terminal connected between the radio-frequency transceiver circuitry and the metal structures; and

a ground antenna feed terminal connected between the radio-frequency transceiver circuitry and the conductive housing.

9. The electronic device defined in claim 1, wherein the electronic device has front and rear surfaces, the electronic device further comprising a display on the front surface of the electronic device, wherein the display has an inactive region through which radio-frequency signals are transmitted from the metal structures.

10. The electronic device defined in claim 1, wherein the metal structures are formed on a flex circuit substrate.

11. An electronic device comprising:

a conductive housing;

a dielectric antenna window in the conductive housing;

conductive structures;

transceiver circuitry that wirelessly transmits radio-frequency signals using the conductive structures; and

proximity sensor circuitry that detects changes in capacitance using the conductive structures.

12. The electronic device defined in claim 11, wherein the conductive structures are mounted within the conductive housing adjacent to the dielectric antenna window.

13. The electronic device defined in claim 11, wherein the proximity sensor circuitry comprises a capacitance-to-digital converter.

14. The electronic device defined in claim 13, wherein the capacitance-to-digital converter is coupled to the conductive structures through a plurality of radio-frequency choke inductors.

15. The electronic device defined in claim 11, wherein the transceiver wirelessly transmits the radio-frequency signals at an output power and wherein the proximity circuitry reduces the output power when an external object is detected within a given distance of the conductive structures.

16. The wireless electronic device defined in claim 11, wherein the conductive structures are formed on a flex circuit substrate.

17. A wireless electronic device comprising:

a housing;

an antenna window in the housing; and

capacitive proximity sensor electrode structures mounted in the housing; and

antenna resonating element structures mounted in the housing and configured to transmit radio-frequency signals through the antenna window.

18. The wireless electronic device defined in claim 17, further comprising:

radio-frequency transceiver circuitry coupled to the antenna resonating element structures that transmits the radio-frequency signals at an output power; and

circuitry coupled to the capacitive proximity sensor electrode structures that limits the output power when an external object is detected within a given distance of the capacitive proximity sensor electrode structures.

19. The wireless electronic device defined in claim 17, wherein the capacitive proximity sensor electrode structures are formed on a flex circuit substrate and wherein the antenna resonating element structures are formed on a dielectric substrate.

20. The wireless electronic device defined in claim 17, wherein the capacitive proximity sensor electrode structures are interposed between the antenna window and the antenna resonating element structures.