ELECTRONIC DEVICE WITH PROXIMITY-BASED RADIO POWER CONTROL

• US 20130172045A1
• Filed: 02/26/2013
• Published: 07/04/2013
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Caballero, Ruben, Schlub, Robert W.
• Granted Patent: US 8,818,450 B2
• Time in Patent Office: Days
• US Class Current: 455/552.1
• 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
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

An electronic device such as a portable electronic device may have an antenna and associated wireless communications circuitry. A sensor such as a proximity sensor may be used to detect when the electronic device is in close proximity to a user'"'"'s head. Control circuitry within the electronic device may be used to adjust radio-frequency signal transmit power levels. When it is determined that the electronic device is within a given distance from the user'"'"'s head, the radio-frequency signal transmit power level may be reduced. When it is determined that the electronic device is not within the given distance from the user'"'"'s head, proximity-based limits on the radio-frequency signal transmit power level may be removed. Data may be gathered from a touch sensor, accelerometer, ambient light sensor and other sources for use in determining how to adjust the transmit power level.

Claims

1. An electronic device, comprising:

a capacitive proximity sensor that detects when objects are present within a given distance of the electronic device;

a radio-frequency antenna with which radio-frequency signals are transmitted with a transmit power; and

circuitry that adjusts the transmit power based at least partly on data from the capacitive proximity sensor.

2. The electronic device defined in claim 1 wherein the circuitry comprises a power amplifier with an adjustable gain, wherein the circuitry generates a control signal for the power amplifier that reduces the gain of the power amplifier when it is determined that an object is present within the given distance of the electronic device.

3. The electronic device defined in claim 1 wherein the circuitry comprises:

an adjustable gain radio-frequency power amplifier that generates the radio-frequency signals at the transmit power;

a radio-frequency coupler that is interposed between the radio-frequency power amplifier and the antenna; and

a detector that detects signals from the coupler to measure the transmit power.

4. The electronic device defined in claim 1 wherein the circuitry comprises:

an adjustable gain radio-frequency power amplifier that generates the radio-frequency signals at the transmit power;

a radio-frequency coupler that is interposed between the radio-frequency power amplifier and the antenna; and

a detector that detects signals from the coupler to measure the transmit power, wherein the circuitry generates a control signal for the radio-frequency power amplifier that reduces the gain of the radio-frequency power amplifier when it is determined that an object is present within the given distance of the electronic device.

5. The electronic device defined in claim 1 wherein the electronic device comprises a handheld electronic device having a touch sensor and wherein the circuitry adjusts the transmit power based at least partly on data from the touch sensor.

6. The electronic device defined in claim 1 wherein the electronic device comprises a handheld electronic device, wherein the capacitive proximity sensor comprises a capacitive touch screen display, and wherein the circuitry adjusts the transmit power based at least partly on data from the capacitive touch screen display.

7. The electronic device defined in claim 1 wherein the circuitry comprise transmitter circuitry that handles radio-frequency wireless transmissions in at least a first wireless communications band and a second wireless communications band and wherein the circuitry is configured to make radio-frequency wireless transmit power adjustments in the first wireless communications band at least partly based on changes that occur in radio-frequency wireless transmit power levels in the second wireless communications band.

8. The electronic device defined in claim 1 further comprising:

at least one additional sensor, wherein the circuitry adjusts the transmit power based at least partly on sensor data from the additional sensor concurrently with the data from the proximity sensor, wherein the circuitry establishes a transmit power ceiling based on the data from the capacitive proximity sensor.

9. The electronic device defined in claim 8 wherein the circuitry prevents adjustments to the transmit power based on the sensor data that produce adjusted transmit powers exceeding the transmit power ceiling.

10. A handheld electronic device operated by a user, comprising:

an antenna with which radio-frequency signals are transmitted at a given transmit power;

a first sensor that generates sensor data;

a second sensor, wherein the second sensor generates proximity data indicative of whether at least part of the user is present within a given distance from the handheld electronic device; and

control circuitry that controls the transmit power based at least partly on the sensor data and the proximity data, wherein the control circuitry establishes a transmit power ceiling for the radio-frequency signals based on the proximity data.

11. The handheld electronic device defined in claim 10 wherein the second sensor comprises a capacitive proximity sensor.

12. The handheld electronic device defined in claim 10 wherein the control circuitry is configured to inhibit adjustments to the transmit power based on the sensor data in response to determining that the user is present within the given distance.

13. The handheld electronic device defined in claim 12 wherein the first sensor comprises an accelerometer.

14. The handheld electronic device defined in claim 13 further comprising:

a proximity sensor having a light source and a photodetector, wherein the control circuitry controls the transmit power by processing the sensor data, the proximity data, and information from the proximity sensor in parallel.

15. A method of operating a handheld electronic device, the method comprising:

with an antenna, transmitting radio-frequency signals at a transmit power;

with a capacitive proximity sensor, determining whether a user is within a given distance from the handheld electronic device; and

with control circuitry, adjusting the transmit power in response to determining that the user is within the given distance from the handheld electronic device.

16. The method defined in claim 15 further comprising:

with the control circuitry, establishing a transmit power ceiling in response to determining that the user is within the given distance from the handheld electronic device;

with an additional sensor, producing sensor data;

with the control circuitry, adjusting the transmit power based on the sensor data from the additional sensor; and

with the control circuitry, preventing adjustments to the transmit power based on the sensor data from the additional sensor that produce an adjusted transmit power exceeding the transmit power ceiling.

17. The method defined in claim 16 wherein the additional sensor comprises an accelerometer and wherein producing the sensor data comprises:

with the accelerometer, producing accelerometer data.

18. The method defined in claim 16 further comprising:

with the control circuitry, determining whether the electronic device is operating in a first communications mode or a second communications mode;

with the control circuitry, allowing adjustments to the transmit power to exceed the transmit power ceiling in response to determining that the electronic device is operating in the first communications mode; and

with the control circuitry, ensuring that the transmit power is maintained below the transmit power ceiling in response to determining that the electronic device is operating in the second communications mode.

19. The method defined in claim 18 wherein the first communications mode comprises a 2G cellular communications mode and wherein the second communications mode comprises a 3G cellular communications mode.

20. The method defined in claim 18 further comprising:

wherein the electronic device wirelessly communicates using time division multiplexing in the first communications mode and wherein the electronic device does not wirelessly communicate using time division multiplexing in the second communications mode.