ELECTRONIC DEVICE WITH PROXIMITY-BASED RADIO POWER CONTROL

• US 20090305742A1
• Filed: 09/09/2008
• Published: 12/10/2009
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Schlub, Robert W., Caballero, Ruben
• Granted Patent: US 8,417,296 B2
• Time in Patent Office: Days
• US Class Current: 455/566
• 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 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 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 proximity sensor comprises a light source.

4. The electronic device defined in claim 1 wherein the proximity sensor comprises a light-emitting diode.

5. The electronic device defined in claim 1 wherein the proximity sensor comprises an infrared light-emitting diode and a photodiode.

6. 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.

7. 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.

8. The electronic device defined in claim 7 wherein the proximity sensor comprises an infrared light-emitting diode and a photodiode.

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

10. 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.

11. The electronic device defined in claim 1 wherein the electronic device comprises a handheld electronic device having 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.

12. The electric 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.

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

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

at least one sensor that generates sensor data that is 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.

14. The handheld electronic device defined in claim 13 wherein the sensor comprises a touch sensor associated with a touch screen display in the handheld electronic device.

15. The handheld electronic device defined in claim 13 wherein the sensor comprises a proximity sensor having a light source and a photodetector.

16. The handheld electronic device defined in claim 13 wherein the sensor comprises a proximity sensor having a light source and a photodetector, the handheld electronic device further comprising a capacitive touch sensor, wherein the control circuitry controls the transmit power based at least partly on both the sensor data from the proximity sensor and data from the capacitive touch sensor.

17. The handheld electronic device defined in claim 16 further comprising an accelerometer that generates accelerometer data, wherein the circuitry adjusts the transmit power based at least partly on the accelerometer data.

18. A method of controlling radio-frequency cellular telephone signal transmit power through an antenna in a handheld electronic device that is used by a user having a head, wherein the handheld electronic device includes control circuitry, the method comprising:

with a sensor in the handheld electronic device, determining whether the head of the user is present within a given distance of the handheld electronic device,

when it is determined from the sensor that the head of the user is not present within the given distance of the handheld electronic device, establishing a first maximum allowable level for the transmit power with the control circuitry; and

when it is determined from the sensor that the head of the user is present within the given distance of the handheld electronic device, establishing a second maximum allowable level for the transmit power with the control circuitry, wherein the second maximum allowable level for the transmit power is less than the first maximum allowable level for the transmit power.

19. The method defined in claim 18 wherein determining whether the head of the user is present within the given distance comprises emitting light with a light source in the handheld electronic device while monitoring how much of the emitted light is reflected back to the handheld electronic device using a photodetector in the handheld electronic device.

20. The method defined in claim 19 further comprising:

receiving commands from a wireless network;

receiving sensor data from a touch screen; and

adjusting the transmit power in response to the commands and the received sensor data from the touch screen.

21. The method defined in claim 18 wherein the transmit power is associated with code division multiple access transmissions and wherein the method further comprises adjusting the transmit power by measuring a tapped radio-frequency signal using a coupler and detector.

22. The method defined in claim 18 wherein the handheld electronic device comprises circuitry that handles radio-frequency wireless transmissions in at least a first wireless communications band and a second wireless communications band, the method further comprising making 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.