Thermal zone monitoring in an electronic device

• US 8,768,530 B2
• Filed: 08/23/2010
• Issued: 07/01/2014
• Est. Priority Date: 06/04/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Liang, Frank Faqiu, Nigen, Jay S., Heresztyn, Amaury J., Cox, Keith
• Primary Examiner(s): Ali, Mohammad
• Assistant Examiner(s): Rao, Sheela S
• Application Number:
  US12/861,770
• Publication Number:
  US 20110301778A1
• Time in Patent Office: 1,408 Days
• Field of Search: 700/299, 702/132, 318/471, 345/173, 374/100, 374/141, 374/166
• US Class Current: 700/299
• CPC Class Codes: G05D 23/1932 to control the temperature of a plurality of spaces
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A predefined mathematical relationship that is stored in the memory of a computing system is accessed, wherein the relationship refers to temperatures of a number of points in the system, wherein the points together define a zone. The mathematical relationship yields a representative temperature for the zone. Temperature data from sensors in the system is obtained and applied to thermal models, to estimate the temperatures of at least some of the points that define the zone. The representative temperature for the zone is computed using the estimated temperatures as input to the mathematical relationship. A decision is then made on whether or not to change a power consuming activity limit in the system, based on the computed representative temperature. Other embodiments are also described and claimed.

Claims

1. A method for controlling the thermal behavior of a computing system having a plurality of embedded temperature sensors, comprising:

accessing a predefined mathematical relationship that is stored in a memory of the system, wherein the relationship refers to temperatures of a plurality of spaced-apart points, respectively, in the system, wherein the points together define a zone of the system, the mathematical relationship to provide a representative temperature for said zone;

accessing a plurality of thermal models that are stored in the memory, wherein each of the thermal models estimates the temperature of a respective one of the plurality of points that define the zone, based on temperature data from the sensors;

obtaining temperature data from the sensors and estimating, using the thermal models, the temperatures of the plurality of points that define the zone;

computing the representative temperature for said zone using the estimated temperatures of the plurality of points as input to the mathematical relationship; and

making a decision on whether or not to change a power consuming activity limit in the system, based on the computed representative temperature, wherein the power consuming activity limit is one of;

the speed of a cooling fan including whether the fan is on or off;

a power supply voltage of a data processing unit;

maximum transmit power of an RF antenna;

clock speed of a data processing unit;

whether a data processing unit is enabled or disabled;

or

intensity of a light source including whether the light source is on or off.

2. The method of claim 1 wherein the zone is an outside surface of a housing of the system where the user touches the system, the zone having an area greater than a footprint of any one of the sensors.

3. The method of claim 1 further comprising receiving power consumption data for a component in the system, wherein the decision on the power consuming activity limit is made further based on the power consumption data.

4. The method of claim 1 wherein the mathematical relationship is defined by:

T_rep=Σ

_i=1^Nƒ

(x)_iT_i

where T_rep is the representative temperature, T_i is a temperature of the i^th point and f(x)_i is a weighting function for the temperature of the point.

5. The method of claim 4 wherein the weighting function is an averaging function that takes an average or mean of a plurality of temperatures T₁, T₂, . . . T_N.

6. The method of claim 1 wherein the zone has dimensions approximately equal to a touch sensory resolution of a user of the system.

7. An article of manufacture comprising:

a machine-readable medium storing executable instructions which program a processor of a portable electronic device to control the thermal behavior of the device so as to regulate a representative temperature of the device, wherein the programmed processor is to

a) obtain temperature readings from a plurality of temperature sensors that are integrated within the portable electronic device,

b) analyze the obtained temperature readings to compute a plurality of virtual temperatures each being an estimate of the temperature at a different spot on an outside surface of an exterior housing of the portable electronic device at which spot there is no temperature sensor,

c) analyze the plurality of virtual temperatures to compute the representative temperature, and

d) take an action that affects thermal generation in the portable electronic device in response to the computed representative temperature being greater than or less than a predefined threshold.

8. The article of manufacture of claim 7 wherein the medium stores instructions which program the processor to repeat the operations in a)-d) a plurality of times during in-the-field use of the device so as to regulate the representative temperature.

9. The article of manufacture of claim 8 wherein the medium stores instructions which program the processor to regulate the computed, representative temperature by preventing the representative temperature from exceeding the predefined threshold through actions taken to reduce thermal generation in the device.

10. The article of manufacture of claim 7 wherein the medium stores instructions which program the processor to reduce performance of the device when the computed representative temperature is greater than the predefined threshold, and to increase the performance when the computed representative temperature is less than the predefined threshold.

11. The article of manufacture of claim 7 wherein the medium stores further instructions which program the processor to compute the representative temperature by also analyzing a temperature reading obtained from a temperature sensor in the portable electronic device.

12. A computing system comprising:

a thermal manager to perform a closed loop thermal control process that regulates a computed representative temperature of the system by changing power consuming activity limits in the system that affect heat buildup in the system, so as to maintain the representative temperature within a predefined constraint during in-the-field use of the system,

wherein the thermal manager is to compute the representative temperature using a stored mathematical relationship that defines the representative temperature as a weighted sum of temperatures of a plurality of points in the system, compare the computed representative temperature to a stored constraint and based on the comparison determine whether or not to change one of the power consuming activity limits in the system;

a plurality of temperature sensors that are not located at any of the plurality of points; and

an estimator to compute one of the temperatures of the plurality of points using a stored thermal model with temperature data from the plurality of sensors as input to the thermal model.

13. The computing system of claim 12 further comprising:

a temperature sensor that is located at one of the plurality of points so as to provide the thermal manager with the temperature of said one of the plurality of points.

14. The computing system of claim 12 further comprising:

an exterior housing in which the thermal manager, the temperature sensors, and the estimator are integrated, wherein the plurality of points are located on the outside surface of the exterior housing.

15. The computing system of claim 14 wherein the plurality of temperature sensors are located inside the exterior housing.

16. The computing system of claim 15 wherein the plurality of points define a zone on the outside surface of the exterior housing whose dimensions are approximately equal to a touch sensory resolution of a human being.