Methods for Enhancing Longevity in Electronic Device Displays

• US 20120188287A1
• Filed: 01/20/2011
• Published: 07/26/2012
• Est. Priority Date: 01/20/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wurzel, Joshua G., Doyle, David A.
• Granted Patent: US 9,142,157 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G06F 1/203 for portable computers, e.g. for laptops
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/045 Protection against panel overheating
• CPC Class Codes: G09G 2360/08 Power processing, i.e. workload management for processors involved in display operations, such as CPUs or GPUs
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

An electronic device may contain components such as a processor, video circuitry, camera flash, communications circuitry, and other components that may generate heat during operation. The device may have a display with a backlight unit that contains light-emitting diodes. Control circuitry within the electronic device can apply drive powers to the light-emitting diodes in a way that is sensitive to the operating temperature of the light-emitting diodes. The control circuitry can determine whether the temperature of the light-emitting diodes is elevated by determining which components are active in the device. Activity levels can be ascertained by gathering status information on each component. Temperature sensors may be used to make real time temperature measurements. Based on factors such as component activity levels and measured temperature values, the control circuitry can adjust the maximum allowed light-emitting diode drive power level to avoid overdriving the diodes during operation at elevated temperatures.

Claims

1. A method of operating an electronic device with a display that is backlit using a light source, comprising:

during operation of the electronic device, powering the light source at a level that is based at least partly on temperature.

2. The method defined in claim 1 further comprising:

measuring the temperature with a temperature sensor in the electronic device, wherein powering the light source comprises powering the light source based at least partly on the measured temperature.

3. The method defined in claim 2 wherein the light source comprises a light-emitting diode, wherein the light-emitting diode and the temperature sensor are mounted within a common package, and wherein measuring the temperature comprises measuring the temperature using the temperature sensor mounted within the common package.

4. The method defined in claim 2 wherein the display comprises a flex circuit, wherein the light source comprises light-emitting diodes mounted on the flex circuit, and wherein measuring the temperature comprises measuring the temperature using the temperature sensor on the flex circuit.

5. The method defined in claim 1 wherein the electronic device comprises at least one component selected from the group consisting of:

a processor, a video driver circuit, a camera flash, and a communications circuit, the method further comprising;

estimating the temperature by gathering operating status information for the at least one component, wherein powering the light source comprises powering the light source based at least partly on the estimated temperature.

6. The method defined in claim 1 wherein the light source comprises light-emitting diodes that produce light when driven at a drive power and wherein powering the light source comprises applying the drive power to the light-emitting diodes at up to a maximum drive power value.

7. The method defined in claim 6 further comprising:

measuring the temperature using a temperature sensor and using control circuitry within the electronic device to adjust the maximum drive power value in real time during operation of the electronic device based at least partly on the measured temperature.

8. The method defined in claim 1 wherein the light source comprises a fluorescent lamp and wherein powering the light source comprises powering the fluorescent lamp.

9. The method defined in claim 8 further comprising:

measuring the temperature with a temperature sensor in the electronic device, wherein powering the fluorescent lamp comprises powering the fluorescent lamp based at least partly on the measured temperature.

10. A method of operating an electronic device that has a display, light-emitting diodes that produce backlight for the display, and components including a processor and a video circuit, the method comprising:

with control circuitry in the electronic device, obtaining operating status information for at least a selected one of the processor and the video circuit; and

with control circuitry in the electronic device, applying a drive power to the light-emitting diodes that has a value that is bounded by a maximum light-emitting diode drive power value, wherein the maximum light-emitting diode drive power value is determined at least partly in response to the operating status information.

11. The method defined in claim 10 wherein obtaining the status information comprises determining whether the video circuit is actively being used to supply video signals.

12. The method defined in claim 10 wherein obtaining the status information comprises determining an activity level for the video circuit.

13. The method defined in claim 10 wherein obtaining the status information comprises determining whether the processor is active.

14. The method defined in claim 10 wherein obtaining the status information comprises determining an activity level for the processor.

15. The method defined in claim 10 further comprising measuring temperature within the electronic device using a temperature sensor, wherein generating the maximum light-emitting diode drive power value comprises generating the maximum light-emitting diode drive power value partly based on the temperature measured with the temperature sensor.

16. The method defined in claim 15 wherein the light-emitting diodes are mounted on a substrate within a backlight unit for the display, wherein the temperature sensor comprises a thermistor mounted on the substrate, and wherein measuring the temperature comprises measuring the temperature using the thermistor.

17. An electronic device, comprising:

a display having light-emitting diodes that generate backlight for the display and that operate at an operating temperature; and

control circuitry that is configured to apply a drive power to the light-emitting diodes at a level that is selected based at least partly on the operating temperature.

18. The electronic device defined in claim 17 further comprising a video circuit that is configured to produce video signals at an activity level, wherein the activity level of the video circuit influences the operating temperature of the light-emitting diodes, and wherein the control circuitry is further configured to apply the drive power to the light-emitting diodes at a level that is selected based at least partly on the activity level of the video circuit.

19. The electronic device defined in claim 17 further comprising a processor integrated circuit in the control circuitry that is configured to operate at an activity level, wherein the activity level of the processor integrated circuit influences the operating temperature of the light-emitting diodes, and wherein the control circuitry is further configured to apply the drive power to the light-emitting diodes at a level that is selected based at least partly on the activity level of the processor integrated circuit.

20. The electronic device defined in claim 17 further comprising a substrate on which the light-emitting diodes are mounted, the electronic device further comprising a temperature sensor mounted on the substrate, wherein the control circuitry is configured to select the level for the drive power based at least partly on signals from the temperature sensor.

21. The electronic device defined in claim 17 further comprising a component, wherein the control circuitry is configured to select the level for the drive power based at least partly on whether the component is active.

22. The electronic device defined in claim 17 further comprising components that generate heat when active, wherein the control circuitry is configured to apply the drive power to the light-emitting diodes at a level that is bounded by a maximum allowable drive power level, and wherein the control circuitry is configured to adjust the maximum allowable drive power level as a function of which of the components are active.

23. The electronic device defined in claim 22 wherein the components comprise at least one component selected from the group consisting of:

a processor integrated circuit, a video driver circuit, a communications circuit, and a camera flash.

24. An electronic device, comprising:

a display having an array of light-emitting diode pixels that generate an image and that operate at an operating temperature; and

control circuitry that is configured to apply drive powers to the light-emitting diode pixels at levels that are selected based at least partly on the operating temperature.

25. The electronic device defined in claim 24 further comprising:

a temperature sensor that is configured to measure the operating temperature.

26. The electronic device defined in claim 24 further comprising a video circuit that is configured to produce video signals at an activity level, wherein the activity level of the video circuit influences the operating temperature of the light-emitting diode pixels, and wherein the control circuitry is further configured to apply the drive powers to the light-emitting diode pixels at levels that are selected based at least partly on the activity level of the video circuit.

27. The electronic device defined in claim 24 further comprising a processor integrated circuit in the control circuitry that is configured to operate at an activity level, wherein the activity level of the processor integrated circuit influences the operating temperature of the light-emitting diode pixels, and wherein the control circuitry is further configured to apply the drive powers to the light-emitting diode pixels at levels that are selected based at least partly on the activity level of the processor integrated circuit.

28. The electronic device defined in claim 24 further comprising components that generate heat when active, wherein the control circuitry is configured to apply the drive powers to the light-emitting diode pixels at levels that are bounded by a maximum allowable drive power level, and wherein the control circuitry is configured to adjust the maximum allowable drive power levels as a function of which of the components are active.

29. The electronic device defined in claim 24 wherein the components comprise at least one component selected from the group consisting of:

a processor integrated circuit, a video driver circuit, a communications circuit, and a camera flash.