Computer screen power management through detection of user presence

• US 6,650,322 B2
• Filed: 12/27/2000
• Issued: 11/18/2003
• Est. Priority Date: 12/27/2000
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Ravichandran, Krishnan, Dai, Xia
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US09/750,622
• Publication Number:
  US 20020080132A1
• Time in Patent Office: 1,056 Days
• Field of Search: 345/212, 345/211, 345/156, 345/741, 713/176, 713/177, 713/182, 725/9, 725/10, 725/11, 382/116, 382/118, 382/119
• US Class Current: 345/212
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

An apparatus is described for detecting presence of a user. The apparatus includes at least one thermal sensor to sense temperature around a define area of a computer system and a user presence detection subsystem coupled to the thermal sensor. The user presence detection subsystem determines presence of a user by analyzing signals output by the thermal sensor during a sampling period.

Claims

1. An apparatus comprising:

at least one thermal sensor to sense temperature around a defined area of a computer system; and

a user presence detection subsystem coupled to said at least one thermal sensor to determine presence of a user based on an amount of temperature fluctuation occurring within a defined time period, wherein the amount of temperature fluctuation is computed based on at least two temperature values measured at different points in time.

2. The apparatus of claim 1, wherein said at least one thermal sensor is placed adjacent to a display screen to sense temperature around a display screen area.

3. The apparatus of claim 1, wherein said at least one thermal sensor is mounted on or adjacent to a keyboard of the computer system to sense temperature around a keyboard area.

4. The apparatus of claim 1, wherein said user presence detection subsystem outputs a power saving command via an output interface to place a selected set of components of said computer system in a power saving mode if said user presence detection subsystem determines that a user is not present in front of a display screen of said computer system, and said user presence detection subsystem outputs a normal operation command via said output interface to place said selected set of components in a normal operation mode if said user presence detection subsystem determines that a user is present in front of the display screen.

5. The apparatus of claim 4, wherein said power saving command and said normal operation commands output by said user present detention subsystem are forwarded to an operating system power management to enable said operation system power management to direct power state transitions of said selected set of components from a normal operation mode to a power saving mode, or vice versa.

6. The apparatus of claim 2, wherein said user presence detection subsystem outputs a power saving command via an output interface to place a selected set of components of said computer system in a power saving mode if said user presence detection subsystem determines that a user is not presently facing a display screen of said computer system, and said user presence detection subsystem outputs a normal operation command via said output interface to place said selected set of components in a normal operation mode if said user presence detection subsystem determines that a user is presently facing the display screen.

7. The apparatus of claim 1, wherein said user presence detection subsystem determines presence of a user by comparing said amount of temperature fluctuation against a threshold value.

8. The apparatus of claim 7, wherein said user presence detection subsystem further comprises a calibration logic to readjust said threshold value.

9. The apparatus of claim 4, wherein said selected set of components comprises at least one of the following:

a display device, a display driver, and a graphics controller.

10. The apparatus of claim 1, further comprising an analog-to-digital converter coupled between said at least one thermal sensor and said user presence detection subsystem to digitize analog signals produced by said thermal sensor into digital data before forwarding the data to said user presence detection subsystem.

11. The apparatus of claim 1, wherein said at least one thermal sensor comprises a front thermal sensor and a rear thermal sensor, said front thermal sensor positioned adjacent to a display screen facing towards a user and said rear thermal sensor is positioned behind the display screen facing away from the user.

12. The apparatus of claim 11, wherein said user presence detection subsystem includes a temperature profile analyzing logic to determine presence of a user by comparing temperature fluctuation output by said front and rear thermal sensors.

13. The apparatus of claim 1, wherein said user presence detection subsystem determines presence of a user by determining if a pattern of temperature fluctuation is consistent with a fluctuation pattern of human breathing.

14. A method comprising:

sensing temperature around a display screen area of a computer system;

detecting presence of a user based on an amount of temperature fluctuation occurring within a defined time period, wherein the amount of temperature fluctuation is computed based on at least two temperature values measured at different points in time;

outputting a power saving command to place a selected set of components of said computer system in a power saving mode if presence of a user is not detected; and

outputting a normal operation command to place said selected set of components of said computer system in a normal operation mode if presence of a user is detected.

15. The method of claim 14, wherein said detecting presence of a user further comprises monitoring temperature fluctuation caused by the difference in the amount of heat emitted during inhale and exhale and determine if the pattern of temperature fluctuation is consistent with a normal fluctuation pattern of human breathing.

16. The method of claim 14, wherein said temperature around said display screen area is sensed by a thermal sensor.

17. The method of claim 14, wherein said temperature around said display screen area is sensed by an infrared sensor.

18. The method of claim 14, wherein said detecting presence of a user comprises comparing said amount of temperature fluctuation against a threshold value.

19. A computer system comprising:

a processor;

a memory coupled to said processor;

an input/output controller coupled to said processor;

a display device coupled to said input/output controller via a display driver; and

a user detection system to determine presence of a user based on an amount of temperature fluctuation occurring within a defined time period, wherein the amount of temperature fluctuation is computed based on at least two temperature values measured at different points in time, wherein said user detection system outputs a power saving command to place a selected set of components in a power saving mode if said user detection system determines that a user is not present within a computer area and said user detection system outputs a normal operation command to place said selected set of components in a normal operation mode if said user detection system determines that a user is present in the computer area.

20. The computer system of claim 19, wherein said user detection system is capable of determining if a user is in front of the computer facing said display device.

21. The computer system of claim 19, wherein said user detection system comprises a thermal sensor to sense air temperature and a temperature profile analyzing logic to determine presence of a user based on signals produced by said thermal sensor during a sampling time period.

22. The computer system of claim 21, wherein said presence of a user is detected by monitoring temperature fluctuation caused by the difference in the amount of heat emitted during inhale and exhale and determining if the pattern of temperature fluctuation is consistent with a normal fluctuation pattern of human breathing.

23. The computer system claim 21, wherein the duration of said sampling time period is selected to cover at least one complete breathing cycle.

24. The computer system of claim 19, wherein said user detection system comprises an infrared sensor and a temperature profile analyzing logic to determine presence of a user based on signals produced by said infrared sensor.

25. The computer system of claim 24, wherein said temperature profile analyzing logic detects a user presence by determining if a temperature of an object within a field of view of said infrared sensor falls within a defined temperature range.

26. The computer system of claim 19, wherein said selected set of components comprises at least one of said display device, said display driver and a graphics controller.

27. The computer system of claim 19, wherein said computer system is portable computer and said display device is a liquid crystal display.

28. The computer system of claim 19, wherein said user detection system determines presence of a user by comparing said amount of temperature fluctuation against a threshold value.

29. A computer system comprising:

a processor;

a memory coupled to said processor;

an input/output controller coupled to said processor;

a display device coupled to said input/output controller via a display driver; and

a user detection system to determine presence of a user based on an amount of temperature fluctuation occurring within a defined time period wherein the amount of temperature fluctuation is computed based on at least two temperature values measured at different points in time, wherein said user detection system outputs a power saving command to place a selected set of components in a power saving mode if said user detection system determines that a user is not present within a computer areaand said user detection system outputs a normal operation command to place said selected set of components in a normal operation mode if said user detection system determines that a user is present in the computer area; and

wherein said user detection system comprises a transmitter to transmit a signal, a receiver to receive said signal transmitted by said transmitter, and a controller coupled to said receiver to determine presence of an authorized user by processing said signal received by said receiver.

30. The computer system of claim 29, wherein said signal transmitted by said transmitter is an encrypted digital signature used by said controller to prove that the user wearing said transmitter has authorization to use said computer system.

31. The computer system of claim 30, wherein said controller comprises a decoder to decode said digital signature received by said receiver and a comparator to compare said decoded digital signature against an authorized user identification stored in a memory.

32. The computer system of claim 29, wherein said transmitter is a short-range transmitter.