Power conservation method for a portable computer with LCD display

• US 5,991,883 A
• Filed: 07/23/1996
• Issued: 11/23/1999
• Est. Priority Date: 06/03/1996
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Atkinson, Lee
• Primary Examiner(s): Sheikh, Ayaz R.
• Assistant Examiner(s): Thlang, Eric S.
• Application Number:
  US08/685,093
• Time in Patent Office: 1,218 Days
• Field of Search: 395/750.01, 395/375, 395/800, 395/750.04, 395/750.08, 371/66, 707/526, 345/509
• US Class Current: 713/300
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3218 of display devices
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 5/363 Graphics controllers
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system and process for power conservation in a portable computer system. When the application or hardware in use allows for reduced video performance, the refresh rate of the video graphics controller is reduced to a level which allows practical use of the display but consumes much less power than a normal mode.

Claims

1. A portable computer system with reduced power consumption, comprising:

a microprocessor;

a graphics controller connected to said microprocessor;

a video display connected to said graphics controller; and

circuitry connected to detect when said portable computer system requires a reduced power mode;

wherein said graphics controller is connected to operate said video display at a first refresh rate during normal operation, and at a second refresh rate, non-zero and lower than said first refresh rate, when said circuitry detects that a reduced power mode is required.

2. The system of claim 1, wherein said circuitry is connected to at least one button which selects whether said reduced power mode is enabled or disabled.

3. The system of claim 1, wherein said circuitry is implemented by said microprocessor.

4. The system of claim 1, wherein said circuitry detects when a system power source has a critically low output value.

5. The system of claim 1, wherein said circuitry indicates that a reduced power mode has been selected at system start-up.

6. The system of claim 1, wherein said circuitry indicates that the state of said system is being stored to a non-volatile memory.

7. The system of claim 1, wherein said circuitry indicates that a "CPU IDLE" Advanced Power Management command has been issued.

8. The system of claim 1, wherein said circuitry includes a tick counter that determines if said CPU has been slowed.

9. A computer system comprising:

a user input device;

a microprocessor operatively connected to detect inputs from said input device;

memory which is read/write accessible by said microprocessor;

a video controller connected to said microprocessor;

a display operatively connected to display data generated by said video controller at a first refresh rate;

a power supply connected to provide power to said microprocessor, said memory, and said display, wherein said power supply comprises a battery;

wherein said display operates said display at a second refresh rate, lower than said first refresh rate, when said video controller receives a power conservation signal from said microprocessor.

10. The system of claim 9, wherein said microprocessor generates said power conservation signal when at least one user-selectable switch is activated.

11. The system of claim 9, wherein said circuitry comprises said microprocessor.

12. The system of claim 9, wherein said microprocessor generates said power conservation signal when said power supply has a critically low output value.

13. The system of claim 9, wherein said microprocessor generates said power conservation signal when a reduced power mode has been selected at system start-up.

14. The system of claim 9, wherein said microprocessor generates said power conservation signal when the state of said system is being stored to a non-volatile memory.

15. The system of claim 9, wherein said microprocessor generates said power conservation signal when a "CPU IDLE" Advanced Power Management command has be en issued.

16. The system of claim 9, wherein said microprocessor generates said power conservation signal when said microprocessor has been slowed.

17. A portable computer system with reduced power consumption, comprising:

a microprocessor;

a graphics controller connected to said microprocessor;

a video display connected to said graphics controller; and

event detection circuitry connected to detect when said portable computer system requires a reduced power mode;

system circuitry connected to detect when any one of several system condition requires a normal refresh rate;

wherein said graphics controller is connected to operate said video display at a first refresh rate during normal operation, and at a second refresh rate, non-zero and lower than said first refresh rate, when said event detection circuitry detects that a reduced power mode is required.

18. The system of claim 17, wherein said event detection circuitry is connected to at least one button which selects whether said reduced power mode is enabled or disabled.

19. The system of claim 17, wherein said event detection circuitry is implemented by said microprocessor.

20. The system of claim 17, wherein said event detection circuitry detects when a system power source has a critically low output value.

21. The system of claim 17, wherein said event detection circuitry indicates that a reduced power mode has been selected at system start-up.

22. The system of claim 17, wherein said event detection circuitry indicates that the state of said system is being stored to a non-volatile memory.

23. The system of claim 17, wherein said event detection circuitry indicates that a "CPU IDLE" Advanced Power Management command has been issued.

24. The system of claim 17, wherein said event detection circuitry includes a tick counter that determines if said CPU has been slowed.

25. The method of claim 17, wherein one of said system conditions comprises the presence of a video master device.

26. The method of claim 17, wherein one of said system conditions comprises the presence of an application requiring a high video refresh rate.

27. A method for conserving power in a computer system, comprising the steps of:

operating a video display at a first refresh rate;

detecting whether any one of a set of events requiring video power conservation has occurred;

if one of said events has occurred, detecting whether any one of a set of system conditions requires said first refresh rate;

if no said system condition requires said first refresh rate, then operating said display at a second refresh rate, which is non-zero and lower than said first refresh rate;

if any said system condition requires said first refresh rate, then continuing to operate said display at said first refresh rate; and

if no said event has occurred, then continuing to operate said display at said first refresh rate.

28. The method of claim 27, wherein one of said events comprises a user selection of said reduced power mode.

29. The method of claim 27, wherein one of said events comprises a detection that a method power source has a critically low output value.

30. The method of claim 27, wherein one of said events comprises a power-on-self-test selection of said reduced power mode.

31. The method of claim 27, wherein one of said events comprises an indication that the state of said method is being stored to a non-volatile memory.

32. The method of claim 27, wherein one of said events comprises a "CPU IDLE" Advanced Power Management command.

33. The method of claim 27, wherein one of said events comprises a tick counter that indicates that said CPU has been slowed.

34. The method of claim 27, wherein one of said system conditions comprises the attachment of a CRT display.

35. The method of claim 27, wherein one of said system conditions comprises the presence of a video master device.

36. The method of claim 27, wherein one of said system conditions comprises the presence of an application requiring a high video refresh rate.

37. The method of claim 27, further comprising the step of:

when operating said display at said second refresh rate, detecting whether a system condition requires said first refresh rate; and

if any said system condition requires said refresh rate, then operating said display at said first refresh rate.

38. A method for conserving power in a computer system, comprising the steps of:

operating a video display at a first refresh rate;

detecting whether any one of a set of events requiring video power conservation has occurred;

if one of said events has occurred, detecting whether any one of a set of system conditions requires said first refresh rate;

if no said system condition requires said first refresh rate, then operating said display at a second refresh rate, which is non-zero and lower than said first refresh rate;

if any said system condition requires said first refresh rate, then continuing to operate said display at said first refresh rate; and

if no said event has occurred, then continuing to operate said display at said first refresh rate;

when operating said display at said second refresh rate, detecting whether a system condition requires said first refresh rate; and

if any said system condition requires said refresh rate, then operating said display at said first refresh rate.

39. The method of claim 38, wherein one of said events comprises a user selection of said reduced power mode.

40. The method of claim 38, wherein one of said events comprises a detection that a method power source has a critically low output value.

41. The method of claim 38, wherein one of said events comprises a power-on-self-test selection of said reduced power mode.

42. The method of claim 38, wherein one of said events comprises an indication that the state of said method is being stored to a non-volatile memory.

43. The method of claim 38, wherein one of said events comprises a "CPU IDLE" Advanced Power Management command.

44. The method of claim 38, wherein one of said events comprises a tick counter that indicates that said CPU has been slowed.

45. The method of claim 38, wherein one of said system conditions comprises the attachment of a CRT display.

46. The method of claim 38, wherein one of said system conditions comprises the presence of a video master device.

47. The method of claim 38, wherein one of said system conditions comprises the presence of an application requiring a high video refresh rate.