Display control apparatus capable of changing luminance depending on conditions of power supply circuit

• US 5,386,577 A
• Filed: 08/20/1993
• Issued: 01/31/1995
• Est. Priority Date: 02/23/1990
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Zenda, Hiroki
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US08/109,476
• Time in Patent Office: 529 Days
• Field of Search: 395/750, 395/575, 364/707, 364/710.06, 364/237.5, 364/DIG. 1, 364/927.7, 364/Dig. 2, 315/169.3, 315/169.4
• US Class Current: 713/340
• CPC Class Codes: G06F 1/3218 of display devices
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/04 Display device controller operating with a plurality of display units

Abstract

In a portable personal computer having a flat panel display and driven by battery or by AC adapter, a LOW battery state of battery is detected. In response to the low battery state, a luminance control signal having a minimum luminance value is supplied to the flat panel display. When the personal computer is driven by the AC adapter, a luminance control signal having a maximum luminance value is supplied to the flat panel display.

Claims

1. A flat panel display luminance control apparatus for a portable computer provided with a flat panel display unit for displaying data in response to luminance control, and first and second power supply means selectively used for supplying power to said flat panel display unit, said apparatus comprising:

first determining means for determining if an output voltage of said first power supply means is greater than "0" but less than a predetermined value when said first power supply means is being used;

second determining means for determining if said second power supply means is being used; and

luminance control means, coupled to said first and second determining means, for supplying a first luminance control signal to said flat panel display unit when the output voltage is less than the predetermined value, and for supplying a second luminance control signal to said flat panel display unit when said second determining means determines that said second power supply means is being used, wherein said second luminance control signal has a value greater than a value of the first luminance control signal.

2. The apparatus according to claim 1, wherein said first power supply means comprises a battery and said second power supply means comprises an AC adapter.

3. The apparatus according to claim 2, wherein said luminance control means supplies the second luminance control signal to said flat panel display unit when said second means determines that said AC adapter is connected, and supplies the first luminance control signal whose luminance level is lower than that of the first luminance control signal to said flat panel display unit, when said first determining means determines that the output voltage of the battery is less than the predetermined value.

4. A luminance control method for a flat panel display unit in a personal computer provided with a flat panel display unit for displaying data in response to a luminance control signal and a power supply for supplying power to said flat panel display unit, said method comprising the steps

a) detecting, when said power supply comprises a of:

battery, whether said power supply has entered a low battery state;

b) controlling the luminance control signal having at least a minimum value greater than "0" and having a maximum value greater than the minimum value; and

(c) supplying the controlled luminance control signal to said flat panel display unit in response to the detection of the low battery state.

5. The method according to claim 4, further comprising the step of:

d) supplying a first luminance control signal to said flat panel display unit when said power supply comprises the battery and a second luminance control signal whose luminance level is higher than that of the first luminance control signal to said flat panel display unit when said power supply comprises an AC adapter.

6. The method according to claim 5, further comprising the step of:

e) supplying a third luminance control signal to said flat panel display unit when the power supply comprises the battery and the battery is not in the low battery state, the third luminance control signal having a luminance level between luminance levels of the first and second luminance control signals.

7. A flat panel display luminance control apparatus for a portable computer provided with a flat panel display unit for displaying data in response to luminance control, and a battery for supplying power to said flat panel display unit, said apparatus comprising:

means for determining whether an output voltage of said battery is at least one of a predetermined value greater than "0" and a value greater than "0" and less than the predetermined value;

control means, coupled to said determining means, for supplying a first luminance control signal when the output voltage of said battery is determined not to be the predetermined value greater than "0" and the value greater than "0" and less than the predetermined value by said determining means, and for supplying a second luminance control signal when the output voltage of said battery is determined to be at least one of the predetermined value greater than "0" and the value greater than "0" and less than the predetermined value by said determining means, wherein said second luminance control signal has a value higher than a value of the first luminance control signal; and

display means, coupled to said control means, for displaying data with a first luminance level in accordance with the first luminance control signal from said control means and for displaying data with a second luminance level higher than the first luminance level in accordance with the second luminance control signal.

8. The apparatus according to claim 7, further comprising:

external power supply means for supplying power to said flat panel display unit from the outside of said portable computer; and

means, coupled to said external power supply means, for detecting that the power is supplied to said flat panel display unit from said external power supply means; and

wherein said control means supplies a third luminance control signal when a supplement of the power from said external power supply means is detected by said detecting means, and said display means displays data with a third luminance level high than the first luminance level in accordance with the third luminance control signal.

9. The apparatus according to claim 8, wherein said determining means and said detecting means comprise a one-chip microprocessor.

10. The apparatus according to claim 7, wherein said determining means and said control means comprise a one-chip microprocessor.

11. A battery-powered computer system, comprising:

a flat panel display unit for displaying data in response to luminance control;

first and second power supply means selectively used for supplying power to said flat panel display unit;

first determining means for determining if an output voltage of said first power supply means is less than a predetermined value greater than "0" when said first power supply means is being used;

second determining means for determining if said second power supply means is used; and

luminance control means, coupled to said first and second determining means, for supplying a first luminance control signal to said flat panel display unit when the output voltage is less than the predetermined value, and for supplying a second luminance control signal to said flat panel display unit when said second determining means determines that said second power supply means is being used, wherein said second luminance control signal indicates a value greater than a value of the first luminance control signal.

12. The apparatus according to claim 11, wherein said first power supply means comprises a battery and said second power supply means comprises an AC adapter.

13. The apparatus according to claim 12, wherein said luminance control means supplies the second luminance control signal to said flat panel display unit when said second means determines that said AC adapter is connected, and supplies the first luminance control signal to said flat panel display unit, when said first determining means determines that the output voltage of the battery is greater than "0" but less than a predetermined value.

14. The system according to claim 11, wherein the first and second luminance control signal indicate a luminance voltage.

15. The system according to claim 11, wherein said flat panel display unit is a plasma display unit.

16. The system according to claim 15, wherein the luminance control signals are supplied to the plasma display unit.

17. A battery-powered computer system, comprising:

a flat panel display unit for displaying data in response to luminance control;

first and second power supply means selectively used for supplying power to said flat panel display unit; and

a controller for determining if an output voltage of said first power supply means is greater than "0" but less than a predetermined value when said first power supply means is being used, for determining if said second power supply means is being used, and for supplying a first luminance control signal to said flat panel display unit when the output voltage is less than the predetermined value, and supplying a second luminance control signal to said flat panel display unit when said second power supply means is being used, wherein said second luminance control signal indicates a value greater than a value of the first luminance control signal.

18. The system according to claim 17, wherein said first power supply means comprises a battery and said second power supply means comprises an AC adapter.

19. The system according to claim 18, wherein said controller supplies the second luminance control signal to said flat panel display unit when said controller determines that said AC adapter is being used.

20. The system according to claim 17, wherein said flat panel display unit is a plasma display unit.

21. The system according to claim 20, wherein the luminance control signals are supplied to the plasma display unit.

22. A battery-powered computer system, comprising:

a flat panel display unit for displaying data in response to luminance control;

a battery and an external power supply selectively used supplying power to said flat panel display unit;

first determining means for determining if an output voltage of said battery is less than a predetermined value greater than "0" when said battery is used;

second determining means for determining if said external power supply is used; and

luminance control means, coupled to said first and second determining means, for supplying a first luminance control signal to said flat panel display unit when the output voltage is less than the predetermined value, for supplying a second luminance control signal to said flat panel display unit when the output voltage is equal to or greater than the predetermined value, and for supplying a third luminance control signal to said flat panel display unit when the second determining means determines that said external power supply is being used, wherein each of the first, second and third luminance control signals indicates a value and the value for the first luminance control signal is less than the value for the second luminance control signal which is less than the value for the third luminance control signal.

23. The system according to claim 22, wherein said flat panel display unit is a plasma display unit.

24. The system according to claim 23, wherein the luminance control signals are supplied to the plasma display unit.

25. The system according to claim 22, wherein the first, second and third luminance control signals indicate minimum, typical and maximum luminance voltages, respectively.

26. A battery-powered computer system, comprising:

a flat panel display unit for displaying data in response to luminance control;

a battery and an external power supply selectively used for supplying power to said flat panel display unit; and

a controller for determining if an output voltage of said battery is greater than "0" but less than a predetermined value when said battery is being used, for determining if the output voltage of said battery is equal to or greater than the predetermined value, for determining if said external power supply is being used, and for supplying a first luminance control signal to said flat panel display unit when the output voltage is less than the predetermined value, for supplying a second luminance control signal to said flat panel display unit when the output voltage is equal to or greater than the predetermined value, and for supplying a third luminance control signal to said flat panel display unit when said external power supply is being used, wherein each of said first, second and third luminance control signals indicates a value and that value for the first luminance control signal is less than the value for the second luminance control signal which is less than the value for the third luminance control signal.

27. The system according to claim 26, wherein said flat panel display unit is a plasma display unit.

28. The system according to claim 27, wherein the luminance control signals are supplied to the plasma display unit.

29. The system according to claim 26, wherein the first, second and third luminance control signals indicate minimum, typical and maximum luminance voltages respectively.