Lamp drive apparatus and drive method of a notebook computer

• US 20030043106A1
• Filed: 07/15/2002
• Published: 03/06/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Woo, Jong Hyun
• Granted Patent: US 7,042,434 B2
• Time in Patent Office: Days
• US Class Current: 345/101
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

This present invention relates to a lamp drive apparatus and a drive method for an LCD equipped portable electronics to maintain a user-selected level of brightness in accordance with surrounding temperature of the lamp. In one operation mode a lamp drive apparatus reduces the current, which is applied into the lamp to maintain the already selected level of brightness in accordance with a detected lamp surrounding temperature where the brightness of the lamp has already been set in the LCD, to make the LCD device to illuminate no brighter than the selected level of brightness. Accordingly, the battery power can be used more efficiently or effectively. Thus, the battery life can be extended.

Claims

1. A lamp drive method of a portable computer, comprising:

selecting a standard temperature of a lamp driving an LCD;

selecting a brightness control level of a plurality of brightness control levels that determines a corresponding brightness in the LCD according to the standard temperature;

detecting surrounding temperature of the lamp;

selecting one of a first mode and a second mode for operating the lamp, wherein operating the lamp in the first mode comprises,

reducing a drive current that is to be applied into the lamp to maintain the corresponding brightness within the plurality of brightness control levels in accordance with a change in the detected surrounding temperature of a lamp, and wherein operating the lamp in the second mode comprises,

reducing brightness of the LCD in accordance with the change in detected surrounding temperature of the lamp to maintain a corresponding drive current of the selected brightness control level.

2. The lamp drive method of claim 1, wherein said reducing a drive current reduces the drive current applied into the lamp in the first mode to maintain the corresponding brightness when a difference between the detected surrounding temperature of the lamp and the selected standard temperature of the lamp is greater than a fixed value.

3. The lamp drive method of claim 2, comprising determining and storing an empirical relationship between temperature and the brightness at the plurality of brightness control levels for each of a plurality of temperatures above the standard temperature for the lamp.

4. The lamp drive method of claim 3, wherein the corresponding drive current sets a maximum power use rate of the LCD drive.

5. The lamp drive method of claim 1, wherein the selecting a brightness control level sets a voltage level of a plurality of voltage levels.

6. The lamp drive method of claim 1, wherein said reducing steps are to be operated in accordance with a lamp brightness maintaining mode chosen by a user.

7. The lamp drive method of claim 6, wherein a battery life of a battery of the portable computer is extended in the lamp brightness maintaining mode.

8. A lamp drive apparatus of a notebook computer, where brightness of a lamp has already been selected in an LCD device using the lamp as a light source of the LCD, comprising:

a thermal sensor that detects a surrounding temperature of the lamp;

a lamp drive unit that controls the brightness of the lamp by applying appropriate drive current into the lamp; and

a brightness control unit that operates in one of a first mode and a second mode, wherein in the first mode the brightness control unit maintains the selected brightness within one of a corresponding plurality of brightness control levels in accordance with a change in the detected surrounding temperature of the lamp by reducing a drive current that is applied into the lamp.

9. The lamp drive apparatus of claim 8, wherein said brightness control unit reduces the drive current that is to be applied into the lamp in the first mode to maintain the selected brightness when a difference between the detected surrounding temperature of the lamp and a selected standard temperature of the lamp is greater than a fixed amount.

10. The lamp drive apparatus of claim 9, wherein the selected brightness is determined at the standard temperature.

11. The lamp drive apparatus of claim 10, wherein in the second mode the brightness control unit reduces brightness of the LCD in accordance with the change in the detected surrounding temperature of the lamp to maintain a corresponding drive current selected at the standard temperature.

12. The lamp drive apparatus of claim 11, further comprising an input unit that receives inputs including a mode selection, wherein said brightness control unit controls said lamp drive unit in the first and second modes in accordance with selection of a brightness maintaining mode from a user through the mode selection received by said input unit.

13. The lamp drive apparatus of claim 8, further comprising a memory that stores brightness control information including lamp drive current in accordance with the brightness of the lamp, wherein said brightness control unit controls said lamp drive unit in accordance with the brightness control information.

14. A method of driving a lamp for an LCD of a portable computer, comprising:

setting a default brightness in the LCD that corresponds to a prescribed value stored in the portable computer;

checking a surrounding temperature of the LCD;

selecting one of a first mode and a second mode for operating the lamp, wherein operating the lamp in the first mode comprises,

receiving a user selected one of plurality of brightness control levels to set a first brightness and determining a corresponding first drive current as a drive current for the lamp,

maintaining the first brightness within a first temperature range while the drive current varies to reduce lamp power consumption,

determining a corresponding drive current at a minimum temperature of the first temperature range as a second drive current for a second temperature range that is below the first temperature range, and

maintaining the second drive current while the temperature of the lamp is within the second temperature range to reduce the lamp power consumption, and wherein the operating the lamp in the second mode comprises,

determining a third drive current that corresponds to the default brightness,

maintaining the third drive current within a third temperature range while the brightness changes,

determining a corresponding brightness level at a minimum temperature of the third temperature range to set a fourth brightness for a fourth temperature range that is below the third temperature range, and

maintaining the fourth brightness while the temperature of the lamp is within the fourth temperature range while the drive current changes.

15. The method of claim 14, wherein said one of the first and second modes is determined by a user action at the portable computer.

16. The method of claim 15, wherein the first mode is a power saving mode, and wherein in the second temperature range the brightness changes.

17. The method of claim 14, wherein the first and third temperature ranges are equal, and wherein the second and fourth temperature ranges are equal.

18. The method of claim 14, wherein the first mode is a brightness maintaining mode.