Technique for increasing the visibility of an LCD panel during warm-up thereof

• US 5,636,041 A
• Filed: 05/24/1995
• Issued: 06/03/1997
• Est. Priority Date: 05/24/1995
• Status: Expired due to Term

• Current Assignee: Dell USA LP (Dell Technologies Inc.)
• Original Assignee: Dell USA LP (Dell Technologies Inc.)
• Inventors: Chidester, Philip, Pearce, John J.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, TIEP HUU
• Application Number:
  US08/449,614
• Time in Patent Office: 741 Days
• Field of Search: 359/48, 359/49, 359/50, 362/85, 362/802, 345/89, 345/101, 345/102, 345/147
• US Class Current: 349/61
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

Method and apparatus for automatically increasing the visibility of an LCD during warm-up thereof is disclosed. In a preferred embodiment, the system of the present invention comprises brightness control circuitry electrically connected to an LCD panel of a portable personal computer (PC) or other battery operated electronic device for controlling the brightness level of the LCD. The brightness control circuitry is also electrically connected to receive a signal indicative of a brightness control level selected by a user using a user-settable control means, such as a brightness control knob located on the device. In operation, on power up of the LCD, the brightness control circuitry increases the LCD brightness to a maximum level, regardless of the brightness level selected by the user. Once the LCD has warmed up, the brightness control circuitry decreases the brightness level of the LCD to the level selected by the user. In one aspect of the invention, the brightness level is decreased incrementally such that its occurrence is virtually undetectable by the user.

Claims

1. In an electronic device having a liquid crystal display (LCD), a method of increasing the visibility of said LCD during a warm-up period thereof, the method comprising, responsive to said LCD being powered on:

setting a brightness level of said LCD to a maximum level;

subsequent to said setting, waiting a first predetermined amount of time;

upon expiration of said first predetermined amount of time, determining whether said LCD brightness level is set to a user-selected brightness level;

responsive to a determination that said LCD brightness level is not set to said user-selected brightness level, incrementally decreasing said LCD brightness level until said LCD brightness level is set to said user-selected brightness level.

2. The method of claim 1 wherein said first predetermined amount of time is determined empirically and is dependent on a plurality of parameters of said LCD.

3. The method of claim 1 wherein said incrementally decreasing said LCD brightness level is performed such that it is substantially undetectable by a user.

4. The method of claim 1 wherein said electronic device is a personal computer.

5. In an electronic device having a liquid crystal display (LCD), a method of increasing the visibility of said LCD during a warm-up period thereof, the method comprising, responsive to said LCD being powered on:

setting a brightness level of said LCD to a maximum level;

subsequent to said setting, waiting a first predetermined amount of time;

upon expiration of said first predetermined amount of time, determining whether said LCD brightness level is set to a user-selected brightness level;

responsive to a determination that said LCD brightness level is not set to said user-selected brightness level;

decreasing said LCD brightness level by a predetermined amount;

waiting a second predetermined amount of time; and

repeating said decreasing and said waiting said second predetermined time period until said LCD brightness level is set to said user-selected brightness level.

6. The method of claim 5 wherein said first predetermined amount of time is determined empirically and is dependent on a plurality of parameters of said LCD.

7. The method of claim 5 wherein said predetermined amount and said second predetermined amount of time are small enough to enable said decreasing and waiting said second predetermined time period to be performed substantially undetected by a user.

8. The method of claim 5 wherein said electronic device is a personal computer.

9. Apparatus for increasing the visibility of a liquid crystal display (LCD) of an electronic device during a warm-up period of said LCD, the apparatus comprising:

means for generating a signal indicative of a user-selected brightness level;

means for setting a brightness level of said LCD to a maximum level and for determining whether said LCD brightness level is set to said indicated user-selected brightness level responsive to expiration of a predetermined time period, and for incrementally decreasing said LCD brightness level until said LCD brightness level is set to said indicated user-selected brightness level responsive to a determination that said LCD brightness level is not set to said indicated user-selected brightness level.

10. The apparatus of claim 9 wherein said generating means comprises a user-settable control located in a user-accessible location on said electronic device.

11. The apparatus of claim 9 wherein said setting means, said determining means and said decreasing means together comprise brightness control circuitry connected to said LCD.

12. The apparatus of claim 9 wherein said electronic device comprises a portable personal computer.

13. Apparatus for increasing the visibility of a liquid crystal display (LCD) of an electronic device during a warm-up period of said LCD, the apparatus comprising:

brightness control circuitry for generating control signals to said LCD for controlling a brightness level thereof;

a user-settable mechanism for generating a signal indicative of a user-selected brightness level to said brightness control circuitry;

wherein responsive to expiration of a predetermined time period, said brightness control circuitry determines whether said LCD brightness level is set to said indicated user-selected brightness level and, responsive to a determination that said LCD brightness level is not set to said indicated user-selected brightness level, incrementally decreases said LCD brightness level until said LCD brightness level is set to said indicated user-selected brightness level.

14. The apparatus of claim 13 wherein said electronic device is a personal computer.

15. The apparatus of claim 13 wherein said brightness control circuitry comprises a microprocessor.

16. The apparatus of claim 13 wherein said user-settable mechanism comprises a brightness control knob located in a user-accessible location on said electronic device.