Intelligent LCD brightness control system

• US 5,952,992 A
• Filed: 08/19/1997
• Issued: 09/14/1999
• Est. Priority Date: 07/17/1995
• Status: Expired due to Term

• Current Assignee: Dell USA LP (Dell Technologies Inc.)
• Original Assignee: Dell USA LP (Dell Technologies Inc.)
• Inventors: Helms, Frank P.
• Primary Examiner(s): Saras, Steven J.
• Assistant Examiner(s): WU, XU MING
• Application Number:
  US08/914,351
• Time in Patent Office: 756 Days
• Field of Search: 345/63, 345/101, 345/102, 345/211, 345/207, 345/199, 348/602, 315/157, 349/61-64
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

Method and apparatus for automatically adjusting the brightness level of an LCD based on the ambient lighting conditions of the environment in which the LCD is being operated are disclosed. In a preferred embodiment, a photodetector located proximate the front of the LCD generates to brightness control circuitry signals indicative of ambient lighting conditions. These signals are correlated to predetermined automatic brightness control values for use in controlling the brightness level of the LCD. Once the ambient light signals have been used automatically to set the brightness level of the LCD, user-selection of a different brightness level, either higher or lower, will override the automatic brightness control setting. In an alternative embodiment, a first photodetector is located proximate the front of the LCD and a second photodetector is located proximate the back of the LCD. In this embodiment, the brighter ambient condition is used to control the brightness level of the LCD.

Claims

1. In an electronic device having a liquid crystal display (LCD), an apparatus for automatically adjusting the brightness of the LCD in response to ambient lighting conditions, the apparatus comprising:

a brightness control circuitry including a microprocessor and a memory;

means for manually adjusting the brightness of the LCD and generating a selected brightness level signal to the microprocessor;

a first photodetector for detecting a level of ambient light directed toward a first side of the LCD and for generating a first ambient light signal to the microprocessor;

a second photodetector for detecting a level of ambient light directed toward a second side of the LCD opposite said first side of the LCD and for generating a second ambient light signal to the microprocessor;

means for converting the first and second ambient light signals for input into the microprocessor;

the memory having automatic brightness level signals indexed by the first and second ambient light signals;

means for selecting one of said automatic brightness level signals using said first and second ambient light signals;

means for determining the lower value of the selected brightness level signal and the selected automatic brightness level signal; and

means for setting the brightness level of the LCD to correspond to either the selected brightness level signal if the user has manually adjusted after the automatic brightness level signals have been indexed, or the lower value of the selected brightness level signal and the selected automatic brightness level signal.

2. The apparatus of claim 1 wherein said means for selecting comprises means for selecting the lower value of the automatic brightness level signal indexed by said first ambient light signal and the automatic brightness level signal indexed by said second ambient light signal.

3. The apparatus of claim 2 wherein said means for selecting comprises means for selecting an average of said automatic brightness level signals indexed.

4. The apparatus of claim 1 wherein said first side is a front side of said LCD.

5. The apparatus of claim 1 wherein said second side is a back side of said LCD.

6. In an electronic device having a liquid crystal display (LCD), an apparatus for automatically adjusting the brightness of the LCD in response to ambient lighting conditions, the apparatus comprising:

brightness control circuitry including a microprocessor and a memory;

means for manually adjusting the brightness of the LCD and generating a user-selected brightness level signal to the microprocessor;

at least two photodetectors for detecting at least two levels of ambient light directed toward a front side and a back side of the LCD and for generating at least two ambient light signals to the microprocessor, wherein one of the at least two signals corresponds to the front side of the LCD and another of the at least two signals corresponds to the back side of the LCD;

means for converting the at least two ambient light signals for input into the microprocessor;

the brightness control circuitry further comprising artificial intelligence for learning over time user preferences with respect to said LCD brightness level in certain ambient lighting conditions as indicated by respective user-selected brightness level signals generated in response thereto, wherein the brightness control circuitry sets the LCD brightness level to a brightness level corresponding to a preferred LCD brightness level associated with said at least two ambient light signals, said preferred LCD brightness level not necessarily corresponding to a current user-selected brightness level signal.

7. In an electronic device having a liquid crystal display (LCD), a method of automatically adjusting the brightness of the LCD in response to ambient lighting conditions, the method comprising the steps of:

manually adjusting the brightness level of the LCD and generating a selected brightness level signal to a microprocessor;

detecting a level of ambient light directed toward a first side of the LCD and for generating a first ambient light signal to the microprocessor;

detecting a level of ambient light directed toward a second side of the LCD opposite said first side of the LCD and for generating a second ambient light signal to the microprocessor;

storing in a memory automatic brightness level signals indexed by the first and second ambient light signals;

selecting one of automatic brightness level signals using said first and second ambient light signals;

determining the lower value of the selected brightness level signal and the selected automatic brightness level signal; and

setting the brightness level of the LCD to correspond to either the selected brightness level signal if the user has manually adjusted after the automatic brightness level signals have been indexed, or the lower value of the selected brightness level signal and the selected automatic brightness level signal.

8. The method of claim 7 wherein said step of selecting comprises a step of selecting the lower value of the automatic brightness level signal indexed by said first ambient light signal and the automatic brightness level signal indexed by said second ambient light signal.

9. The method of claim 7 wherein said step of selecting comprises a step of selecting an average of the automatic brightness level signals indexed by said first and second ambient light signals.

10. The method of claim 7 wherein said first side is a front side of said LCD.

11. The method of claim 7 wherein said second side is a rear side of said LCD.

12. In an electronic device having a liquid crystal display (LCD) and a microprocessor, a method of automatically adjusting the brightness of the LCD in response to ambient lighting conditions, the method comprising the steps of:

detecting at least two levels of ambient light directed toward a front side and a back side of the LCD and for generating at least two ambient light signals to the microprocessor, wherein one of the at least two ambient light signals corresponds to the front side of the LCD and another of the at least two ambient light signals corresponds to the back side of the LCD;

converting the at least two ambient light signals for input into the microprocessor;

detecting a user-selected brightness level signal generated to the microprocessor;

learning over time user preferences with respect to said LCD brightness level in certain ambient lighting conditions as indicated by respective user-selected brightness level signals generated in response thereto; and

setting the LCD brightness level to a brightness level corresponding to a preferred LCD brightness level associated with said at least two ambient light signals, said preferred LCD brightness level not necessarily corresponding to a current userselected brightness level signal.