Intelligent LCD brightness control system

• US 5,760,760 A
• Filed: 07/17/1995
• Issued: 06/02/1998
• 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): Wu, Xiao
• Assistant Examiner(s): WU, XU MING
• Application Number:
  US08/503,346
• Time in Patent Office: 1,051 Days
• Field of Search: 345/63, 345/102, 345/101, 345/211, 345/207, 345/199, 348/602
• 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. In another alternative embodiment, the brightness control circuitry comprises some form of artificial intelligence for "learning" a user'"'"'s preferred brightness level, or range of brightness levels, in various ambient lighting conditions.

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;

means for converting the ambient light signal for input into the microprocessor;

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

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

means for setting the brightness level of the LCD to correspond to the lower level indicated by the automatic brightness level signal and the selected brightness level signal.

2. The apparatus of claim 1 wherein said electronic device is a portable personal computer.

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

4. An apparatus for automatically adjusting the brightness of a liquid crystal display (LCD) in response to ambient lightning conditions, the apparatus comprising:

a brightness control circuitry including a microprocessor, a memory and an analog-to-digital (A/D) converter;

means for manually adjusting the brightness of the LCD and generating selected brightness level signals 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 through the A/D converter to the microprocessor;

the memory having automatic brightness level signals stored therein indexed by the first ambient light signal;

means for generating a brightness control signal to correspond to the selected brightness level signal;

means for generating a brightness control signal to correspond to the automatic brightness level signal;

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

means for setting the brightness level of the LCD to correspond to the lower level indicated by the automatic brightness level signal and the selected brightness level signal.

5. The apparatus of claim 4 wherein said means for manually adjusting is a function key of said electronic device.

6. 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 one side of the LCD and generating an ambient light signal to the microprocessor;

storing an automatic brightness level signal in a memory;

indexing the automatic brightness level signal to the ambient light signal;

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

setting the brightness level of the LCD to correspond to the lower value indicated by the automatic brightness level signal and the selected brightness level signal.

7. The method of claim 6 wherein said electronic device is a portable personal computer.

8. The method of claim 6 wherein said first side is a front side of said LCD.