Knowledge Base

What is the Ambient Light Sensor feature on a portable computer, and how do I adjust the settings? - KB Article - 301197

Ambient Light Sensor Functionality

The Ambient Light Sensor (ALS) automatically adjusts the brightness of the system's LCD panel based on surrounding light levels. Dell™ portable systems equipped with the ALS have a small square window located on the bottom edge of the LCD panel (Figure 1).

Figure 1: Ambient Light Sensor Location

The ALS may not function properly if a focused light source (such as a flash light) is close to the sensor window, or if the sensor window is blocked.

The ALS will increase the brightness of the LCD panel when used in a brightly lit area, and dims the display when used in darker areas. By design, brightness changes are made gradually to prevent flickering and may not be easily noticed.

The ALS is disabled by default when the system is shipped from the factory, but can be enabled by using:

  • The <Fn> + <left arrow> keyboard shortcut
  • The Dell QuickSet utility
  • The System Setup (BIOS)

Enable or Disable the Ambient Light Sensor (ALS) Using the Keyboard

To enable or disable the Ambient Light Sensor (ALS) using the keyboard:

  • Hold the <Fn> key and press the <Left Arrow> key to enable or disable ALS.
  • Hold the <Fn> key and press either the <Up Arrow> key or the <Down Arrow> key to disable ALS and set the LCD brightness manually. Pressing the <Up Arrow> key brightens the display, and pressing the <Down Arrow> key dims the display.

Enable or Disable the Ambient Light Sensor (ALS) Using the Quickset Tool

When changing the status of the Ambient Light Sensor (ALS) using the keyboard shortcuts, the Dell™ Quickset utility will pop up messages indicating if the ALS has been disabled (Figure 1) or enabled (Figure 2).

Figure 1:
Quickset pop up
indicating ALS is disabled.

Figure 2: Quickset pop up
indicating ALS is enabled.

To configure the ALS using the Dell Quickset utility, perform the following steps:

  1. Double-click the Quickset icon in the system tray.

  2. On the Dell Quickset window, click the Panel Brightness link.
    The Quickset LCD Panel Brightness Control windows opens (Figure 3).

    Figure 3: ALS operating range setting.

  3. Select a radio button to choose from the following:
    • Enable Ambient Light Sensor: Enables the ALS. The minimum and maximum brightness range can be set using the slider controls.
    • Enable Ambient Light Sensor to optimize BATTERY SAVINGS: Enables the ALS using a preset brightness range to enhance battery performance. The maximum brightness cannot be increased beyond the default setting.
    • Disable the Ambient Light Sensor: Disables the ALS and the brightness range slider. The LCD panel brightness must be manually set using keyboard shortcuts or the System Setup (BIOS).

Enable or Disable the Ambient Light Sensor (ALS) Using the System Setup (BIOS)

To enable or disable the Ambient Light Sensor (ALS) using the System Setup (BIOS):

Disabling the ALS setting in the System Setup (BIOS) does not override other configuration methods for this feature. The ALS can still be enabled or disabled by using the keyboard shortcuts or the Dell™ Quickset Utility.

  1. Reboot the computer.

  2. Press <F2> at the Dell splash screen to enter the BIOS (System Setup).

  3. Use the <Down Arrow> key to highlight Video, then press <Right Arrow> to expand the menu.

  4. Press <Down Arrow> to highlight Ambient Light Sensor, then press <Enter>.

  5. Press <Right Arrow> to select Off or Enabled, then press <Enter>.

  6. Press <F10> to Save and Exit.

  7. When prompted to Save changes and exit now, press <Enter>.

    Your computer now restarts.

Quick Tips content is self-published by the Dell Support Professionals who resolve issues daily. In order to achieve a speedy publication, Quick Tips may represent only partial solutions or work-arounds that are still in development or pending further proof of successfully resolving an issue. As such Quick Tips have not been reviewed, validated or approved by Dell and should be used with appropriate caution. Dell shall not be liable for any loss, including but not limited to loss of data, loss of profit or loss of revenue, which customers may incur by following any procedure or advice set out in the Quick Tips.

Article ID: SLN57456

Last Date Modified: 05/28/2009 12:00 AM

Rate this article

Easy to understand
Was this article helpful?
Yes No
Send us feedback
Comments cannot contain these special characters: <>()\
Sorry, our feedback system is currently down. Please try again later.

Thank you for your feedback.