Closing your laptop lid often triggers a power-saving state like sleep or hibernation, which causes connected external monitors to turn off automatically.
When you close the lid of your laptop, your computer interprets this action based on its pre-configured power settings. By default, most operating systems, especially Windows computers as highlighted in the reference, are set to enter a sleep mode or sometimes hibernate when the lid is closed. This behavior is designed to conserve battery life and power.
How Closing the Lid Affects Your Monitor
External monitors require a signal from the computer to display content. When your computer enters a low-power state like sleep or hibernation, or is powered off entirely, it stops sending a display signal to connected monitors.
As stated in the reference, "External monitors will shut off automatically when the computer is powered off, hibernated, or goes to sleep." This is the primary reason why your monitor goes black or enters standby mode when you close your computer's lid. The computer is essentially telling the monitor, "I'm powering down or going to sleep, so you can too."
Default Behavior vs. Desired Outcome
Here's a simple comparison of typical default behavior and what you might want:
| Action | Default Lid Close Behavior (Common) | Result for Monitor |
|---|---|---|
| Closing Laptop Lid | Go to Sleep or Hibernate | Monitor Turns Off |
| Closing Laptop Lid | Do Nothing (Desired) | Monitor Stays On |
How to Keep Your Monitor On
If you want your external monitor to stay on even when your laptop lid is closed (e.g., when using the laptop in a dock or with external peripherals), you need to change your computer's power settings.
As the reference points out, "Windows computers tend to go to sleep by default when closing the laptop, so the "Power Options" will need to be modified to prevent this from happening."
Here are the general steps to modify this behavior in Windows:
- Open Power Options: Search for "Power Options" in the Windows search bar and open it.
- Choose what closing the lid does: On the left-hand side, click on "Choose what closing the lid does".
- Adjust settings: You will see options for "When I close the lid" for both "On battery" and "Plugged in".
- Select "Do nothing": Change the action for both scenarios to "Do nothing".
- Save changes: Click "Save changes" to apply the new settings.
By setting this option to "Do nothing," your computer will remain fully active even when the lid is closed, allowing your external monitor(s) to continue receiving a signal and stay on.
Note: Steps may vary slightly depending on your specific version of Windows.
In Summary
Your monitor turns off when you close your computer because closing the lid typically triggers a sleep or hibernation state based on default power settings. When the computer enters these low-power states, it stops sending a signal to connected external monitors, causing them to turn off automatically. Modifying your power settings to prevent the computer from sleeping or hibernating when the lid is closed is the solution if you want your monitor to remain on.
