Turning off display when connecting external monitor

[east1999]

I'm connecting a Macbook to an LG 4k display via usb-c.

Every time I connect it, MacOS recognises the previous resolution and arrangement choices (mirrored, "looks like" 1440p). I then have to lower the brightness in my Macbook to 0, to turn off its display, and then launch an app like Lunar or Monitor to control the brightness of the monitor with the Macbook's function keys.

My question is, is there a way to make this automatic? Have the Macbook turn off its display when I connect it to the monitor, or have the app do it before it syncs with the function keys?

Thank you

 

[alinpanaitiu]

Hi @east1999 ! Developer of Lunar here.

I could add this functionality in Lunar if you find it useful.

Lunar can detect when it goes from no connected displays to at least 1 connected display, and could set the MacBook brightness to 0 then.

But you have to understand the implications of this, which I laid here: https://lunar.fyi/faq#turn-off-macbook-display

I'll also write down some of the implications here:

• Windows and spaces on the built-in display will not move to the external monitor, you just won't be able to see them anymore (seems like you're solving this with mirroring)
• The GPU will still use power to render to that display even though you won't be able to see anything
• The light sensor response curve will be completely messed up because it will try to adapt to you wanting 0% brightness even in well lit environments (you'll have to disable Automatically Adjust Brightness in System Preferences to avoid this)
• Lunar's Sync Mode won't work correctly because that mode reads the built-in display brightness to Sync it to external monitors. The system doesn't offer a way to read the ambient light sensor directly

 

[alinpanaitiu]

@east1999 Just chiming in to let you know that the latest version of Lunar (v4.8.0) introduced this feature.

It is called BlackOut and you can read more about it here: https://lunar.fyi/#blackout

It isn't automatic, to avoid confusion and angry support emails, but it is very easy to use.

Just move the cursor to the monitor that you want to turn off and press Ctrl+Cmd+6. It works with both built-in and external monitors.

Press Ctrl+Cmd+6 again to toggle it off.