Why can’t you turn off the iMac screen?
Why is there no way to turn off the screen on an iMac? I mean, properly turn it off?
It’s not something I thought about when I was thinking about buying an iMac - I just assumed it would have such a basic feature. For something that’s generally well designed and usable, this omission sticks out like a sore thumb.
I’m sure lots of people have their own reasons for turning off their computer screens. Here’s mine.
I run 3 types of nightly backups on my Mac (I’m paranoid). One does a rotating backup to DVD. One does an rsync backup to my wife’s iMac. And one does an rsync backup of our server in the UK (in case it ever goes tits-up).
And in a few months’ time, my iMac will be in the bedroom (I’m being turfed out of the office so we can turn it into a nursery for our upcoming wee nipper). So you can see why having the screen off might be a good idea. IN THE BEDROOM.
Here are the solutions I’ve heard from various people:
- Just put the iMac to sleep. Er, then how are the backups supposed to work?
- Turn the brightness all the way down. You’d think that’d work, wouldn’t you? But oh no - unlike Mac laptops, where zero brightness really does turn off the backlight, an iMac’s idea of “zero brightness” is “ever-so-slightly darker than maximum brightness”. Useless.
- Set the display to sleep in 1 minute. There are even scripts available to do this for you (and reset the sleep time back to normal afterwards).
Setting the display to sleep is not a bad approach, apart from two fundamental problems. Firstly, I don’t want the screen to turn off in 1 minute - I want it to turn off now.
Secondly - and more seriously - it’s not reliable. What I mean is, the screen spontaneously and randomly turns itself on. This seems to happen when certain specific activities occur during the backup process - spinning up the DVD seems to do it, as does network activity. (I’m still trying to pin down exactly what triggers set it off.)
As you might imagine, having a gorgeously brilliant white screen is wonderful when you’re working on it during the day. It’s not so nice when it turns itself on at 3AM in your bedroom.
So that’s the current situation. Apart from cracking open the iMac and installing a manual switch for the backlight, the best I can hope for it probably to put a towel over the thing at night. Ridiculous for such an otherwise well-designed machine. If you’re thinking about buying an iMac, and you want it doing stuff with the screen off overnight, I suggest you heed this warning. Memo to Apple: Fix this. Now.
If anyone has a decent solution, please tell me. I would absolutely love to hear it.
UPDATE May 2: Found a way to sleep the display instantly. 
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March 1st, 2007 at 5:05 pm
Hi Matt
Have you had a look at http://www.splasm.com/products/productbrightness.html ? That might do what you want. Free, and universal too, which is nice.
Nightynight might also work: http://mildmanneredindustries.com/products.html
Alternatively, you can use Applescript to go beyond what the energy saver control panel lets you do. use the following script:
tell application “System Events”
tell application “System Preferences” to reveal anchor “displaysDisplayTab” of pane “com.apple.preference.displays”
tell process “System Preferences”
set value of slider 1 of group 2 of tab group 1 of window 1 to 0
end tell
end tell
hope that helps! I would have thought that the iMac would be the least of your lack-of-sleep worries right now!
March 12th, 2007 at 11:07 am
Thanks Charles.
Nightynight just seems to do the “sleep in 1 minute” trick, which as I say, works but is not reliable - the display comes on by itself during the middle of the night (I think when the DVD backup kicks in).
That AppleScript seems to reduce the brightness to about the same level as the F14 key (ie still way too bright for the bedroom).
However, I tried Splasm’s Brightness Control and it was better than I expected - it does actually reduce the screen brightness down to almost black!
I can then do Ctrl+F8-right-right-right-right-right-down-down-return to switch to the Login Window, and it’s good to go. The acid test will be once I move the Mac into the bedroom and try it at night, but it seems pretty good. I can always stick a cloth over the top of the screen to improve matters further. Nice one 
You’re right, though - since our little 1-monther is waking us up every 3 hours anyway, the point is kinda moot right now
April 20th, 2007 at 8:38 am
Hi there!
I have kinda the same problem as you do. And those tricks you mention works for me neither.. I have my iMac connected to the TV and want to watch movies on my TV and have my iMac screen turned off.. I think this trick would help you with your problem tough: Download http://www.versiontracker.com/dyn/moreinfo/macosx/14051 double klick the icon blankscreen.saver to install. Then you just choose that screensaver and pick the “active corner..” ex. the downer left corner. And when you put your mouse there the screen goes black. And also you dont need to have the screensaver set at any time, you can have it set to “never” and it will work anyway. Hope this will help!
April 24th, 2007 at 10:47 pm
Thanks David. That’s a pretty good solution! It makes the screen go about as dark as Splasm’s Brightness Control, but without the hassle of dragging a slider around. I wonder if the screensaver will stay active even while DVD backups etc are going on? Time will tell I guess.
The screen is still bright enough to cause an eerie glow and light up the bedroom at night, but a black T-shirt over the Mac reduces it to almost negligible levels. So I guess the black screensaver combined with black T-shirt is the best solution for now!
I still can’t believe there’s no simple “screen off” switch on an iMac. Hrrumph…
August 15th, 2007 at 2:39 am
I Have Searched about and found a good programs also available as a widget called sleep display.
It Puts Your monitor to sleep at the click of a button.
Won’t solve the problem of the display awakening again but i believe this is the best we can hope for with this display.
I am still looking for a way to turn of only the built in monitor and leave my second display (the TV) on. I Don’t know if this is posable.
Hear is the link i used to get the app.
http://linestreet.googlepages.com/sleepdisplaywidget
August 15th, 2007 at 8:29 am
Thanks Russell. Yeah I mentioned this app here:
http://mac.elated.com/2007/05/02/sleep-your-imac-screen-instantly/
It’s what I use at the moment. That - and not running the DVD backup overnight - works a treat!
I thought if you plugged an external display into the iMac then the main display turns off (or at least, it can be configured to turn off in System Preferences somewhere). Is this not the case?
November 12th, 2007 at 6:53 am
2 easy steps
1) turn your screen saver to Never turn on
2) goto your energy savings setting set your display to turn off within 1 minute of inactivity
thats what i do when im trying to listen to music and what ever else it is im doing
November 13th, 2007 at 8:13 pm
Thanks for your comment Rustom. I know you can set the display to sleep in 1 minute, but the point of my post was that there was no way to sleep the display instantly on the iMac. (Though I since found a great solution: http://mac.elated.com/2007/05/02/sleep-your-imac-screen-instantly/ )
January 20th, 2008 at 5:33 am
I have been following this conversation now for a little while and I am still not finding an answer for a solution to keep the TV as a secondary monitor active (on) and have the built-in display turned off.
I have connected my TV (main floor - livingroom) to my iMac (Tiger; basement). I am using my TV with a wireless keyboard as my 2nd computer station.
Problem is: I have to keep using the Mirror-function which means my iMac is on at the same time in the basement while I am working at the TV location.
NEED SOLUTION TO MANUALLY TURN OFF BUILT-IN DISPLAY WHEN NOT USED.
Thanks in advance for any solution. It would be greatly appreciated!!!
April 7th, 2008 at 3:01 pm
If you have recent imac with leopard(2007) then you can use control+shift+(eject key) to turn off the display immediately. I don’t know if this will work on previous versions. But this will turn off all the displays (means no video out signal).
To turn off the main display and keep the external display on you can use the solution suggested by (ONLY ME?) at the following link:
http://discussions.apple.com/thread.jspa?threadID=1235392&tstart=225
Here is what he says
“…if you want to play a quicktime movie on your TV drag the movie too the TV and select Full Screen (Play Movie cool) then create in “imovie” a very small black movie only needs to be say 5 seconds long using title but with no text. Save as a quicktime movie. Now play this on your imac main screen.. pause this and make this also full screen… Hay pretso black screen..
It works and no burning screen.. “
May 10th, 2008 at 4:34 pm
Here is another option, and it has to do with Rustom’s comment above :
“2 easy steps
1) turn your screen saver to Never turn on
2) goto your energy savings setting set your display to turn off within 1 minute of inactivity”
Instead of step 2, go to System Preferences - Desktop and Screen Saver
Click on the hot corners button
Set a corner to “Sleep Display”
When you move the mouse to that hot corner, the monitor will turn off, but the CPU will remain running.
PS: to do with Arun’s comment above, I have a G5 IMac, and the keyboard shortcut works as well. Thanks for the help.
June 29th, 2008 at 8:26 am
Is there any way to easily turn the main LCD off while keeping my external monitor on.
Example:
I want to watch a movie off my 17″ Imacs (Leopard) hard drive via my 42″ LCD Flat Screen I have hooked up to it, but want to turn off my computer monitor and still have the movie play on my TV.
June 30th, 2008 at 12:10 pm
@Kevmacs: You and countless others, judging by the other comments on this post! I suggest trying Arun’s idea above as a workaround…
August 18th, 2008 at 3:02 pm
Try ctrl+shift+eject, shuts off my imac 24″ and I can use my ipod touch remote app and play different songs without it turning the screen back on.
August 25th, 2008 at 7:17 am
Hi guys,
gust bought 24 inch imac, and found this same problem - no way to switch off built in display and use only external one - e.g. LCD TV to watch movies. I mean are they really serious about it in Apple? that sucks a lot, and tricks like playing blank movies is …. (no comments). Windows drivers lets you control the video output completely, choosing which display is on. Imac seems like a toy from stone age in some respects when compared to windows - simple functions are absent!!!
September 11th, 2008 at 6:38 am
Its damn too easy… ctrl + shift + eject .. on the new Aluminium mac.. turns the display off!!
-rakesh
September 14th, 2008 at 8:20 am
Hi rakesh,
Check the date of this blog post - February 2nd, 2007. Sleeping the display is a Leopard feature.
It’s great that you can now do this, of course.
October 14th, 2008 at 1:31 pm
I am so glad I found this post, now I can use CTRL+SHIFT+EJECT to turn off my display, I was getting so angry!
Haha!
October 18th, 2008 at 4:56 am
Hello everybody!
I have such a problem: I need to turn off built-in iMac display, leaving the second (Cinema HD) working.
How could I do that? Is there any software or sth?
Expose turns off both…
October 29th, 2008 at 4:51 pm
@Chris: Ha ha, glad it helped!
@Yul: I’m starting to get a feeling from this thread that you can’t!
At least, not at the moment…
November 5th, 2008 at 10:21 am
Let’s wait…
Excuse me. First time I didn’t read all comments carefully so my problem wasn’t so unique…
November 8th, 2008 at 7:56 pm
I believe I have found a solution to this problem and it doesn’t involve having to set a dark desktop background, use Shades or brightness dimmers, use black screen savers, use ‘hot corners in expose’ to sleep or power save the imac or have to make black videos and pause them on one display as none of the methods are really very practical or fully solve the problem . So, here’s what I did.
My setup is;
Mini DVI to DVI + HDMI video adapter (made by ex-pro) then an HDMI lead connecting my iMac to my HD LCD TV.
First of all you need to set up the arrangement settings for the two displays.
Begin by choosing Apple > System Preferences, then click Displays. By default, the Display pane appears. If you have recently added an external display, click the Detect Displays button so that Mac OS X can adjust to the change in the hardware configuration. Then click the Arrangement tab to open the Arrangement pane
By default, Mac OS X mirrors your primary display on external displays. That means that all the displays always show exactly the same thing. Mirroring doesn’t increase your screen area, to make that magic happen, deselect the “Mirror Displays” checkbox at the bottom of the Arrangement pane
As soon as you turn off mirroring, extended desktop mode kicks in and the amount of usable screen area grows by the size of the external display(s). Before you begin spreading out into all this space, take a moment to configure two things.
First, drag the thumbnails of the displays so that they mimic the physical arrangement of your displays (as you drag a thumbnail, its edge turns red, as does the edge of the actual display it represents). For example, if the top edges of both displays line up in the real world, make their thumbnails align, too. That way when you move the cursor from one display to another, it acts as if the two desktops were one big expanse of pixels instead of jumping up or down when it crosses the border.
Second, after setting up the arrangement, set your iMac as the primary display. This is where the menu bar, Dock, and Finder icons appear, and where applications open new windows. To designate your primary display in the Arrangement pane, drag the thin white menu bar to the appropriate thumbnail.
With the arrangement set and the primary display designated, you should check that your extended desktop is working correctly. Quit System Preferences, return to the Finder, then choose Finder > Hide Others to clear away unnecessary window clutter. Now move your cursor to the edge of one display and watch it appear on the next display as if the two separate displays were one large continuous display.
Now you need to open the movie you want to watch in Quicktime drag and position the Quicktime window within the TV’s display (now hear comes the clever part) you have to tell Quicktime to output the movie to the TV and black the imac screen - to do this read on)
Select Quciktime Player > Preferences. Under the ‘Full Screen’ Tab you need to click the TV’s display in the top white box, so the Quicktime logo appears within this display. Then, set the movie size to ‘fill screen’, set the background colour to ‘Black’ and check the tick box that says ’show on all displays’. Close the preferences tab. With the Quicktime window positioned within the TV’s display start to play your movie then, click View > Fit to screen (Shortcut - Command + 3) then click View > Enter Full Screen (Shortcut - Command + F)
TV then displays movie full screen, iMac screen goes black…. problem solved thank you and good night.
Lewis
November 8th, 2008 at 10:00 pm
Wow Lewis, I’m seriously impressed! Thanks so much for posting that solution. I hope it helps others solve this annoying problem.
November 17th, 2008 at 9:12 pm
Some good comments and solutions here, indeed. What about ultra-sensitive mice? The minute there’s some not-that-important-but-enough-to-reactivate-the-screen vibration, I have to do it all again. Is there a way to combine corners and wake the screen only from a keyboard command, i.e. mouse independent? Thx!
November 19th, 2008 at 7:59 pm
Some discoveries since my initial post:
1) Best solution I have found, short term: cloth mouse pad (kudos to http://www.webmasterworld.com/webmaster_hardware/3655083.htm). Using a folded tissue as a test pad to activate Sleep Display via a corner, things were so stable that my iMac eventually went down to the deep sleep state. Nice.
2) Haven’t had the time do confirm if Light Me! 2.5 (http://www.webmasterworld.com/webmaster_hardware/3655083.htm) dims or shuts down the screen, but I definitely prefer programming is activation by using does a complete shutdown of the Command-Z than the excellent three-key sequence above
3) The Shades freeware (http://www.charcoaldesign.co.uk/shades) is the perfect solution for my everyday dimming needs.
November 20th, 2008 at 8:37 pm
@SensitiveMouse: I rarely have a problem with mouse movement causing the display to awaken; I guess it depends very much on the mouse in question! Glad you found a workaround though.
January 27th, 2009 at 4:01 pm
I finally came up with a hardware solution: X10 modules control each of my monitors while my Harmony remote controls them AND my Mac.
X10 modules literally cut the power to the monitors - it’s a standard way to implement home automation. I got mine at http://www.smarthome.com/
February 12th, 2009 at 1:45 pm
@andrabr: Nice lateral thinking there!
February 17th, 2009 at 8:22 am
Hi Matt, I quickly read all the comments here but I don’t seem to have found a solution to the real problem.
As you do, I’ve got a (24″) iMac in my bedroom so I know how annoying it is when the display turn itself on. I’m also a wannabe-energy-saver, so I don’t like to come home and find the display on, every time.
Opening a fullscreen NicePlayer window half-dims the light so one problem is half-solved, but there’s still the energy question. I want - it - off.
Have you found a working solution?
February 17th, 2009 at 8:26 am
@Federico: I don’t have any problems now that Leopard lets me sleep the display with Shift-Control-Eject. The display always stays asleep for me.
February 17th, 2009 at 8:27 am
Hi Matt, I quickly read all the comments here but I don’t seem to have found a solution to the real problem.
As you do, I’ve got a (24″) iMac in my bedroom so I know how annoying it is when the display turn itself on. I’m also a wannabe-energy-saver, so I don’t like to come home and find the display on, every time.
Opening a fullscreen NicePlayer window half-dims the light so one problem is half-solved, but there’s still the energy question. I want - it - off.
Have you found a working solution?
I was thinking that there should be an application to automatically turn the screen off the it turns itself on without a user input.
Something like:
display on?
then: mouse is moving or key is pressed?
- then: close application.
- else: turn the display off.
February 28th, 2009 at 7:25 am
My anecdotal hypothesis as to why the screen turns on in the middle of the night is the optical mouse erroneously detects motion which activates the screen. This may be why the DVD backup turns on the screen (the momentum of the disc spinning is enough to move the mouse ever so slightly)… On the topic of DVD authoring, whenever I use the Disc Utility to burn a .IMG file, I find that my screensaver is disabled until the burn is done. I presume this has to do with the screensaver taking up CPU cycles and bus bandwidth which might make a coaster out of your burn…
March 5th, 2009 at 5:08 pm
Well this works for me. Just hold down, “shift+control+eject” at the same time. It should put your display to sleep.
March 5th, 2009 at 5:51 pm
@Sosa: This post was written 2 years ago about Tiger (which didn’t support Shift-Control-Eject)!
April 3rd, 2009 at 4:57 am
I’ve had the same problem with my iMac’s display turning itself on in the middle of the night. I think, however, I have found a workaround…
I turn the mouse upside down before I leave the desk. The optical sensor’s light has to be dim, too - If it’s bright, it’s active and it will still wake up the display.
May 7th, 2009 at 5:19 pm
I have a 24 inch 2.93ghz Imac early 2009 and My monitor stays off pretty much for most apps but when i am trying to do a 13hour render using Bryce 6.1 every option listed above works about the same….for about 3-10 seconds then blink..its back on, Apple really should have left an option to turn off the backlighting and an option to ignore all processes running in the background…. Love my Imac but this is really irritating.. how long do these backlight bulbs last? I have a 3 year applecare plan but the more i read the more i see about peoples backlights burning out ..and sometimes on only half the screen… what we need is a good script that tells the monitor to ignore all processes except the space bar being used….. and that would solve the problem of an active system waking the screen.