Have a time machine drive automatically disconnect itself after backup Ive got a time machine hd (its actually a samsung external hd configured as a time machine) plugged into an external monitor at work, when i connect my laptop to the monitor via 1 usb and 1 thunderbolt i get connected to the time machine and it automatically backs up. 

When i leave each day and want to take my laptop with me i used to just disconnect all the cable and go, but now because there is an HD attached i need to disconnect it first, before i remove the cable.

Is there a way to tell the time machine to auto disconnect itself after a daily backup or auto disconnect after each backup ?
I suppose you could put together a script which runs a diskutil eject command on the specific volume, then schedule it to run at 4:30 PM each day via cronx or another scheduling app.  When you go to leave at 5:00 PM, the disk has already been ejected.  The drive will always be something like /dev/disk2, so the script only needs to eject the specific volume name.

I would suggest ejecting it at the end of your day versus after a single backup.  This way, you're getting the benefit of multiple backups throughout the day.