To blank your screen on the console, the command screenblank(1) is what you need. It is part of the base system, so you don't need to install it.
This will activate blanking with a default of 600 Seconds (10 Minutes). If you wish to activate it in another time interval use the -d Option.
# screenblank -d 300
If you are using screenblank on a filesystem that is mounted with noatime/nodevmtime (such as a system running off of a compact flash card), screenblank will not properly time out when you set -d, nor will it receive keyboard inputs to wake. Often on small devices that do not have a hardware method of turning off the screen, this can be problematic and actually lock you out of a session until you reboot. Thus, the following is a known "safe" method for blanking a small devices screen even with noatime/nodevmtime:
#!/bin/sh /usr/sbin/screenblank -d 0 -e 0 && read /usr/bin/pkill screenblank
- screenblank(1) Manpage