Oddly, I cannot find a manual for the Home Patrol. If it is anything like the Battery Save feature of the handheld units (BC346XT, BCD396XT), this is an option that will turn off the radio inside of the scanner for 300ms and then re-energize it for 1sec when the scanner is held on a particular frequency.
If you turn it off. The screen will go dark after like 10 seconds if no freq keys up, but it will get bright when a freq locks on again, then go dark as no one keys up again and so on. Its a battrey saver if your on batt power. And a light saver I think, as you all know some scanners light gos out sometimes. So can save both I guess.