Oppo
Turn Always-On Display On or Off auf Oppo
Always-On Display uses the OLED panel's ability to light up only the pixels needed for time, date and battery level, without waking the full screen. On Oppo phones running ColorOS, this function sits inside the display settings and works independently from your lock screen PIN or pattern.
If the setting is off, your screen stays completely black when locked, even though the phone is not asleep. If it is on but notifications don't show up, check whether your ColorOS version supports notification icons on the Always-On Display, since this depends on the software generation, not just the toggle.
To change the behavior, open Settings ➔ Home screen, Lock screen & Always-On-Display ➔ Always-On Display. From here you can enable or disable the display, and on supported models choose between a permanent display or a scheduled time window.
Keep in mind that Always-On Display adds a small but constant power draw, since part of the panel stays lit while the phone is idle. If battery life matters more than glanceable info, disabling it or limiting it to a schedule is usually the better trade-off. Turning it off does not affect notifications reaching your lock screen once you wake the phone normally.