Hi,
Does it happen if you're also using the built in display? If it's not happening with the built in display it may have something to do with the graphics driver or some settings with your TV.
- Try to uninstall/reinstall the graphics card driver.
- Go to Device Manager and uninstall the graphics driver.
- Reboot your laptop and it should reinstall the driver automatically.
- After the restart observe your screen if the issue will still persist.