I am trying to give some lighting effect on screen using the following code.

FOR I=1 TO 500
IF MOD(I,2)=0 
_screen.BackColor= RGB(255,255,255)
ELSE
_Screen.BackColor= Rgb(60,60,60)
ENDIF
ENDFOR
_Screen.BackColor= Rgb(60,60,60)

Will in effect my screen or monitor in long term, Is there some code that could give me a Photo copier Effect ?