High Quality Content by WIKIPEDIA articles! The vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time difference between the last line of one frame or field of a raster display, and the beginning of the first line of the next frame. It is present in analog television, VGA, DVI and other signals. During the VBI the incoming data stream is not displayed on the screen. In raster cathode ray tube displays the beam is blanked to avoid displaying the retrace line; see raster scan for details.