​KembaraXtra-Computer Terms – blanking:
Blanking refers to the temporary suppression of the display signal in a raster-scan video monitor while the electron beam repositions itself to draw the next line or frame of the image. During normal display operation, the beam scans across the screen line by line to form the image.
After finishing each horizontal line, the beam must move back to the left side of the screen to begin the next line. During this movement, called horizontal retrace, the display signal is turned off to prevent unwanted marks. Similarly, after the final line at the bottom of the screen is drawn, the beam returns to the top left corner during vertical retrace, and the signal is again suppressed to maintain a clean display.