horizontal scan frequency - Computer Definition
The number of lines illuminated on a CRT in one second, which is based on how fast the electron beam moves across the screen from left to right and back again. For example, a resolution of 400 lines refreshed 60 times per second requires a scan rate of 24 kHz (60 x 400) plus time to bring the beam back to the beginning of the next line. Same as "horizontal sync frequency" in TV. Contrast with vertical scan frequency.