Visual image signal processing apparatus using arithmetic operation on brightness reference signal overlaid in fly-back period of input visual image signal

摘要

A visual image signal processing apparatus includes: an overlaying unit for overlaying a brightness reference signal at a predetermined position in a fly-back period of an input visual image signal; a first clamping unit for clamping an output from the overlaying unit at a predetermined clamping voltage; a detecting unit for applying an output from the first clamping unit to a driving electrode of a cathode ray tube and for detecting a beam current flowing based on the brightness reference signal overlaid in the input visual image signal; and a second clamping unit for controlling the predetermined clamp voltage based on the beam current detected by the detecting unit.