| 摘要 |
PURPOSE: An apparatus for controlling a luminance of an image display device is provided to decrease the number of a circuit element, simplify a circuit composition, and generate a mute signal by processing the luminance through a DC level control in software and detecting a change of a horizontal synchronous signal or a vertical synchronous signal to generate the mute signal according to a mode change. CONSTITUTION: A luminance level control block(11) outputs a luminance level adjusted according to an adjustment of a user as a DC voltage level, discriminates a mode change according to a horizontal synchronous signal(H-Sync) and a vertical synchronous signal(V-Sync), and outputs a certain control signal for generating a mute signal. A transistor(Q11) receives the DC voltage level signal outputted from the luminance level control block(11) at its base and performs a switching operation for supplying a certain bias voltage(B+) inputted in its emitter to a grid terminal(G1) of a CRT. A Zener diode(ZD12) is connected with the transistor(Q11) for setting a minimum voltage of the transistor(Q11). A power supply voltage(-Vcc) is operated as a mute signal voltage in the grid terminal(G1) of the CRT when performing an off-operation of the transistor(Q11).
|
