RASTER WIDTH ADJUSTING DEVICE

PROBLEM TO BE SOLVED: To attain display with high quality by obtaining an increased deflection current requiring to compensate a reduced raster width caused by a increased alter voltage which might sometimes decrease the raster width in a short time. SOLUTION: On the occurrence of a short-time increase in an alter voltage which might sometimes cause reduction in the raster width, the reduction in the raster width is given to an inverting terminal of an amplifier U1. As a result, the conduction amount of a serial current path transistor(TR) Q10 is increased thereby increasing a deflection voltage. Thus, the increased deflection current requiring to compensate the reduced raster width caused by the increase in the alter voltage is obtained. When the alter voltage that might sometimes causes the decreased raster width increases, a line deflection voltage adjustment device 60 of a line receiving the feedback voltage acts like increasing its output thereby increasing the deflection current resulting that the raster width is increased. As a result, the reduction in the raster width caused by the alter voltage is compensated.