Improved scanning circuit structure of a television receiver

摘要

A television receiver is disclosed which is designed to display two types of input picture signals, for example, an NTSC signal and a VGA signal on at least two display areas of one image screen simultaneously. The television receiver includes an auxiliary coil and a switching circuit. The auxiliary coil is operable in first and second operation modes. The first operation mode is such that an electron beam is scanned in sequence along the scanning lines to reproduce the VGA signal having a horizontal scanning frequency of substantially twice that of the NTSC input signal, while the second operation mode is such that the scanning line intervals are controlled so as to scan the electron beam two times along the same scanning line to reproduce the consecutive two of line signals of the frequency-converted NTSC signal which are formed by the same portion of the NTSC input signal. The switching circuit is responsive to an area signal indicative of the display area of at least one of the frequency-converted NTSC signal and the VGA signal to switch between the first and second operation modes of the auxiliary coil for displaying high-quality images on the different display areas of the image screen. <IMAGE>