| 摘要 |
PURPOSE:To recognize the present channel visually clearly by displaying a numeral for channel display on a CRT by means of a character generator and displaying a scale signal during automatic scanning. CONSTITUTION:A horizontal synchronizing sawtooth signal generated by a sawtooth generating circuit 21 is converted into a rectangular wave by an inverter 2 and inputted to one input terminal of a NAND circuit 27. A control signal deciding whether or not a display bar is generated is fed to the other input terminal of the NAND circuit 27 from a central control circuit 30 and the phase of an output waveform is opposite to the phase of an input rectangular wave. The signal is differentiated by a differentiation circuit 28 and a thin pulse is generated via an inverter 29. Moreover, the central controller 30 controls a tuning voltage variable circuit 24 to move a tuning voltage vertically to vary the position of an indication mark. Thus, a channel display number and a scale symbol are displayed at the lower ridge of the CRT 40.
|
