Automatic device null of wide operational band in order to make the horizontal deflection frequency of the multi synchronous monitor

摘要

PURPOSE: To provide an automatic device with wide operation band for varying the horizontal deflection frequency of the multi-synchronizing monitor. CONSTITUTION: This device includes an integrated circuit (2) wherein a frequency measuring circuit (3) to which an analog synchronizing signal (S1) is inputted at one input, a phase comparing circuit (14) which has two inputs (15 and 16) and to which the synchronizing signal (S1) is inputted at one input (15), a voltage-controlled oscillation circuit (12) which has a frequency depending upon an input voltage (Vc) and outputs a signal (S3) interlocking with the output (22) of the phase comparing circuit (14), and a counter (9) which has one input connected to the output (11) of the voltage-controlled oscillation circuit (12) and the other circuit connected to the output of the frequency measuring circuit (3), and also has its output (21) connected to the other input (16) of the phase comparing circuit (14) and outputted as the output signal of the integrated circuit (2) are incorporated.