Patent ID: 6466270
Filing Date: 2002-10-15
Classification: H03L,H04N

Abstract:
A phase locked loop circuit comprising:a phase comparing means, a charge pump connected to said phase comparing means, a variable low-pass filter connected to said charge pump, and the time constant of which is variable, a voltage-controlled oscillation means connected to said low-pass filter, a frequency dividing means connected to said voltage-controlled oscillation means, and a control means for generating and outputting a control signal for varying a time constant of said variable low-pass filter, wherein said phase comparing means receives an external signal used for controlling an on-screen display function and an output signal from said frequency dividing means, and detects the phase difference between the phase of the external signal and that of the output signal from said frequency dividing means, and said control means generates a control signal for changing the time constant to a predetermined value in accordance with the state of the external signal used for controlling the on-screen display function, and outputting said control signal to said variable low-pass filter to change the time constant of said variable low-pass filter, thereby to control jittery movements of the characters displayed by the on-screen display function.