Abstract: In a television receiver including a digital circuit processing an input video signal in a digital mode, a clock generating circuit applies a system clock signal to the digital circuit, and comprises a phase comparator to which a horizontal synchronizing signal is applied, a low-pass filter connected to the phase comparator, a voltage controlled oscillator connected to the low-pass filter to generate the system clock signal, a first frequency divider dividing the frequency of the system clock signal generated from the voltage controlled oscillator to generate a horizontal deflection drive pulse signal, and a second frequency divider connected to the phase comparator. The phase comparator, the low-pass filter, the voltage controlled oscillator, the first frequency divider and the second frequency divider constitute a single PLL circuit, and the system clock signal and the horizontal deflection drive pulse signal are respectively generated from the PLL circuit.

Abstract: An automatic focusing apparatus for use in a video camera and the like wherein one optical element other than a focusing lens means of an optical system is moved for focusing in the in-focus direction while being vibrated slightly by means of a motor capable of being driven by pulses.

Abstract: A rotary magnetic head cylinder device for use in a helical-scanning system video tape recorder has a projection provided on a tape running race of a stationary lower cylinder near a location at which a magnetic tape leaves from the lower cylinder. The projection is preferably integral with the tape running race and has a small area which is defined by a shoulder circumferentially extending identically with a tape guide shoulder contouring the lower edge of the tape running race and which spreads perpendicularly to the tape running race, and an upper surface coplanar with the top face of the lower cylinder, and a height defined by a protruded length radially outwardly toward the outer circumferential surface of the lower cylinder. The projection serves to reduce vibrations of the magnetic tape generated when the video head carried by the rotary upper cylinder leaves from the magnetic tape.

Abstract: A digital signal recording and reproducing apparatus comprising a dynamic range compression/expansion apparatus. The compression/expansion apparatus receives a digital signal from, for example, an analog-to-digital converter and compresses the dynamic range of the digital signal and the so compressed digital signal is supplied to a recording signal processing circuit in the recording operation mode, while the apparatus receives a digital signal reproduction output from a recording/reproducing head and expands the dynamic range of the reproduced digital signal and the so expanded digital signal is supplied to, for example, a digital-to-analog converter in the reproducing operation mode.