Hitachi, Ltd.

Hitachi Video Engineering, Incorporated

Tomomitsu Kuroyanagi

Akira Shibata

Michio Masuda

Isao Nakagawa

Shuzo Matsumoto

Masanori Kamiya

Noboru Kojima

Yukinari Ueki

Takuya Imaide

Masuo Oku

Takashi Kimura

Atsushi Yoshioka

Toshinori Murata

Yoshimichi Kudo

Katsuyuki Watanabe

Tetsuya Ikeda

Kazuo Kondo

Hiroaki Nabeyama

Toshimichi Terada

Akio Nakashima

Toshiro Aizawa

Keiichi Komatsu

Osamu Takase

Masafumi Kazumi

Hisanobu Tsukazaki

Hitoshi Miyagawa

Noboru Kozima

Noboru Kojiam

A luminance and chrominance signal separation circuit for use in a video tape recorder wherein in the recording mode a three-line comb filter is made to be an adaptive type comb filter for separating a luminance signal from a chrominance signal and in the playback mode the comb filter is made to eliminate residual chrominance signal components in the luminance signal. Switching circuits are provided in the invention to permit the switching of the luminance and chrominance signal separation circuit between recording and playback modes and noise reduction is accomplished by a feedback line correlation circuit.

Comb filter type luminance/chrominance signal separation circuit

A reproducing apparatus of a video disc player, wherein for a special reproduction such as a fast forward reproduction, or a reverse reproduction from a CLV disc, a field memory is provided for storing video signals of length of one field. A reading-in operation to the field memory is synchronized with a reproduced synchronizing signal. A writing-out operation from the field memory is synchronized with a reference synchronizing signal. A discontinuity of phase caused by a track jump is eliminated, and a stabilized picture on a TV monitor can be provided.

Reproducing apparatus of a video disc player

A phase shift circuit comprises a variable phase shifter responsive to an externally supplied voltage to change the amount of phase shift, and a phase detector operative to detect a phase difference between input and output signals of the variable phase shifter and supply a voltage complying with the phase difference to the variable phase shifter. When the center frequency of the variable phase shifter is changed by reason of production errors and temperature variations to deviate the phase shift amount from a desired value, the phase detector controls the center frequency such that the phase shift amount can be fixed to the desirably predetermined value.

Phase shift circuit for electrical signal

An amplifier suitable for use as an active filter such as a low-pass filter, a high-pass filter or a phase shifter, which can be easily formed as part of an integrated circuit. The amplifier includes first and second transistors, which together form a first differential amplifier for converting the voltage of the input signal thereto to a signal current. It also includes third and fourth transistors, which together form a second differential amplifier for dividing the signal current from the second transistor in a given ratio. A capacitor is connected to the collector of the fourth transistor, and first and second resistors are connected, respectively, to emitters of the first and second transistors. The current division ratio of the current flowing through the third and fourth transistors is controlled by a control voltage DC supplied to the base of the third transistor and the base of the fourth transistor. In the amplifier, the signal current shunted in the current division ratio K between the third and fourth transistors flow through the load capacitor so that the time constant of the active filter is controlled, the ratio K being controlled by the control voltage V.sub.c. The control voltage V.sub.c also compensates for the inaccuracy of the values of the resistors and capacitors.

Amplifier circuit suitable for use as an active filter circuit

A chrominance signal recording and reproducing circuit for a video tape recorder in which a frequency-modulated luminance signal and a low-frequency converted chrominance signal are mixed to be recorded and reproduced. A sideband emphasis type dynamic emphasis circuit composed of a diode limiter circuitry and an LC trap circuitry is provided in a recording system for recording the chrominance signal, while a sideband deemphasis circuit composed of at least a diode limiter circuitry and an LC trap circuitry is provided in a chrominance signal reproducing system. A circuit configuration is adopted in which the functions of the emphasis circuit and the deemphasis circuit are exchangeably performed by a common circuit.

Chrominance signal recording and reproducing apparatus

A color signal processing circuit in a video tape recorder for recording a low frequency converted color signal has a voltage controlled oscillator for generating a carrier having a center frequency which is M times as high as a low-frequency sub-carrier frequency, where M is an integer, and a detection circuit for detecting a variation of the oscillation frequency of the voltage controlled oscillator in at least a reproduction mode. A suppression circuit suppresses the change of the oscillation frequency of the voltage controlled oscillator in response to the output signal from the detection means and a control circuit changes the center oscillation frequency of the voltage controlled oscillator depending on whether the signal is processed in the NTSC system or the system in such a way that the suppression range for the change of the oscillation frequency of the voltage controlled oscillator by the suppression for the NTSC system is equal to or wider than that for the system. The control circuit includes a pulse-eliminating frequency divider or a variable frequency division factor.

Automatic phase control color signal circuit for video tape recorders

The output signals from the first set of delay elements of m each with a first delay time are selectively applied to a second set of delay elements of n each with a second delay time by means of a switch. The output signals from the said first and said second of delay elements are processed by the individual gain controllable circuits and are composed by an adder. The gains of the gain controllable circuits are respectively controlled by output signals from the control voltage generating circuits which are set by the output signals from comparators for comparing the television signal supplied to the input terminal with a reference signal from the reference signal generating circuit, so that the ghost interference in the television receiver can be reduced by a lesser number of delay elements by subtracting the output signals of the adder circuits from the television input signal in subtractor circuits.

Ghost reduction circuit arrangement for a television receiver

Disclosed is a color video signal recording apparatus wherein the chrominance signal and the luminance signal are separated from the composite color video signal, the luminance signal is transformed into a frequency modulation signal and the chrominance signal is converted to have a lower frequency so that both reformed signals are recorded on a frequency multiplex basis on a recording medium. In processing a TV signal of CCIR system, the chrominance signal is controlled to have a frequency of 3/8 N.multidot.f.sub.H (where N is an odd number) and have its phase shifted by 90.degree. in every horizontal scanning period; in processing a TV signal of NTSC system, the chrominance signal is controlled to have a frequency of 3/8 N.multidot.f.sub.H (where N is an integer) and have its phase shifted by 90.degree. or 180.degree. in every horizontal scanning period, while the control being made such that 1/4 N is an integer in case of 90.degree. phase shift of (3N-2)/4 is an integer in case of 180.degree. phase shift.

Color video signal recording apparatus

In a video tape recorder of the rotary two-head helically scanning type, a magnetic recording/reproducing system provided with a mode judging device in which a video signal is recorded onto a recording track in a multiplex manner together with a pilot signal for use in judgement of the recording time mode and when the record is reproduced the pilot signal is detected to thereby judge the recording time mode.

Magnetic video pilot signal recording/reproducing system

A chroma signal recording and reproducing circuit of a magnetic recording and reproducing apparatus having a recording circuit for frequency-modulating a luminance signal of a color video signal, low-frequency converting a chroma signal and frequency-multiplexing those signals for recording and a reproducing circuit for frequency-converting the low-frequency converted chroma signal in a reproduced signal and frequency-demodulating the FM luminance signal to reproduce a color video signal is disclosed. The circuit comprises a chroma signal recording circuit including a first ACC circuit and a first frequency converter connected to the first ACC circuit, and a chroma signal reproducing circuit including a second ACC circuit, a second frequency converter connected to the second ACC circuit, a comb filter connected to the second frequency converter and a deemphasis circuit connected to the output of the comb filter.

Chroma signal recording and reproducing circuit

A wide-band ghost reduction circuit apparatus for a television receiver comprises a ghost detector, two transversal filters having delay characteristics different from each other, a switch for selecting one of the filters and an automatic gain control circuit responsive to the output of the ghost detector for controlling the filters and the switch. Each of the transversal filters includes tap amplifiers whose gains are controlled by the automatic gain control circuit and having outputs connected, respectively, to tap inputs of delay devices formed of such as a CCD each provided with a tap and included in the associated transversal filter. Output end of one of the transversal filters having a smaller delay is connected to a selected one of the input tap of the other transversal filter through a switch so that input video signal components join together at every input terminal or every individual tap position of the delay devices.

Ghost reduction circuit for television receiver

A picture-in-picture color television receiver for simultaneously displaying on a screen a first and a second picture read out from a memory in a state that the second picture is inserted in the first picture, is disclosed. A DC restoration circuit for DC-restoring a color difference signal of the second picture DC-restores a color difference signal of the second picture at the reference level coincident with the reference level of the color difference signal of the first picture, thereby to make the white balance of the first picture coincident with that of the second picture.

Picture-in-picture color television receiver

A picture-in-picture television receiver is disclosed in which a television picture to be inset is compressed at a compression rate of 1/n and inset as a small-picture in part of a main television picture or large picture, and a single field memory for small-picture reproduction is provided therein in or from which a video signal can be randomly read and written line by line as a unit. In the single field memory is stored the small-picture video signal line by line by the application of a writing clock in which case the time taken in the writing is less than 1/(n+1) of a horizontal period. Then, from the memory is read the stored small-picture information by the application of a reading clock of n times the frequency of the writing clock during the time that writing is not performed, and supplied to be inset in the main television picture. A small-capacity buffer memory is provided at the prestage or following stage of the field memory to prevent the read/write timing overlap in the field memory irrespective of whether the small-picture and the main television picture are synchronized or not in the transmission systems. Thus, the capacity of the field memory essential for the small-picture is about a half of the conventional one.

Picture-in-picture television receiver

A color signal processing circuit comprising a first bandpass filter for extracting a modulated color signal from a composite video signal, a first comb filter having two charge transfer devices and a subtractor for providing a first sampled color signal, a second comb filter having two charge transfer devices and a subtractor for providing a second sampled color signal, an adder circuit for arithmetically determining a sum of the first and second sampled color signals, a second bandpass filter for reproducing only the modulated color signal from the sum of the first and second sampled color signals, and a subtraction circuit for arithmetically determining a difference signal between the composite video signal and an output signal from the second bandpass filter, so that first and second demodulated color signal outputs utterly free of a luminance signal component are obtained from the first and second comb filters respectively through a low pass filter while a luminance signal output is obtained from the subtraction circuit which is utterly free of a color signal component, whereby the prevention of the cross-color phenomenon as well as the dot interference can be achieved.

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Katsuta, Japan

Tomomitsu Kuroyanagi