Victor Company of Japan, Limited

Yasutoshi Matsuo

Hiroshi Yamada

Ryo Nakano

Seiichi Mikami

Akira Hirota

Masayuki Shimizu

Koichi Kido

Masaji Yoshida

Takeyoshi Ito

Hironao Sakaguchi

In a magnetic recording and reproducing apparatus, a video signal of a high-quality format which has a first given frequency band is recorded on a standard magnetic tape designed to record a video signal of a standard format having a second given frequency band narrower than the first given frequency band. In the magnetic recording and reproducing apparatus, a video signal of the high-quality format is reproduced from a standard magnetic tape.

Magnetic recording and reproducing video signal in magnetic tape at video quality selectable from prescribed different qualities

A crosstalk cancelling circuit for a VTR eliminates adjacent-track crosstalk in a playback down-converted chrominance signal, with the resultant signal and a playback luminance signal being supplied to respective output terminals for re-recording by another VTR. Substantially improved display image quality is obtained from the re-recorded video signals, by comparison with prior art methods.

Crosstalk cancelling circuit for playback chrominance signal of VTR

A luminance signal/color signal separation circuit comprises a bandpass filter which separates a first color signal partially including a luminance signal component from a composite image signal, a delay circuit which delays the first color signal to obtain a second color signal, a logic circuit which outputs a luminance component signal from the first color signal and the second color signal, a first adder/subtracter which extracts a third color signal free from the luminance signal component by combining the luminance component signal and the first color signal, and a second adder/subtracter which extracts luminance signal by combining the third color signal and the composite image signal. Another luminance signal/color signal separation circuit comprises a wide range bandpass filter which separates a first color signal from a composite image signal, a delay circuit which delays the first color signal to obtain a second color signal, a logic circuit which outputs color signal with a wide range or with a reduced level is response to the degree of vertical correlation of pictures, and an adder/subtracter which outputs a luminance signal. Color signal with a narrow range can be outputted in place of the signal with the reduced level.

Luminance signal/color signal separation circuit

A crosstalk cancelling circuit for use in video tape recorders. The cancelling circuit comprises a first multiplier for multiplying a frequency-lowered conversion chrominance signal reproduced from a magnetic tape by a local oscillating signal with a predetermined frequency and a delay device for delaying the frequency-lowered conversion chrominance signal by one horizontal scanning period. The local oscillating signal is further supplied to a phase-shifting circuit which in turn produces either a signal leading the local oscillating signal by a phase angle of 90.degree. or a signal lagging the local oscillating signal by a phase difference of 90.degree. in synchronism with a field frequency of the frequency-lowered conversion chrominance signal. Also included in the cancelling circuit is a second multiplier for multiplying the output of the delay device by the output of the phase-shifting circuit, the output of which is fed to an operation circuit for effecting addition or subtraction between the output of the first multiplier and the output of the second multiplier to output the result as a carrier chrominance signal.

Crosstalk cancelling circuit for removing crosstalk component from

A luminance signal/color signal separation circuit includes a band-pass filter for picking up a color signal from a composite image signal; a delay circuit for sequentially delaying by one line the color signal picked up by the band-pass filter and obtaining three past, present and future line information; a first operation circuit for outputting a signal which takes a value having a larger absolute value when the past and future line information have the same sign, and takes an algebraic sum of the past and future line information when the past and future line information have different signs; a second operation circuit for outputting a signal which takes a value having a smaller absolute value when the output from the first operation circuit and the present line information have the same sign, and takes a reference value when the output from the first operation circuit and the present line information have different signs; and a third operation circuit for obtaining a color signal by subtracting the output from the second operation circuit from the present line information.

In a YC separator for generating a chrominance signal C including no chrominance separation error by selecting a second highest potential signal of the first chrominance signal a, the second chrominance signal c' including a separation error and a reference signal, only when a picture having two different colors at a border between n-th line and (n-1)th line is displayed, a correction value of 1/2 is generated as the reference signal, in order to obtain C=1 and Y=0 for prevention of n-th line dot crawl. Further, when a vertical stripe picture (black and white lines are alternately arranged) is displayed, a chrominance signal Cc including much less unnecessary signal components can be obtained through an arithmetic circuit and on the basis of a chrominance signal Cc' including error components and an average signal D between the past and future line chrominance signals A and C, in order to eliminate cross-color at the upper and lower ends of the picture and Yc signal blur.

YC separator for video signal processing circuit

In a circuit for removing crosstalk components in a carrier chrominance signal, there are provided a first delay circuit (20), an inverter (21), a first higher-voltage detecting circuit (18), a second delay circuit (22), a second higher-voltage detecting circuit (19), a third higher-voltage detecting circuit (25), a first lower-voltage detecting circuit (23), a second lower-voltage detecting circuit (24), a third lower-voltage detecting circuit (17), and an adder (26) thereby producing a crosstalk-removed carrier chrominance signal. Furthermore, the first delay circuit (20), the inverter (21), and an adder (28) form a comb filter for correcting a time delay due to said circuit for removing crosstalk components in a carrier chrominance signal.

Circuit for removing crosstalk components in a carrier chrominance signal

A recording and reproducing device for a video signal comprises a recording circuit for changing an input video signal to a recording video signal, and a reproducing circuit for changing a reproduced video signal to an output video signal. Particularly, the reproducing circuit of this device includes a first high-pass filter having a time constant Ts, a first limiter for limiting the amplitude of the output signal of the first high-pass filter, and a first coefficient multiplier circuit for multiplying an output signal of the first limiter by a first coefficient K. The reproducing circuit further includes a first computation circuit for summing an output signal of the first coefficient multiplier circuit and the output video signal to deliver a signal indicative of the summed result to the first high-pass filter, a second coefficient multiplier circuit for multiplying the output signal of the first limiter by a second coefficient X, and a second computation circuit for subtracting the output signal of the second coefficient multiplier circuit from the reproduced video signal to output the output video signal. In this circuit, when a time constant corresponding to a frequency at which the noise reduction effect becomes effective is assumed as T, the time constant Ts is set within a range expressed as T&gt;Ts&gt;T/(X+1). Thus, this device can satisfactorily cope with both the random noise and the impulse noise even when the emphasis quantity is set to a large value.

Reproducing device for video signal

A luminance signal/color signal separation circuit comprises a color signal separation circuit for obtaining a first color signal partially including luminance signal component from a composite image signal, a computation circuit for obtaining a second color signal including a color separation error signal by eliminating the luminance signal component from the first color signal to take out a signal of the second highest potential of the first and second color signals and a reference potential, thus to take out a third color signal excluding the color separation error signal, and a luminance signal separation circuit for obtaining a luminance signal from the composite signal and the third color signal. This circuit is constituted to first consider a signal which seems to be a C signal as a C signal once at least to effect computation between that signal and current line data, whereby when the result thereof indicates that considering that signal as C signal is correct, that signal is used as C signal, while when erroneous, that signal is not used as C signal. Thus, drawbacks, e.g., dot crawl of Y signal and/or half tone or color shift of C signal do not occur.

A video signal recording apparatus comprises a sampling circuit for sampling an input video signal by a signal having a predetermined frequency f.sub.s, a circuit for obtaining a multiplexed signal by multiplexing a reference burst signal to the output sampled signal of the sampling circuit, and a circuit for recording the multiplexed signal on a recording medium. A video signal recording and reproducing apparatus comprises in addition to the constituting elements of the recording apparatus, a circuit for reproducing the recorded multiplexed signal from the recording medium, a circuit for obtaining from the reproduced multiplexed signal first and second reproduced sampled signals having a relative time difference of one horizontal scanning period, a circuit for generating first and second sampling pulses having the same frequency f.sub.s and having phases which mutually differ by 180.degree., a circuit for re-sampling the first and second reproduced sampled signals by the respective first and second sampling pulses so as to obtain first and second re-sampled signals, and a circuit for at least adding the first and second re-sampled signals so as to obtain a reproduced video signal.

Video signal recording and/or reproducing apparatus

A noise reduction circuit for use in a video signal recording and/or reproducing apparatus for eliminating noise components from an input luminance signal comprises a high pass filter circuit for extracting a high frequency signal component from the input luminance signal, a first limiter circuit for limiting the high frequency signal component at a first limiting level, a multiplier circuit for determining the degree of preemphasis and/or deemphasis by multiplying a predetermined coefficient to the limited signal, summing and subtracting circuits respectively for adding and subtracting the output signal of the first amplifying means to and from the input luminance signal, and a feedback loop for feeding back the output signal of the high pass filter circuit to its input port. The feedback loop comprises a second multiplier circuit which modifies the amplitude of the signal passing therethrough by a second level which is set substantially higher than the first level of the first limiter circuit.

Noise reduction circuit of a video signal

A noise reduction circuit for a video signal recording and/or reproducing apparatus comprises a high pass filter for extracting high frequency signal component form the input luminance signal, a limiter circuit for limiting the high frequency signal component, a multiplier for determining the degree of preemphasis and/or deemphasis by multiplying the limited signal, and summing and subtracting circuits respectively for adding and subtracting the high frequency signal component processed by the limiter circuit and the multiplier to and from the original luminance signal. The limiter circuit has an amplitude characteristic which changes a gradient so as to have a characteristic curve of at least three different gradient slopes interconnected in succession with an increase in amplitude of the signal supplied thereto.

Noise Reducing circuit of a video signal

A video signal recording and playback apparatus in which in a record mode operation a frequency-modulated luminance signal and a carrier chrominance signal whose frequency has been converted to a one lower than that of the luminance signal are written superposed on each other in a magnetic recording medium and, in a playback mode operation, the signal read out of the recording medium is separated into a reproduced color signal and a reproduced luminance signal, then the two reproduced signals are subjected to predetermined signal processing by individual signal processing systems, and then the processed signals are mixed by a mixer to produce a reproduced color video signal. The mixer to which the reproduced luminance signal is applied is preceded by a comb filter which is operable using a chrominance subcarrier frequency of the reproduced chrominance signal as a reference.

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Kawasaki, Japan

Yasutoshi Matsuo