Mitsubishi Denki Kabushiki Kaisha

Yoshiki Mizutani

Hiroshi Ito

Hiroshi Itoh

Tadashi Kasezawa

Koichiro Kurahashi

Toshio Idei

Toshiya Adachi

Eiji Arita

Hiroyuki Nakayama

Masahiko Nakamura

Shigehiro Tamaki

Tomohiro Ushio

Yoshiro Nakajima

An image reproduction apparatus which converts a sampling frequency from a first frequency to a second frequency, performs interfield interpolation at a third frequency, and converts the sampling frequency from the third frequency to the first frequency, wherein the interfield-interpolation is performed at the first frequency between signals one field apart from each other. The apparatus also converts a number of vertical scanning lines to convert a high definition TV signal of the MUSE format to a signal of NTSC format, sets a scanning period used in the vertical scanning line conversion, and generates a coefficient used in the vertical scanning line conversion.

Image reproduction apparatus performing interfield or interframe

A video signal synthesizer for producing a picture-in-picture effect on a display device utilizes a phase locked loop circuit to generate a carrier wave synchronized with a color burst signal of a composite video signal representing a main picture to be reproduced, which carrier wave is used to modulate a time compressed second composite signal which represents a sub-picture to be superimposed on the main picture. A time division multiplexer is used to multiplex the first and time compressed second video signals to produce a picture-within-a-picture video signal for application to the receiver of a display device. By using a carrier wave generated from a phase locked loop circuit, the color subcarrier signals of both the main and sub-picture signals have the identical frequency.

Video signal synthesizer for producing a picture in-picture effect on a

In a judgement circuit for an adaptive filter for use in a color television system, sample values of a composite video signal are obtained by sampling the composite video signal at a predetermined sampling frequency in synchronism with a horizontal scanning frequency in such a manner that the corresponding sample points are arranged in a grating on the screen. A horizontal filter receives the sample values corresponding to a first sample point and a second and a third sample points positioned at the left of and at the right of the first sample point. A vertical filter receives the sample values corresponding to the first sample point and a fourth and a fifth sample points positioned over and under the first sample point. The variation of the signal in the vertical direction and the variation of the signal in the vertical direction are detected, and are compared. One of the output of the horizontal filter and the output of the vertical filter is selected in accordance with the result of the comparison.

Judgement circuit and adaptive filter incorporating the same

A contour detecting filter device samples composite video signals of the system by sampling signals at a frequency four times the chrominance subcarrier frequency thereof through an A-D converter (2), to input sampling value series thus sampled in a delay circuit group (81-84). Detected from the delay circuit group are four sampling values (P1, P2, P4, P5) which are point-symmetrically positioned around a noted sampling value (P3) on the screen and having the same-phased chrominance subcarriers. The noted sampling value and the four sampling values are employed to perform arithmetic on second order differentiations in the direction of horizontal scanning lines and in the vertical direction on the screen by a coefficient multiplier (85), an adder (86) and a multiplier (87), thereby to detect the contour signal of the noted sampling value. Therefore, it is not necessary to separate luminance signals from the composite video signals, from which the contour signals can be directly detected.

Contour detecting filter device using PAL samples of composite video

A contour detecting filter (8, 10, 11) sequentially inputs series of sampling values obtained by sampling composite video signals, which are composed of frequency-multiplexed video luminance signals and chrominance signals and include chrominance subcarriers, at a frequency four times that of the chrominance subcarriers to detect four sampling values point-symmetrically positioned around a reference sampling value and having the same-phased chrominance subcarriers by utilizing delay circuits. The reference sampling value and the four sampling values are so employed as to perform arithmetic on second order differentiations in the direction of horizontal scanning lines and the vertical direction on the screen thereby to detect the contour signal of the reference sampling value. A contour detecting filter (12) detects contour signals in the direction of horizontal scanning lines from composite video signals utilizing a vertical low-pass filter (14) and a horizontal high-pass filter (15) which are cascade-connected with each other while detecting contour signals in the vertical direction on the screen by utilizing a vertical high-pass filter (16) and a horizontal low-pass filter (17) which are cascade-connected with each other. Switched and outputted are the contour signals in the direction of the horizontal scanning lines and the vertical direction on the screen.

Contour detecting filter

A ghost cancellation circuit system comprises an amplifier for forming an output signal of a composite wave of a direct wave and a ghost wave; a carrier wave extracting circuit for extracting the carrier wave having the reference phase from the output signals of the amplifier; phase shifting means for generating a detection axis signal having the specific phase of the output of the carrier wave extracting circuit; a pair of phase detection circuits for a phase detection of the output of the amplifier by the detection axis signal of the phase shifting means or the carrier wave extracting circuit, and a delay circuit for forming the output in delay for a time substantially equal to the delay time of the ghost wave by receiving the output of the pair of phase detection circuits through a pair of coefficient circuits, whereby at least a specific component of the ghost wave is cancelled by summing the output of the delay circuit to the output of the phase detection circuit.

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Nagaokakyo, Japan

Yoshiki Mizutani