Matsushita Electric Industrial Co., Ltd.

Hiroshi Moribe

Nobuo Taketani

Hiroshi Ando

Ryuichi Shibutani

Hisao Morita

Masahiro Takeshima

Masahiko Sasada

Yutaka Otani

Koji Matsuhira

The vertical/horizontal amplitude control device for controlling a vertical amplitude and a horizontal amplitude of an image display device for displaying a video signal includes a brightness level detector for detecting a brightness level of the video signal, a vertical amplitude controller for controlling the vertical amplitude based on the brightness level, and a horizontal amplitude controller for controlling the horizontal amplitude based on the brightness level. The device controls the vertical and horizontal amplitudes into constant without a delay from a change of a video signal even when the brightness level of the video signal abruptly changes.

Vertical/horizontal amplitude controller

The automatic cut-off system includes a video data processing circuit, a cut-off control circuit, a drive circuit, and a level control section. The video data processing circuit adds a cut-off reference pulse having a predetermined level to primary-color signals of red (R), green (G) and blue (B) at different timings within a single vertical blanking interval, and outputs latch timing signals respectively indicating the timings. The cut-off control circuit shifts a level of each primary-color signal having the cut-off reference pulse added thereto based on a corresponding cut-off control signal. The drive circuit drives each cathode of a CRT (cathode-ray tube) based on a corresponding one of the shifted primary-color signals, and outputs a voltage corresponding to each cathode current as a common feedback signal. The level control section latches the feedback signal in response to each latch timing signal, and outputs the cut-off control signal of one of the primary-color signals.

Automatic cut-off system

A phase controller of a horizontal drive pulse fed into a horizontal deflection circuit supplying a horizontal deflection pulse, and a control method of the same are disclosed. A frequency discriminator identifies a format of video-input-signal by detecting a frequency of the horizontal sync signal. A reference phase generator generates a reference phase signal based on the output from the frequency discriminator. A sawtooth waveform generator generates a sawtooth waveform signal responsive to the output from the frequency discriminator. A phase difference voltage detector outputs a phase difference voltage responsive to the phase difference between the reference phase signal and the horizontal deflection pulse. A phase control signal generator generates a phase control signal using the phase difference voltage and the sawtooth waveform signal. Horizontal drive pulse generator outputs a horizontal drive pulse having a phase responsive to the phase control signal. The phase controller and the phase control method as structured above realize a stable phase control of the horizontal drive pulses in video display devices.

Phase controller of horizontal drive pulse and method of the same

Color demodulating device

A color signal reproducing circuit having A/D converter , sync separator , YC separator , gain controller , multipliers and , low-pass filters and , burst-period cumulative adders and , SINCOS generator , clock generator , and ramp-wave generator . The simple structure allows a color signal reproducing circuit to be used commonly in a different television systems without changing its clock frequency considerably in accordance with broadcasting systems and also achieves YC separation and color signal demodulation from analog composite signal with a higher degree of precision.

Digital color signal reproducing circuit

In a horizontal deflection circuit, a waveform response of a horizontal output pulse must be adequately taken into account before and after a switching of the horizontal output pulse so that the waveform does not lack in shape and does not lose continuity at the switching. A switching apparatus for a horizontal driving apparatus includes (a) a horizontal driving pulse generator which generates a horizontal driving pulse from a horizontal synchronization signal, (b) an alternative signal generator which outputs an alternative signal different from the horizontal driving pulse, (c) a horizontal output control device which determines a timing to switch between the horizontal driving pulse and the alternative signal, and (d) a switching device which switches an output pulse with a control signal which is output from the horizontal output control device. The switching device switches only when both the output signal from the horizontal driving pulse generator and the output signal from the alternative signal generator change from a low level to a high level at the same time.

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Osaka, Japan

Hiroshi Moribe