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Video signal and output device for freeze-frame video telephone

  • US 5,117,286 A
  • Filed: 09/07/1990
  • Issued: 05/26/1992
  • Est. Priority Date: 09/09/1989
  • Status: Expired due to Fees
First Claim
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1. A video input and output device for a freeze-frame video phone, which inputs video data for transmission from a camera and outputs video data to a monitor, comprising;

  • a bus;

    a host connection means connected to the bus so as to allow checking of control and operation status of the equipment by a CPU,a mode control signal generation means connected to the host connection means, which receives control signal from the host connection means and generates a bypass mode signal, a display mode signal, an acquisition mode signal, and a video image size signal for controlling each operation;

    a synchronization signal separation circuit which separates an input composite video signal into a vertical synchronization signal, a horizontal synchronization signal, a composite synchronization signal, an odd/even field signal, and a burst signal;

    a PLL (Phase-Locked Loop) circuit which generates a signal with frequency of 384 times the horizontal synchronization signal from the synchronization signal separation circuit;

    a window signal generation means connected to the PLL circuit, which selects a part of video image size out of an input video signal;

    address buffer means connected to the bus, the window signal generation means, and the mode control signal generation means, which generates address for access of a video image data storage memory;

    a first analog interface means for reception of the input video signal;

    an A/D (Analog to Digital) converter connected to the first analog interface means;

    a data buffer means connected to the bus and the A/D converter and the mode control signal generator, which transmits and receives data to and from the video image data storage memory;

    a multiplexer connected to the data buffer means, the A/D converter, and the mode control signal generator;

    a D/A converter which converts a digital signal from the multiplexer into an analog signal; and

    a second analog interface means connected to the D/A converter.

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