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Image transmission system

  • US 4,953,196 A
  • Filed: 05/11/1988
  • Issued: 08/28/1990
  • Est. Priority Date: 05/13/1987
  • Status: Expired due to Term
First Claim
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1. A video phone comprising:

  • input means for sequentially entering image data;

    digitizing means for digitizing said input image data into digital image data;

    memory means for sequentially storing said digital image data;

    image signal producing means for producing an output image signal based on said digital image data sequentially read out from said memory means;

    display means for sequentially displaying an image described by said output image signal;

    compression and expansion means for compressing said digital image data read out from said memory means into compressed image data in an image transmitting mode and for expanding compressed image data into digital image data in an image receiving mode;

    telephone means having telephone functions for transmitting and receiving a call;

    line control means coupled to a public analog telephone line for selectively coupling one of said compression and expansion means and said telephone means to said public analog telephone line, said line control means including modem means for modulating said compressed image data from said compression and expansion means into a voice frequency signal in the image transmitting mode and for demodulating a voice frequency signal received through said public analog telephone line into compressed image data in the image receiving mode; and

    control means for controlling at least said memory means and said compression and expansion means,said control means having means for freezing the image displayed on said display means at an arbitrary time by stopping the sequential storage of said digital image data into said memory means so that said compressed image data related to a frozen image is read out from said memory means and supplied simultaneously to said image signal producing means and said compression and expansion means in the image transmitting mode,said control means controlling said memory means and said compression and expansion means in the image receiving mode so that said compressed image data related to said voice frequency signal received through said public analog telephone line is first stored in said memory means and read out therefrom to be expanded in said compression and expansion means into digital image data which is then stored in said memory means, said digital image data being read out from said memory means to be supplied to said image signal producing means.

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