US 6,788,331 B1 · Videofax system with progressive image display

Abstract

An improved videofax system for displaying a video image from a digital memory, while the digital memory is being updated with data representing a new image and received from a standard telephone line or other communication channel with relatively slow data access time. A video processor circuit uses a first digital counter to increment the address of a digital memory sequentially and load the stored data to a digital-to-analog converter for display of the resulting analog composite signal on a standard monitor. The video processor uses the address provided by a second digital counter to temporarily switch the digital memory address provided by the first counter and sequentially update the digital memory with new data received from a modem, a microcontroller, or any other data storage components with slow access time, enabling a user to view the new image as it overwrites the old image with a sense of continuity between the old image and the new image.

Claims16

Dependent claims

An apparatus for displaying a video image on a standard video monitor, comprising:

a digital memory for storing said video image as digital video data between a start address and an end address in sequential order;
a digital-to-analog converter for converting said digital video data stored in said digital memory to an analog composite video signal for display on said video monitor;
a first digital counter having a plurality of logic elements and arranged to control the transfer of said digital video data from said digital memory to said digital-to-analog converter for display of said digital video memory on said video monitor;
a second digital counter having a plurality of logic elements and arranged to control the transfer of new digital video data received from a data channel to said digital memory;
and
a digital multiplexer for selecting either said first digital counter or said second digital counter to control the addresses of said digital memory, such that said second digital counter is temporarily selected to enable the transfer of new data received from said data channel only when said new data is available.

3 more elements

A method for displaying a video image stored in a digital memory while data on said digital memory is being updated with new data received from a data channel, comprising:

reading said digital memory by advancing a storage address in said digital storage means from a start address to an end address in sequential order using a first digital counter means;
writing the data read from said digital memory and controlled by said first counter means to a digital-to-analog converting means to reconstruct a composite video signal for display on a video monitor;
switching a multiplexer means to enable an output of a second counter means to control the address of said digital memory means;
writing said digital memory means by advancing a storage address from said start address to said end address in sequential order using said second counter means, to transfer new data received from said data channel to said digital memory means;
switching said multiplexer means to enable an output of said first counter means to control the address of said digital memory means, for displaying the video image from said digital memory means after said new data received from said data channel has been written to said digital memory means.

2 more elements

Dependencies are inferred from the claim text.

Videofax system with progressive image display

Life of this patent

Videofax system with progressive image display

Life of this patent

Abstract

Claims16