US 4,024,501 A · Line driver system

Abstract

A line driver system for digital communication, using logic-level voltages, between an electronic transmitter-receiver device and an electronic receiver device, such as between a computer and a typewriter, a line printer or a cathode ray tube, has the transmitter-receiver device at a location remote from the receiver device. An output of the transmitter-receiver device is electronically coupled to an input of the receiver device using one line of a communications bus. This output of the transmitter-receiver device is coupled to that line of the bus through an optical isolator and then through a power booster. The receiver device has an output that provides a voltage signal when the receiver device is switched on-line. This voltage signal is provided at that output of the receiver device when the receiver device is capable of transforming digital information, that is provided at its input, to a readable form that is printed or displayed by the receiver device. This output of the receiver device is coupled through another optical isolator and through another power booster to a second line of the bus so that this second line of the bus receives a voltage signal when the receiver device is in the on-line condition. This second line of the bus is electronically coupled to an input of the transmitter-receiver device that senses the presence of this signal at that input prior to initiating a transmittal of digital information as logic-level voltages to the first line of the bus to provide logic-level voltages at the input of the receiver device. Each power booster has a high current gain amplifier with unity voltage gain. When the receiver device is also a transmitter device another output of the receiver device is electronically coupled through an optical isolator and a further power booster to a third line of the bus that is electronically coupled to another input of the transmitter-receiver device so that digital information as logic-level voltages are received from the receiver device by the transmitter-receiver device.

A line driver system for digital communication between an electronic transmitter device and an electronic receiver device which comprises:

an electronic transmitter-receiver device, at a first location, having an output and an input, said transmitter-receiver device being constructed to provide digital information to said output as logic-level voltage signals only if there is a voltage signal at said input just prior to said transmitter-receiver device being operative to provide said signals to said output;
an electronic receiver device, at a second location, having an input to receive logic-level voltage signals and an output, said receiver device being constructed to convert logic-level voltage signals from its said input to a readable form and to provide at its said output a voltage signal while said receiver device is in an on-line condition to provide said conversion of said logic-level voltage signals when received at said input of said receiver device;
a bus extending between said first and second locations and including first and second lines;
a first power booster as a digital line driver, at said first location, comprising a high current gain amplifier with unity voltage gain and having an output and an input;
first electrical conducting means connected to said first line only of said bus, at said first location, and to said output of said first power booster, said first electrical conducting means providing the only connection for logic-level signal transmission to said bus from said first power booster;
second electrical conducting means connected to said output of said transmitter-receiver device and to said input only of said first power booster, said second electrical conducting means providing the only connection between said transmitter-receiver device and said first power booster;
third electrical conducting means connected to said second line of said bus at said first location and to said input of said transmitter-receiver device to provide said voltage signal at that input when there is a voltage signal on said second line of said bus;
a second power booster as a digital line driver, at said second location, comprising a high current gain amplifier with unity voltage gain and having an output and an input;
fourth electrical conducting means connected to said second line only of said bus at said second location and to said output of said power booster, said fourth electrical conducting means providing the only connection for logic-level signal transmission to said bus from said second power booster;
fifth electrical conducting means connected to said output of said receiver device and to said input only of said second power booster, said fifth electrical conducting means providing the only connection between said receiver device and said second power booster;
and
sixth electrical conducting means connected to said first line of said bus at said second location and to said input of said receiver device to provide said voltage signal at said output of said receiver device to said second line of said bus.

9 more elements

Line driver system

Life of this patent

Line driver system

Life of this patent

Abstract

Claims15