Apparatus for simultaneous double sided printing

A dot matrix ink jet-type desktop printer adapted to be connected to a personal computer over an RS232 serial connector, the improvement comprising:

• (a) a platen-less paper transport system, further including a first pair of pick-up pinch roller assemblies arranged in contacting, opposed, counter rotating fashion, and a second pair of tension roller assemblies, spaced-apart from the pinch roller assemblies, the paper transport system securing a sheet of paper to be printed in a substantially rigid plane between the first and second pairs of rollers;
• (b) a first print head carriage assembly disposed to one side of the plane of the paper, the first print head carriage assembly including a first print head;
• (c) a second print head carriage assembly disposed in mirror-image fashion on the opposite side of the plane of the paper from the first print head carriage assembly, the second print head carriage assembly including a second print head;
• (d) processor controlled electronic printer control circuitry including parallel pipelined data paths for providing front and back page printer information to said first and second print heads, wherein said first and second print head carriage assemblies are independently operable in response to front and back page control signals provided by said control circuitry, and wherein said first and second print heads are independently operable so as to effectuate simultaneous printing on both sides of a piece of paper.