The typewriter has changed very little in appearance since its invention in 1867. The first radical development came almost a hundred years later with the commercial availability of the electric typewriter. Mechanically it is very similar to the manual typewriter, still having a moving carriage and type bars. The paper is fed around the cylinder, or platten, in the same way as the manual version, and the appearance of both versions is very similar.
When a key is pressed, a cam comes into contact with the drive roller, which is driven by a constant speed motor. As the cam is forced upwards, a lever moves back, propelling the appropriate type bar up towards the ribbon. The raised character (normally either a letter or number) on the end of the type bar strikes the ribbon, pressing it against the paper, causing the character to be printed onto the paper.
As the type bar drops back, the carriage is automatically advanced one space to the left. At the end of the line, the return (carriage return) key is pressed, causing the carriage to return to its rightmost position, whilst rotating the platten to move the paper up to the next line.
The main advantage of the electric version over its manual predecessor is that it does not matter how hard the keys are pressed - the force of the type bar is the same each time. This is better for two reasons. Firstly, it requires less effort on the part of the typist, and secondly the characters are printed with a more uniform appearance.
The electric typewriter should not be confused with the electronic typewriter, the latter being far more advanced and completely different in operation. Faced with competition from the electronic version, with its superior facilities and more competitive prices, even the electric typewriter could soon become obsolete.
