Electric typewriters are increasingly replacing the mechanical typewriters. The first commercial typewriter was produced in 1874 by Christopher Latham Sholes. It was produced by Remington Company of USA. The first electric typewriter was marketed in the mid 1930s.
An electric typewriter along with its functional diagram is shown in the figures. An electric typewriter involved less manual labour as compared to the old mechanical machines. The mechanism of this typewriter is more efficient.
When a key (1) is pressed, a cam (2) makes contact with a drive roller (3) powered by an electric motor (4) The cam is propelled upwards with an even force, causing the cam lever (5) to move back. This makes the upwards movement of the appropriate type bar. (6) The paper is wound on a cylinder which moves along one character at a time during typing. A typing ribbon is forced against the paper by the metal bar, so printing a letter on the paper. As the type bar falls back, the carriage moves one character space to the left. The force of the typing strokes does not depend on the pressure applied by the typist so the results are more even. At the end of a line the typist presses a key that shifts the carriage to the right and at the same time rotates the cylinder, carrying the paper to the beginning of the next line.
Electronic typewriters are move sophisticated than electric typewriters. Based on microchip control they are usually very quiet to use and their action is faster since they contain less moving parts. They offer more functions especially they have memory that allows user to make corrections.
The word processor while retaining the advantages of the electronic typewriter keyboard has replaced the movement of the carriage and cylinder by the movement of a cursor on the screen. This means that mistakes can be erased and passages added, removed or repositioned before the matter is typed on the paper.
