Printing is a process in which a large number copies of text and pictures is produced on paper in a short time. This art was developed in the sixth century in
. After about 500 years, movable type was also invented in China . From China , this technique became popular in European countries. In the fifteenth century, Johannes Gutenberg of China Germany developed the printing process in Europe. In 1476, William Caxton introduced the first printing press in . London
Platen press, which used to print sheet by sheet, was replaced by rotary press. A rotary press continuously prints a paper roll. The printing which uses movable type is called letter press. In lithography, smooth plate is used. Text or picture is taken on a greasy surface, while the remaining part of plate is covered with grease repelling material. When greasy link is applied onto the plate, it adheres on the greasy parts only.
The invention of computer has brought many improvements in printing. Nowadays, edition of text, printing and designing of page is done with the help of computers.
The type and designing of any text, newspaper or book can be done very fast and easily in required size in a work processor with the help of a computer. A word processor makes use f electronic system by which written matter can be edited on its own. We can alter the sequence of words and sentences, even delete or add words without typing the total matter again.
Whatever you type on the keyboard gets displayed on the visual display unit VDU like a TV screen. Operators can do any change or correction in the text by using the editing key and movable pointer. Text gets stored in the memory of the word processor, which can be arranged accordingly by looking at the screen. Operators can store the text permanently on disk or tape, which can be used afterwards whenever needed. Word processor has a link with the electronic printer, by which a typed copy of text stored in memory comes out.
Word processor also helps to set the text into pages. Line length, spacing, indentation, margins, etc. can be set according to will. When it is printed, the machine can arrange the text on its own, if a word a longer and is coming out of the line; the word processor brings this word in the next line and adjusts the spacing of the first line. In the same way, the size of the letters etc. can also be changed.
Offset Printing Machine