Q17. Explain working of a dot-matrix printer.
Ans. In the dot-matrix printer (dmp), an arrangement of tiny hammers strikes to produce the desired characters. Each hammer prints a small dot in the paper.
The printing head of dmp’s contains a vertical array of pins. As the head moves across the paper, selected pins “fire” against an inked ribbon to form a pattern of dots on the paper. Using this feature, a dmp can even pictures, graphs etc. In the figure, the capital letters are formed by 5-dot rows and 7-dot columns (i.e., a row having 5 dots and a column having 7 dots). Such a pattern is called a 5 x 7 matrix. But, the printing head of a dmp consists of 9 pins where bottom 2 pins are used for descender (lower portions) of small letters like y, j etc.