Epson LX-90 User Manual download pdf (Page 18)

Chapter 3

Elements of Dot Matrix Printing

and Computer/Printer Communications

This chapter is for those of you who want to know something about

how your printer works. It’s a simple, non-technical explanation of

the basics of dot matrix printing that will help you understand some of

the later chapters, particularly the ones on user-defined characters and

graphics.

The Print Head

The LX-90 uses a print head with nine pins or wires mounted verti-

cally. Each time a pin is fired, it strikes the inked ribbon and presses it

against the paper to produce a dot. This dot is about 1/72nd of an inch

in diameter. The size varies slightly depending upon the age of the

ribbon and the type of paper used. As the head moves horizontally

across the page, these pins are fired time after time in different patterns

to produce letters, numbers, symbols, or graphics.

For example, to print a pica capital T, the head fires the top pin,

moves 1/60th of an inch, fires the top pin again, moves 1/60th of an

inch, fires the top pin and the six below it at the same time, moves

1/60th of an inch, fires the top pin, moves another 1/6Oth of an inch,

and fires the top pin once more to finish the letter. All this happens in

only l/lOOth of a second.

Figure 3-7. A capital T

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Epson LX-90 User Manual Page 18