define character printers in detail?

Answer 1

As a computer printer question, this is messy. As a psychological or moral question, it's more so. I'll have a go at the first.

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two approaches

A printer might make marks on paper by forcing a formed character onto an inked ribbon and then onto paper. Typewriters used to work this way universally, with some keeping the molded characters on individual typebars, others on a rotating ball (the IBM Selectric design), or on the 'petals' of rotating type wheels (eg, the 'daisy wheel' printers from Qume), or a thimble (the NEC spinwriters). Line printers used to work this way, fast and loud, with type chains moving at very high speed and whacked by little hammers at just the right time and place to make a character mark on paper. If done well, these printers can produce 'letter quality' output and can look good; the faster ones have tended to be somewhat crude. Early line printers were even restricted to uppoer case letters. But, changing type face sizes, or fonts, etc. is very awkward (even difficult, in some cases). slowing down printing jobs, and needed human attendance. And, for some of these approaches, there are limits to the number of characters simultaneously available (eg, wheels have only so many circumferential positions for characters).

A more flexible approach builds each character from multiple very small dots. Usually these are built up, one dot row at a time, across the page in each line of type. Depending on the size of the dots the mechanism can produce, the precision of their placement, and the type of mark made (eg, micro drops of ink in inkjets, melted pigment in thermal dye transfers, patterns of toner dust in laser printers, dot marks made by mechanical impact (dot matrix printers), electrostatic explosive exposure of dots of an underlying black layer in special aluminized paper, ...), these range from crude looking (unacceptable as 'letter quality') to very high quality output indeed.

Currently, most typographic systems work just this way, including the highest quality. All characters are possible, in any size and variation, limited only by software capabilities. These are often termed 'raster printers' from the method of character construction.

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a third possibility

It's also possible, and Sanders Associates did so a few decades ago, to make a printer which uses a stylus, rather like a person with a pen. These are neither character printers, nor dot matrix printers. And are no longer available for general purpose printing.

For specialized purposes, they are still made and used. Larger format plotters are usually of this type and use small pens at the writing head. They change ink colors by automatically changing pens (selected from a multiple pen holder) and make lines and curves by moving the paper and the print head simultaneously. Printing quality is usually ulititarian (lmited fonts and type faces) since there is little demand for typographic artistry in the situations in which these ploters work.

These are being replaced by inkjet printing techniques in modern plotters. These use the usual dot matrix techniques, but for lines and shading, as well as characters.

Answer 2

A printer which is able to print text only - ASCII characters table ONLY. If the question is about this kind of printer...well ..old dot matrix printers and some sort of electrical typewriters (serial printers) ...15 - 20 years ago was able to print text only.

Answer 3

DPI and resolution should be higher for better quality (think less pixelly and more detail). same with scan resolution. The scanning bit depth tells how vivid the colors it scans are, the higher the better. A duplexer allows the printer to print double-sided instead of only on one side.