Most impact printers are Dot Matrix; however, there may still be a few Daisy Wheel printers left, but probably no hammer printers except with large volume mainframe printers.

Since DOT matrix printers are the primary impact printers on PCs, lets talk about them. First, a character on a dot matrix is represented by anywhere from 14 to 24 pins, with 24 pins being the common number today. Not all pins are used to display a character. Certain pins are used to represent each character. Various codes may cause different pins to be used, i.e. italic letters versus a courier font would use different codes. A code is used for each character that is used to determine which of the pins to strike a ribbon that is pressed against the paper.

Matrix printers are not as popular as other types of printers, but they are less expensive. Dot Matrix printers are normally when you have multi-layer forms. Dot matrix printers are an inexpensive means for printing draft copies of documents for editing.

Ink Jet printers basically spray ink onto the paper! Well, it is true, but the spraying of ink is controlled as strictly as are the pins in a dot matrix printer, or the points that are charged on a laser printer's image drum. The price of ink jet printers are between that of dot matrix and laser printers. They are quiter that impact printers.

OK, lets talk a little about how they work:

1. The print head contains 4 cartridges of ink (red, blue, yellow, and black). A cartridge has many (50) ink filled chambers, each with a tiny nozzle.
2. The print head moves along a bar from one side of the paper to the opposite side. It writes as it is spaced across the paper. The print head gets its information from the formatting information and data sent to it. It uses this information to activate the chambers of the ink cartridges.
3. Anyway, once the proper nozzles are selected to form a character or area on the paper, an electrical pulse flows through thin resistors in the chambers that will be used to form the character to be printed.
4. The resistor is heated and used to heat a thin layer of ink in each selected chamber. This causes the ink to boil or expand to form a bubble of vapor.
5. The expansion causes pressure on the ink, which pushes the ink through the nozzle onto the paper. A typical character may be 20 drops across and 20 drops high - wow - that means for a single character, you may have heated up to 400 chambers of ink and sprayed it onto the paper using pressure of the heated ink.

   Yet, the quality is very near that of a laser. But it doesn't print multicopy forms. Sorry.

   I see ink jet printers advertised as add-on's ranging in price $299. to $799.00. The lower prices are for home use, and the higher priced models are generally for office use.

   Bubble jet printers can be purchased for the home for as little as $179.00 (Canon BJC-240) and $300.00 for a office color printer (Canon BJC-70). Obviously, you can purchase for higher prices also.

Without a doubt, the laser printer is the fastest and most popular printer on the market. It does not however, print multiple copy forms. It does produce a printer quality document, both for text and graphics. It is somewhat more expensive than a dot matrix printer, especially if you purchase a high volume, high quality laser printer.

A laser printer operates basically as follows:

1. Your PC's software sends instructions to the laser printer. A page sent to a printer includes the instructions and the information to be printed. The instructions are control information telling the printer where to place information on the page, how to format the page, etc.
2. The instructions control the turning on/off of the laser beam.
3. Laser printers usually print either 300 or 600 dots per inch.
4. The laser flashes tiny points of light on a drum, which results in a single row of points across the drum. Then, the drum rotates either 1/300 or 1/600 of an inch and the dots for the next row are reflected (placed) on the drum of the laser printer.
5. Where each point of light has touched the drum, whic is covered with a negatively charged film, the charge is changed to that of the paper. Each dot marks a dot that will eventually print black on the paper.
6. The drum rotates, and the dots on the drum pass the "toner", it sticks to the drum. This is because the "toner" and the points of light on the drum have opposite charges.
7. The drum continues to rotate and presses the toner against the sheet of paper that has been feeding into the printer. It deposits the toner onto the paper resulting in many tiny dots along the row. As row after row of dots are placed on the paper, they form characters or images.
8. Note the paper begins feeding and is coordinated with the rows of dots. A single row of characters may represent 50 or 100 rows of dots if the characters are 1/6 of an inch in height.

   Just remember: The toner (ink equivalent) is attracted to a magnetized point on the drum. Many of these points make a row, and many rows of these tiny points make a row of characters, or a part of an image. The toner has an opposite charge than the points on the drum, and the toner jumps to the drum, which eventually presses the toner onto the paper.

These are the most expensive types of printers. They are high quality. These use special coated paper that costs approximately $.25 per page. Let's talk about how it works:

1. The paper is fed into the printer engine. The paper is held against a ribbon coated with colored ink (cyan, magenta, yellow, or black).
2. As the paper moves through the paper feeders, it presses against the cyan bank of the ribbon. One or more heating elements are turned on, and they melt small dots of the cyan dye. The melted dots are then pressed against the paper.

3. The paper continues to move through the paper feeders until the paper peels away from the ribbon. As it peels, the unmelted ink remains on the ribbon, and the melted dye sticks to the paper.

4. The paper is pulled back into the printer, and the next color (magenta) band goes through the same process. This repeated for the magenta, yellow, and black.
5. After all color cycles, the paper is ejected into the paper tray at the exit.

You should know the following about color printing:

1. All color from printers is from a mixture of colors.
2. All colors are mixed as dots of different colors.
3. Each printed color is a mixture of at least 3 colors.
4. Color thermal printers are higher quality than laser or ink jet printers because the heated wax does not bleet into each other or soak into the special paper.
5. You pay for what you get!

PURCHASING PRINTERS:

You should list several criterial before purchasing a printer. Among them are:

1. Want to print color?
2. Want to print "book" quality color pages?
3. Want to print multiple copy forms?
4. Want to print less than 100 copies per day?
5. Want to print 100-1000 copies per day?
6. Want to print 1000+ copies per day?
7. Do you require letter quality document print?

Here are some of the characteristics of each type of printer listed above that might help you decide pertaining to the questions.:

1. Dot Matrix Printers

   Dot Matrix printers have poor quality printing when compared to most other types of printers. They do not satisfy the need for letter quality printing, and they are relatively slow. However, for multiple copy forms, they are an excellent choice. Wide carriage dot matrix printers are also good for large layout printing. In general:

   1. Dot Matrix printers last forever.
   2. They use inexpensive ink ribbons.
   3. They cost less.
   4. They are cheaper than other printers from the standpoint of paper, and you don't have toner cartridges, ink or wax refills, etc.
   5. But - they don't print high quality letters.

2. Ink Jet or Bubble Jet Printers:

   These are slightly less expensive than laser printers, produce high quality documents, but are not fast. They are an excellent choice for home or low quantity printing. For large quantities of documents purchase an expensive jet printer, or preferably, get a high quality laser printer.

3. LASER Printers:

   Laser printers are the choice for letter quality printing for both home and the office. Be careful - the least expensive laser printers may be ok for home use or low volume use; however, they probably cannot cope with the mechanical requirements of heavy office printing. Probably the best printer for high volume printing. Xerox has introduced a "color" laser in 1997 for a price of approximately $3500.00. They require "toner" cartridges which are somewhat expensive, but each cartridge will produce several thousand pages of print.

   If you only print letters and black/white graphic images, laser printers are probably your best buy.

4. COLOR Thermal Printers:

   This type of printer is too expensive for normal use. Buy one of these if you have to produce "publisher" or book quality printouts, with low volume; or, if you desire to produce quality overhead slides for briefings. The wax cartridges are expensive and do not last for any length of time. The paper is a special type of paper and is very expensive.