Dot matrix printers

FIG. 21.48 Label example printed hy a high density dot matrix printer. (Courtesy of SATO AMERICA, Inc., 2761-A Marine Way, Mountain View, CA 94043.)... 

Use a laser printer (as opposed to an inkjet printer, dot matrix printer, or a typewriter) to print any document you know is going to be scanned. 

Print the figure on clean, opaque, white paper, using a fresh ink or toner cartridge. Do not use a dot matrix printer. Set the laser or inkjet printer to a resolution of at least 600 ppi. 

If you are printing line-art figures for subsequent scanning, always check that the toner or ink cartridge is fresh, and never use a dot-matrix printer. 

VCR Fax machine Dot matrix printer Camcorder Laser printer ... 

So what a chemist draws as a band in 5, repeated at left in 8 (and the chemist tires and draws 35 lines or just a block instead of Avogadro s number), the physicist will alternatively draw as an E(k) vs. k diagram at right. Recall that k is quantized, and there is a finite but large number of levels in the diagram at right. The reason it looks continuous is that this is a fine dot matrix printer there are Avogadro s number of points jammed in there, and so it s no wonder we see a line. 

The graphical output can be sent to an Epson (or compatible) dot-matrix printer or a Hewlett-Packard (or compatible) laser printer. 

Malvern ALPS 100 system liquid particle counter is a modular system that can be used with an autosampler for multiple samples or with an online sampler for direct measurement of flowing liquids. It can be used with sample volumes down to 0.5 ml and uses a built-in multi-channel analyzer to perform size distribution analyses of low concentration dispersions. Suitable for both aqueous liquids and solvents, it measures up to 50 size bands in the 2 to 100 pm or 3 to 150 pm size range with output from a built-in thermal printer or external dot matrix printer. 

Dot-matrix printers are the oldest type of printer, as well as the simplest. This type of printer uses an array of pins to strike an inked ribbon, which in turn makes a pattern of dots on the paper. The patterns of dots ultimately form letters and images. Dot-matrix printers are easy to use as well as very inexpensive. However, they are relatively slow and very noisy (as anyone who has tried to talk on the phone while using one can attest). The best dot-matrix printers are only near letter quality (letter quality is the quality found with a typewriter). They are still in use because they are the only printer that can print on carbon copy forms (invoices, receipts, etc.). Because the pins on dot-matrix printers actually strike the paper, they can make simultaneous copies when used with pressure-sensitive forms or carbon paper. 

The other type of impact printer we re going to discuss is the dot-matrix printer. These printers work in a manner similar to daisy-wheel printers, except that instead of a spinning, character-imprinted wheel, the printhead contains a row of pins (short sturdy stalks of hard wire). These pins are triggered in patterns that form letters and numbers as the printhead moves across the paper (see Figure 7.2). 

The main disadvantage to dot-matrix printers is their image quality, which can be quite poor compared to the quality produced with a daisy wheel. Dotmatrix printers use patterns of dots to make letters and images, and the early dot-matrix printers used only 9 pins to make those patterns. The output quality of such printers is referred to as draft quality —good mainly for providing your initial text to a correspondent or revisor. Each letter looked fuzzy because the dots were spaced as far as they could be spaced and still be perceived as a letter or image. As more pins were crammed into the printhead... 

Dot-matrix printers are still noisy, but the print wires and printhead are covered by a plastic dust cover, making them quieter than daisy-wheel printers. Also, dot-matrix printers use a more efficient printing technology, so the print speed is faster (typically in the range of 36 to 72cps). Some dot-matrix printers (like the Epson DFV series) can print at close to a page per second Finally, because dot-matrix printers are also impact printers, they can also use multipart forms. Because of these advantages, dot-matrix printers quickly made daisy-wheel printers obsolete. 

Ink is a liquid that is used to stain the paper. There are several different colors of ink used in printers, but the majority use some shade of black or blue. Both dot-matrix printers and bubble-jet printers use ink, but with different methods. 

Dot-matrix printers use a cloth or polyester ribbon soaked in ink and coiled up inside a plastic case. This assembly is called a printer ribbon (or ribbon cartridge). It s very similar to a typewriter ribbon, except that instead of being coiled into the two rolls you d see on a typewriter, the ribbon is continuously coiled inside the plastic case. Once the ribbon has run out of ink, it must be discarded and replaced with a new one. Ribbon cartridges are developed closely with their respective printers. It is for this reason that ribbons should be purchased from the same manufacturer as the printer. The wrong ribbon could jam in the printer as well as cause adverse quality problems. 

D. Of the choices listed, only dot-matrix printers are impact printers and therefore can be used with multipart forms. 

D. The daisy-wheel printer is much slower when compared to the dot-matrix printer and therefore speed is a disadvantage. 

Dot matrix printers are relatively simple devices. Therefore there are only a few problems that usually arise. We will cover the most common problems and their solutions here. 

If I had a wish for the service department I worked in, I would wish that all the dot matrix printers ever bought would be made by Okidata. Okidata dot matrix printers are a technician s dream machine. With nothing but a flat-bladed screwdriver and your hands, you can completely disassemble an Okidata dot matrix printer in less than 10 minutes. Replacing parts on them is just as easy. All parts "snap" into place, including the covers. They also have an excellent reputation. If a customer asks you for a recommendation when buying a dot matrix printer, you can t go wrong recommending an Okidata. 

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