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- Generalities and definitions


- Printers GDI or Win-Printers

- Types of printers
  - Of impact (matriciales)
  - Of ink
  - Laser printers

- Other types of printers
  - Plotters
  - For photos
  - Of big format
  - For groups

- Adequacy to the use

Updated page
2/10/2000


Author:
Juan Herrerías Rey
 

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What is... a printer?


 

As it indicates his name, the printer is the peripheral one that the computer uses to present information printed on role. The first printers were born many years before the PC and even before the monitors, being for years the most usual method to present the results of the calculations in those primitive computers, the whole advance with regard to the cards and perforated tapes that were used till then.

Although in anything there look like the modern printers to his ancestresses of those times, there is no doubt that just as there were printers rather than PCs, they will be after these, although they are based on technologies that still have not been invented even. It turns out to be very improbable that the human beings we leave completely the role for a cold computer screen; Gutenberg would be proud, I suppose.

 

Generalities and definitions

Before penetrating into this complex world of the printers, we are going to exhibit some of the basic concepts on the same ones.

Speed

The speed of a printer usually measures itself to two parameters:

  • ppm: pages in minute that is capable of printing;
  • cps: characters (letters) in second that is capable of printing.

At present the value of ppm is used almost exclusively, while of cps it are reserved for few printers matriciales that are still made. Anyway, the manufacturers always calculate both parameters of completely deceitful form; for example, when it is said that an ink printer comes to 7 pages per minute we are not warned that are pages with like much 5 % of printed surface, in the lowest quality, without graphs and deducting the time of calculation of the computer.

And nevertheless it turns out to be practically impossible to obtain the above mentioned number; in fact, rarely they are obtained more than 3 ppm of text with an ink printer, although with one laser is easier to approach the theoretical numbers that the manufacturer indicates.

 

Resolution

Probably be the parameter that better it defines to a printer. The resolution is the best or worst quality of image that it is possible to obtain with the printer measured in number of individual points that is capable of drawing a printer.

Sample of two images with different resolution

One speaks generally of ppp, points for (square) inch that prints a printer. This way, when we speak about a printer with resolution of "600x300 ppp" we are referring that in every horizontal line one inch long (2,54 cm) can place 600 individual points, while in vertical it comes up to 300 points. If only there appears a number ("600 ppp", for example) it usually means that the horizontal resolution is just as the vertical one.

Anyway, not everything is "to throw points" on the role. Two printers of the same theoretical resolution can give very unlike results, since also it influences the size of these points and the precision at the time of placing them on the role. Of nothing it serves to place 360.000 points in a square inch if some are put on others making blots on the image.

 

The memory buffer

Eye, finished in "R", is not going to be wrong and to ask the clerk for the "buffet" of the printer; the laugh can belong to órdago. It is a small quantity of memory that all the modern printers have to store part of the information that is providing the computer to them.

Thus the computer, perceptibly more rapid than the printer, does not have that to be waiting for it continuously and can spend earlier to other tasks while the printer finishes his work. Obviously, major all that is the most rapid and comfortable buffer will be the impression process, therefore some printers go so far as to have up to 256 Kb of buffer (in very professional printers, even several MB).

 

The interface or connector

The printers get connected to the PC almost exclusively by means of the parallel port, which in many operating systems it is named LPT1 (LPT2 in case of the second parallel port, if more of one existed). As the original parallel port was not too rapid, at present there are used ports more advanced like the ECP or the EPP, which are more rapid and add bidireccionalidad to the communication (that is to say, that the printer can "to speak to him" to the PC, what formerly was impossible) at the time that they support the compatibility with the ancient standard. The method of work of the parallel port (standard, ECP...) one usually selects EPP in the BIOS of the computer; to know how to do it, pulsates here.

Physically, the connector for parallel port presents this aspectParallel connector in the end of the cable that gets connected to the computer, with 25 pines in 2 tiers, while in the end that gets connected to the printer 36 usually has pines planes and a few clampsParallel connector. To connect both devices one usually names the cable a parallel cable Centronics; for bidireccionalidad it is necessary to use specific, more advanced cables and of major quality.

Other less common ways of connecting a printer there is by means of the port series (the one that the external modems and many mice use; it turns out to be quite slow), by means of a connector USB (rapidly and simply, although with few advantages opposite to the parallel port), by means of a device of infrared (very useful in case of portable) or straight connected to a network (and not to a computer connected to the same one) in case of big printers for groups.

 

Printers GDI or Win-Printers

Before beginning describing the types of printers as the technology of impression that they use, we are going to comment something on a special type of printers of recent appearance on the market: the printers GDI.

GDI is the initials of Graphical Device Interface, a type of proper technology of Windows by which there can be made printers that load part of the work that they should realize to the computer to which they are connected; for example, they can lack proper memory by means of using the RAM of the computer. Thanks to this system diverse electronic components save themselves in the manufacture of the printer, what reverberates in a descent of his price.

The Win-Printers nickname is given them because the support for this task only is usually implemented for Windows (especially for Windows 95/98), generally by means of a program named Windows Printing System (literally, system of impression of Windows). Since Windows represents more than 90 % of the bought PC, the manufacturers bother to incorporate support for OS/2, neither Linux nor other operating systems.

The disadvantages of these printers are two: firstly, they depend on the potency of the computer to which they are connected, that will have to be like little a rapid Pentium with a generous RAM quantity; and also, only they work in Windows; out of this operating system they are not capable of writing not even a line (not even in TWO, as it should not be covering TWO in a window of Windows).

Those that only Windows uses to work it is possible that they do not see it like a problem, but we must bear in mind that the printer is one of the most expensive elements and of major useful life of the PC. So: who makes sure us that our flaming printer GDI is going to work with the versions of Windows of inside a pair of years? Who makes sure us that inside a pair of years Windows is going to keep on being the king of the operating systems (although yes it is the most probable thing)? And is he sure that it is ever never going to need to use the printer out of Windows?

The truth is that approximately 10.000 pesetas save themselves buying one of these printers hardly ever is worth it before such suspense; also, a printer GDI will be always a little slower than the "classic" equivalent model (unless a powerful computer is had), apart from loading enough on the operating system, what with the unstable Windows is never anything desirable...

Anyway, they are more and more common, therefore if he decides on one of these printers I tried if only he is not a model pure GDI, but a printer with a certain quantity of memory and components that only there takes given part of the capacities of the computer (if he has left his own memory short, for example).

 

Types of printers

If we want to classify the diverse types of printers that exist, the most logical method is to do it attending to his impression technology, that is to say, to the method that they use to print in the role, and to include in the above mentioned classification like particular cases other considerations like the use of color, his speed, etc. That takes us to three classic guys: matriciales, of ink and laser.

 

Impact printers (matriciales)

There were the first ones that arose in the market. They are named "of impact" because they print by means of the impact of a few small pieces (the counterfoil of impression) on a tape impregnated in ink, which is usually a source of many headaches if his quality is not the one that would be desirable.

According to how is it the impression compress, they split into two principal groups: of daisy and of needles. Those of daisy incorporate a metallic ball in which the diverse letters and symbols are in relief to print; the ball pivota on a mobile support and it beats to the ink tape, with what the corresponding letter is printed. The method is absolutely the same one that is used in many electrical typewriters, the only thing that differentiates them it is the keyboard lack.

The printers of daisy and other methods that use fixed types of letter are in finished desuetude because they are only capable of writing text; also, to change type or size of letter we should change the counterfoil of impression (the ball) every time. On the other hand, the quality of the text and the speed are very high, in addition to that they allow to obtain multiple copies in role of autocopy or carbon paper.

A printer matricial of needles typical, of the mark Epson

The needles printers, often named simply matriciales, have a counterfoil of small needles that affect the role forming the wished image; all the more needles possess the compress of major impression it will be the resolution, which is usually between 150 and 300 ppp, being almost impossible to overcome the latter number.

Although the resolution is not very high it is possible to obtain graphs of certain quality, although black and white, not in color. The use of color implies the use of several tapes or more wide tapes, in addition to be almost impossible to obtain a realistic scale of colors, beyond the most basic.

On having been impact printers, they can obtain multiple copies, what makes them especially useful in offices or commerce for the achievement of lists, invoices, delivery notes and other documents. His speed in text is of the highest, although at the cost of producing a noise certainly highly, that sometimes it becomes annoying. It turns out to be very common to find them with feeders for continuous role, what only happens with some printers of ink of high price.

In general, the printers matriciales of needles posicionan like printers of limited price, quality average - fall, scarce maintenance and high capacity of impression. Between few manufacturers who stay of these printers Epson stands out, with an enormous catalog with options and prices for all the tastes.

 


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