TYPES OF PRINTER

What is a Printer?
A printer is an electromechanical device which converts the text and graphical documents from electronic form to the physical form. Generally they are the external peripheral devices which are connected with the computers or laptops through a cable or wirelessly to receive input data and print them on the papers. A wide range of printers are available with a variety of features ranging from printing black and white text documents to high quality colored graphic images.

There are broadly two types of printers, they are

1. Impact Type
2. Non-Impact Type

Impact Type

To create text or image by physically make the print head to press the ink ribbon and  cause the ink deposition on the paper in desired form is called impact type. Normally it is quite louder in nature when compared to other  types of printers. The well known example for impact type is Dot Matrix and Daisy wheel . Some of the latest impact based in the market are Line printer (high speed impact printer), IBM electromagnetic table printing machine, and Apple Image writer.

Non-Impact Type

This  produce text or images on paper without striking the paper physically are called as non-impact type. These are not louder when compared to  other types of printers. The well known example of this type is Thermal printer, lasers and inkjets . Some of the latest non-impact printers in market are HP Laser Jet and Apple Laser Writer (The laser printer with built-in postscript interpreter).


1.      Daisy Wheel Printers
Daisy wheel printers print only characters and symbols and cannot print graphics. They are generally slow with a printing speed of about 10 to 75 characters per second. By 1980 daisy wheel printers were the dominant printers for quality printing but since the prices of laser and inkjet printers have declined and quality of dot matrix printers has been improved, the daisy wheel printers are now obsolete.

2.      Dot Matrix Printers
It is a popular computer printer that prints text and graphics on the paper by using tiny dots to form the desired shapes. It uses an array of metal pins known as printhead to strike an inked printer ribbon and produce dots on the paper. These combinations of dots form the desired shape on the paper. Generally they print with a speed of 50 to 500 characters per second as per the quality of the printing is desired. The quality of print is determined by the number of pins used (varying from 9 to 24).

The key component in the dot matrix printer is the ‘printhead’ which is about one inch long and contains a number of tiny pins aligned in a column varying from 9 to 24. The printhead is driven by several hammers which force each pin to make contact with the paper at the certain time. These hammers are pulled by small electromagnet (also called solenoids) which is energized at a specific time depending on the character to be printed. The timings of the signals sent to the solenoids are programmed in the printer for each character.

Working of dot matrix printer, how dot matrix printers work
The printer receives the data from the computer and translates it to identify which character is to be printed and the print head runs back and forth, or in an up and down motion, on the page and prints the dots on the paper.

3.      Inkjet printers
Inkjet printers are most popular printers for home and small scale offices as they have a reasonable cost and a good quality  of printing as well. A typical inkjet printer can print with a resolution of more than 300 dpi and some good quality inkjet printers are able to produce full colored hard copies at 600 dpi.

An inkjet printer is made of the following parts:
·         Printhead – It is the heart of the printer which holds a series a nozzles which sprays the ink drops over the paper.
·         Ink cartridge – It is the part that contains the ink for printing. Generally monochrome (black & white) printers contain a black colored ink cartridges and a color printer contains two cartridges – one with black ink and other with primary colors (cyan, magenta and yellow).

4.      Laser Printers 
 Laser printers are the most popular printers that are mainly used for large scale qualitative printing. They are among the most popularly used fastest printers available in the market. A laser printer uses a slight different approach for printing. It does not use ink like inkjet printers, instead it uses a very fine powder known as ‘Toner’. Componetns of a laser printer is shown in the following image:
 
Working of laser printers, components of laser printers

The control circuitry is the part of the printer that talks with the computer and receives the printing data. A Raster Image Processor (RIP) converts the text and images in to a virtual matrix of dots. The photoconducting drum which is the key component of the laser printer has a special coating which receives the positive and negative charge from a charging roller. A rapidly switching laser beam scans the charged drum line by line. When the beam flashes on, it reverses the charge of tiny spots on the drum, respecting to the dots that are to be printed black. As soon the laser scans a line, a stepper motor moves the drum in order to scan the next line by the laser.

A developer roller plays the vital role to paste the tonner on the paper. It is coated with charged tonner particles. As the drum touches the developer roller, the charged tonner particles cling to the discharged areas of the drum, reproducing your images and text reversely.  Meanwhile a paper is drawn from the paper tray with help of a belt. As the paper passes through a charging wire it applies a charge on it opposite to the toner’s charge. When the paper meets the drum, due to the opposite charge between the paper and toner particles, the toner particles are transferred to the paper. A cleaning blade then cleans the drum and the whole process runs smoothly continuously. Finally paper passes through the fuser which is a heat and presser roller, melts the toner and fixes on the paper perfectly.

Difference between a Line Printer and a Dot Matrix Printer

Printing

  • A line printer print pages exactly as its name implies, one line at a time. Dot matrix printers use pins arranged in a matrix that physically strike an ink ribbon between the pin and the paper to print characters.

Speed

  • Line matrix printers can print roughly 1,200 lines per minute, or generally about 20 pages per minute. Dot matrix printers print about 40-300 characters per second, or about six to seven pager per minute, at best.

Quality

  • Dot matrix printers have a lower print quality than line printers. The characters' shapes on pages printed using a dot matrix printer appear as a number of dots connected together. Line printers print solid characters and can use a wide variety of font face and sizes.


Difference between a Dot Matrix and Thermal Printer

Printing

  • Thermal transfer printers heat and melt a colored ribbon to produce images while direct thermal printers simply create images directly on pages without a ribbon. Dot matrix printers have between nine and 24 pins that physically strike an ink ribbon between the pin and the paper to print characters to the page.

Quality

  • Dot matrix printers print characters that appear as a series of dots connected together, not with the actual shape of a character. Thermal printers have a higher print quality and can produce photo-realistic images, but extended exposure to heat or light can cause the images to fade over time.

Uses

  • Retail stores commonly use thermal printers to print receipts for customers. They use rolls of paper for fast printing, but sometimes the ink remains wet and can smudge. Dot matrix printers more commonly appear as an output device for a computer.


Difference between a Dot Matrix and Laser Printer

Distinction

  • Dot matrix printers are a type of impact printer. An impact printer works by striking against an ink ribbon. The ribbon is pressed against the paper, leaving the desired mark. Inkjet and laser printers, on the other hand, are nonimpact printers because they do not physically strike the page.

Mechanism

  • Dot matrix printers use a grid of pins that strike against a ribbon in different combinations to produce different characters.

Dot Matrix Display

  • Dot matrix printers use a dot matrix display, or 2D matrix of dots, to represent images and characters, like a computer screen. The more dots used, the clearer and more accurate the representation. The human eye blends the dots together to make an image.

Laser Printing

  • Laser printers work on an entirely different basis. A laser beam fires at the surface of a cylindrical drum with an electrical charge, usually positive, that is reversed in the areas that the laser hits. The pattern is then coated with positively charged toner, which clings to the negatively charged areas. A strong negative charge when the paper passes through the printer allows the toner to transfer to the paper.

Considerations

  • Dot matrix printers have largely been replaced by inkjet and laser printers by businesses due to their low resolution.



S.  No.TypeMode  of  PrintingSpeed
1Dot  –  Matrix
printer
Prints  the  character  in  dotted  pattern
 through  printer  ribbon  using  either  24  pin  or  9  pin
200/300  to  700
CHARACTER PER SECOND (CPS)
2Ink  Jet  printerWork  by  spraying  ionized  inkSlow,  90  CPS
3Laser  printerAlso  called  page  printer.  Uses  laser
 beam  to  produce  an  image.
6  to  12  PPM
4Line  printerPrints  lines  at  a  time  instead  of  single
 
characters.
300  to  600  LPM
5PlotterProduces  drawings  or  graphs  through
 pens which  are  filled  with  different  colours.