Printer Types

Printer Types

Printer is often defined as a type of output device which produces both graphics and text on a medium like paper; and the printed information is known by the term Hard Copy. Usually, the speed of every printer types are expressed in ppm or pages per minute and its resolution is expressed in dpi or dots per inch. Some reputed manufacturers of printers include Hewlett Packard, Lexmark, Epson, Xerox and others.

General Structure of Printer Types

The main blocks of a printer include:

• Printing Block,
• Paper Feeding System
• Control System and
• Interface.

Main heart of the printer is the control system. It helps to divide a page into several logical pages. Figure below shows the general structure of the control system in a printer. The command processor in the control system is used to control the transfer of data between PC and the printer, also it processes and stores data to the page memory and it interrupts commands. While the area processor performs the changes given by the user for the data stored in the page memory and it is then transferred to the area buffer.  From the area buffer, the data gets transferred to the image processor which defines the status of each dot on the page based on the data received and formats. Now the data prepared for the printing process is transferred to the accumulators. To increase speed, several accumulators may be used. Another processor controls the printing block and the paper-feeding system. This processor interprets the commands referring to the printing format, which will also determine the paper movement.

Printer Types

There are several classification criterias for the printers. A general criterion is discussed below.

A. Based on the Operating Principle

• Impact printers;
• Non-impact printers.

B. Based on to the Printing Quality

• Low or draft quality;
• Medium or near-letter quality;
• High or letter-quality.

C. Based on to the Printing Speed

• Serial printers,
• Line printers,
• Page printers.

Impact Printer Types

In impact printer types, the printing is performed by means of an inked ribbon. Here there will be a mechanical contact between the paper, inked ribbon and the printing assembly. Advantage of the impact printer types is that they will allow making several copies simultaneously, but the noise and the relative slow nature is their major drawback.

Most commonly used impact printer types are:

• Daisy-Wheel Printer
• Dot-Matrix Printer

Daisy Wheel Impact Printer

Daisy wheel impact printer is a type of impact printer which prints symbols and characters only. From this point, it is clear that it cannot print the graphics. Generally, Daisy Wheel impact Printer uses a printing speed of about 10 to 75 characters per second (cps) which is generally slow. The working of daisy wheel printer is similar to typewriters. Here daisy wheel is the main part of the printer. It is a circular printing element which has all the text, symbols and characters moulded on the circle. The daisy wheel rotates with the help of a motor and it pauses the printing hammer for striking the characters on the paper.

Dot Matrix Printer

This impact printer prints graphics and text on paper. Generally, the dot matrix printer uses a printhead which consists many metal pins. Here the printhead strikes the inked ribbon and produces the dots on the paper. Combinations of dots forms the character or shape on the paper. Dot matrix printer has a printing speed of about 50 to 500 characters per second and the quality of print is determined by the number of pins used. Also, they print 80 columns, and 132 columns per line. Here the printhead has 1 inch length and it is made into action by the hammers which will insert the pin inorder to make contact with the paper. These hammers are made into action by the electromagnets.  When the printer receives the data from the computer, first it translates it to know which character is printed and the printhead moves up and down on the page and prints the character.

Advantages of Dot matrix printer

1. Use continuous paper feed.
2. Low print costs.
3. Withstand dusty environment
4. Prints on carbon copies.

Disadvantages of Dot matrix printer

1. Dot-matrix printers are very noisy.
2. The print quality is not very good.
3. Dot matrix printer is slow.

 

 

Non-Impact Printer Types

In non–impact printer types, no direct contact is there between paper and the printing engine. Here, the data to print is first formed on the primary support and then it is transferred to the paper. High speed, good quality and low noise are the basic advantages. But the disadvantage is that several copies cannot be created simultaneously.

Some non-impact printers are:

• Ink- jet Printer
• Laser Printer
• Plotter

Ink Jet Printer

Inkjet printer is a type of non-impact printer which allows drops of ink to the paper to create an image. They use a pump, reservoir of ink, and nozzle. Essentially they work by firing ink onto the paper. Here the dots are very tiny, about 50-60 microns diameter and are placed very closely providing better resolution. Ink-jet printers can produce letter-quality text and graphics in both black-and-white and colors. Generally, the printer resolution is measured in (dpi) dots per inch and the speed of the ink-jet printer is measured in lines per minute (lpm).

     

Advantages

• They are not noisy.
• Produce high quality printed output.

Disadvantages

• Specialized papers must be used to get good quality printed output.
• Ink cartridges and the specialized papers are expensive.
• Ink smears when printed on ordinary paper.

Parts of Inkjet Printer Type

• Print Head- It is the main part of the printer. Mainly it has nozzles which are used to spray the drops of ink.
• Ink Cartridges- it is a component of an inkjet printer which contains the ink that must be deposited onto paper during printing.
• Print head motor - Motor helps to move the print head assembly across the paper back and forth.
• Belt - It attaches the motor and print head assembly.
• Stabilizer bar – It is used to know that the print head assembly operation is precise and controlled.
• Paper feeder - The feeder opens at an angle at the back of the printer which allows us to place the paper in it.
• Rollers – They pull out the paper from the feeder and feed in another paper when the print head assembly requires.
• Paper feed stepper motor – this motor power the rollers essentially to move the paper.
• Power supply – Provides the power required for the operation of the ink jet printer.
• Control circuitry - Controls all the operation and helps in decoding out the information given to the ink jet printer from PC.

Ink jet Printer Types

There are two main inkjet technologies discussed below. They are: Thermal Bubble and Piezoelectric.

• Thermal Bubble Printer Types

In thermal inkjet printer, the resistors create heat and this heat vaporizes the ink to create the bubble. When the bubble expands, the ink gets pushed out of the nozzle to the paper. Now when the bubble collapses, a vacuum is created. This process will push out more ink into the print head from the cartridge.

• Piezoelectric Printer Types

This type of inkjet printer a piezoelectric crystal is placed at the back of ink reservoir of each nozzle. When the crystal receives a tiny electric current it vibrates. When the vibration is inside, a small amount of ink will move out of the nozzle. When more vibration occurs, more ink will come to the reservoir to replace the ink that has been sprayed out.

Laser Printer

Working of a laser printer is similar to a photocopier. Generally, the laser printer process and stores the entire page before they actually print it. So they are also known popularly by the name page printer. Today laser printer can print graphics and text in high quality. Their resolution ranges from 600 dpi to 1200 dpi and they can print text at speeds ranging from four to thirty pages per minute.  

Working

Laser beam from the GaAs semiconductor laser projects the image to be printed in a horizontal or back and forth motion onto an electric charge drum. Toner, a photoconductive black powder particles are then made to attract to the charged areas of drum that are not laser beamed. The drum now transfers the image onto the paper. At last, the paper is moved to the finisher.

Advantages

• Fast and not noisy.
• Produce high quality output.

Disadvantages

• Initial cost is high.

Plotter

Plotter is a non-impact printer which produces better quality documents by moving ink pens over the page. This printer types are useful to architects and engineers. Two main types of plotters are pen plotters and XY plotters.

Advantages

• Good printing.
• Can print on large printers.