09 Output Devices Printers ot bfb dbve.pptx

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1. PRINTERS

2. Printers The most commonly used output devices to get the hard copy of results. A printer is connected to a parallel port or USB port of system unit by a cable. It is an electro-mechanical device. The electronic circuits control the mechanical assemblies. Electronic circuits to decode the command, generate control signals and activate the printer mechanism to print the data received from the computer. The mechanical assemblies include print head assembly, ribbon assembly, sensor assembly etc.

3.  spooling refers to the process of placing data in a temporary working area for another program to process The most common spooling application is print spooling: documents for printing are stored usually into an area on a disk and retrieved and printed by a printer

4. Printers The output quality of a printer is measured by Dots per inch  (DPI). Printers are classified into two types according to printing techniques. Impact printer : characters are printed by the physical contact of the print head against the ribbon and hence onto the paper. E.g. are. dot matrix Letter Quality Printer Daisy wheel printer Non impact printer : there is no physical contact of the print head with the paper. Laser Printer Inkjet Printer Line printer Drum Printer Chain Printer Thermal Printer Electromagnetic Printer

5. Dot matrix printer This is an e. g. of character printer , it can print one character at a time. Dot matrix has little pins that strike a ribbon (much like a regular typewriter) to print a dot of ink onto a page.  The cheaper dot matrix printers have 9 (adv. Printer have 24 pin ) pins and these pins are close together and the combination of dots forms the picture.  This type printer print speed is very poor. While increasing the print speed then get less quality output and hence print with low speed, then get good quality (NLQ- Near Letter Quality) print. Newer type Dot matrix printers are print bi- directional .

6. Dot matrix printer Advantages Low purchase cost. Can handle multipart forms. Cheap to operate low repair cost Simple mechanism Disadvantages Noisy. Poor print quality. Less speed Cannot print multi colour

7. letter-quality printer This is also an example of character printer, therefore it can print one character at a time. A letter-quality printer operates in much the same fashion as a typewriter. A metal or plastic printwheel embossed with letters, numbers, or symbols strikes an inked ribbon, depositing the ink on the page and thus printing a character . The most popular letter quality printer is daisy wheel printer . This speed has up to 90 characters per second.

8. LINE PRINTER The line printer is a form of high speed impact printer in which one line of type is printed at a time . This print speed may vary 300-3000 lines per minute. Drum printer and Chain printer are an example of line printer. The disadvantages of line printers are It cannot print graphics The print quality is low and Very noisy.

9. An old line printer technology that used formed character images around a cylindrical drum as its printing mechanism. When the desired character for the selected position rotated around to the hammer line, the hammer hit the paper from behind and pushed it into the ribbon and onto the character. DRUM PRINTER

10. Drawbacks of drum printer are In Drum Printer, drums are expensive and can’t be changed often. Fixed font size. Hammer must strike very quickly and must be accurately matched with drum movement. If the hammer striking is untimely, then the printed line looks curly and slightly blurred.

11. CHAIN PRINTER Line Printers are normally designed for heavy printing applications and can print continuously for a few hours. Advantages: Curly lines do not appear. Chain printer may produce different font size This have 132 character in a line

12. CHAIN PRINTER This uses a rapidly rotating chain which is called print chain. The magnetic print hammer strikes to paper then the paper strikes on the ribbon and hence strikes to print chain then print the line to paper. This noise level is very high and print speed is also high. This may print 400- 2400 lines per minute.

13. Non Impact Printer A printer that uses heat to transfer an impression onto paper. This uses a special heat sensitive coated paper. When the spot of the paper is heated, it become dark. The character printed with a matrix of dots (5 x 7 or 7 x 9 matrix). To print a character the print head is moved to the correct position then heating element is turned on and print it and move to the next position. This printer have a speed of 200 character per second. Thermal printer

14. Electromagnetic Printer This printer uses electromagnetic technique to write a character. This printer make an output for print onto a drum then the this surface is passed through magnetic powder which hold to the charged area and pressed onto the paper.

15. This also a non impact printer. A type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print. A typical ink-jet printer provides are solution of 300 dots per inch, although some newer models offer higher resolutions . Inkjet printer

16. This can print multi color images.  the price of ink-jet printers is lower than that of laser printers. Main drawback of ink-jet printers is that they require a special type of ink that is make blur on inexpensive copier paper. Advantages Lower price Portable Simple mechanism Can print color documents Print quality is high No Noisy Disadvantages Cartridges need to be replaced periodically Requires special type of ink Resolution is not high Low speed

17. Inkjet printer The Print Head Assembly Print Head Cartridge Print Head Stepper Motor Belt Stabilizer Bar The Paper Feed Assembly Paper Tray/ Feeder Roller Power Supply Control Circuitry Interface Port

18. Print head - The core of an inkjet printer, the print head contains a series of nozzles that are used to spray drops of ink. Ink cartridges - Depending on the manufacturer and model of the printer, ink cartridges come in various combinations, such as separate black and color cartridges, color and black in a single cartridge or even a cartridge for each ink color. The cartridges of some inkjet printers include the print head itself. Print head stepper motor - A stepper motor moves the print head assembly (print head and ink cartridges) back and forth across the paper. 

19. Belt - A belt is used to attach the print head assembly to the stepper motor. Stabilizer bar  - The print head assembly uses a stabilizer bar to ensure that movement is precise and controlled. Paper tray/feeder  - Most inkjet printers have a tray that you load the paper into. Some printers dispense with the standard tray for a feeder instead. The feeder typically snaps open at an angle on the back of the printer, allowing you to place paper in it. Feeders generally do not hold as much paper as a traditional paper tray. Rollers - A set of rollers pull the paper in from the tray or feeder and advance the paper when the print head assembly is ready for another pass.

20. Interface port(s) - The  parallel port  is still used by many printers, but most newer printers use the USB port . A few printers connect using a  serial port  or small computer system interface ( SCSI ) port.

21. Laser Printer LASER stands for Light Amplification by Simulated Emission radiation . Print by using Electro- photography principle. The laser printer consists of a Organic photo conductive (OPC) cylinder or drum , the drum given + ve or negative charge (initially +ve) with the help of wire (Corona Wire) and the drum starts rotating. Then the printer shines a laser beam to the surface of a drum and make a letters and image for printing as the pattern of electric charge. In order to draw the pattern on drum the laser receive the page data (text and images as tiny dots) one horizontal line at a time .

22. Laser Printer The Laser does not move itself; instead, it emits to a movable mirror, the mirror moved and shines the beam through the series of lenses on the surface of drum . After the pattern is set the printer coats negatively charged with toner (Black Powder) . Then the drum rolls over the positively charged sheet of paper. The positive charged sheet attracts the negatively charged toner from the drum it makes print the data to the paper. After the sheet passes through the fuser (heated rollers). The fuser makes the print is permanent. The fuser rollers are non- sticky material (Teflon), thus prevent the collection of toner on the fuser. At last the drum is cleaned and discharged the laser lamp. Then the corona wire reapply the positive charge to drum and prepare for next printing.

23. Laser Printer Laser printers use laser beams to produce an image on a photosensitive drum. A laser printer uses a special ink called toner , which is coated onto the page in the form of whatever you are printing. The page with ink then moves over a very hot metal roller which burns the ink to the page. Advantages are: Very excellent quality output, Very high speed, it can support different fonts of characters, No mechanical movements and hence noiseless Disadvantages: High initial cost, Toner cartridge is to be replaced frequently.

24. Laser Printer Ink Jet The Toner is dry or powder Ink is wet Print Cost is less (comparatively refill less time) Print Cost is high, because printer need refill frequently. Use more electric power because this use thermal energy. Inkjet printer use less power Print quality is very high Quality less than laser Print speed is high Slow

25. Components Of Laser Printer Corona Wire Toner Hopper (Stored Toner ) Discharge Lamp (Erase the pattern) Laser scanning Unit (Lighten and make heat) Fuser (finishing the print job) Photoreceptor (Drum)

26. Characteristics of printers Quality of type Speed Impact or Non impact Graphics Fonts Resolution Speed Colour Memory

27. Quality of Type Only daisy wheel, inkjet and laser printers are produce letter quality result. Speed This measured by character by Character per second (CPS). Daisy wheel is the slowest printer- 30 CPS Line printer is the fastest- up to 3000 lines per second Dot Matrix Printer- 500 CPS and Laser Printer- up to 20 pages per minutes. Impact or Non impact Printer Impact printer make noisy but Non impact printers are noiseless.

28. Print Graphics Capability . Some printers can print only text other some can print both characters and graphics. Support various Fonts. Some printers may support limited number of fonts like dot matrix printer. Another ones have support lot of fonts like laser/ inkjet printer. Main aspects of printer while buying are. Resolution . Measurement of resolution is DPI. General printer will give up to 600 DPI. DPI is also define the print quality.

29. Speed . If you need more print- outs the speed is main aspects while choosing . Color. Some printers may not print the color images/ multi color text . Main aspects of printer while buying are. Memory . Printers have a small memory for store the data for the use of spooling, the user can increase this, this helps to take printout quickly.

30. A plotter is a computer hardware device much like a printer that is used for printing vector graphics. Instead of toner, plotters use a pen, pencil, marker, or another writing tool to draw multiple, continuous lines onto paper rather than a series of dots like a traditional printer. Though once widely used for computer-aided design, these devices may replaced by wide-format printers PLOTTER

31. Advantages of plotters Plotters can work on very large sheets of paper while maintaining high resolution. They can print on a wide variety of flat materials including plywood, aluminum, sheet steel, cardboard, and plastic. Plotters allow the same pattern to be drawn thousands of times without any image degradation. Disadvantages of plotters Plotters are quite large when compared to a traditional printer. Plotters are also much more expensive than a traditional printer.