impact and non impact printers

inkjet
laser

1. COMPUTER SCIENCE Chapter 5 INPUT AND OUTPUT DEVICES

2. PRINTERS IMPACT PRINTERS NON IMPACT PRINTERS

3. PRINTERS A device used for printing is known as printer It receives information from computer and print it on paper All printing devices have a paper transport that automatically moves the continues forms or single sheets as printing progresses

4. IMPACT PRINTERS.  Impact printers  are  printers  which works by creating a direct contact between ink ribbon and paper. These  printers  are noisy yet popular .   Impact printers  have mechanical moving parts to conduct printing. Examples: line   printers. Dot-matrix printers Daisy-wheel   printers

5. NON IMPACT PRINTERS A non - impact printer  prints characters and graphics on a piece of paper  without  striking the paper. Some of these  printers  use spray ink while others use heat and pressure to create images. These  printers  are faster than  impact printers . The three main  types  of  non impact printers   are Thermal   printers Laser and Ink Jet  Printers .

6. INKJET PRINTERS An inkjet printer is a computer  peripheral  that produces  hard copy  by spraying ink onto paper. A typical inkjet printer can produce copy with a  resolution  of at least 300 dots per inch (  dpi   ). Some inkjet printers can make full color hard copies at 600 dpi or more. Many models include other devices such as a  scanner  ,  photocopier  , and dedicated  fax  machine along with the printer in a single box.

7. INKJET PRINTERS INKJET PRINTERS are essentially made up of: • a print head which consists of nozzles which spray droplets of ink on to the paper to form characters • an ink cartridge or cartridges; either a group of cartridges for each colour ( blue, yellow and magenta) and a black cartridge or one single cartridge containing all three colours + black • a stepper motor and belt which moves the print head assembly across the page from side to side • a paper feed which automatically feeds the printer with pages as they are required.

8. NOZZLE When referring to a non-impact printer, like an inkjet printer, a nozzle is a small hole found on a  printer cartridge's print head. Nozzles can be smaller than a human hair. Each  nozzle produces millions of ink droplets used in creating the images and text generated by the printer.

9. STEPPER MOTOR Stepper motors are used in printers, disk drives, and other devices where precise position control is required. Stepper motors do not turn continuously like DC motors. They move in steps such as 1.8 degrees. There are several types of stepper motors such as unipolar and bipolar.

10. Ink Droplets Technologies Thermal Bubble https://www.youtube.com/watch?v=QNIeVR8luOA Piezoelectric https :// www.xaar.com/en/about/technology- overview /

11. THERMAL TECHNOLOGY Thermal technology is the technology of producing, storing, controlling, transmitting, and getting work from heat energy. Whenever the amount of energy in one place or form diminishes, the amount in other places or forms increases by the same amount .

12. The process of droplet ejection in a thermal bubble inkjet system: (a) initial state (b ) DC voltage applied across the piezo electric material and a droplet is ejected (push ) (c ) DC voltage is removed (pull).  

13. PIEZOELECTRIC TECHNOLOGY   Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word Piezoelectric is derived from the Greek pieze in , which means to squeeze or press, and piezo, which is Greek for “push”. Piezoelectric  inkjet printing, generation of high voltages, electronic frequency generation, microbalances, to drive an ultrasonic nozzle, and ultrafine focusing of optical assemblies.

14. LASER PRINTERS

15. LASER PRINTERS What is a laser printer? A  laser printer  is a popular type of personal computer  printer  that uses a non-impact (keys don't strike the paper), photocopier technology. When a document is sent to the  printer , a  laser  beam "draws" the document on a selenium-coated drum using electrical charges .

16. How a laser printer works. ... It makes a laser beam scan back and forth across a drum inside the printer, building up a pattern of static electricity. The static electricity attracts onto the page a kind of powdered ink called toner. Finally, as in a photocopier, a fuser unit bonds the toner to the paper.

17. What printers are laser printers? Laser printers are machines that melt toner powder onto paper to create a print. Laser printers are more expensive than inkjet printers upfront and uses pricier toner cartridges but is still a more economical option in the long run with its overall lower cost per page, faster print speeds.

18. What is the advantage of laser printer over inkjet? The main advantages of laser printers are speed, precision and economy. A laser can move very quickly, so it can "write" with much greater speed than an ink jet. And because the laser beam has an unvarying diameter, it can draw more precisely, without spilling any excess ink.

19. PRINTING PROCESS STAGES Ink Jet Printer 2.Laser Printer

20. PRINTING PROCESS STAGES Ink Jet Printer The data from the document is sent to a printer driver. The printer driver ensures that the data is in a format that the chosen printer can understand A check is made by printer driver to ensure that the chosen printer is available to print

21. PRINTING PROCESS STAGES Ink Jet Printer The data is sent to the printer and it is stored in a temporary memory known as a printer buffer A sheet of paper is then fed into main body of the printer Sensor detects whether paper is available in the paper feed tray –if it is out of the paper then the error message is send back to the computer

22. PRINTING PROCESS STAGES Ink Jet Printer As the sheet of paper is fed through the printer, the print head moves from side to side across the paper printing the text or image ; the four ink colours are sprayed in their exact amounts to produce the desired final colour . At the end of each full pass of the print head, the paper is advanced very slightly to allow the next line to be printed; this continues until the whole page has been printed

23. PRINTING PROCESS STAGES Ink Jet Printer If there is more data in the printer buffer, then the whole process from stage 5 is repeated until the buffer is finally empty Once the printer buffer is empty, the printer sends an interrupt to the processor in the computer; this is a request for more data to be sent to the printer; the whole process continues until the whole of the document has been printed

24. PRINTING PROCESS STAGES Laser Printer If there is more data in the printer buffer, then the whole process from stage 5 is repeated until the buffer is finally empty Once the printer buffer is empty, the printer sends an interrupt to the processor in the computer; this is a request for more data to be sent to the printer; the whole process continues until the whole of the document has been printed

25. PRINTING PROCESS STAGES Laser Printer The data from the document is sent to a printer driver. The printer driver ensures that the data is in a format that the chosen printer can understand A check is made by the printer driver to ensure that the chosen printer is available to print (e.g. is it busy, is it off line, is it out of ink, and so on)

26. PRINTING PROCESS STAGES Laser Printer The data is then sent to the printer and it is stored in a temporary memory known as a printer buffer The start of the printing process involves a printing drum being given a positive charge; as this drum rotates, a laser beam is scanned across it removing the positive charge in certain areas; this leaves negatively charged areas which exactly match the text/images of the page to be printed

27. PRINTING PROCESS STAGES Laser Printer The drum is then coated with positively charged TONER (powdered ink); since the toner is positively charged, it only sticks to the negatively charged parts of the drum A negatively charged sheet of paper is then rolled over the drum

28. RINTING PROCESS STAGES Laser Printer The toner on the drum now sticks to the paper to produce an exact copy of the page sent to the printer To prevent the paper sticking to the drum, the electric charge on The paper is removed after one rotation of the drum

29. PRINTING PROCESS STAGES Laser Printer The paper finally goes through a fuser which is a set of heated rollers ; the heat melts the ink so that it fixes permanently to the paper At the very end, a discharge lamp removes all the electric charge from the drum making it ready to print the next page

30. Applications of inkjet printers Inkjet printers  are closely related to the advertising industry and are widely used, such as posters, car stickers, personalized decorative painting Inkjet printers have great advantages in realizing the printing output of high-precision advertising images both inside and outside the homes , etc http://www.subli-star.com/application-inkjet-printers-various-fields/

31. Applications of Laser Printers Businesses use  laser printers  almost exclusively because they have the reputation of being reliable while making a quality print product . Some common  uses for  laser printers   include  printing company stationery, making labels, and creating company fliers and brochures . http://hyperphysics.phy-astr.gsu.edu/hbase/optmod/lasapp2.html

32. ASSIGNMENT Activity 5.8 Find out how the operation of color laser printers differs from the operation of monochrome laser printers. Find out how stepper motors work in disk drive .

33. Thank You