1. 4/19 Inkjet Printers. Roll call Video (10 seconds) Lecture: –inkjet printers

2. Inkjet Printers: the parts Paper feeder & tray The print head The ink cartridge(s)

3. Inkjet Printers: the parts Paper feeder & tray The print head The ink cartridge(s) Image courtesy of http://www.hp.com

4. Inkjet Printers: the parts Paper feeder & tray The print head The ink cartridge(s) Image courtesy of http://www.hp.com

5. Inkjet Printers: the parts Paper feeder & tray The print head The ink cartridge(s) –ink reservoir –nozzles –circuitry Image courtesy of http://www.hp.com

6. The Ink Cartridge. The ink cartridge(s) –nozzle –firing chamber –thin-film resistor –path from reservoir Cross-section of a nozzle.

7. How the ink gets out. 2 ways: –Thermal method –Epson piezo-electric method

8. How the ink gets out: thermal method. Used by Hewlett Packard & Canon A thin-film resistor is heated by electric current. The resistor heats up the ink that is next to it. Nozzle Firing Chamber Resistor

9. How the ink gets out: thermal method. The ink- now gaseous - expands, forming a bubble. The bubble pushes out the rest of the ink in the firing chamber. Nozzle Firing Chamber Resistor

10. How the ink gets out: thermal method. The resistor cools, causing the bubble to shrink. The shrinking creates a vacuum, which draws new ink from the reservoir. Nozzle Firing Chamber Resistor

11. Or, the piezo-electric method. Instead of a resistor that heats up, Epson uses a piezo crystal. A piezo crystal flexes when a current is applied. This pushes the ink out. Nozzle Firing Chamber Piezo crystal

12. Advantages of the piezo. Ink doesn’t have to be heat resistant. Piezo’s flex can be controlled to put more or less ink on the page. Nozzle Piezo crystal Firing Chamber