Earlier this week I had an appointment for an interview, but just when I arrived at the venue I realized I forgot an important document at home. Although I was quite lucky that I had a soft copy of the document on my smart phone so I excused myself and tried to locate the closest café to my location so I could print out the document.
I signed with relief once I located the nearest café, Immediately I sent my document to their computer and was ready to print. But then the Printer refused to function and all effort to get it to work was futile. But in that moment I looked at the printer and I just wondered what exactly goes on behind the scene when printing takes place.
This event inspired today’s topic, I would be showing you how inkjet printers function.
It’s almost impossible to walk into a standard organization without seeing some basic machines, one of such machines is a printer which come in different, shapes, sizes and designs, however the technology utilized relatively determines their mode of operation. Printer technology are majorly grouped into two main groups with each having different types within it.
The first group of printer technology is the Impact printers which create images using mechanisms that touch the printing paper. This could either be Dot matrix printers or character printers. In the case of Dot matrix printers, they are designed to utilize small pins that strikes an ink coated ribbon thereby causing ink to get transferred to the paper as the impact takes place. While character printers are designed using balls or series of bar with letters and numbers engraved on their surface such that during printing the letters or numbers required is typically stuck against the ribbon coated with ink, this operate like a computerized typewriter.
The Second group of printer technology is the non-impact printers which creates images without touching the paper. These could either be an inkjet printer, laser printer, solid ink printers, Dye-sublimation printers, Thermal wax printers, Thermal auto chrome printers. However, amongst this list of printers the most popular impact printers used nowadays is the Inkjet and laser printers. In the case of an inkjet printer the paper is sprayed with drops of inks directly using series of nozzles. While the laser printers utilize toners, static electricity and heat to print images.
Today we would be focusing on the operations of inkjet printers
An inkjet printer is simply a type of printer that creates images on paper using small droplets of ink. The dots created by the ink are relatively small, tiny and they are placed on the paper with immense precision. For the printer to create quality images these dots used will be a combination of different colors.
Inkjet printer have dominated the printing scene for decades, and over the years with the ever growing advancement in technology the performance of inkjet printers has greatly improved and have become more efficient while still being quite affordable.
Let’s take a brief look at the major components
The heart of an inkjet printer is the print head which is made up of a number of nozzles which are utilized by the printer to spray drops of ink on the paper. There is also ink cartridges located within the printer where the ink is stored. These cartridges are designed with different specifications by manufactures to suit specific needs. Some printers are designed with different cartridges for black and other colors while others have just a single cartridge that houses both black and other colors or some others have a cartridge for each color. For printing to effectively take place there is a print head stepper motor that basically stirs the ink cartridge and the print head over the paper in a back and forth direction. Adequate connection between the stepper motor and the print head assembly is facilitated using a belt for proper attaching and a stabilizer bar for controlled and precise movements.
The Paper feeder are designed to open at an angle behind the printer for users to load paper into it although they cannot hold so much paper at the same time. Once the paper has been placed in the paper feeder there are a set of rollers within the printer that drags the paper in and moves the paper once the print assembly is ready for printing. For effective printing to take place there are paper feed stepper motor in place to ensure that progressive image is printed and the paper is moved sequentially. There is also an inbuilt control circuitry that is responsible for controlling the mechanical operations within the printer and adequately decodes data sent by the computer to the printer. Latest Inkjet printers make use of USB port as their interface port while others utilize parallel ports or serial ports.
Next let’s take a look at the two main ways droplets of ink are formed in an inkjet printer.
Thermal bubble: in this case the printer utilizes tiny resistors which are used to produce heat, this would be used to create a bubble after it has vaporized the ink. Once the bubble begins to expand, ink is transferred to the paper from the nozzle, however when the bubble eventually collapses then a vacuum is produced which ultimately drags some amount of ink directly from the cartridge straight into the print head. These tiny nozzles are numerous and can produce droplets of ink simultaneously and typically a print head can have about 300 to 600 nozzles.
Piezoelectric: just as the name implies it utilizes piezo crystals which are positioned directly behind the ink reservoir of each nozzle. So it functions simply by vibration, such that the crystal gets a small amount of electric charge which ensures it vibrates. The printer is designed such that when the crystal can vibrate inward or outwards, a small amount of ink is forced out while ink is pulled in to replenish the ink sprayed respectively.
Let’s take a look at what goes on behind the scene
Immediately you turn on your inkjet printer and then push the click button, this is what happens,
The Printer driver receives the information that is to be printed from the computer software program through the connection interface which could either be a USB or parallel interface, this driver is responsible for converting the information sent into a readable format for the printer then it ensures the printer is online and ready to print.
As soon as the data is received by the printer it immediately stores some data in a buffer. This buffer is a Random Access Memory that could range from 512Kb to about 16MB, typically it differs depending on the specification of the printer. The buffer facilitates the speedy operation of the printer such that it holds documents regardless of how complex or simple, this ensures the printer is not delayed by waiting for printing of the actual page before other information are processed.
For cases where the printer has not been used in a while, the print head is cleaned in a short clean cycle process before the printer indicates its ready to commence printing. At this point the paper feed stepper motor is immediately activated by the control circuitry, so the rollers automatically start operating and then feeds the paper on the paper tray straight to the printer. For the printer to accurately alert the user when there is no longer paper on the paper tray, there is a trigger mechanism in the tray that is put in place such that when the trigger is depressed there is paper in the tray however when the trigger isn’t depressed there is no more paper on the tray and the printers sends alert to the computer and then an LED light gets turned On.
As soon as the paper makes its way into the printer at the page’s beginning, the print head assembly is moved across the page by the print head stepper motor sequentially while dots of ink are sprayed on the pages by the print head sprays, then the paper keeps moving slightly and stopping as each dots are made and this process continues. This whole process is so fast that its almost similar to a continuous process such that once the print head gets to the end of a complete pass, it either changes direction and starts to move back across the page while it prints or the print head simply resets to the initial portion of the page and resumes printing.
For the printer to ensure other colors are visible, CMYX colors are sprayed with utmost precision. This whole process continues till the page is completely printed, after printing is completed the print head is parked and the roller pushes the printed page straight to the output tray. However, the time taken for a page to get printed varies depending on the specification of the printer and the size and page complexity of the images. For instance, it could take a printer 1minute to print 16 pages of black text but for it to print just one colored page size d image might take a few minutes. To avoid smudging most printers utilize fast drying ink so the users can immediately make use of the printed documents.
With the advancement of technology Inkjet printers have improved immensely over the years and have become faster, capable and more versatile while still remaining quite affordable. Different technologies are utilized for printing, so it’s imperative that when refiling cartridges, the refill kit must be compatible with that of your printer because different manufacturers have distinct ink composition, so using the wrong type of ink would ultimately degrade the output of the printed document or in some extreme cases damage the printer.
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