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Dots Per Inch (DPI) Resolution The True Measure Of Print Quality

DPI resolution. Imagine a laser print on paper that is one square inch in size. Under a resolution size of 1200 DPI x 1200 DPI , the printer’s scanner can accurately pack 1200 dots on a single horizontal row that is 1 inch wide. Depending on how fast paper or media moves, 1200 dots in a single column file (also1 inch in length) can be generated vertically as well. The finished print is sharp, smooth and no longer grainy because of the 1,440,000 (1,200 multiplied by 1,200) dots that comprise the 1 square inch image. Images set with high Dot Per Inch (DPI) resolution differ from a 300 x 300 DPI or a 600 x 600 DPI (lower resolution sizes) image because dots generated are far in between that reduces print intensity, resulting to images that are dull and absurdly grainy. The process of converting images into a raster graphics image composed of dots forms part of the electro-photographic (EP) printing process.

Electro-Photographic Printing Process. Images coming from the server are converted into a raster graphic image represented by dots and then projected unto the rotating Organic Photo-Conductive (OPC) Drum. Toner powder is literally sprayed into the dots formed on the OPC Drum where media moving along the paper path force toner particles to cling to its surface and complete image resolution. Thereafter, the material moves into the fuser assembly to properly bond toner powder to paper fibers before moving out of the exit rollers as a finished, hard copy document.

Before EP printing can commence, the OPC Drum surface should be set with a positive polarity because the dots projected by the scanner carry a negative charge. Toner powder inherently carry a positive charge. Therefore, only negatively charged dots will electro-statically allow toner powder to cling; thus completing the latent image created unto the OPC Drum. This is where the toner’s physical properties and quality comes in. Conventional, jet-milled toner powder particles have jagged edges that reduce the possibility of particles to roll over freely unto the negatively charged dots.

During the early years of EP printing, toner powder particles manufactured range from 8 to 12 microns resulting to print quality that is grainy, rough and easily flakes out. The advent of chemical toner powder produced by way of Emulsion Aggregation (EA) Technology produced toner particles that are smaller than 3 microns in size and practically with conical or spherical edges; improving toner adhesion and therefore reducing waste. Said toner technology made it possible for DPI resolution to reach the 1,200 DPI plateau when it used to hover only between 300 to 600 DPI under the a conventional jet-milled toner.

Dots per inch (DPI) resolution dictates printout quality. As such, it is not only OEM toner powder that can produce high resolution prints since high quality compatible toner produced by third party manufacturers and packaged in toner refill kits can likewise deliver similar print quality as the OEM toner when loaded to a high DPI resolution laser printer. In the end, the true measure of print quality is DPI or dots per inch resolution.

Photo by Maarten De Wispelaere

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