Color theory and application of laser printer - printer, laser, digital - printing industry
Understand the principle of black and white laser printer is to understand the basis of color printing, you can use several images to illustrate the transformation process of its implementation.
Original variable bitmap. Laser printers will print the page raster image processor into a bitmap, and then converted to electrical signals sent to the laser scanning unit.
Bitmap variable charge of "negative image" in the laser scanning unit, the page bit map image points are converted to laser signal transmission to the imaging drum, corresponding to a bitmap in each pixel, a pixel value of the presence of the emitted laser beam, no value is not fired. Laser emission when the imaging drum to produce a small light point, the imaging drum with a charge in advance, by laser beam irradiation will be discharged to the point, not to the point of exposure is still with the charge, through this process, the page bit Figure on the imaging drum is converted into the charge of "negative image."
Charge "negative image" into a toner, "just as" toner and imaging drum with the same nature of the charge, imaging drum rotation, the charge of "negative image" through the imaging roller, the discharge point will be adsorbed on the charged toner, which is not the point of discharge is not absorbed as homosexual repel toner, so the charge of "negative image" was turned into a toner "As."
Toner "just as" a bitmap into a piece of paper with the image transfer drum rotating drum also was charged through the transfer of paper drum, the toner is adsorbed to the paper as printed images. As the toner come off easily, so printing paper to go through a heating roller so that toner closely adsorbed on paper.
As color laser printers use 4 color toner, so the first charge over the "negative image" and toner, "just as" the formation of steps to be repeated four times, each time on the adsorption of different color toner, the final transfer drum will form a green, products, yellow, black four-color image. It is precisely because there is a color laser printer is repeated four times in steps, so color printing is significantly slower than the speed of black and white print.
The latest color laser printing technology is the so-called "time imaging" technology. The key to this technology is the need to do laser LED is small enough, light tube in an existing location to put the four colors corresponding to the four LED. Currently this technology is too expensive, so a "one-image" of the color laser printer, an ordinary user can afford, but there is no doubt that this is the future direction of development.
TV, film is synthesized by self-luminous colors, its composition law known as the "additive principle", the three primary colors red, green, blue, secondary color as "white." Printing, coating is formed through the absorption of some light color, so the law known as the "subtraction theory" Three color is green, products, yellow, secondary color as "black."
Color laser printer color in the end is how the synthesis of the bargain? HP's technology as an example to do an analysis. ImageRet2400 HP Color Layering Technology is the technology used. Determine if the basic resolution of print 600DPI, 600DPI resolution images can be calculated, the pixel distance between the centers of 42 microns.
HP 5 microns in diameter ultra-fine toner UltraPrecise, in fact, results can be achieved 2400DPI, 2400DPI resolution when the center pixel spacing between about 10 microns. That is, if the final result is 600DPI color printing pixel resolution, then a pixel, you can use 16 × 16 blue, products, yellow and black toner particles together with four blank to modulate the pixel color, as the human eye can no longer distinguish the color of these fine particles, so the human eye to see the total effect is, after blending.
This technology can provide the number of colors in the end, is calculated by permutation and combination in a classic example: a green, products, yellow, black and white colors of the infinite number of five ball-packing in the five jars China is now free to work out from 16 balls into an empty jar, the total will work out how many possible outcomes? Calculate the theoretical value is ImageRet2400 technology to achieve the number of colors, according to manufacturer's argument is that hundreds of thousands.
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