How Does A Laser Printer Work?

In stores on the shelves, you can see different brands’ printers, but they can be divided into two types, inkjet and laser. If with inkjet more or less clear, liquid ink is applied in a drip way, then how the laser printer works, not everyone understands.

 

History of Laser Printing Technology

History of Laser Printing Technology

The laser printer prototype was invented in 1938 by Chester Carlson, who was studying law at the time of his invention and worked as a lawyer in the U.S. Patent Office. The first sheets printed with static electricity were obtained from his home laboratory. At first, he tried to sell his development to IBM. But they refused to buy the invention. It was not until 1946 that Xerox became interested in its scientific development. And in 1949, printers first appeared on the market, which uses dry ink for printing.

The first models were very cumbersome and required a certain level of training from operators. Ten years after the first production of the industrial model, more compact and comfortable devices appeared. The model was called Xerox 914. It was printing at a rate of 7 sheets per minute, which was considered a very high indicator. Simultaneously, the quality of the image was much higher than that of the then-popular matrix printers.

The first laser printer appeared in 1969, all at the same Xerox. In 1978, one of the company’s employees, Gary Starkuezer, managed to invent a laser and install it in the machine. It was the first laser printer device. However, the first model turned out to be too expensive. The price of the device was about 350,000 dollars.

Importantly! Some printer models use a toner with positively charged particles, and the drum is charged not with negative but positive charges.

This difference arose because different companies used their own developments, which were considered the firm’s secret. At that time, little was known about what a laser printer was and how it was designed, but its principles should work were known. When choosing a toner to fill the cartridge, this should be taken into account!

As laser printers’ demand grew in the early 1980s, other companies wanted to make money in this market. Cannon produced the first available model of the device. Xerox eventually lost its position and left the market. Today in the stores of office equipment you can see laser printers of different brands. There were different models, but the device and the principle of the laser printer remained the same.

 

What’s inside

The laser printer consists of a board, a laser head, a printed block – it is built into the stove and electric engine for the rotation of the drum and the cartridge. A laser printer cartridge is a removable replacement part.

A fee is the brain of a printer. Through the board, commands are transferred from the computer to the printer, controlling all the inside the printer, including the laser beam’s direction.

Printed block. The printing block has a complex structure. It combines mechanical elements – gears and levers. Thee drum, rollers of paper, toner, and the printed sheet’s output; thermal – electric-heating strip (oven). Such a printing machine is sometimes called a thermoprinter.

Cartridge. This is the main printed element of the laser printer. The laser printer cartridge device includes several interconnected components.

 

How the cartridge works

The laser printer cartridge consists of a drum, a rubber roller, a magnetic roller, a dosing blade and a box in which the toner falls asleep. On the sides of the cartridge are gears, with the help of which rollers and drum are set in motion. The magnetic roller consists of an external body and a magnetic core. The magnet attracts particles of toner, and the blade aligns them on the shaft’s entire surface.

It’s an interesting fact! A cartridge is a purely mechanical device that is driven. The cartridge has a small chip, but it is only needed to collect information from the computer about the number of pages printed during the printer’s entire time. The chip can be removed – the cartridge will work as before.

Almost all cartridge models support the ability to re-fill with a toner. A cartridge is a replaceable element of a printer. After a while, the photo-drum and magnetic roller come into disrepair. This is accompanied by a deterioration in the quality of printing and white and black stripes’ appearance.

 

Birth imprinting process

Birth imprinting process

The process of how the printer works is as follows:

  1. After receiving a printing command from the computer, the drum begins to rotate. Along with it rotates a rubber roller that charges the photo drum with negative particles.
  2. The laser zeros the charge in the places where the text or drawing should be applied.
  3. Negatively charged particles of the toner get to neutral areas – this is how the image is formed.
  4. With special rollers’ help, a sheet of paper is charged with positive particles that occur during friction.
  5. The drawing or text is transferred due to the difference in charge on paper.
  6. The image is fixed because a special stove, which is located in the printed block, is “baked” in the paper under the influence of high temperature (about 200 degrees Celsius).
  7. The remnants of spent ink are cleaned with a rubber roller; the same roller again charged the drum.

Importantly! Some printers use image transfer tape. The image is formed on it first and then transferred to the photo drum if it is available.

 

Drum charge

Initially, its charge is neutral. However, for the printing process to begin, its surface is charged with negative charges. Do it with a special rubber roller. Charges occur as a result of rubbing surfaces against each other. The surface of the drum is covered with a special photosensitive coating. Therefore, under the influence of a laser, the charge on its surface can change.

 

exposure

The laser is located in front of the laser printer or side. The laser beam hits the photo vai and changes the charge on its surface from negative to neutral (not to be confused with the positive!). Exhibiting (lighting) with laser line layout with high frequency. In older models, the complex focus was done using mirrors and lenses. The scheme of the printer was very complex, and the device itself occupied a large area. Modern printer models are simpler, but they have a higher print quality. They take up little space and can print at high speed – up to 27 pages per minute.

Importantly! The drum is very sensitive to scratches. In places where the photosensitive coating is ripped off, the charge is always neutral. This is reflected in the quality of the print. Black or white stripes appear in these places.

 

The appearance

A mirror image is formed on the surface of the drum. The toner particles are transferred from the magnetic roller to the drum’s surface and stick to it due to the difference in charge. The design of the monochrome and colour printer is different, as the colour printer is more complicated. In colour printing, the image is first formed on the image transfer tape and then only transferred to the drum and paper.

Interesting! If you interrupt the printing and pull the cartridge out of the printer, you can see the drum’s image, but only if you do not touch the surface with your fingers.

 

transfer

Transfer to paper is carried out under the same static electricity. At the same time, the paper does not even touch the surface of the photo urban! Before being allowed to pass under the photo dump, the paper is electrified with rubber rollers’ help. When it passes by the drum, the negative particles from it fly to the paper’s surface, positively charging. On paper, an image is formed, and its surface becomes neutral-charged.

 

Pinning the image

Once the picture or text is transferred to the paper, they must be fixed. Otherwise, the image will be sprinkled as soon as a piece of paper falls into the hands. The toner is fixed on paper with the help of a stove. The stove heats the ink particles; they melt, become liquid, penetrate deep into the paper and instantly harden. A non-fire and unburnable high-definition image is formed.

Importantly! Particles of ink (toner) begin to melt at 180-200 degrees, regardless of whether they melted before or not. Therefore, there is no two-way printing (software) on the laser printer, as printing on the backside leads to a deterioration in the front quality. Besides, caustic, poisonous substances are released into the air, which is part of the toner and paper.

 

How colour laser printing is carried out

The printer for the colour laser printer has a more complex structure, but the printer’s principle is the same for monochrome. This applies not so much to the printing block as to the cartridge, laser and board devices.

Below is a description of how the colour printing process is going:

  1. First, the digital image is processed using specially designed algorithms and transferred to the printer control board.
  2. A laser forms an image on the surface of the drum.
  3. A certain order from different boxes under the toner from individual nozzles is served toner of a certain colour.
  4. Small multicoloured particles of dry ink are applied to the image transfer tape. Under the tape is a photo vai, which attracts particles of toner.
  5. The image is transferred to paper, and the stove bakes the pieces of toner.

The result should be a high-definition image. The printing process on a colour printer will take longer, as boxes with ink move to a particular area on paper eventually acquired the desired colour and shade. The boxes contain blue, yellow, mauve and black ink.

It’s important! Colour photos on a colour laser printer are worse than on an inkjet. This is since on such an image, there are many half-tones, which the device is more difficult to print. But the image of graphs and diagrams is better on the laser, and the colours hold on longer.

Even though there are colour laser printers on sale, they are less in demand than coloured inkjet. The price and complexity of service repel customers. However, with monochrome models, everything is exactly the opposite. High print speed, clarity of image and low maintenance cost (toner is cheap and grabs it for a long time) have made him an indispensable assistant in the office and home.

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