The principle of working a laser printer is not as complicated as it might seem to an ordinary user who has not previously delved into the workings of office equipment. This article will take a closer look at what the device consists of and how it works a laser printer. A detailed scheme of the “laser” working will help in this. We will separately consider what a cartridge is and what makes it print, which does 80% of the work of the entire mechanism.
Parts of a laser printer
You can buy a model for any need with a minimum or an extensive set of different functions in stores. But at the heart of every laser printer is the same technology and operating principle. The basis is photoelectric xerography, and inside the device can be divided into several large parts.
- Laser scanning mechanism. The unit consists of a large number of lenses and mirrors. All of them can rotate to eventually apply the desired image to the surface of the drum. The application itself takes place with a special laser only in the right places. It turns out an invisible picture because the surface charge changes, and it is unrealistic to see it with the naked eye. A controller with a raster processor controls the operation of the scanning mechanism.
- Unit for transferring the image to paper. The second unit consists of a cartridge and a charge transfer roller. The cartridge itself is a rather complex mechanism, including an imaging drum, a charge shaft, and a magnetic one. It is the fotoval that can change its charge under the influence of the laser.
- The node in which the final fixing on the paper takes place. When the toner from the photocylinder hits the paper, it is immediately placed in the printer’s oven, where it melts under high temperature and is fixed on the surface of the sheets.
Data exchange and “communication” between different printer nodes occur using an interface unit.
- In most cases, laser devices use powder dyes that are initially positively charged. Therefore, the laser will “paint” the image negative, due to which the toner will be attracted to the surface of the photo gallery. This option is used in equipment from Xerox, HP, Canon. This allows you to maximize the detail of the drawing on paper.
- In the technique of the Brother, Epson, and Kyocera brands, a different method is used. The toner has a negative charge, and the laser does not change the charge of the areas where the dye will fall in the future, but, on the contrary, the places where it will not be. This option allows you to achieve a more uniform distribution of the dye on the paper on the paper.
- Some “processing” also occurs with the paper after it enters the printer. Its property is changed using the transfer roller. And to be precise, the static charge is simply removed after using the neutralizer. This prevents it from being attracted to the photo value in the future.
- Toner powder contains substances that melt easily at high temperatures and reliably adhere to the paper. Laser prints are not erased and keep well for a long time.
Cartridge Print device
The main element of any printing device is the cartridge. It can be a conventional one, consisting of two hoppers, toner and waste, and a photo cylinder. There are also drum cartridges. Their design allows it to be divided into toner and photocell.
What’s the difference between drum and toner cartridges
One of the compartments contains toner. This is a special fine-grained powder in black or magenta, yellow and blue for a color printer. The substance has specific physical properties, and from different manufacturers, they differ in grain size, magnetization, and dispersion. Therefore, there is no universal dye that fits all printer models.
The cartridge looks something like the picture below. The appearance may differ depending on the model. But the printing principle of a laser printer remains the same regardless of the design.
Consists of the following parts:
- Toner hopper that stores powder while waiting for its time to be used for printing.
- The magnetic roller through which the toner is transferred from the storage location to the photocell.
- The metering blade controls the thickness of the powder layer that is applied to the drum surface.
- The squeegee cleans the drum after it comes into contact with a sheet of paper after transferring ink to the paper from its residues.
- The charge roller charges the surface of the photo roll.
- Waste powder compartment.
- Some models are equipped with chips. These are small micro-boards for collecting information about the number of printed sheets. The chip can be replaced if needed.
Almost all the main elements deteriorate over time, but can be replaced, as they are consumables. The cartridge itself can be refilled many times until the gears and housing elements are completely worn out.
Scheme and principle of operation
The photocylinder of the laser cartridge is coated with a special sensitive green or blue layer. Less common, but there are other shades. Depending on the laser printer manufacturer, the charge transferred to the shaft can be positive or negative. The process itself can be carried out in two ways.
A special tungsten filament (corotron) is used, coated with carbon, as well as gold or platinum particles. To charge the drum, a magnetic field is created by applying a high voltage to the filament. The main disadvantage of this element is constant pollution, which leads to a deterioration in the display of a picture or text already on paper.
The charge roller does the job better (does not leave dirt on the paper over time) than the corotron. It serves the same function. Visually it looks like a metal shaft covered with an electrically conductive substance. These are mainly unique rubber or foam rubber. The transfer of charge occurs during contact with the photo value. The resource of the roller is much less than that of the coronation.