-From the functional structure, the laser printer is divided into two parts: the print engine and the print controller. The printing engines of laser printers are provided by a few engine manufacturers such as Canon, Minolta, Xerox, Brother, Samsung and Hitachi. The printer manufacturer buys or customizes the print engine from the engine manufacturer, and designs the controller and print driver according to the engine, thus completing the design and production of the whole printer. This is the reason why the laser printer field has formed a two-level market of printing engine and printer.
-In the laser printer, the role of the printer controller is to communicate with the computer through the interface or network, receive the control and printing information sent by the computer, and transmit the printer status to the computer. The print engine transmits the received print content to the printing paper under the control of the print controller. Therefore, the performance and quality of print controller and print engine affect the performance and quality of the whole printer, which is also an important reason for the performance difference of laser printers with the same engine in the market at present.
-All print controllers are fully functional computers, which basically include four basic functional modules: communication interface, processor, memory and control interface. Some high-end models are also equipped with mass storage such as hard disks. The communication interface is responsible for data communication with the computer; The internal memory is used for storing the received printing information and bitmap image information generated by interpretation; The control interface is responsible for controlling the laser scanner, motor and other components in the engine, and controlling the input and output information of the printer panel; The processor is the core of the controller, and all data communication, image interpretation and engine control work are completed by the processor.
-The configuration and performance requirements of the print controller are different due to the different control methods and control languages adopted by the printer. For example, for printers using PCL and PostScript languages, the standard page description language is used to transmit printing information between the computer and the printer. In a printer, the printing information described in standard language received from a computer should be interpreted as raster bitmap image information that can be received by a printing engine. The performance and memory size of the print controller will directly affect the performance of the whole printer, so such a printer requires very high speed and memory size of the processor in the print controller.
-GDI printers are different from printers that use page description languages. In the process of printing, the interpretation of printed content to raster bitmap image information is completed in the computer and directly transmitted to the printer. Therefore, the print controller in the printer mainly stores the received raster bitmap image and controls the print engine to finish printing. Because there is no need to undertake complex image interpretation work, GDI printers have relatively low performance requirements for print controllers.
The structure of the printing engine is shown in the attached figure, including a laser scanner, a reflective prism, a photosensitive drum, a toner box, a thermal transfer unit and a paper feeding mechanism.
-During the operation, the raster bitmap image data in the print controller is converted into laser beam information of the laser scanner, the photosensitive drum is charged through the reflective prism, so that the image information on the surface of the photosensitive drum is completely consistent with the printed image, and then the toner particles in the toner box are adsorbed to form a toner image on the surface of the photosensitive drum. The printing paper is negatively charged by the charging unit before contacting with the photosensitive drum. When the printing paper passes through the photosensitive drum, the toner image of the photosensitive drum is transferred to the printing paper due to the mutual attraction of positive and negative charges. After being heated by the thermal transfer unit, the carbon powder particles are completely absorbed by the paper fibers, thus forming a printed image.
The basic structure of color laser printer is the same as that of black-and-white laser printer, and the printer controller, interface, control mode and control language are completely the same, so the data transmission, data interpretation and printing control processes are basically the same.
-As for the print controller, since the printed content contains color information and the same page is printed, the data generated by the computer on the color laser printer is much larger than that of the black-and-white laser printer, which puts higher demands on the performance of the print controller. Therefore, the speed of the internal processor of a general color laser printer is higher than that of a black-and-white laser printer, and the configured memory is also larger than that of a black-and-white laser printer.
At present, the more popular printing languages of color laser printers are PCL and PostScript. In recent years, with the application of color laser printers in general business office, these users are not as strict with the accuracy of graphics and colors as some professional users, so GDI mode has also been applied in some low-end color laser printers. With the improvement of PC performance, GDI mode has less and less influence on printer performance, but it can greatly reduce the cost of color laser printers, and also make the price of color laser printers begin to decline, laying the foundation for the popularization of color laser printers.
The biggest difference between a color laser printer and a black-and-white laser printer is the engine structure. The color laser printer uses four-color toner C (cyan and blue) M (magenta and magenta) Y (yellow and yellow) K (black and black) to realize full-color printing. Therefore, the color of a page of color content should be reconciled by CMYK, and the printing of a page of content should be done by four-color toner CMYK. Theoretically, a color laser printer should have four sets of mechanisms exactly the same as a black-and-white laser printer to realize the color printing process.
-In order to simplify the mechanism and save the cost, at present, color laser printers mostly adopt four-color drum separation in structure, while others, such as paper feeding mechanism, photosensitive drum and fixing unit, adopt four-color 1 set system. Therefore, in the printing process, the printing paper has to go through four identical processes in the engine, and only one color toner is transferred in the four processes, which is also an important reason why the color printing speed of most color laser printers is generally one quarter of the black-and-white printing speed. There are two kinds of photosensitive units used in color laser printers, one is the photosensitive drum method used in black and white laser printers, and the other is the photosensitive belt method.
-Because all colors except CMYK are mixed with toner of these four colors, there should be a four-color mixing process before fixing in the workflow of color laser printer. In order to achieve better color harmony, color laser printers use blending oil (also known as fixing oil, generally using silicone oil). In the use of blending oil, the products of different manufacturers are different. Most color laser printers have a separate blending oil box, and blending oil is added to the medium at the same time of fixing, which is also an important reason why most color laser printers print oil. Some color laser printer products, such as HP's ColorLaserJet 4550 and ColorLaserJet 8550, adopt another hybrid technology. Instead of a separate blending oil box in the machine, the blending oil and the toner box are combined into one, and a blending oil particle is wrapped in the middle of each tiny toner particle, which not only simplifies the internal structure of the machine, but also greatly reduces the oil feeling in the printed content.
Structure diagram of color laser printer
-According to the structure of the color laser printer, the consumables (parts that need to be replaced regularly) of the color laser printer are: four color toner cartridges, 1 photosensitive drum or photosensitive belt, 1 charging unit, 1 fuser, 1 blending oil cartridge, 1 waste ink bottle.
However, compared with color inkjet printer, the service life of color laser printer consumables is very long, which greatly reduces its single-page printing cost.
At present, inkjet printers can be divided into piezoelectric inkjet technology and thermal inkjet technology according to the working mode of print head. According to the material characteristics of inkjet, it can be divided into water-based materials, solid ink and liquid ink printers. Let's explain it separately. Piezoelectric inkjet technology is to place many small piezoelectric ceramics near the nozzle of the inkjet printer, and apply voltage to them in time by using the principle that they will deform under the action of voltage. The piezoelectric ceramics expand and contract, so that the ink in the nozzle is ejected and a pattern is formed on the surface of the output medium.
The cost of inkjet print head made by piezoelectric inkjet technology is relatively high, so in order to reduce the use cost of users, the print head and ink box are generally made into separate structures, and it is not necessary to replace the print head when replacing ink. This technology was originally created by Epson, because the structure of the print head is reasonable, and the size and usage of ink droplets can be effectively adjusted by controlling the voltage, so as to obtain higher printing accuracy and printing effect. It has a strong ability to control ink drops and is easy to print with high precision. Now the ultra-high resolution of 1440dpi is maintained by Epson. Of course, it also has shortcomings. Assuming that the nozzle is blocked during use, the cost of dredging or replacing it is relatively high and it is not easy to operate. Maybe the whole printer will be scrapped. At present, the products using piezoelectric inkjet technology are mainly inkjet printers of Epson company. Thermal inkjet technology is to let ink pass through a tiny nozzle. Under the action of strong electric field, some ink in the nozzle pipeline will vaporize to form bubbles, and the ink at the nozzle will be sprayed onto the surface of the output medium to form patterns or characters. So this kind of inkjet printer is sometimes called bubble printer. The nozzle manufactured by this technology has mature technology and low cost, but the electrode in the nozzle is always affected by electrolysis and corrosion, which will have a lot of influence on the service life. Therefore, the print head using this technology is usually manufactured together with the ink cartridge, and the print head is updated while replacing the ink cartridge. In this way, users don't have to worry too much about nozzle blockage. At the same time, in order to reduce the use cost, we can often see the situation of injecting ink cartridges (filling ink). After the print head finishes printing ink, fill the special ink immediately. As long as the method is proper, you can save a lot of consumables. The disadvantage of thermal inkjet technology is that the ink will be heated during use, and the ink is prone to chemical changes at high temperature and its properties are unstable, so the authenticity of the printed color will be affected to some extent. On the other hand, because ink is ejected through bubbles, the directionality and volume of ink particles are difficult to grasp, and the edges of printed lines are easy to be uneven, which affects the printing quality to some extent, so the printing effect of most products is not as good as that of piezoelectric technology products.
There are many products using thermal inkjet technology, mainly used by Canon, Hewlett-Packard and other companies. Solid-state inkjet printer is Tektronix's patented technology. The phase change ink it uses is solid at room temperature. When working, the wax-like pigment block is heated and melted into liquid, and then it works according to the above-mentioned inkjet method. The advantage of this printer is that the pigment has good water resistance, and there is no problem that the print head is blocked due to the drying of ink. However, at present, the production cost of printers using solid ink is relatively high, and there are few products. Inkjet printer is divided into two parts: mechanical part and circuit part. We mainly look at the mechanical parts, which usually include ink cartridges and nozzles, cleaning parts, font machines, paper feeding mechanisms and sensors. There are two types of ink cartridges and nozzles, one is a two-in-one structure, and the other is a split structure. These two methods have their own advantages. Cleaning system is the maintenance device of nozzle. Word carriage machinery is used to realize printing position positioning. It provides a paper conveying function for the letter delivery mechanism, and it must cooperate with the letter delivery mechanism to complete the printing of the whole page. The sensor is specially designed to check the working conditions of various parts of the printer. Canon BJC-6000 In order to facilitate everyone to have a more comprehensive understanding of inkjet printers, we have specially summarized the following main performance indicators reflecting performance differences for your reference when purchasing. L. Resolution DPI is an important standard to measure printing quality in the industry. It itself shows the number of dots that an inkjet printer can print in an inch. When printing in monochrome, the higher the dpi value, the better the printing effect. When printing in color, the situation is more complicated. Generally, printing quality is affected by dpi value and color coordination ability. Because the black-and-white printing resolution and color printing resolution of general color inkjet printers may be different, you must pay attention to what kind of resolution the merchant tells you when buying, and whether it is the highest resolution. Generally, you should choose an inkjet printer with at least 360DPI. 2. Color harmony ability For users who use color inkjet printers, the color harmony ability of printers is a very important indicator. When traditional inkjet printers print color photos, if they encounter transition colors, they will choose a close combination of three basic colors for printing. Even if black is added, this combination can't exceed 16, and the color scale performance is not satisfactory. In order to solve this problem, early inkjet printers used the method of adjusting the density of spray points to represent the color scale. However, for the products with a color resolution of only about 300dpi at that time, the result of adjusting the density is that the transition color effect is very poor and there will be many spots. At present, color inkjet printers, on the one hand, make the printed dots finer by increasing the printing density (resolution), thus making the picture more delicate; On the other hand, they all improved their own technology in color harmony, such as increasing the number of colors, changing the size of ink droplets, and reducing the basic color density of ink cartridges. Among them, increasing the number of colors is the most effective at present. Usually, five-color ink cartridges are used, and the original black ink cartridges form so-called six-color printing. The number of tones obtained by this arrangement and combination is improved many times at once, and the effect is obviously improved.