Analysis of laser printers
The laser technology appeared in the 1960s, truly putting practical applications began in the early 1970s. The earliest laser emitter is an electronic laser tube with a helium-neon (HE-ne) gas, which is very limited in practical applications. In the late 1970s, the semiconductor technology was mature. The semiconductor laser is born, and high sensitivity photosensitive materials are constantly discovering, coupled with the development of laser control technology, laser technology is rapidly mature, and enters practical application. The researchers represented by the United States, Japan, combined with laser technology and computer technology, and semiconductor laser printers were developed in combination with laser technology and computer technology. This type of printer has a good print quality, fast speed, no noise, so it has been widely used.
In the early 1990s, the laser printer produced by HP and Japan Canon Company, the printing speed can reach 8 pages per minute, the printing accuracy is 600dp1. Among them, HP's resolution enhancement technology (Resolution
Enhancement
TECHNO1OGY) and PCL printer language have become world standards. Laser printer can be divided into three categories according to its printout speed: low-speed laser printer (output 10 ~ 30 pages per minute); medium-speed laser printer (40 to 120 pages per minute); high-speed laser printer (130 per minute) 300 pages. Now the laser printer still occupies the main market with HP, Canon, Epson, in addition, LEXMARK, Xerox, Panasonic, 理 光 and other series. In recent years, Lenovo Company and Fang Zheng Company have also produced applicable laser printers and also occupy some market share.
Given that the laser printer is very widely used, most users are not in line for repair and troubleshooting, in order to make many intelligence to better understand and use laser printers, I feel in many years, for the nature of the laser printer , Structural and working principles, etc., which are greatly helpful for excluding the fault of laser printers. Therefore, the structure, principle, and the like of the laser printer are summarized as follows, for reference. First, the basic structural laser printer is composed of a laser, an acoustic modulator, a high frequency drive, a scanner, a synchronizer, and a light deflector, and its function is to modulate the binary point information sent by the interface circuit in the laser bundle. Then scan onto the photoconductor. The photoreceptor forms an electrophotographic transfer system with the photographic mechanism to transfer the graphic image of the photosensitive drum to the printing paper, and the principle is the same as the printer. The laser printer is a non-hitting output device combined with laser scanning techniques and electronic imaging techniques. Its model is different, the print function is also different, but the working principle is basically the same, it must pass: charging, exposure, development, transfer, power generation, cleaning, fixing seven steps, and five steps are surrounding the photosensitive drum of. When the text or image to be printed is input into the computer, it is pre-processed by the computer software. The printer driver is then converted to a printer to identify the print command (printer language) to the high frequency drive circuit to control the opening and closing of the laser emitter, form a dot matrix laser beam, and then scanned the mirror The photosensitive drum in the axial scan exposure is performed, and the longitudinal scan is achieved by its own rotation of the photosensitive drum. The photosensitive drum is a photosensitive device with a characteristic of light. The surface of the light guided coating is uniformly charged by the charging roller before scanning exposure. When the laser beam is scanned onto the photosensitive drum in a dot matrix, the distal point is exposed, and the charge is quickly released by the conductive group. No exposure is still maintained, so that a potential difference image (electrostatic latent image) is formed in the surface of the photosensitive drum, when the photosensitive drum rotating the static latent image is rotated to the position carrying the toner magnetic roller. The toner with opposite charge is adsorbed to the surface of the photosensitive drum forming a toner image.
When the photosensitive drum carries the toner image continues to rotate, when the image transfer device is reached, a printing paper is simultaneously sent to the middle of the photosensitive drum and the image transfer device, at which point the image transfer device is cast a strong voltage on the back of the printing paper. When the toner on the photosensitive drum is attracted on the print paper, and then feed the printing paper carries the toner image to the high-temperature fixing device to warm, press the hot melt, and the toner is immersed in the printing paper, and finally output It is a print text or image. Second, the basic principle The composition, design structure, control method, and components used in the working process of the laser printer work process will be different due to the different manufacturers and models, such as: 1 to the polarity of the photosensitive drum different. 2 The components used by the photosensitive drums are different. Some models use electrode wire discharge to charge the photosensitive drum, and some models are charged using a charging rubber roller (FCR) to charge the photosensitive drum. 3 The components used in high pressure transfer are different. 4 Different forms of photosensitive drum exposure. Some models use scanning mirrors to scan the photosensitive drums directly, and some models expose the photosensitive drum using the scanned reflective laser beam. However, their principles are basically the same. The laser beam emitted by the laser, which is transmitted into the acoustic deflection modulator by the reflective lens, and the binary graphic information sent by the computer is sent from the interface to the glyph generator, forming the required glyphic binary pulse. Information, the signal generated by the synchronizer controls 9 high-frequency oscillators, and then adds a laser beam injected from the reflective lens to the sound modulator to be added to the sound modulator via frequency synthesizer and power amplifier. The modulated beam is injected into a multi-faceted mirror, and the beam focusing on the beam is converted to the surface of the light guide drum (toner cartridge) on the surface of the light guide drum (toner), and the angular velocity scanning is changed to complete the entire scanning process. The toner cartridge is charged by charging, so that it obtains a certain potential, and then the exposure of the laser beam containing the graphic image information, the electrostatic latent image is formed on the surface of the toner cartridge, and the magnetic brush display is developed, and the latent image is transformed into the latent image. Visible ink powder, when the transfer area is passed, under the electric field of the transfer electrode, the toner is transferred to the ordinary paper, and finally the preheated plate and the high temperature hot roll, that is, in the paper. Text and images. Before printing the graphic information, the cleaning roller removes the uncovered toner, and the console lamp removes the residual charge of the drum, and then enters the new round of work cycle by cleaning the paper system. Third, the work process 1. Working principle and structure of the laser us usually called light sources, such as sun, electric light, burning candles, etc. The light has energy, which can heat the object to the photographic substrate, which is an energy conversion. Light energy is included in the beam, the beam is injected into the human eye, so we can see the light emitted by the light source. So why should we see the object that does not shine? It is because the light emitted by the light source is illuminated, and the light that does not shine is light, and the light reflected in the four-sided eight-way, so we can also see non-illuminating objects. Producing the light source of the laser, and the normal light source is significantly different. If the ordinary incandescent light source is a atom to the excitation state by current heating tungsten wire, the atom in excited state is constantly emitting radiation. This ordinary light source has a large scattering and diffraction, and cannot control the beam forming a concentrated beam, which is not available to the laser printer. The laser beam required for laser printers must have the following characteristics: 1 high directionality.
The emitted beam is not scattered and diffuse within a certain distance. 2 high monochrome. Pure white light consists of seven-color light. 3 High brightness, which is conducive to the concentration of the beam and has high physical energy. 4 High coherence, easy to overlay and separation. The laser is the light source of the laser scanning system, has a good direction, monochromatic, high coherence, and energy concentration, easy to modulate and deflect. Early production laser printer multi-use helium-(HE-NE) gas laser, its wavelength is 632.8 μm, which is characterized by high output power, large volume, is long life (generally greater than 10,000 hours) performance reliable, noise Low, output power. But because the size is too large, it is now basically eliminated. Both modern laser printers use semiconductor lasers, commonly, gallium arsenide-calas-calas series, the emission laser beam wavelength is generally near infrared light (λ = 780 μm), and can be highly sensitive to the wavelength of the photosensit toner cartridge Features match. The semiconductor laser is small, low cost, and can directly perform internal modulation, which is the light source of a lightweight desktop laser printer. Laser scan is a very small high-precision spot, printing for high quality text and images, commonly used lane scanning system works is: set two-piece-parallel mirror (gate at both ends of the working material) Pole), between the two mirrors constitutes a cavity. A mirror of the resonant cavity is a full mirror, and the other is a semi-mirror, and when the working material is tempted, the atom spontaneously radiated photons are constantly reflective in the resonant cavity, and the radiated photons are increasing. When the photon in the resonant cavity is added to a certain amount, a very strong light will be transmitted through the half-reflection mirror, which is laser. The light beam thus emits is very concentrated, and there is almost no scattering as long as we use control technology to control the optical wave wavelength at 700 ~ 900 μm (nanometers), which can meet the exposure of the laser printer photosensitive drum. Modern semiconductor lasers typically use laser diodes, which are extremely similar to those of ordinary diodes. If there is a pair of PN junctions, when voltage and current are added to the laser diode, holes and n types in the p-type semiconductor material. The free electrons in the material produces relative motion, and the density of the carriers from the PN junction is very large, free electron and hole recombination, thus generating electrical radiation, release photon having laser characteristics, reflected by the laser resonant cavity The mirror reflection, the laser beam is emitted through the laser hole and the hole. As can be seen from the production of lasers, a laser beam only includes a major wavelength of light, which is monochrome. Each ray is propagated in one direction to combine with each other, we call it coherent. This feature allows the lamination to be shot on a target at a very thin beam, and there is almost no scatter. And each laser beam is like a bullet that is shot in the gun, each bullet can only play a hole on the target.
If you want to play a word, you have to shoot a lot of bullets, play a lot of holes in one word, form a one-point horizontal arrangement, which is what we said, it is going to talk about image. technical foundation. The graphic information of the laser printer is also composed of a dot matrix. The higher the print quality requirements, the more dot matrix constituting a character. There are four ways to form a laser scan. Single-line scan: Distance information of each line of a line of characters, sent to the scanner, called single scan. Multi-line sequence deflection scan: High-frequency signal generator generates nine different frequencies in turn, according to Bregg diffraction principle, which generates nine deflection angles in the deflection modulator, and then rotates a minor angle. Scan from the left to right of the dot matrix information. Since this method only needs to turn a small angle, it is equivalent to 1/132 of the single-wire scanning method, so that 1 word can be formed, but it is also known as a small grating scan. Multi-line simultaneous deflection scanning: means that nine different frequencies simultaneously in the high frequency drive circuit, and is served to the deflection modulator. Multi-line simultaneously deflecting multiple scans: This method is to deflect the same class at the same time and the multi-line simultaneously, just from the formation of 1 character. That is, when scanning a high point array character, a complete character is divided into multiple scans. The dot matrix formation of graphics information is substantially similar to the dot matrix of characters. 2. The working principle of the photosensitive drum and the structural photosensitive drum are the core components of the laser printer. It is a photosensitive device that is mainly made of light guiding material. Its basic working principle is the process of photoelectric conversion. It is used as a consumable material in the laser printer, and its price is also relatively expensive. Photochantically semiconductors have a commonality of semiconductors, such as thermal exciting, doping, alter conductivity, and the like. In addition, it also has its semiconductor does not have optical conductivity characteristics. After the photosensitive semiconductor is illuminated, its conductivity can rise several orders. From the band, the electrons in which it's the electrons absorbed the energy of the light, jump into the conduction band, producing electron-hole pair. This electron-hole pair generated by light is called an optical carrier. The optical carrier generated by the photochanctar is increased, and its conductivity is rising. This conductivity increased after the light-receiving irradiation is referred to as the intrinsic optical conductivity. In practical applications, the photosensitive semiconductor material needs to be doped to make the semiconductor material used by the laser. In addition to having the present emission electrical conductivity, it is also necessary to have the properties of the impurity photoconductivity of electron or hole formed in the optical excitation impurity level. In some photosensitive semiconductors, impurity photoconductivity plays a major role. After the photosensitive semiconductor is illuminated, the carrier mobility in the body is changed varying degrees (the mobility is the ratio of the migration speed of the carrier and the external electric field). The conductance of the conductive capacity of the indicator object is equal to the carrier density multiplied by the migration rate. The mobility rises, the electrical conductivity, and the conductivity are commonly determined by the value of the optical conductivity, the impurity photoconductivity, and the mobility of the mobility, but it is only the main factor in some conditions. Various optical conductors actually applied are different from the degree of sensitivity of light. The conductivity of the optical conductor is proportional to its sensitive degree of light. Therefore, the conductivity of the light-sensing to the light conductor has a great effect. The light conductor is different to the light sensitivity of the light. A certain kind of light guide, only highlights the light of a certain region spectrum, and may lose light sensitivity.
Photochantically semiconductors form an absorption peak to light in the optical wavelength range thereof. In this peak range, the optical conductivity is best. It also has a relationship with light illumination. The higher the illuminance, the more carriers, the higher the photoconductivity. However, each of the characteristics of each of the light conductors is different, so the illumination required to achieve the same photodational conductivity indicator under the same conditions is different. At present, the photoconductive material commonly used in the photosensitive drum has cadmium essence (CDS), selenium-arsenic (SE-AS). Several organic light guide materials (OPC). The light guiding material for making photosensitive drums should have the following characteristics: 1 Wear resistance. The surface of the optical conductor must have a certain hardness, and it is necessary to withstand the mechanical wear during development transfer and cleaning. If the photosensitive drum (light conductor) is worn or scratched, it will result in a decrease in print quality or destroy the photosensitive drum, and only scrapped when the wear is severe. In actual work, the scrapped drum scrapped by wear and scratching. Now a new type of long life ceramic drum (A-Si) has been applied, can print more than 300,000. 2 Temperature stability is good. The performance of the optical conductor is easily affected by temperature, so that in the laser printer performance, it is particularly emphasized that there is a suitable temperature and humidity in the use environment, otherwise it will affect print quality. 3 Optical conductivity is good. Optical conductivity is an important indicator of the photosensitive drum, which directly affects the quality of print quality. Because the photosensitive drum continuously operates during charging, discharge cycle, the potential is required to rise, the surface saturation potential is high than the application potential; otherwise, the initial potential will not be able to affect the print quality. The darkness of the photosensitive drum after charging is small, otherwise it is not possible to maintain the surface of the surface, and the necessary potential differences cannot be formed. When the drum is exposed, the discharge is fast, that is, the light decline is rapid. The more the discharge is more and better. Because the remaining potential is much, it affects the contrast of the latent image, which will bring the bottom ash of the print. 4 fatigue. During use, the printer is repeatedly charged, thus having good fatigue resistance, and print quality cannot be decreased due to continuous use during predetermined life. The light guiding characteristics of the photosensitive drum should be good and should meet the requirements of continuous use. The photosensitive drum used by the laser printer is generally three-layer structures. The first layer is an aluminum alloy cylinder (conductive layer), and the second layer is a method of vacuum vapor deposition on the surface of the cylinder, plated with a layer of light conductor material (light guide layer), and the third layer is outside the light guide material. A layer of insulating material (insulating layer) is plated. Some photosensitive drums are plated with a superconducting material in the middle of the light guide layer and the aluminum alloy conductive layer in order to better releasing charges to allow the charge to be released rapidly. The insulating layer of the photosensitive drum, one is to improve the wear resistance, increase the life of life; the second is to provide protection to the light guide layer, prevent the light conductor from being worn, and maintain the photoconductive characteristics of the photoconductor. The conductive layer aluminum alloy tube is connected to the ground wire of the laser printer, so that the potential after the exposure is released quickly. It is a cylinder that is very accurate. During operation, it can maintain a uniform speed and maintain uniform charge.
3. Data Translation and Pass (1) Data Translation: To print a complete text, image, in addition to the function of the laser printer itself, must also print content, ie, text or image processing software or graphics processing software through the computer, ie text or image processing software or graphics processing software. Editing into a computer language with a certain format. The contents of the description are determined by computer editing software, and there is no relationship with the laser printer. When we selected the printer command and press the OK button, the computer transmits the editing data to the printer through the printer interface, interpret the print content by the printer driver, and converts the language that can be identified by the printer ( Also called the printer language), printed by the printer in accordance with its own language. Different models of laser printers, different print languages, the drivers used are also different. Of course there is also a compatible printer driver. The laser printer produced now, generally uses standard print language PCL5 or PCL6 language. (2) Data transfer: There are many kinds of communication transfer ports between printers and computers, and more common are serial ports or parallel ports. EP P / ECP (Enhanced Parallei Port / Extended Capabilities Port) is called enhanced / extended parallel ports. The serial port is generally rarely used due to slow speed. Others such as SCSI interfaces, due to fast, mostly on higher-end printers. There is also a video interface (VDO) mode with computer communication, communication mode is different from other interfaces, which is not data, but the laser beam, faster. Its data is completed by another video transfer card, but because it is with the computer, it is required to have sufficient cache space. Generally, the typographic version of the project is more printers in this interface. Some high-end printers have a variety of interfaces that can be connected to multiple computers. Many of the printers produced are now equipped with a faster USB interface. When the print controller receives data from the computer, the printer generally takes two ways: one is to directly send the data directly to the interpreter, referred to as a paragraph working mode, this way the printer does not need a lot of caches and memory The ordinary printer uses this way of working. The other is to store the transmitted data in the hard disk of the inside of the printer. It can be printed at any time when used, also known as a pool, and many high-end printers use this way of work. Its advantage is that when many users share a printer, they can simultaneously send a print command without waiting, and can save the waiting time for data transmission transmission, but their prices are also more expensive. 4. Generate the text or image of the laser printer of the raster or dot matrix, if observed under the magnifying glass, it will find the text or image consisting of a lot of white spots and black points (also called the pattern), and Ordinary dot matrix printing effect is similar. The former is an arrangement of the dot array by controlling the opening of the laser beam, and the latter is a dot array arrangement by printing a hitting.
The raster image is a video digital image that requires the grating converter in the printer to rasterize the video data, converted into a dot matrix image printing used by the printer, the so-called grating image is an image consisting of a separate point. As shown by the newspaper or on the TV screen, the image displayed is a grating image. The laser printer's dot array arrangement is a square array control consisting of binary data. Each point corresponds to a binary number, and the arithmetic controller controls the laser to emit a bundle laser surface to the photosensitive drum surface, referred to as exposure, exposed point is called pixels. point. To print a text or an image, there is a lot of pixel points. Therefore, the more the number of pixel points in units, the higher the resolution of the print. If a laser scanning device, along the axial surface of the photosensitive drum, 300 points per inch, and the photosensitive drum is driven by the main motor to rotate at 1/300, then the laser printer can be 300 × 300dpi per square inch Resolution prints text or images. Now, the high-grade laser printer output accuracy can reach 2400DPI. The dot matrix image is formed by the pixel point, and also through an acoustic modulator, a high-frequency drive, a scanner synchronizer, and an optical system to be completed. (1) The acoustic modulator knows that the images and sounds received by the television are emitted by the television station to emit the acoustic signal modulation as the electrical signal. The TV has received the electrical signal and then demodulated, restores it into image and sound. The light beam emitted by the laser printer laser also contains data information, and the conversion process of this information is similar to the television information transfer process. However, this process is converted by an acoustic modulator. The modulation frequency of the sound and light modulator can reach about 30 MHz, which is stable, so most laser printers use this modulator. The working principle of the sound modulator is the characteristics of the Bragg diffraction generated by the acoustic optical effect, and achieve control of the direction of the laser beam propagation direction. The laser beam wants to complete the image task of the graphic information, and must be modulated by the graphic information. It is appropriate to modulate the image and sound signal to radio waves, and can solve the image in the TV. The working principle of the sound and light modulator is to use the acoustic effect to produce Bragg diffraction. If ultrasonic medium such as glass and crystals, ultrasonic media will cause periodic refractive index changes, and become a phase-type diffraction gate, grating constant is equal to Ultrasonic wavelength, when the laser beam is amjected to the ultrasonic medium, the laser beam produces diffraction, the intensity of the diffracted light, and the frequency and intensity of the ultrasonic wave, that is, the acoustic optical effect. When the ultrasonic wave is emitted to the glass or crystal, the reflection is generated, and the rays refracted by the incident angle are propagated to form a diffraction grating of the phase change, the grating constant is equal to the wavelength λ of ultrasonic waves. If the laser beam is incident in the ultrasonic medium, the laser beam produces diffraction, the strength and direction of the diffracted light, and the direction of the frequency and intensity of the ultrasonic wave, which is the acoustic optical effect.
According to the reinforcing conditions of the wave interference, the direction of the incident light and the diffracted light satisfies the Bray equation: θi = θd = θb sin θb = λ / 2A = λf / 2V (V = FA) formula: θi: incident light and ultrasonic wave surface Corner; λ: Wavelength in the medium; θd: angle of diffractive light and ultrasonic wave surface; A: Ultrasonic wavelength; θb: Bray angle; F: Ultrasonic frequency. When θB is small, sin θb≈θd, the equation can be simplified to: θi = θd = θb = λf / 2V, when the diffracted light and the angle of incident light are α, then: α = θi θd = 2θb = λf / v . The α in the formula is a deflection angle, which is proportional to the frequency of ultrasonic waves. Changing the ultrasonic frequency f can change the deflection angle α to achieve the purpose of controlling the direction of the laser beam. According to the Bregg diffraction theory, when ultrasonic waves maintain a high frequency signal of a frequency, the incident laser beam is generated in addition to a 0 level, and a 1-stage diffracted light is generated. The 0-level light control synchronizer and the start stop of the high frequency signal, and the 1-stage diffractive light forms a pixel point. Brazz diffracted in ultrasonic waves only a high frequency signal incident, in addition to generating unfoused 0 level light, there is still a 1-stage diffraction light, and the acoustic modulator is changed by the transmission of the beam, The strength of the 1-level light varies with the modulation signal. If several different high-frequency positive wave is added to the transducer, a number of rigid light can be generated, referred to as multi-frequency diffraction. In the laser printer, the function of the high frequency drive circuit is to generate a plurality of high-frequency sine wave signals, and the voiced light modulator is used. A typical high-frequency signal source generates nine high-frequency signals, and 9 diffractive light is generated via the acougrance. These 9 high-frequency signal frequencies should be stable, and the waveform distortion is small. When adding to the transducer in the plug-in circuit, the signals of each frequency need to be small, not to produce distortion, in order to ensure diffraction-diffraction Light has good linear.
(2) The scanner should generate a text or image after the laser beam passed through the sound modulator, and the laser beam needs to complete the movement of the lateral and longitudinal direction, and cannot rely on the laser motion because of the photoelectric device movement. The vibration brought about the accuracy of the laser beam. Therefore, the laser of the laser printer uses a fixed structure, and a plurality of rotated mirrors to complete the laser beam lateral scan, and the longitudinal scan is realized by the rotation of the photosensitive drum. To make the modulated laser beam generate text and images on the photosensitive toner cartridge, it should still complete the lateral (direction of the paper line) and the longitudinal two directions. The longitudinal motion is done by the rotation of the toner cartridge, and the lateral movement of the beam is accomplished by the scanner. According to the working mode scanner, light, electro-optical, reseudolic, and transfer mirror, etc. Given that the rotation mirror scanner has the advantages of large scanning angles, high resolution, small light energy loss and simple structure, and is widely used in laser printers. In order to reduce the nonlinear error generated by the multi-frame rotation, the error of the rotation geometric accuracy and the transfer of the rotation drive motor speed is uniform, and the trajectory of the longitudinal pitch and the character is uneven, generally in the scanner There is a synchronous signal sensor. This sensor is a 0-level light generated by Bragg diffraction, which does not generate a deflection, thereby having a feature of the irradiation position after the multifaceted rotation mirror reflects, which uses it as a synchronization signal to control the start and stop of the high frequency signal generator. Ensure the scanning spacing, eliminating the above errors. In order to integrate the scanning beam generated by the scanner, a good linear movement is performed on the photosensitive drum, and a better optical path system should be employed. The optical path system is in the front and rear position of the lens in the scanner, and the front / rear form is severely distorted by the objective mirror after scanning larger patterns, rarely. The front-type scanning line is straight, but there is also distortion. In the laser printer produced by later production, a wide-angle focus mirror combined with multiple lenses is 300mm, and the multi-faceted mirror is 37mm, and the distortion is only only It is 0.0011%, which can fully meet the requirements of laser imaging. The laser printer is used for multi-rib scanner (mirror), three types of two-glasses, four-glasses, and six-glasses, rotating by scanning motors, and performs lateral scan movement. It is a key component that guarantees laser printer printing accuracy. The scanner completes the principle of the lateral scan: We set MN as a mirror of the scanner. When the incident laser beam is incident on the A point of the MN surface, if the incident angle is θi, the reflected beam is reflected in the reflective angle θD, θ = θd, when the MN turns an angle φ, The incident light beam is not changed, and the reflected beam is rotated 2 φ, that is, the reflected beam rotates twice in the MN. If P is a reflected light point at one end of the photosensitive drum, and P1 is a reflected spot, the lateral scan of the photosensitive drum is completed in the other end of the photosensitive drum, and of course the rotation speed of the scanner is extremely fast, so P ~ P There is also a lot of reflective laser beam points between 1. When the main motor drives the photosensitive drum, the longitudinally scanned reflected laser beam is also completed, in this end, the final completion of the dot array arrangement of the image.
(3) The synchronizer scanner rotates at a speed of the scanning motor, and due to the error of the nonlinear distortion and scanner geometric accuracy generated when the motor is rotated, the longitudinal pitch and the character trajectory are uneven. In the scanning system, a synchronous signal sensor is equipped with a synchronous sensor using the 0-level light generated by Bragg diffraction, and after the scanner (mirror) reflects, the absorbent window of the synchronous sensor is converted into a synchronization signal. Use it to control the start and stop of the high-frequency signal generator, to ensure the consistency of the scanning, eliminate the error. (4) The optical system is a laser beam generated by the scanner reflection, forming a specified size of the specified size, eliminating the diffusion of the beam propagation, and requires modulation of the beam with a set of optical lenses to improve the scanning precision. It includes: curved lens, spherical lens, mirror. This set of lenses only the laser beam correction is 0.1 ‰ to meet the technical requirements of laser imaging. 5. Electronic development system laser printer is a precision mechanical system, which utilizes light, electricity, heat physics, chemical principles to output text or images by interacting, these complex processes are implemented by an electronic control system, called Electronic imaging system. The theory of electrostatic imaging is that the Americans Carlson first proposed, and therefore also known as Calcson. Alternatively, a discharge imaging method. The basic procedure can be divided into 7 steps of charging, exposure, development, transfer, fixing, cleaning, and excitation, where five steps are performed around the electronic development system. (1) The surface of the charging photosensitive drum surface light conductor material is insulator in the absence of light, in a neutral state, without any charge. To achieve an electrostatic latent image on the surface of the optical conductor, it must be charged on the surface of the light conductor to make the charge. Only in this way, when the laser beam is scanned into the light guide, the light conductor is exposed, and the light beam is formed. The dot matrix charge is turned on to form a potential difference, and when the photosensitive drum rotates to the surface of the developing magnetic roller, the magnetic roller is attracted to the photosensitive drum surface with the toner surface with the surface charge attribute of the photoconductor surface, thereby The toner image is displayed on the photosensitive drum. To make the photosensitive drum can be adsorbed on the toner according to the graphic information, the toner cartridge should be charged, and the charging electrode is a tungsten wire parallel to the photosensitive drum, which has a DC high pressure of 5 to 7 kV, as the toner cartridge surface When tungsten wire is very close, the surrounding air is ionizing generating corona discharge, so that the photosensitive drum is charged. The voltage of the voltage is determined by the voltage of the tungsten wire, and when the light guide material is supplied to the selenium alloy, the electrically, the photosensitive drum rotates, and the entire surface is charged after a week. The method of charging the photosensitive drum is also different from the specific charging method of the photosensitive drum, but the charged protocol is basically consistent, which is charged with a corona discharge of DC high pressure. Early production of laser printers with more structural charging of electrode wire and grid composite, and now, most of the new laser printer is charged with the charging rubber roller (FCR).
When the high voltage generator is sent to a high voltage of the electrode, a strong electric field is formed between the electrode wire and the grid and releases the electricity. The air between the electrode filaments and the photosensitive drum is ionized, and the air ions are moved to the surface of the photosensitive drum to allow the surface of the photoconductor (photosensitive drum). This method can make the photoconductor (photosensitive drum), but also produce a large amount of negative ion (ozone). When the ozone gathers to a certain amount, it is harmful to the human body. Such as Canon Early Products LBP-SX, ST type, HP's early products HP2, 3 and Japan production of Panasonic KX6500, Lenovo LJ6L, LJ6P and other models are charged. Most of the laser printers in modern production are charged with charging rollers. Due to the use of contact charging, there is no need for high charging voltages, and there is no ozone production, but due to the intensity of the dust, the wear of the drum is increased, and will also There is a phenomenon that is charged uneven. (2) Scanning exposure is like we use a pen to write on paper. The scanned tool is to use the laser beam to write exposure on the photosensitive drum. This text or image is invisible, this is what we said is static Like. When the tonal surface is electrode the tungsten wire, the surface is charged with positive electricity, and the interface of the light guide layer and the base group may be negative. When the light portion in the laser beam takes a certain area of the drum surface, it is called exposure. After exposure, the electrical resistivity is significantly reduced, and the surface of the positive charge and the negative charge of the interface are disappeared. Because there is a good insulating performance between the selenium alloy particles, the positive charge without exposure remains unchanged. That is, a layer of electrostatic latent image is formed. The scanning exposure is the use of the photosensitive properties of the photosensitive drum surface light guide material. When the photoconductor is irradiated by the laser beam scanning, the light-illuminated portion and the photosensitive drum conductive layer are turned on to disappear, and the portion where the light is not irradiated is still charged, so that a potential difference image is formed, and it can be understood as a pair The excitation process of the drum. The potential of the surface of the optical conductor is changing, and this potential change has a great impact on the print quality. When charging the photosensitive drum surface, as the charge accumulates on the surface of the photosensitive drum, the potential is constantly rising, and finally the saturation potential is the highest potential. The surface potential declines over time, the potentials in general work are lower than this potential, which naturally decreases with time, called the dark failure process. When the photosensitive drum scans exposures, the dark area (refers to the optical conductor surface of the unproduced irradiation portion) is still in the dark failure process; the bright area (referring to the light conductor surface of the light-irradiated portion) The inner carrier density increases rapidly. The electrical conductivity rises sharply, forming a light guiding voltage, and the charge is quickly disappeared, and the surface potential of the photoconductor is also lowered. It is called light failure, and finally slowed down. In theory, the faster, the more it is, the better, it is actually difficult to achieve. The high low of the remaining residual potential will affect the quality of printing, such as the residual potential is too high, will appear in the print bottom ash. After an electrostatic latent image is formed, it is also necessary to pass the developing process as described below to convert into a toner image.
(3) Develop an electrostatic latent image formed on the surface of the light conductor, and the toner image is shown, which is called electron developing. The developing work is done by the developer, and its function is to turn the electrostatic latent image into visible images. The development is accomplished using the material between the charge between the material, is completed. Iron powder and toner are equipped with iron powder, and the iron powder is negatively applied after rubbing, so that the iron powder is surrounded by toner and adsorbed the toner of the toner and is adsorbed by the permanent magnet. A layer of iron powder and toner mixture. When the toner drum is passed from this magnetic brush, the carbon powder is sucking the portion of the toner cartridge to be electrically charged by negatively charged, and the visible toner image is formed. The action of the agitator is to make iron powder with toner friction. The electrostatic latent image charge on the surface of the photosensitive drum is opposite to the charge polarity of the developing toner, and when the optical drum is adjacent to a certain distance from the magnetic roller carrying the toner, or the toner jump To the surface of the photosensitive drum, a toner image is also referred to as a beating. Note: The electric charge of the surface electrostatic latent image after the laser impenetration drum exposure is negatively polarity, while the charge charge of the toner is positive. The toner transmission of the developing unit is completed. When the toner is mixed in the powder cartridge is uniform, the toner is carried by the doped carrier and is adsorbed to the outer surface of the magnetic roller in the magnetic roller in the magnetic roller, and the toner does not appear. When the magnetic roller is rotated and is tangent to the toner blade, when it is rubbed, the tape is positively charged. The toner forms a hate thin and uneven ink powder on the surface of the magnetic roller under the surface of the toner blade and magnetic field. The toner blade also functions to limit the amount of ink powder, so that the toner is not adsorbed too much. As mentioned earlier, the photosensitive drum residual potential is an important reason for printing to produce a bottom ash, and the solution is to add appropriate intersection and DC bias on the magnetic roller sleeve to counteract excessive delivery of toner. There are two effects of the developing bias, appropriately adjust the developing bias, one to prevent the generation of bottom ash, and the other is to adjust the printed concentration. In practical applications, the print concentration regulating rotary button is to adjust the developing bias. Such as HP, Canon, Epson, some laser printers in Lenovo have this knob. However, the improvement of print concentration also means a decrease in resolution, because excessive toner will affect the resolution after fixing. Now the newly produced laser printer generally has a resolution enhancement mode (RET). Through the RET method, the flaws of the slash or arc dot matrix cavity can be filled, and RET is in the horizontal, vertical dots cannot be used. It has three ways: 1 mild (2 mode); 3 depth (DARK). RET can combine the print concentration to print out beautiful text or images, also known as smoothing technology. Different settings, the marker blocks on the printing are different. Development magnetic roller: The developing magnetic roller is an important part of the cargo toner. The permanent core is not rotated, and its effect is to use magnetic adsorption toner to the surface of the magnetic roll. The surface of the magnetic roller is sprayed with a coarse graphite layer, so that the toner blade is electrically connected to the holes and is beneficial to toner delivery.
When the magnetic roller carries the toner is rotated from the squeegee position, the toner surface of the magnetic roller is in addition to the charge, and since the magnetic field is formed by the function of the magnetic field, it is ink fog, and the magnetic roller jacket is applied. Pressure, so that the magnetic raid is arranged in order. The effect of the magnetic roller spacer is to control the effective attraction distance between the magnetic raid between the surface of the magnetic roll and the photosensitive drum, which is beneficial to improve the toner jumping imaging. Toner: The toner used by the laser printer is a single-component toffee, the principle of the projection method is similar to the NP copier, that is, NP method. Single-component toffee is not a carrier, because there is no drill, the toner cannot carry it. It is a mixture of the carrier to be mixed with the toner, and the micro-suction powder should be less than 10 nm. Different models of laser printers are different from the exposure intensity and developing bias, and the toner used is different, and the content of the toner content of the same mass of different models cannot be different. There is also a part of the printer uses a non-magnetic toner. 6. Transfer and Power Dispenser (1) The transfer device is transferred to the toner image of the photosensitive drum onto ordinary paper with high pressure static electricity. This process is referred to as transfer. When the positively charged carbon powder is rotated adjacent to the print paper, the electrode placed behind the paper is applied, since the voltage is up to 500 ~ 1000V, the electrostatic attraction makes the paper on the light guide plate. The negative charge toner is attached to the surface of the paper. Since this transfer is related to the degree of insulation of paper, when the paper is tidy due to weather, the toner will not be fully and closely adsorbed due to the leakage of the paper surface, resulting in poor printing. There are two methods for transfer, one is corona discharge transfer (electrode wire), and the other is transferred in discharge rubber roller. The working principle of both is the same. The model is different, the transfer method is different. Early production of laser printers multi-use corona discharge transfer method. When the photosensitive drum of the toner image is rotated to the position of the transfer electrode or the transfer rubber roller, a printing paper is also sent between the two, and the high pressure is added to the transfer electrode. When the discharge is started, while the printing paper is pushed to the photosensitive drum, the toner image on the photosensitive drum is attracted to the print paper due to the transfer of high pressure electric fields on the bottom surface of the printing paper. The transfer electrode wire or the transfer rubber roller is the same, which is puzzled, but this negative voltage is high than the negative voltage with the photosensitive drum exposure zone, so that the printing paper is pushed to the photosensitive drum, The toner is most attracted to the print paper. However, when the toner is transferred to the paper, if the paper is tidy, the insulation performance is not good, it will affect the toner transfer efficiency, so the image defect, the character hollow raises the problem of poor print quality. (2) When the donor image is transferred to the print paper, the printing paper also has a charge. During the transfer paper delivery, the structure of the toner image may be destroyed from the electric field and the friction, so after the toner image transfer, a power generating device (elimination electrode or downtown teeth) is also referred to as separation. tooth.
Its effect is to cause the charge from the printing paper and the adsorption toner to eliminate the polarity, physically attached to the print paper, thereby ensuring the accuracy of the toner image prior to fixing. The power generation process uses the AC voltage to achieve the best consumer and effect. 7. The heating fixing system will print the toner image adsorbed onto the paper, using a method of pressurizing the hot melt, so that the dissolved toner is immersed into the print paper, and the process of forming a fixed image is referred to as a fixing. The toner adsorbed on the paper is a tiny particle formed by a thermal resin and toner, and when the carbon powder is adsorbed, the carbon powder is adsorbed, when two high and unclear metal rollers are slit, The resin in the toner is dissolved and tightly attached to the paper together with the toner, thereby forming a permanent image while also completing the entire process of laser printing. The melting temperature of the toner is about 10 0 ° C, and the temperature of the hot roll is related to the speed of the paper, generally between 150 and 180 ° C. The photosensitive drum passes through the removal of residual powder and the light removal of the remaining charge, that is, enter the next round of cycles. The laser printer uses a composite hot pressing method to complete the fixing using the fixing assembly. The working process of the toner image fixing is as follows: When the printing paper containing a toner image, when the thermal roller and the pressure rubber roller in the fixing device are heated (185 ° C) due to the heating roller heating lamp (185 ° C). At the same time, the toner flipped into the printing paper due to the pressure of the pressure rubber roller. The surface of the heating roll is applied with a polytetrafluoroethylene coating, which is not easily adhered to the ink powder. Some of the pressure rubber roller surfaces also have a layer of polytetrafluoroethylene film, which is conducive to the toner on the back of the back surface without adhering. The printing paper after heating fixing is separated from the separation claw with the heating roller, and is exported by the paper discharge, and the full process of fixing is completed. (1) The heating roller heat roll is made of seamless aluminum alloy, and the thickness of the tube wall is between 1 to 3 mm, and the surface is coated with polytetrafluoroethylene. The toner which is melted when fixing is prevented from being adhered to the roller. The polytetrafluoroethylene coating on the surface of the heating roller will have a slightly softening phenomenon at high temperatures. When the paper is called inside the fixing device, it is not allowed to use sharp hard objects (such as a substance, the shell) to take out. This will damage the surface coating of the heating roller and affect the completeness of the toner image after fixing.
There are now a lot of laser printers with more advanced ceramic heaters (PCTs), which is fast, power saving, such as HP 4L. 4P, 5L, 6L, 6P, 2100, 4000, 5000 and Canon 460, 660, 800 and JX are used in ceramic heater. (2) Heating lamp Some laser printers are used by the halogen tube. The power is generally 350 to 750W, which is fixed in the middle of the heating roller, and does not rotate with the heating roller. When the printer is powered, the heating lamp is lit, and the fixing roller is preheated. After about 1 to 2 minutes, the temperature of the hot roller reached around 185 degrees. When the surface temperature of the heating roller reaches the fixing temperature, the thermistor notification master logic circuit is stopped by the temperature of the heating roller surface to detect the temperature, ready to light, The printer can start printing. When the heating lamp is broken, the whole machine does not work, and the model with the display panel will display the error indication or error code 50 Error information. (3) Pressure rubber roller pressure rubber roller is also known as the lower roller, and its effect is to complete the heat pressing and transfer of the toner on the printing paper together with the heating roller. The size of the pressure is controlled by the stent spring at both ends, and the pressure roller is generally made of high temperature-resistant silicone rubber, and the pressure rubber roller in the laser printer is made of honeycomb heat-resistant sponge, and the outer surface is a layer of polytetrafluoroethylene film. This is more advantageous for the printing paper from the pressure rubber roller to prevent paper jam.
(4) Temperature controller (thermistor) The method of temperature control of laser printer is mostly thermally induced, with a small thermistor to contact the heating roller, perceive the heating roller temperature (165 to 200 ° C). Then control the opening and closing of the heating lamp by the logic circuit, and realizes the constant fixed temperature of the laser printer. The performance of the thermistor is the higher the external temperature, the lower the resistance of the thermistor. When the heating roller is not energized, the resistance of the thermistor is approximately at 200K, the logic control circuit 0101 is turned on, the thyristor SSR101 is turned on, and the heater starts heating. When the heating roll temperature gradually increases, the thermistor resistance value decreases. When the surface temperature of the heater reaches about 180 ° C, the thermistor resistance value is also lowered, about 10 k, and the thermistor to the logic control circuit input voltage rises. High, after a certain value, 0101 is closed, the heater stops heating. Control the surface temperature of the heater in the temperature range of the design. The laser printer has a power saving function (sleep mode), and if there is no printing within the set time, the main logic circuit controls the heater into the power-saving state, so that the heater surface temperature is left around 165 ° C. This control can save energy consumption, on the other hand, when the print job is started again, the time (time of entering the power-saving state) can be set) when the print job is started again. (5) The heat protector (thermal switch) is unlimited to prevent temperature in the laser printer, and a thermal protector (thermal switch) is connected in series in the heating lamp circuit in the heating lamp circuit. Close to the heating roller. There is a set of long-closed contacts and a titanium metal sheet and a hit stalk. Titanium is a memory metal material, and the memory temperature is 210 ° C during manufacture. If the temperature control circuit is out of control, when the temperature of the heating roll exceeds the set temperature of 210 ° C, the titanium metal is heat shrink deformed, and the compression hitting rod is difficult to turn closion, and the cut circuit functions to protect the heater. When the temperature is lower than 180 ° C, the titanium metal restores the original memory state, the normally closed contact is closed, the circuit is turned on. Some printers use a fuse protector, which is similar to the current fuse. 8. The main function of the cleaning system laser printer cleaning system is to remove the residual toner of the drum surface without complete transfer, so that the next print cycle has a clean photosensitive drum. In theory, the toner image should be completely transferred, but it is difficult to do it. In the printing process, the laser printer is charged, scanned, imaging, and transfers several processes. Due to the motor migration, toner transfer, plus the photoreactors of the optical conductors, the toner image is not possible to transfer to the paper On, then whose residual surface toner is left directly affects the quality of print quality. If the residual toner on the surface of the photosensitive drum cannot be completely cleared, it will be brought into the next print cycle, destroying the newly raised toner image. Therefore, it is necessary to completely clean the surface of the drum, which requires a photosensitive drum cleaner. Laser printers have two cleaning methods: rubber scraper cleaning and brush cleaning.
Their roles are cleaned on the surface of the photosensitive drum. (1) Scraper cleaning rubber cleaning blade is made of uroal solvent, there is a straight blade and has wear resistance and flexibility. The blade is formed with a shear angle and has a certain pressure surface. When the photosensitive drums to rotate the toner remaining on the surface, the residual toner is scraped into the waste powder collection in the cleaning blade. There is also a check-back sheet with the position of the blade to prevent the flying of the waste powder. Since the rubber squeegee is always cut with the photosensitive drum and has a certain pressure, it can cause the surface of the photosensitive drum to be worn on the blade blade, coated with a lubricating powder. If the cleaning blade blade is damaged, the toner remaining on the surface of the photosensitive drum cannot be completely removed, making the image overlap the image of the next print cycle to produce a bad printing effect. During the printer, the phenomenon of melting toner particles adhesion to the blade blade may occur, and the adhesion will be scratched into the light guide layer of the photosensitive drum. (2) The brush cleaning brush is cleaned, that is, the rotating roller brush is cleaned to the surface of the photosensitive drum surface, and the residual toner is cleaned, and the warehouse is shaken into the waste powder collection. The brush is generally made of artificial fibers, and the residual toner is removed from the photosensitive to the photosensitive while rotating, while using the abrasive adsorption residual suction powder, the toner is not flying and contaminated the other components of the printer. The use of brush cleaning is small due to the surface wear of the photosensitive drum, so that the life of the photosensitive drum can be extended. (3) Waste powder collection warehwasher collecting warehouse is a recycling cleaning toner device. The toner after collecting is generally no longer used. Because, there will be many impurities in the collected toner, which will affect the print quality, and some printers use the use of circulating toners. The scraped toner is sent back to the supply powder warehouse by a spiral powder apparatus and is cycled. However, after a period of use, the amount of new powder is insufficient or the new old powder can not be mixed, and the print quality will fall a lot. 9. The transfer of paper during the mechanical transmission system is transferred by the electronic control system to control the mechanical device. These include transmission gear, and the operation of the photoelectric sensor and the action of the pulley wheel. Mechanical transmission system, due to different machine types, structural differences, but the working principle is basically consistent. The high-grade mechanical structure is more complicated. For example, the general non-paper-free alignment device below the mid-range, while the high-end machine except this device, there is also a paper feed garnish and a paper release. Multiple volume packages can make the transfer of the paper more stable, and the jam phenomenon will also be reduced. The mechanical transmission system is mainly a gear transmission between the components, and it is more intuitive. The mechanical transmission action of the electromechanical devices is complete. (1) The paper transfer device of the attractive electromagnetic clutch HP series printer is to use the attractive electromagnetic clutch to control the stop and rotation of the feed cam to complete the paper conveyance. When the electromagnet receives the signal voltage of the control circuit, the electromagnet coil has a current flow, generates an electromagnetic field, the cam is released, and the drive gear is rotated together, and the surface of the rubber wheel has a rubber layer, with the pickup wheel Rotate, the front edge of the cam drives a print paper into the print channel.
(2) Friction-type electromagnetic clutch HP, Canon, Epson and other series of high-grade model printer paper feeders, multi-friction-type electromagnetic clutch, direct shot pulley, paper pair of paper. Its working principle is: When the current signal flows through the electromagnetic clutch internal coil generating electric field, the linkage of the clutch is pushed to one end of the coupling, and the two grinding sheets generate friction stop, and the sheet pulling the pulley will be printed by the fork. Paper is fed into the papers within the printer to the front of the roll and make the print paper slightly bow, and the paper is aligned with the alignment roller. At this time, the alignment roller does not rotate, and when the alignment roller clutch is rotated, the printing paper is sent to the print channel (the pulverin wheel of the friction of the electromagnetic clutch is circular rather than the cam shape). (3) The sensor photoelectric sensor is mounted from two sealing small boxes, respectively. In the opposite position of the two diode, each has a sensing window. Timely 2 windows There is a lever blocking piece, blocking the light beam of the light emitting diode. The photosensitive diode is not light, and it cannot be turned on. The logic circuit does not work. When the printing paper in the motion hits the occlusion lever in the middle of the photoelectric sensor, the light beam of the light emitting diode is transmitted to the photosensitive diode, the photosensitive diode lightly, and the notification logic control circuit issues an instruction to control the next time period in the printer. The laser printer's printing paper sensor, paper feed sensor, and paper feed sensors are photoelectric sensors. It is a logic control device for the main control circuit for timing control of printing. If there is no inductive action in the specified period in the print job, the logic circuit immediately issues a termination information to the master circuit, so that the printer stops, and the display panel also shows the error message, waiting for inspection or maintenance. . 10. The operation of all devices of the electronic control system laser printer, relying on a control system, this system is called an electronic control system. The different models of control systems are different, but the working principle is basically the same. The electronic control system consists mainly of the following parts. (1) The power supply circuit provides a control voltage for each portion of the printer. The power supply circuit is rectified by 220V AC, filtered, and transformer, provides 24V, 5V DC operating voltage for the laser printer. (2) The interface circuit establishes communication with the printer. Receive computer data information and convert it into a printer language to provide print data to the printer master circuit. The interface circuit includes a microprocessor (CPU). Memory (RAM / ROM). (3) The main control circuit main control circuit is the data received by the interface circuit, and control the various devices of the printer according to the command mode to complete the printing process. (4) The scan drive circuit generates a laser beam with the high-frequency oscillator, and controls the scanning motor to rotate, drive the scanning mirror, and complete the scanning exposure to the photosensitive drum to form an electrostatic latent image.
