静电复印机的工作原理.doc

无 锡 职 业 技 术 学 院毕业设计说明书（英文翻译）英文The working principle of electrostatic copiersElectrostatic duplicating machine is a static imaging. Optical technology. Electronic technology and mechanical technology in one office equipment. It uses a lot of imaging methods, such as the indirect electrostatic copying method (ie Carlson method), NP electrostatic copying method, KIP persistence of the polarization method, TESI electrostatic transfer imaging method. Modern electrostatic copiers commonly used indirect electrostatic copying method and NP electrostatic copying method. The following introduces the two basic principles of electrostatic copiers and working process. First ,Carlson electrostatic copying method Carlson electrostatic copying process is essentially a photoelectric process, it has the potential to generate a static charge like the composition of the static image, the charge, develop and transfer process are based on the electrostatic principle to tangible benefits. Because of its electrostatic potential in the light of such resistance lower photoconductive layer caused Chongdian film formed on the charge-discharge, so Carlson electrostatic copying method drum has the following requirements: have a very high dark resistivity. This photosensitive drum in the case of no illumination, the surface charge once there, can a long time to save the charge; in light of the circumstances, the photosensitive drum resistivity should be decreased, that is a good conductor of electricity, make sense of drum surface charge released soon disappear. Carlson electrostatic copying method used by the drum major from the selenium and selenium alloys, zinc oxide, organic photoconductive materials, etc., and is generally conductive substrate (such as aluminum or other metal plates) directly or deposition of a thin coating layer of photoconductive material. The structure is above the optical guide layer, the following is conducting substrate. Carlson electrostatic copying method can be divided into charging, exposure, development, transfer, separation, fixing, cleaning, consumer electrical eight basic steps. 1. charge Charge is to make the photosensitive drum in the dark, and impose a polarity of the electric field in a make uniform areas on the surface of a certain amount of electrostatic charge and polarity, which has a surface potential of the process that is actually sensitive Drum sensitization process, so that the original did not have photosensitive photosensitive photosensitive drum good. Photosensitive drum charging only for receiving image information prepared for the original image information is not dependent on pre-process, but it is in the photosensitive drum electrostatic latent image formed on the surface the premise and foundation. When the photosensitive drum in the dark to the charge on the surface of a layer of electrostatic charge, due to photosensitive drum has a high resistance in the dark, so electrostatic charge to be retained in the photosensitive drum surface, the photosensitive drum to maintain a certain degree of potential exchange with photosensitive. Photoconductive properties for different materials of the imaging drum should be sufficient to charge of different polarity, which is fighting the conductivity of conductor is determined that allows only one kind of polarity of the charge (holes or electrons), injection and to prevent another polar charge (electron or hole) of the injection. So for N-type semiconductor, the surface should be fully negative; while P-type semiconductor, it should be under the charge suddenly. When using positive corona charge on the positively charged P-type photosensitive drum, because of P-type semiconductor in the negative charge can not be moved. Therefore, the surface of photoconductive layer positive charge and negative charge on the interface can only be attracted to each other, not in and. If the use of negative corona on the P-type photosensitive drum charge negative, due to photoconductive layer and a total interface, the sensor produced a positive charge, while the P-type semiconductors, the main carrier is the hole, free movement of exchange as easily (or for the injection), easy with the photosensitive drum surface negative charge neutralization. Thus, on the P-type photosensitive drum negative charge, its charge efficiency is very low. For the N-type photosensitive drum, due to its main carrier is electronic, if sufficient positive charge of its time, its charge efficiency is extremely low. Electrostatic copiers usually present in the corona charging device on the photosensitive drum. 2. exposure Exposure is the use of drum major in the dark when the resistance, into the insulator; in the open when the resistance is small, as conductor of the features that have been charging a photosensitive drum to light as the exposure of the right to use light district (manuscript sub-reflector products) disappeared due to discharge of surface charge; no light areas (original lines and ink part) by keeping the charge, which formed in the photosensitive drum surface potential of the image brightness changes with the ups and downs of the electrostatic latent image of the process. For exposure, the original image by light exposure, the image of light signals through optical imaging system projected onto the photosensitive drum surface of the photoconductive layer by the irradiation part as out area, but not by the light irradiation part of the natural numbers dark area. In the next area, light guide layer to create an exciton, which generates photo-carriers, the optical guide layer resistivity decreases rapidly from the insulator into a good conductor, showing conductive state, so that photosensitive drum surface potential due to light guide layer surface charge interacts with the anti-polarity charge and in the quickly fading. In the dark area, light guide layer insulating state is still present, making photosensitive drum surface potential remained unchanged. Photosensitive drum surface electrostatic potential of the level of original image with different shades and different, the corresponding image on the photosensitive drum surface potential of the high concentration part, the part of the surface potential image of low light. Thus, the photosensitive drum surface with the original image of a shade corresponding to the fluctuations of the electrostatic surface potential latent image. 3. contrast Imaging is to use the charged toner to the imaging drum of the electrostatic latent image into a visible toner image process. Imaging toner polarity electric charge, and the photosensitive drum surface electrostatic potential of the opposite polarity as the charge. Imaging time, the photosensitive drum surface electrostatic potential role of such market forces, the dye is adsorbed on the photosensitive drum. Electrostatic latent image potential of the higher part of the stronger adsorption ability of dye; electrostatic latent image potential of the lower part, the weaker the adsorption capacity of dye. Electrostatic latent image corresponding to potential (the amount of charge) of the different dye adsorption capacity is different. This photosensitive drum surface, the electrostatic latent image is not visible, becomes visible in line with the original shades of color dye images of different gray levels. In the electrostatic copier, the toner charged toner and carrier is usually by friction to get. After the friction of the ribbon electrode carrier charged with opposite polarity. 4. transfer Transfer is to copy media closely aligns with the photosensitive drum, the back of the copy medium with the toner image to the opposite polarity charge to the imaging drum has been formed toner image transferred to the process of copying media. Currently electrostatic copier corona device is usually used on the photosensitive drum on the toner image transfer. When the copy paper (or other media) and has been imaging the photosensitive drum surface contact, in his paper on the back of device using corona discharge, the corona corona polarity and charge the same electric charge with extremely Toner of the opposite. As the transfer corona electric field strength dye adsorption than the drum and strong electric field much, so the role of electrostatic forces, the photosensitive drum of the toner image to be attracted to the copy paper, thus completing the image transfer India. In the electrostatic copier in order to easily transfer and improve the image dye in the transfer rate, usually with pre-transfer or pre-transfer lamp electrode of the photosensitive drum unit pre-transfer treatment. 5. Isolation In the aforementioned transfer process, the copy paper as electrostatic adsorption, will be tightly affixed to the photosensitive drum, the separation is to close in the photosensitive drum surface of copy paper peeling off from the photosensitive drum (separation) process down, electrostatic copier in general with separation corona (AC and DC) and the separation claw or split with other parties not to carry out the separation of paper and imaging drum. 6. snapshotSnapshot is to copy the instability of the paper can erase the process of fixing toner images, by transfer, separation transferred to the reproduction of red dye on image, not with the copy paper for the integrated, then the color powder image extremely erased, thus subject to be cured of their snapshot device, to form the final copy products. Electrostatic copiers now use more heat and pressure combination of hot melt toner to the fuser. Snapshot device heating temperature and time, the size of Phoenix and the pressure of pressure, strong adhesion to the toner images have a certain degree of influence. Among them, the heating temperature control, image snapshot quality is the key to good or bad. 7. cleaning After cleaning is also clear by the transfer residual toner on photosensitive drum surface of the process. Photosensitive drum surface of the toner image due to surface potential, the level of voltage transfer, copying medium humidity and contact time with the photosensitive drum, methods of transfer, the transfer efficiency can reach 100% in Most of toner transfer from the photosensitive drum surface by the transfer to the copy media, the photosensitive drum surface is still some residual toner, if not promptly removed, would affect the quality of follow-up copying products. On the photosensitive drum must be cleaned, so before entering the next copy cycle back to the original state. Electrostatic copier machines generally use the scraper, brush or cleaning conveyor belt on the photosensitive drum surface to remove residual toner. 8. power consumption Consumer power is the elimination of residual charge photosensitive drum surface of the process. Because charging the photosensitive drum surface deposition of electrostatic charge, not because of the transfer of the adsorption of dye particles disappeared after the transfer to remain in the photosensitive drum surface, if not promptly removed, would affect the process of follow-up copy. Therefore, before proceeding with the second copy of the photosensitive drum to eliminate electricity, so that the surface potential of photosensitive drum to return to its original state. Electrostatic copier in general with the exposure device to a full exposure of the photosensitive drum, or consumer electronic device on the photosensitive drum Corona anti-polarity charge to eliminate the residual charge on the photosensitive drum. Second, NP electrostatic copying method Canon NP invented method is a new electrostatic copying method, which is different from the traditional Carlson electrostatic copying method, it is Carlson electrostatic copying method improvement and development. NP is the basic process of electrostatic copying method mainly by the former Consumers Power / pre-exposure, a charge (main charge), the second charge / image exposure, full exposure, development, transfer, separation, fuser, drum cleaning 9 basic steps. We can see from the above steps, NP law electrostatic copying over the Carlson method than the typical electrostatic copying process is complex, mainly due to NP method used photoconductive photosensitive material although very good, but the dark resistivity is too low, the charge decline after dark too fast, not like selenium photoconductive materials such as base as it can be a long time to save the charge. So using CdS photoconductive materials such as basic as it can keep a charge long. So using CdS photoconductive photosensitive material drum knot is also typical of the photosensitive drum Carlson method different structures. Carlson electrostatic copying method photosensitive drum is a two-tier structure, namely the basic photoconductive and conductive layers. The NP method is a photosensitive drum by a transparent insulating layer, photoconductive layer and the conductive layer constitute the basic. NP Act electrostatic copying process in addition to static latent image formation and imaging processes, base it with the Carlson method is basically the same process of electrostatic copying. NP Act electrostatic latent image formation, including the former Consumers Power / pre-exposure, on a single charge, second charge / image exposure and full exposure of four basic steps. 1. the former consumer electric / pre-exposureBefore the consumer electronic / pre-exposure process is the first charge (main charge) before the use of negative high-voltage corona discharge to eliminate the surface of photosensitive drum loop as the previous copy of the residual charge left, while fluorescent lamps (light before the exposure) full exposure to sensitive drum (known as pre-exposure) to reduce the internal CdS photoconductive layer resistance. The role of pre-exposure, on the one hand is to make the residual charge photoconductive layer can be fully released into the earth, on the other hand is later carried out the main charge on the photosensitive drum, can evenly into the number and polarity of the charge to provide the conditions to prevent the electrostatic charge distribution potential as the concentration of poor reproduction caused by inequality and the black solid image white spots appear in the phenomenon. NP method using CdS photoconductive layer as a dispersion, the material placed in the dark after a period of resistance will be greatly increased, if the copying in this case the bottom ash produced goods, and even makes the whole screen black. After the first consumer electric / former exposure to this process, due to the negative impact of high-voltage corona discharge, will slightly negative potential of photosensitive drum surface. 2. one chargeNP electrostatic copying method by adding a charge corona device for positive polarity DC high voltage corona discharge is to charge the photosensitive drum surface layer of uniform positive charge, that the formation of a potential. When the corona charging device with a DC high voltage, the corona discharge device started to make the air around the corona wire ionization, positive polarity of the ions in electric fields, to the photosensitive drum surface insulation layer movement, not as insulating layer conducting, playing the role of barrier layer, so that they can not pass through corona ions deposited on the insulating layer and the insulating layer surface, so that charge on the insulating surface layer of uniformly positive charge. As the role of electrostatic induction, the conductivity of the ground-based lateral sensing the same amount of anti-polarity charge (negative charge), but N-type semiconductor CdS is mainly a negative charge carriers (electrons), after pre-exposure and because , light guide layer (CdS) and resistance decrease, making these sensors out of the negative charge more easily injected into the photoconductive layer and the insulating layer of the surface positive charge, attracted to the surface positive charge direction, and finally reach the light guide layer and the insulation layer interface, so that the surface of CdS film and the insulating layer with the opposite surface of the same amount of negative charge, positive charge equilibrium with the surface to form a stable state. Thus, the surface of CdS photoconductive layer on the surface with a certain potential to form the insulating layer conductive substrate Angeles and formed a certain potential difference so that the surface of photosensitive drum (ie insulation level) has a certain surface potential. As the charging time of growth, the more positive surface charge more photosensitive drum surface potential also increased. 3. the second charge / image exposure The second charge / image exposure is a process of two ways. This process is the use of AC corona, or anti-polarity DC corona charging device on the photosensitive drum surface, the charge for electricity consumption, while the image on the photosensitive drum exposure. The role of the second charge is in the insulating layer and the surface of the positive charge; image exposure is the process will move to the consumer electrical insulating layer formed on the surface shading corresponding with the original distribution of electrostatic charge. When the original image is irradiated through the projection optical system to the photosensitive drum surface (ie exposure), the photosensitive drum surface to form two regions: with images of dark areas and without images of clear zone. In the next area, due to light to light guide layer (CdS) significantly reduced the resistivity to become conductors. The original resides in the optical layer and the insulating layer interface negative charge (electrons), with the insulating layer surface positive charge was second in the negative corona and the same time, optical layer to a grounded c