Zhongwei recommended copy machine optical scanning system detailed
The copier is a common office equipment, which integrates optical technology, electrostatic imaging technology, electronic technology and mechanical technology, and structural principles are more complicated. The optical system is an important part of the electrostatic copying machine. Its function is to expose the original by each optical element, thereby forming an image, and transmits the photograph to the photosensitive drum surface of the charge with uniform charge, resulting in The original image of the original image corresponds to the static latent image. The optical system of all kinds of copiers has a large difference, but the working principle and the function of each functional component are substantially the same.
First, the basic requirements of the optical system
Since the structure of the optical system has a large impact on the overall structure of the copier, and the quality of the photocopy is closely related to the optical system, the optical system of the electrostatic copier must meet the following basic requirements:
1. The spectral characteristics of the light source and the lens should match the photosensitive drum used.
2. The light source should have sufficient strength to quickly reduce the sensitized drum.
3. A light source having a small power is small and the luminescent efficiency should be used to reduce power consumption.
4. The optical path system is adjusted in performance, high passive efficiency (i.e., low loss of light).
5. The optical path system and the synchronization error of the optical conductor shall not be greater than 0.5%, and the optical distance is always unchanged during the full process of the scanning point to the endpoint.
6. Ensure that the entire original illuminance is evenly illuminated.
7. Good heat dissipation should be made to ensure continuous copying of the copier, and the temperature of the draft table does not exceed 70 ° C.
8. The system's repetition accuracy is high, the structure is durable, safe and reliable.
9. There should be good sealing to prevent external environment from pollution of optical systems.
10. The system should be easy to load, adjust, clean, and replace the loss.
11. The installation of the light source should be kept horizontally, especially the halogen lamp, otherwise it will affect its service life.
12. Through the optical path system, the illumination of the light conductor should be substantially consistent with the light energy accepted by each point of the light guide layer;
Second, optical scanning system
The optical system for scanning exposure to the original is called a scanning system, which includes a manuscript glass, an exposure lamp, a mirror, and a scanner, a scanner position detecting sensor and a lens unit.
(1) Optical scan system type
At present, the scanning method used by the electrostatic copier mainly has the original manuscript mobile slit exposure, and three types of optical fiber exposure and mirror moving slit exposure are used. The so-called slit exposure is illuminated by a light strip when exposed, and the scan exposure is performed synchronously with the photosensitive drum, and an electrostatic latent image is formed on the photosensitive drum.
1. Documentary mobile slit exposure
The manuscript mobile scanning exposure system is a reciprocating motion of the original table to complete the image scan. Among them, both exposure lamps, lens and mirrors are fixed, and the original stage is synchronously moved synchronously with the surface line speed of the photosensitive drum or a certain proportion. Therefore, this scanned exposure method has the advantages of simple optical system, small size, clear, accurate, etc., but such a machine is poor, the document load is poor, the copy speed is generally low, and the original original, and The working space is large, and the magnification is small.
2. Manuscript mobile light guide fiber exposure
The optical fiber optical system is stacked by the two-row of light guide fibers, and the light guide fiber matrix is used instead of the lens and the mirror in the optical system, directly transmitting the reflected light of the original image to the photosensitive drum surface to form an electrostatic latent image. . This type of copier is characterized by a manuscript moving manuscript; the optical fibers are not moving, the structure is simple, small, but cannot be changed, and the resolution is low. The optical fibers used in general, the diameter of about 1.1 mm, the fiber length is 29.4 mm. As the old model of CanonNP-200 copiers.
3. Manuscript fixed exposure
The document fixed optical system copier is currently the exposure mode used in most electrostatic copiers. The process of exposure is that the original table and the imaging lens are fixed when performing copying, and the moving speed of the first scanning anti-gear is always And the surface of the photosensitive drum is equal or a certain proportion, and the second scanning mirror is inhaled with the first scanning mirror movement with the first scanning mirror with the first scanning mirror, and the first anti-glossy mirror to fourth or fifth anti-glossy mirror Whether on the left side of the imaging lens or on the right, it must always be on the focus of the imaging lens, that is, keep the conjugate distance unchanged. The manuscript fixed copy machine is characterized by a large manuscript load capacity, copied with thicker books, small working space, fast copy speed, etc. For optical scanning devices, the mobile accuracy requirements are high, and the scanning system is required to be light, and It must be kept steadily during the exercise process and the vibration is small. Ricoon FT-4085 copier is a manuscript fixed. (2) Composition of scanning systems
The scanning system of the electrostatic copier is also divided into two parts: light source components and optical path components. The light source component is mainly composed of an exposure lamp, a reflective cover, a light amount adjustment plate, and the like. The optical path components mainly include a manuscript glass, a plane mirror, and an imaging lens. Some copiers have a dust glass in the middle of the excellent and imaging components for optics and imaging components.
1. Light source component
In the electrostatic copy machine, since the original is not illuminated, it is necessary to illuminate the original using a certain optical means (light source or lamp), and the active reflected light obtained by satisfying the surface of the optical conductor reaches the desired illuminance, which requires The exposure lamp is illuminated to enable the photosensitive drum imaging to achieve the illuminance required to complete the exposure task, which is generally mounted in the reflective cover. For the exposure lamp, its brightness and spectral characteristics must match the sensitivity, sensorism of the photosensitive drum, to achieve the ideal copying effect.
There are many types of light sources, and various technical indicators (such as geometric size, power consumption, luminous efficiency, brightness, color temperature, etc.) are also different. Due to the light source of the electrostatic copier, it is generally a dedicated copying lamp, and various technical indicators of the luminaire must match each other with the material of the photosensitive drum (sensitivity, photosensitive performance, etc.), so it is possible to achieve the ideal copying effect. . The ideal light source of the electrostatic copier should be less power consumption, high luminous efficiency, low temperature, and long life. These technical indicators can be achieved on the current technical level, but from practical applications, the matching relationship between brightness and color temperature is more prominent.
(1) Brightness of the light source
As the "light" of the light source, the luminous intensity is required (i.e., high brightness), high luminous efficiency, in order to make the surface of the photosensitive drum after the charge pass through the reflected light to form an electrostatic latent image that is sufficiently large.
Various different types of electrostatic copiers are determined by the light source (lighting) brightness according to the amount of exposure required for the photoconductor, and the exposure amount is the product of the image surface (the photosensitive film layer of the light conductor), the illuminance and exposure time. Decided, ie: exposure = illuminance X exposure time. The exposure time of the electrostatic copier is determined when designing and manufacturing, is fixed, and therefore, the illuminance is sufficiently or not, which directly affects the quality of the electrostatic latent image on the surface of the light conductor. The factors affecting the illuminance are related to the light source luminescence, and the light loss is related to the light of the light transmission during the light transmission process. If the exposure lamp and the mirror are substantially new, the illuminance is 100%, after four mirror reflection, only 38.4-38.8% left in the surface of the light guide layer, if the mirror is polluted, then reach The illuminance of the light guide layer will be considered a considerable amount of loss, thereby affecting the quality of the static latent image. Therefore, not only requires sufficient brightness of the light source, but also the light transmission system is cleaned, and the light transmission "unobstructed" is guaranteed.
(2) Color temperature of the light source
The color temperature of the light source is the color temperature of the exposure lamp, that is, the wavelength range of the light source light. The color temperature of the exposure lamp should be adapted to the spectral sensitivity sensitivity of the light conductor material, which also has a certain relationship with factors such as the optical wave reflectance of the light source. Since the photosensitive material is different from the sensitivity of the spectrum, if some light guide materials are sensitive to a certain wavelength of light, while the light of other wavelengths may not be very sensitive or not sensitive, so choose some kind of light guide as much as possible The material can mostly feel the light of a certain wavelength required, such as the ZnO photosensitive material is not sensitive to the red light wave, so the red seal on the original can be performed well, and the selenium alloy light guide material is used. (Toner cartridge) is the most sensitive to the wavelength of 400-550 nm, and if you want to copy the original, you can use the green light exposure source, you can improve the efficiency of the light source. Therefore, the spectral characteristics of the light source are properly used, determine the color temperature of the light source should receive good exposure effect, which is a good foundation for copying high quality copying. (3) Types of exposure lights
Currently, the exposure lamps commonly used by electrostatic copiers are: high-color temperature-sensitive emitting halogen lamps, slit high power fluorescent lamps.
1 high-colored temperature-sensitive emitting halide lamp
This lamp belongs to the hot source, which is based on most electrostatic copiers, and the light source component is approximately a fluorescent lamp, which is made of work principle based on radiation and tungsten regeneration cycle. When the current is passed through the filament (tungsten wire), the electric energy is heated to reach an incandescent state, and a very bright light is emitted. This lamp is characterized by high light, long life, small life, small geometric size, and the luminous intensity can be made uneven according to design requirements, and the luminescence intensity is adjustable. Its disadvantage is that the operating temperature is high. The halogen lamp is composed of copper foil, tungsten wire, stent and quartz glass tube.
According to the basic knowledge of the optical, when the light passes through the lens in the propagation process, the intensity attenuation of the light is different. Due to the light path of the light, the light intensity of the drum is also different. It can be seen that the light on the upper ends of the drum should be the weakest, and the intermediate portion is the strongest, however the photosensitive performance of the drum surface is the same, uniform, and therefore, it will result in uneven exposure. Choosing the appropriate exposure lamp can basically solve the uneven exposure unevenness due to the different optical paths.
In addition, a cooling fan and a manuscript temperature control device are generally installed due to high temperature. The lamp should be noted when using: 1 The distance between the lamp and the original is moderate, so that the original can obtain the maximum illuminance and is not baked; 2 make the light source center in the focus position of the reflective cover elliptical curve 3 The lamp tube and original are parallel to ensure uniform illumination of the original; 4 placed the pumping position of the lamp in the side.
2 slit high power fluorescent lamp
This lamp belongs to a cold light source and is a more advanced and ideal copier light source. On the entire tube length, there is a light sewing. The inner wall coated with a reflective material (phosphor), which is equivalent to a concave mirror that makes the lighting intensity of the lamp greatly improved. In order to further increase the directional light intensity of the lamp, a layer of reflective layer (titanium trifluoride) is also coated between the tube wall and the reflective material, and in order to prevent the tube wall from black, the tube wall is blocked, affecting the glow strength, A layer of tin oxide is also coated in the outlet portion. Each of the tube has a wire by a tungsten wire, which is used to transmit electrons, and then charge a vacuum and then charge a certain amount of argon and a small amount of mercury. When working, an arc discharge is generated and an ultraviolet ray that produces a very short wavelength, and the phosphor absorbs ultraviolet rays, and the visible light in the daylight is issued. Then, the optical reflection of the tube wall reflective material is then irradiated from the light sewing to illustrate the original.
The fluorescent lamp is used as the exposure light source of the electrostatic photocopter, which has the characteristics of high luminous efficiency, uniform light emission, low radiation temperature, no cooling device, small power consumption. A disadvantage is that the luminous intensity is lower than that of the tungsten halide. Its luminescence intensity adjustment is achieved by adjusting the size of the light slit, i.e., an apparatus that generates a light sewing on the optical path, so that the intermediate portion of the light seam is small by light, and there are more light passing through both sides. It changes the size of the light by changing the size of many metal superposition angles (similar to the aperture adjustment in the camera). (2) Reflective cover
The photocopier typically places the exposure lamp in a concentrator (reflective cavity or reflective chamber), and the reflective cover is more common in an optical system using a halogen exposure lamp as a light source. This is because in the optical system of the electrostatic copier, due to the long optical path, there are many light mirror, the loss of light energy is extremely serious. In order to solve such problems and improve the light intensity of the halogen lamp, improve its light energy utilization, and usually need to increase the bright reflective shroud after the exposure lamp to improve the bright intensity of the exposure lamp, the ideal reflective cover curve Its cutting surface is an elliptical curve, and the center of the light source should be located at a focus of the ellipse, and the other focus should be located at a certain distance from the original (below). According to the characteristics of the ellipse, at this time, the light emitted from the light source is converged on the original to form a narrowband, which should be greater than the maximum width of the light seam. The reflective hood is generally made of aluminum alloy, and the parabolic reflective wall is preferably good, and is generally also plated with transparent antide-aluminum protective layer on its surface. In use, the filament of the exposure lamp should be placed on the focus of the elliptical column surface so that the light emitted by the exposure lamp can be aggregated to the original, and the illumination of the original will be aggregated. There is also a lightweight adjustment plate on a reflective cover, which is to cover the scattering light of the exposure lamp, so that it should not be irradiated on the photosensitive drum.
(3) Light amount adjustment board
The light amount adjusting plate is used to adjust the amount of exposure light radiated to the original according to the photosensitive sensitivity of the photosensitive drum, and its position can generally be moved and fixed with a screw. It is a method of adjusting the amount of light by adjusting the light sewing between the light source and the original to the actor. When the light is increased, the light-absorbing area is large, the exposure is large; when the light sewage is reduced, the light-ranging area is small, and the exposure is small.
2. Optical circuit components
(1) Article Glass
In order to place the original, the electrostatic photocopier is irradiated with the original and can be reflected in the original table. The light is irradiated by the light source (exposure lamp) to the original, and then reflects the light after reflection of the light, then passes through the original glass, and projected by the optical system (mirror and the lens) A charged drum is charged. Therefore, the original glass should be made of small refractive index, high light transmittance, and require that the original glass should be smooth and smooth, thick thick, non-bubble, etc. to reduce light loss and affect imaging quality.
(2) Mirror
In order to reduce the geometric size of the copy machine and reduce the weight of the machine, the mirror is typically used to change the volume of the photocope.
The mirror is divided into two, one is a planar mirror, and the other is a reflective prism. The plane mirror has the advantages of simple structure, low cost, but in long-term use, the coating will damage or deteriorate, and the reflective prism itself does not require a coating layer, rugged, long life, and high reflectance, but manufacturing Process and processing accuracy requirements are high.
The planar mirror is an optical element made of light reflective characteristics. In the electrostatic copy machine, an outer reflective plane mirror is generally used, which is made of a layer of silver, aluminum or chromium, such as a layer of silver, aluminum or chromium, and a flat glass in a plate glass. Only play the role of the support. The main function of the planar mirror in the optical system is to change the forward direction of the beam and the transmission of the light beam with a twist optical path. Since the image generated by the planar mirror does not reverse, the left and right is changed, so when the image is required to be completely identical, the even block plane mirror needs to be employed. Therefore, in an optical system of an indirect electrostatic copier, the number of plane mirrors is even. The flatness and finishness of the surface of the plane mirror have a great influence on the image quality formed on the photosensitive drum. In order to further improve the reflection ability of the planar mirror, the low refractive index substance and the high refractive index substance are typically alternately vapor into the reflective surface coating to form a reflectance of the incident light to increase the reflectance of the incident light, and add silica, etc. The material is formed to form a mirror protective film. In use, the reflective surface of the plane mirror should face the optical path. If it is reversed, the imaging will deform or return.
(3) Imaging lens
The lens is an important part of the optical electrostatic imaging system. It is a certain proportion of light reflected by the original, and then projected from the mirror to the photosensitive drum to obtain an appropriate electrostatic latent image.
The imaging brightness of the imaging lens is in the middle, the edge is weak, and the light axis is gradually attenuated from the center to the edge. The front focal length of the lens is equal, and it is fixed. The spacing and the image can be changed according to the needs of the zoom magnification. When the orientation of the orientation is equal, it can be obtained for the original 1: 1, and when the mantage distance is equal to 2 times the sputum, the imaging is the most clear; when the matrix is smaller than the sub-distance, it is possible to obtain an image of the original; When the sputum is larger than the pitch, it can obtain the image of the original reduction. In the electrostatic photocopying machine, two or more lenses are used in a mirror group structure that makes a certain as required, and is to improve the imaging quality and the change in the parameters in the imaging. The mirror structure is generally complicated, and the distance accuracy between each lens is high, and they have a large impact on the quality of imaging.
The focal length, the relative aperture and the angle of view are the main parameters of the lens. Common lens focal lengths Series are: 105, 150, 180, 350, 400, 450, 500, 600, 700, 900. The unit of focal length is mm (mm). The longer the focal length, the longer the lens of the lens is also corresponding, the longer the original to the lens and the lens to the photosensitive drum). The ratio of the relative pore size is the ratio of the lens aperture and the focal length, is usually used to scale with a "f". F number is 3.5, 4, 4.5, 5.6, 6.3, 8, and 11, etc. The larger the value of F, the smaller the relative pore size (similar to the camera lens of the camera lens). The angle of view is also the viewing range of the lens to obtain a clear object. Typically, the angle of view is angled between 45 ° and 70 °, 80 °, wide-angle, 45 ° or less is long focal plane.
3. Other parts
In the optical system of the electrostatic copier, a color mirror and a cooling fan are generally mounted in addition to the above main optical components.
1. Color filter
The photosensitive drum used by the electrostatic copier is different from the color of the color due to the difference in spectral response characteristics. Although the exposure source matching the spectral characteristics of the drum is used in the electrostatic photocopying machine, the spectral response of the photosensitive drum can always be achieved, and there is always a problem that is poor in a particular color sensing. In this way, it is necessary to make a complement to achieve a full color spectral response. The color filter is a device for complementing the color of the photosensitive drum. It generally uses a method such as color glass color filter and multilayer interference membrane. The specific application is as follows:
(1) The light source is pre-filter, i.e., the color filter is prepared in front of the exposure source.
(2) The lens color filter is colored, that is, a multi-layer interference film or a color filter color filter is added to a certain surface of the lens.
(3) The coating of a particular color of a layer of photosensitive drum is plated on the reflective surface of the mirror, so that the reflective mirror can reflect this particular spectrum, i.e., specific spectral properties to achieve the purpose of color filter. 2. cooling fan
The halogen lamp used by the electrostatic copier, although the brightness is strong, the heat efficiency is high, but the heat release of this lamp is very large, and it is easy to generate high temperatures to fract out the original table. The temperature is increased, affecting the physical properties of the photosensitive drum. Therefore, it is necessary to add a fan for cooling cooling. The cooling fan is rotated for each copy cycle of the electrostatic copier, and the air outside the air is sent to the optical chamber, then discharged from the hot air in the optical cavity from the top cover or side cover.
(3) Control of scanning system
1. Scanning system drive control method
In the electrostatic copy machine, the drive (commutation and speed) control of the scanning device is mainly achieved by controlling the electromagnetic clutch or DC motor by a DC drive circuit.
(1) Electromagnetic clutch control method
Using the electromagnetic clutch to realize the drive control, the drive control is used, and when the scanning device (exposure lamp or original table) needs to move, the control circuit outputs the corresponding signal to control the corresponding signal according to different signals (in the case of fixed magnification). The wire rope driving of the traction exposure lamp (or original stage) is driven to the main drive chain connection to the main motor, thereby realizing the shift and commutation control of the scanning device.
When the scanning device is moving forward, the drive shaft of the optical system is rotated to the main transistor chain forward. When the scanning device returns, the drive shaft is rotated in reverse rotation. When the correlation is changed, the speed of the scanning device moves will vary depending on the copying rate. When the copying is reduced, the speed of the scanning device moves to speed, so the drive shaft of the scanning device is driven to the number of drive gears; in turn, when the copy is placed, the speed of the scanning device moves slowly, and the drive shaft is more than the number of teeth. Less drive gears.
(2) DC motor control method
Use a DC motor to control the shifting and commutation of the scanner (or original stage), and change the direction of the rotation by changing the polarity of the working voltage added to the DC motor by changing the polarity of the working voltage of the DC motor, and by changing the DC motor The reference signal frequency required for the speed change is required to control the speed of the DC motor. The control circuit is typically controlled by the motor start, rotation speed, forward and reversing four control signals to move forward or reverse rotation by a certain speed of rotation, so that the scanning device moves forward or reverse.
2. Scanning system positioning control
The electrostatic copier typically detects the stroke of the scanning device (exposure or original table) using a sensor such as photoelectric, micro-motion, or a reed switch and drives the electromagnetic clutch or DC motor by controlling the circuit. Typically, there are at least three sensing switches on the stroke of the scanning device: the first point position located in the scanning device, used as the in-situ detection; the second is located in the intermediate portion of the stroke, used as a bit detection; third in the scanning device stroke The end position is used as a return detection. These stroke switches are triggered when the scanning device reaches the corresponding position, allowing them to generate a corresponding position detection signal. The control circuit controls the scanning device in front of the scan movement and returning movement based on these detection signals.
When the exposure scan, the electrostatic copier first detects the protocol detection signal of the scanning device. If the scanning device is not in the start position, the control circuit controls the return clutch or scan motor to return the scanning device to the starting position. If the scanning device has controlled the scanning device forward scanning in the starting position. Subsequently, when the electrostatic copier detects the opposite detection signal, the control pair roller will send the copy paper to implement the pair of position control of the copy process. Finally, after the scanning device is detected, the electrostatic copy control scanning device reverse scan returns to the original position.
Third, optical variation system
Optical system used to zoom in or reduced the original is called a variation system, which includes lens units, lens frames, variable magnified motors, and lens position detecting sensors.
The modified function of the electrostatic copier is implemented by the optical system, and the correlation copy is copied by the copying process to copy the image size of the photocopy with the original. It is generally divided into longitudinal variation and lateral magnification. We typically refer to the direction of the advancement of the copy paper as a longitudinal direction, and is referred to as a horizontal direction. The electrostatic copier mainly achieves the transverse magnification of the image by changing the imaging conditions of the lens; the longitudinal variation is achieved by changing the ratio of the scanning device to the original scanning speed by changing the surface line speed of the photosensitive drum. (1) Transverse magnification
The transverse dimension of the image in the electrostatic copy machine is an amplification or reduction of the transverse magnification of the photoconolithient by changing the conjugate distance of the lens or changing the lens. It has the following three types of modes.
1. Change the conjugate distance
By moving the lens, the position of the imaging lens assembly is changed, thereby changing the spacing and the pitch, eventually makes the copy image amplify or shrink. It has the advantage that the option can be selected; the disadvantage is that the conjugate distance is longer.
2. Change the focal length
By changing the focal length of the lens, thereby causing a change in the sputum and the varying distance to achieve a variation of the purpose. Its variation is:
(1) Turning mode: The lens of a limited number of different focal lengths is mounted in the turntable, and the rotation can be used according to the need to rotate according to the copy magnification.
(2) Auxiliary lens method: This method is to reach the target before or after the lens is inserted into the standard (equal) shot.
3. zoom lens
The copier of zoom lens is used, and its copy ratio can be selected from 1/2 to 2, and the magnification has not changed.
At present, most electrostatic copiers typically use a dedicated DC motor or electromagnetic clutch to push the lens assembly to change the spacing, the image distance of the lens to achieve the object of the magnitude. The photoelectric sensor is used to detect the position of the lens and determine how much the lens displacement is used, and the correlation amount is realized. When a copying rate is required, the lens assembly is moved under the drive of the DC motor to adjust the subordinate and the spaster. When the lens contacts the sensor switch in each of the magnification positions in the lens stroke during movement, the sensor switch emits a lens position detection signal until the lens moves to the position of the respective magnification, the control circuit stops the movement of the lens.
(2) verticality
The longitudinal magnification of the copy is not only relying on the lateral magnification of the optical system, but the longitudinal variation is achieved by changing the exposure lamp scan speed and the mole of the photosensitive drum speed. This is because in the electrostatic copying machine, the image exposure of the optical system is ultimately imaged on the surface of the photosensitive drum, while the process of imaging is constantly moving on the surface of the scanning device and the photosensitive drum, and is achieved throughout the photosensitive drum surface. When the scanning device is faster than the rotation of the photosensitive drum, the longitudinal direction of the photocopy is compressed (or amplified), so that the entire copy is reduced (or amplified).
In the electrostatic copying machine, the control of this longitudinal variation is achieved by control of the rotational speed of the electrostatic photocopying machine and the scanning speed of the scanning device. Its control methods are:
1. The scan speed of the copier is fixed, and the longitudinal magnification is achieved by changing the speed of the photosensitive drum.
2. The rotational speed of the photocopier drum is fixed, and the longitudinal magnification is achieved by changing the scanning speed of the scanning device.
3. At the same time, change the speed of the electrosplerotic drum and the scanning speed of the scanning device to achieve longitudinal magnification.
Since the photosensitive speed of each of the photosensitive drums is certain, if the speed of the photosensitive drum is too high, it is larger than the photosensitive speed of the photosensitive drum, so that the exposure time of the photosensitive drum is shortened, it is easy to cause insufficient photosensitive, so most copiers are copied. In the case of being able to maintain a strict ratio relationship with the speed of the surface of the scanning device to move the line speed of the photosensitive drum and the speed of the scanning device to achieve longitudinal amplification and reduction purposes.
Note that when changing the scanning speed of the scanning device, the related mirror movement speed must also be changed so that the linear magnification of the optical system is stabilized. At the same time, in the case of the magnification change, the exposure amount of the exposure lamp should also be changed accordingly. When amplified, the exposure should be improved, and the exposure should be reduced when it is reduced. The change in exposure is generally implemented by changing the power of the supply exposure lamp. When the like is copied, the linear speed of the photosensitive drum is equal to the speed of the scanning device, that is, the scanning means moves much long distance, the photosensitive drum surface rotates how long distance; the scanning device moves more fast, the surface of the photosensitive drum How fast, that is, the scanning speed of the scanning device is synchronized with the line speed of the photosensitive drum surface. When magnification or reduction is made, the longitudinal direction of the image is changed. At this time, the line speed of the photosensitive drum and the speed of the scanning device move should not synchronize, that is, the scanning speed is greater than the photosensitive drum surface line speed, copy The vertical direction of the image is compressed; the longitudinal direction of the copy image is elongated when the scanning speed is less than the surface of the photosensitive drum. The ratio of longitudinal compression and elongation is equal to the magnification of magnification and reduced.
Fourth, optical system basic control circuit
(1) Exposure Light Brightness Control Circuit
The exposure lamp brightness detection control circuit is mainly used to adjust the brightness of the exposure light. During the electrostatic copying process, the measurement of the copy exposure can be adjusted by changing the brightness of the exposure lamp, thereby obtaining a copying crystal of various different toner concentrations.
The exposure lamp control circuit of the electrostatic copier has the following main functions:
1. Exposure light switch control. In this circuit, when the output power of the light regulator power is 0, since there is no power supply phase control circuit, the curved circuit is turned off, and therefore, the exposure lamp is also closed; when the output of the lamp regulator switch circuit is 1, the power supply can be supplied For phase control circuits, the curved circuit work, the exposure lamp is lit.
2. The exposure light is on the detection circuit for the self-diagnosis of the circuit board on the exposure lamp regulator board. The exposure light is on, the exposure light is on the detection circuit, and when the microprocessor and the lamp adjuster are exceeding a certain period of time, the exposure lamp is abnormal, and the main power switch is turned off.
3. Exposure light control. Even if the supply voltage fluctuates, the exposure lamp is kept constant; at the same time, it can control the brightness of the exposure lamp according to the manuscript concentration according to the amount of manual exposure, or in the automatic exposure control mode.
(2) Original concentration detection circuit
The original concentration detection circuit of the electrostatic copying machine is used to detect the original concentration, the detected data input microprocessor, which automatically controls the high and low of the DC component in the developing bias according to different concentrations, to obtain an ideal copy.
(3) Automatic detection of original field
The original web detection sensor of the electrostatic copier is only played only when the automatic selection method (APS) is selected.
When the paper mode is automatically selected (APS), the scanner scans the original once with the original size, the light beam of the exposure lamp is detected by the original length detection sensor, the original concentration detection sensor and the original width detection sensor reception, optical CPU and main CPU Perform data processing to select the appropriate paper size.
The original width data is detected by the width sensor. The optical CPU monitors this signal only when the length detects less than 220 mm. If the length is greater than 220 mm, it can only determine the size according to the data of the length sensor.
(4) Perpetual Temperature Temperature Detection Control
The active detection control of the articulation of the electrostatic copier is: When the manuscript glass thermistor detects that the manuscript glass temperature is greater than the rated value, a signal is output to the main control circuit board. The main control circuit board starts the optical system cooling fan until the manuscript glass is cooled.
V. How to determine the decline in copy quality caused by optical system failure
There is a copying machine that reduces the copy apparatus, which can be used to change the copying rate, and the copy sample is compared. If the fault changes with the magnification, the fault may be caused by an optical system; if the magnification change is changed, the failure may be caused by other processes. The photocopy of the photocopying device can be developed on the photoconductor, and then take out the light conductor, then take out the light conductor, observe the developing image on the surface, and compare the previous sample, such as the fault condition, may be by the optical system It is also possible, but it is also possible to cause charging and development, which is determined according to the fault condition.
