JP2009276650A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of obtaining an highly accurate image while preventing generation of rotation irregularity of a photoreceptor drum. <P>SOLUTION: The image forming apparatus includes: a drive transmission system 8 for driving a photoreceptor drum 71; a rotation state sensing part 32 for sensing data of the rotation state of the photoreceptor drum 71; a display part 34 for displaying the rotation state of the photoreceptor drum 71; and a control part 31 for drive control of the photoreceptor drum 71. The control part 31 includes: a rotation speed control part 31a for controlling the rotation speed of the photoreceptor drum 71; a rotation accuracy analysis part 31b for calculating the relationship between the rotation speed of the photoreceptor drum 71 and the rotation irregularity based on the sensing results of the rotation state sensing part 32; and a display control part 31c for controlling display on the display part 34. In the case the rotation irregularity exceeds a preset reference rotation irregularity Yb, the display control part 31c outputs a control signal to the display part 34 for displaying a message requesting change of the natural frequency by a natural frequency changing part 84. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these.

  The image forming apparatus has a rotating body such as a photosensitive drum, and the rotation speed of these rotating bodies is usually controlled. When the rotational speed of the photosensitive drum is not uniform, that is, when uneven rotation occurs, it is difficult to obtain a highly accurate image.

  Possible causes of uneven rotation include vibrations due to gear meshing, motor cogging, drive shaft eccentricity, and the like. In addition, when these vibrations resonate with the natural frequency of the rotating body or the gear box (gear case), even larger vibrations are generated, which causes larger rotation unevenness and damage to the machine itself.

  Various methods for suppressing these vibrations have been proposed. For example, Patent Document 1 describes an inertia automatic adjustment device that automatically adjusts inertia of a drive transmission system. This apparatus first obtains the frequency response characteristic of the drive transmission system, and calculates the natural frequency of the drive transmission system from this characteristic. Then, the inertia is automatically adjusted so that the calculated natural frequency does not overlap with the frequency of the excitation source such as the rotational frequency of the shaft and gear constituting the drive transmission system, the meshing frequency between the gears, and the like.

  Further, Patent Document 2 absorbs vibration by matching the natural frequency determined from the rigidity of the drive system and the inertial moment of the drive shaft with the disturbance frequency depending on the rotational speed generated in the transmission mechanism. A drive transmission device is described.

By using the inventions described in Patent Literature 1 and Patent Literature 2, the occurrence of vibrations in the image forming apparatus is suppressed, the occurrence of rotational unevenness is reduced, and a highly accurate image can be obtained.
JP-A-8-115041 JP 2002-272156 A

  However, in order to realize the inventions described in Patent Document 1 and Patent Document 2 described above, it is necessary to create a complicated simulation model and calculation formula, and it takes time and effort to perform these operations. was there. In addition, in order to ensure accuracy, it is indispensable to combine experiments with these simulation models and calculation formulas, and the required work increases.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is an image that can be easily implemented, can prevent rotation unevenness of the photosensitive drum, and can obtain a highly accurate image. A forming apparatus is provided.

  According to the first aspect of the present invention, a drive transmission system that drives a rotatable image carrier, a rotation state detection unit that detects data relating to the rotation state of the image carrier, and items relating to rotation of the image carrier are displayed. A display unit that controls the drive of the image carrier, and a natural frequency changing unit that can change the natural frequency of the drive transmission system. To the display unit, a rotation speed control unit that controls the rotation speed of the carrier, a rotation accuracy analysis unit that derives a relationship between the rotation speed of the image carrier and rotation unevenness based on the detection result of the rotation state detection unit, and the display unit A display control unit that controls the display of the display, and when the rotation unevenness of the current rotation speed exceeds a preset reference value by the analysis of the rotation accuracy analysis unit, the display control unit The natural frequency change It is characterized in that to perform a display to the effect that changing the natural frequency by means.

  According to such a configuration, the rotation accuracy analysis unit analyzes the detection result of the rotation state detection unit based on the relationship between the rotation speed and the rotation unevenness of the image carrier that has been actually rotated. When the rotation unevenness in the rotation number exceeds a preset reference value, the display control unit displays on the display unit that the natural frequency of the drive transmission system should be changed by the natural frequency changing unit. Therefore, the vibration of the drive transmission system can be suppressed without changing the number of rotations of the image carrier by the operation of changing the natural frequency of the drive transmission system by an operator who visually recognizes this display.

  As described above, the relationship between the number of rotations of the image carrier and the rotation unevenness can be easily derived by a simple measure of causing the rotation state detection unit to detect the rotation state of the image carrier. Since it is possible to easily know how the rotational speed of the image carrier that is actually rotating is related to the rotation unevenness in suppressing the vibration of the drive transmission system, It is not necessary to create complicated simulation models and calculation formulas that require time, and an effective vibration absorbing process for the image carrier is executed by changing the natural frequency of the drive transmission system more easily.

  The invention according to claim 2 is the invention according to claim 1, wherein the natural frequency changing means changes the rigidity of the drive transmission system by adding a weight.

  According to such a configuration, it is possible to easily change the rigidity of the drive transmission system by a simple operation of adding a weight to the drive transmission system after simplifying the configuration of the natural vibration changing means.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, even if the rotation unevenness exceeds the reference value, the rotation by the rotation speed control unit within a predetermined range of the image carrier. When the rotation unevenness can be suppressed within the reference value by controlling the speed, the display control unit does not display a display indicating that the natural frequency should be changed on the display unit. .

  According to such a configuration, slight rotation unevenness of the image carrier can be dealt with by changing the rotation speed of the image carrier without changing the natural frequency of the drive transmission system. Therefore, it is possible to reduce the rotation unevenness of the image carrier and avoid image defects without performing a troublesome operation.

  According to the image forming apparatus of the present invention, it is possible to obtain an image with excellent image quality with high accuracy by preventing the occurrence of rotation unevenness of the photosensitive drum while ensuring the simplicity that it can be easily implemented. Can do.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  First, an overall configuration of a tandem color printer which is an example of an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a schematic sectional view showing the overall configuration of an embodiment of a color printer according to the present invention. FIG. 2 is an enlarged explanatory view showing the image forming unit 3 and the fixing unit 4 extracted from the color printer shown in FIG.

  As shown in FIG. 1, a color printer (image forming apparatus) 1 includes a box-shaped device body 1a. Inside the apparatus main body 1a, a paper feeding unit 2 that feeds the paper P, an image forming unit 3 that transfers an image to the paper P while conveying the paper P fed from the paper feeding unit 2, and A fixing unit 4 that performs a fixing process on the image transferred to the paper P by the image forming unit 3 is provided. Further, on the upper surface of the apparatus main body 1a, a paper discharge unit 5 for discharging the paper P subjected to the fixing process by the fixing unit 4 is installed.

  The paper feed unit 2 takes out the paper feed cassette 21 for storing the paper P of each size, the pickup roller 22 for taking out the paper P stored in the paper feed cassette 21 one by one, and the pickup roller 22. Paper feed rollers 23, 24 and 25 for sending out the fed paper P to the paper transport path, and a predetermined timing after the paper P sent to the paper transport path by the paper feed rollers 23, 24 and 25 is temporarily held. 1 and a pickup roller 27 for taking out the paper P placed on a manual feed tray (not shown) attached to the right side surface shown in FIG. It has.

  The paper feed cassette 21 is provided so as to be detachable from the apparatus main body 1a. The pickup roller 22 is provided at the upper right position of the paper feed cassette 21 shown in FIG. The paper P taken out from the manual feed tray by the pickup roller 27 is sent out to the paper transport path by the paper feed rollers 23 and 25 and is supplied to the image forming unit 3 by the registration roller 26 at a predetermined timing.

  The image forming unit 3 supplies an image forming unit 7, an intermediate transfer belt 11 on which a toner image is primarily transferred onto the surface (contact surface) by the image forming unit 7, and a toner image on the intermediate transfer belt 11. A secondary transfer roller 12 for secondary transfer to the paper P sent from the paper unit 2 is provided.

  The image forming unit 7 includes a black unit 7K, a yellow unit 7Y, a cyan unit 7C, and a magenta unit 7M which are sequentially arranged from the upstream side (left side in FIG. 1) to the downstream side. ing. At the central position of each unit 7K, 7Y, 7C, 7M, each photosensitive drum 71 as an image carrier is disposed so as to be integrally rotatable around a drum shaft 711 in the direction of an arrow (counterclockwise). Around each photosensitive drum 71, a charger 75, an exposure device 76, a developing device 72, a cleaning device 73, and a static eliminator 74 are arranged in this order from the upstream side in the rotation direction.

  The charger 75 uniformly charges the peripheral surface of the photosensitive drum 71, and may be a scorotron charger, for example. The exposure device 76 is a so-called laser scanning unit. The exposure device 76 irradiates the peripheral surface of the photosensitive drum 71 uniformly charged by the charger 75 with laser light based on the image data input from the image reading device or the like, and converts the image data onto the photosensitive drum 71. Forming an electrostatic latent image based thereon; The developing device 72 supplies toner to the peripheral surface of the photosensitive drum 71 on which the electrostatic latent image is formed, thereby forming a toner image based on the image data. This toner image is primarily transferred to the intermediate transfer belt 11. The cleaning device 73 cleans the toner remaining on the peripheral surface of the photosensitive drum 71 after the primary transfer of the toner image to the intermediate transfer belt 11 is completed. The neutralizer 74 neutralizes the peripheral surface of the photosensitive drum 71 after the primary transfer is completed. The peripheral surface of the photosensitive drum 71 cleaned by the cleaning device 73 and the charge eliminator 74 is directed to the charger 75 for a new charging process, and a new primary transfer is performed.

  The intermediate transfer belt 11 is an endless belt-like rotating body, and includes a driving roller 13, a driven roller 14, a backup roller 15, and a primary roller so that the surface (contact surface) side is in contact with the peripheral surface of each photosensitive drum 71. It is stretched around a plurality of rollers such as the transfer roller 16. Further, the intermediate transfer belt 11 is configured to rotate endlessly by the plurality of rollers in a state where the intermediate transfer belt 11 is pressed against the photosensitive drum 71 by a primary transfer roller 16 disposed to face each photosensitive drum 71.

  The drive roller 13 is rotationally driven by a drive source 18 such as a stepping motor to give a drive force for rotating the intermediate transfer belt 11 endlessly. The drive roller 13 has an elastic layer made of urethane rubber or the like on the surface. It is preferable that the roller has. By doing so, slippage between the intermediate transfer belt 11 and the drive roller 13 is suppressed, driving force transmission is improved, and the intermediate transfer belt 11 is easily driven to rotate.

  The driven roller 14, the backup roller 15, and the primary transfer roller 16 are rotatably provided. These are driven rollers that rotate with the endless rotation of the intermediate transfer belt 11 by the driving roller 13. The driven roller 14, the backup roller 15, and the primary transfer roller 16 are driven to rotate via the intermediate transfer belt 11 according to the main rotation of the driving roller 13 and support the intermediate transfer belt 11.

  The primary transfer roller 16 applies a primary transfer bias (a polarity opposite to the toner charging polarity) to the intermediate transfer belt 11. Thereby, the toner image formed on each photoconductive drum 71 is an intermediate transfer belt that circulates in the direction of the arrow (clockwise) by driving the drive roller 13 between each photoconductive drum 71 and the primary transfer roller. 11 are sequentially transferred (primary transfer) in the overcoating state.

  A cleaning brush 17 is provided at the upper left position of the driven roller 14 in FIG. 2, and the toner remaining on the surface of the intermediate transfer belt 11 after the transfer of the toner image onto the paper P is cleaned. The intermediate transfer belt 11 removed by the brush 17 and cleaned by the brush 17 is supplied to the photosensitive drum 71. The fixing unit 4 performs a fixing process on the transfer image transferred to the paper P by the image forming unit 3. The fixing unit 4 is disposed opposite to the heating roller 41 heated by the energized heating element, and is disposed on the circumferential surface. Is provided with a pressure roller 42 pressed against and contacted with the peripheral surface of the heating roller 41.

  The secondary transfer roller 12 applies a secondary transfer bias having a polarity opposite to that of the toner image to the paper P. By doing so, the toner image primarily transferred onto the intermediate transfer belt 11 is transferred to the paper P between the secondary transfer roller 12 and the backup roller 15, whereby a color transfer image is transferred to the paper P. It is formed.

  The fixing unit 4 performs a fixing process on the transfer image transferred to the paper P by the image forming unit 3. The fixing unit 4 is disposed opposite to the heating roller 41 heated by the energized heating element, and is disposed on the circumferential surface. Is provided with a pressure roller 42 pressed against and contacted with the peripheral surface of the heating roller 41. The transferred image transferred to the paper P is fixed on the paper P by a fixing process by heating when the paper P passes between the heating roller 41 and the pressure roller 42. The paper P subjected to the fixing process is discharged to the paper discharge unit 5. Further, a conveyance roller 6 is disposed at an appropriate position between the fixing unit 4 and the paper discharge unit 5.

  Next, a rotation control mechanism of the photosensitive drum (image carrier) 71 in the color printer 1 will be described. FIG. 3 is a perspective view for explaining a drive transmission system of the photosensitive drum of the color printer according to the embodiment of the present invention. FIG. 4 is a block diagram for explaining the control of the rotation speed of the color printer according to the embodiment of the present invention. First, the configuration of the drive transmission system of the photosensitive drum will be described. As shown in FIG. 3, the drive transmission system 8 includes a motor 81, a drive gear 82, a driven gear 83, and a natural frequency changing unit 84.

  The motor 81, the drive gear 82, the driven gear 83, and the natural frequency changing unit 84 correspond to each of the photosensitive drums 71 and four are installed. When the drive gear 82 is driven, the driving force of the motor 81 is transmitted to the output shaft 811 via the natural frequency changing unit 84, and is output so that it can be rotated concentrically and integrally by rotation around the axis of the output shaft 811. The drive gear 82 installed on the shaft 811 rotates. The drive gear 82 is meshed with a driven gear 83 installed at one end of the photosensitive drum 71. Therefore, when the drive gear 82 rotates, the driven gear 83 is interlocked, and the photosensitive drum 71 that is concentric with the driven gear 83 also rotates.

  The natural frequency changing unit 84 is for suppressing uneven rotation of the photosensitive drum 71 around the drum shaft 711 by changing the natural frequency of the drive transmission system 8. The natural frequency changing unit 84 will be described in detail later with reference to FIG.

  Next, an electrical configuration of the color printer 1, particularly a configuration related to a rotation control mechanism around the drum shaft 711 of the photosensitive drum 71 will be described. In FIG. 4, the color printer 1 includes a photosensitive drum 71, a drive transmission system 8, a control unit 31, a rotation state detection unit 32, a storage unit 33, and a display unit 34. There are four types of photosensitive drums 71 and drive transmission systems 8 for black, yellow, cyan, and magenta. FIG. 4 shows only one of them.

  The rotation state detection unit 32 detects data relating to the rotation state of the photosensitive drum 71. The data relating to the rotation state is data necessary for grasping the rotation state of the photosensitive drum 71.

  Here, the rotation state includes rotation unevenness, rotation speed, and the like. The rotation unevenness refers to the rate of speed change with respect to the average rotation speed. Further, when the rotation unevenness is obtained by the FFT analyzer 35 described later, it is obtained by the sum of amplitudes at the respective frequencies. The rotation state detection unit 32 includes a rotary encoder 36 having a function of extracting a rotation signal indicating the rotation state of the photosensitive drum 71 as an electric signal, and FFT (Fast Fourier Transform) that performs frequency analysis on the signal from the rotary encoder 36. : Fast Fourier transform) analyzer 35.

  The rotary encoder 36 includes a disc-shaped encoder disk 36a concentrically and integrally rotatable around the drum shaft 711, a light emitting element facing one surface side of the encoder disk 36a, and a light receiving surface facing the other surface side. And an encoder detection unit 36b including an element. The encoder disk 36a has a plurality of slits 361 formed by being cut at equal intervals along its circumference. The light emitting element and the light receiving element are arranged such that light from the light emitting element is received by the light receiving element through the slit 361. The light receiving element outputs the received light from the light emitting element as an electrical signal. An electric signal from the rotary encoder 36 is input to the FFT analyzer 35. The FFT analyzer 35 performs frequency analysis on the input signal.

  In addition, it is preferable that a pulse signal based on a drive signal for controlling the rotation speed of the motor 81 output from the control unit 31 is input to the FFT analyzer 35. Thereby, since the FFT analyzer 35 can monitor the rotational speed of the motor 81 more accurately, a highly accurate frequency analysis becomes possible.

  The rotation state detection unit 32 may not include the FFT analyzer 35. If the FFT analyzer 35 is not provided, frequency analysis cannot be performed, but it is possible to detect the rotation speed and rotation unevenness of the photosensitive drum 71 only with the rotary encoder 36 alone. However, the FFT analyzer 35 is necessary if a complicated and highly accurate analysis is required, such as analyzing the cause of rotation unevenness. For example, the cause of rotation unevenness may be gear meshing, motor cogging, eccentricity, natural vibration, and the like. If frequency analysis using the FFT analyzer 35 is used, it is possible to identify which of these causes of rotation unevenness. You can also

  The storage unit 33 includes a rewritable nonvolatile EEPROM (Electrically Erasable Programmable Read Only Memory), a volatile RAM (Random Access Memory), and the like. Based on the frequency analysis result relating to the rotation of the photosensitive drum 71 by the FFT analyzer 35, the control unit 31 calculates rotational accuracy information including the relationship between the rotational speed and rotational unevenness of each photosensitive drum 71, and the storage unit 33. Remember me. The storage unit 33 may store various data calculated by the control unit 31 such as rotation unevenness not only at the initial value but also at every calculation. When various data are stored, time information is also stored in association with rotation accuracy data.

  The information regarding the time may be, for example, the actual time or the accumulated time during which the color printer 1 is operated. When various data are stored, the rotation state at that time is also stored in association with each other. Thereby, when calculating the current rotation accuracy information, the past rotation accuracy information can be taken into account, and more effective rotation accuracy information can be calculated.

  The display unit 34 displays a rotation state, for example, a value of rotation unevenness, an error display when repair is necessary, and the like. The display unit 34 is preferably configured using, for example, a liquid crystal display, an organic EL display, or the like in terms of compactness and easy viewing.

  The control unit 31 controls the rotation speed of the photosensitive drum 71, analyzes data on the rotation state (calculation of rotation unevenness, etc.), controls the optimum rotation speed according to the rotation state, and controls according to the function of each unit. Etc. The control unit 31 includes, for example, a storage element that stores a control program, a microprocessor that operates according to the control program, and a peripheral circuit thereof, and functionally includes a rotation speed control unit 31a and a rotation accuracy analysis. A unit 31b and a display control unit 31c are provided.

  The rotation speed control unit 31 a controls the rotation speed of the motor 81, and specifically includes a motor driver that controls the motor 81. Further, it is preferable that the rotation speed control unit 31a further includes a pulse oscillator, and a pulse signal based on a control signal sent from the rotation speed control unit 31a to the motor 81 is sent to the FFT analyzer 35. As a result, as described above, the FFT analyzer 35 can monitor the accurate rotation speed of the photosensitive drum 71. If the optimum rotation speed of the photosensitive drum 71 is calculated as a result of the analysis by the rotation accuracy analysis unit 31b, the rotation speed control unit 31a controls the motor 81 so as to be the rotation speed.

  The rotation accuracy analysis unit 31 b calculates rotation accuracy information based on the data regarding the rotation state output from the rotation state detection unit 32. The rotation accuracy information is various parameters for grasping the rotation state of the photosensitive drum 71. For example, the rotation unevenness and the relationship between the rotation speed and the rotation unevenness. Further, the rotation accuracy information may be calculated using the previous rotation accuracy information stored in the storage unit 33. For example, the current rotation unevenness value or the like may be calculated based on the initial value of the rotation unevenness. According to this value, the degree of deterioration of the rotation state can be easily understood, and rotation unevenness can be easily evaluated. The rotation unevenness calculated by the rotation accuracy analysis unit 31b is stored in the storage unit 33 in association with the rotation speed and time information.

  The rotation accuracy analysis unit 31b controls the rotation speed control unit 31a and the rotation state detection unit 32 in order to obtain data related to the rotation state. Further, based on the calculated rotation accuracy information, the suitability of the rotation speed of the photosensitive drum 71 is determined, and the optimum rotation speed is determined.

  The display control unit 31 c controls image display so that a predetermined image is displayed on the display unit 34. For example, if it is determined by the rotation accuracy analysis unit 31b that the rotation speed is appropriate, it is determined that the rotation speed is not preferable. In addition, the display control unit 31c causes the display unit 34 to display a distinction between a rotation speed zone with a good rotation state and a rotation speed zone with a bad rotation state. In addition, the display control unit 31c displays a display of the current rotation speed and rotation unevenness of the photosensitive drum 71, a result of frequency analysis, an error display indicating that repair is necessary, and the like. You can make it.

  Next, the determination of the appropriateness of the rotation speed of the photosensitive drum 71 performed by the rotation accuracy analysis unit 31b will be described. FIG. 5 is a graph showing the relationship between the rotation speed and the rotation unevenness in one photoconductor drum 71. The dotted line shows the state before the drive transmission system 8 is subjected to the high-rigidity processing, and the solid line is driven. A state after the transmission system 8 is subjected to the high rigidity processing is shown.

  In determining whether or not the rotational speed of the photosensitive drum 71 is appropriate, first, the rotational speed control unit 31a changes the rotational speed of the motor 81 within a certain range in accordance with an instruction from the rotational accuracy analysis unit 31b, and the rotation within the range. The FFT analyzer 35 performs frequency analysis of the rotation signal from the rotary encoder 36 at speed. Furthermore, based on the data relating to the rotation state, which is the frequency analysis data output from the FFT analyzer 35, the rotation accuracy analysis unit 31b is indicated by a dotted line (indicated as before the countermeasure in FIG. 5) in the graph of FIG. The relationship between the rotational speed and rotational unevenness is calculated.

Incidentally, in the graph of FIG. 5, the value of the uneven rotation Y in response to the rotational speed omega of the photosensitive drum 71 is increased even continue to increase, uneven rotation Y at the time the rotational speed omega becomes omega ₁ Is the maximum value Y _max1 . Accordingly, when the rotational speed ω increases thereafter, the rotation unevenness Y decreases. In the present embodiment, the value of the reference rotation unevenness (reference value) Y _b is set in advance, and the value of Y _b is stored in the storage unit 33. Note that the value of the reference rotation unevenness Yb may be different depending on the characteristics of the photosensitive drums 71 of the units 7K, 7Y, 7C, and 7M, or the same value may be uniformly set. It may be set.

On the other hand, the rotational speed of the current state of the photosensitive drum 71 omega is set to omega _0. The value of the rotation unevenness Y corresponding to the current rotation speed ω ₀ is Y ₀ in the example shown in FIG. In the example shown in FIG. 5, the value of the current rotation unevenness Y ₀ before this measure is greater than the value of the reference rotation unevenness Y _b. Then, in the present invention, when the value of the current rotation unevenness Y ₀ is greater than the value of the reference rotation unevenness Y _b, this is determined by the rotation speed control unit 31a, speed control unit 31a, the display control unit 31c (For example, a display such as “Rotation unevenness exceeds a reference value. Call a service person to perform a predetermined action to reduce the rotation unevenness”). To do.

Then, when this action, which will be described later in detail, is performed to increase the rigidity of the drive transmission system 8 and increase the natural frequency, the relationship between the rotational speed ω of the photosensitive drum 71 and the rotation unevenness Y in the graph of FIG. As shown by the solid line, the curve indicating the movement moves to the right from the dotted line as a whole, and when the rotational speed ω is ω ₂ larger than ω ₁ , the value of the rotation unevenness Y is Y _max1 A slightly lower Y _max2 is obtained. The value of rotational irregularity Y corresponding to the current rotation speed omega ₀ in this case, low Y ₁ next standard rotational irregularity Y _b as shown in FIG. 5, the irregular rotation Y without changing the rotational speed of the photosensitive drum 71 The value of can be suppressed.

Note that when the value of the current rotational speed ω ₀ is lower than the value of the reference rotational unevenness Y _b , only data indicating the relationship between the obtained rotational speed ω and the rotational unevenness Y is stored in the storage unit 33. In particular, no action is taken.

In the present invention, the rotational speed ω of the photosensitive drum 71 is changed within a predetermined range (within the specifications of the color printer 1) without changing the natural frequency of the drive transmission system 8 botheringly. When it is possible to suppress the rotation unevenness of the photosensitive drum 71, a change in the rotation speed ω is handled as a category of control by the normal rotation speed control unit 31a. Specifically, for example, in the case of the example shown in the graph of FIG. 5, the current rotation unevenness Y ₀ on the dotted line at the current rotation speed ω ₀ exceeds the reference rotation unevenness Y _b , but the rotation speed ω is set to, for example, ω _3. if the rotation unevenness Y consists lower _{Y 2} reference rotation unevenness _{Y b.} If the rotational speed ω ₃ is within the specification range of the color printer 1, the rotational speed ω of the photosensitive drum 71 can be changed without changing the natural frequency of the drive transmission system 8. be able to.

  FIG. 6 is a perspective view showing an embodiment of a natural frequency changing unit 84 for increasing the rigidity of the drive transmission system 8 and changing its natural frequency, and FIG. 6 (A) is a transmission gear mechanism. 6B shows a state before the weight 86 is attached to the casing 85, and FIG. 6B shows a state where the weight 86 is attached to the casing 85 of the transmission gear mechanism.

  As shown in FIG. 6, the natural frequency changing unit 84 includes a rectangular parallelepiped casing 85 in which a gear mechanism for speed change interposed between the motor 81 and the output shaft 811 is installed, and the casing 85. And a weight 86 fixed to the side wall 851 with screws B. The motor 81 is fixed to the left surface of the casing 85 in FIG. A screw seat 853 is projected from the right end of the casing 85 in FIG. The casing 85 is fixed to the frame F by the screws S passing through the screw seats 853 and screwed into the screw holes of the predetermined frame F.

  In addition, a plurality of bushes 852 having a female screw threaded on the inner peripheral surface project from the side wall 851 of the casing 85. In the example shown in FIG. 6, one bush 852 is provided at the center in the left-right direction at the top of the side wall 851, and two bushes 852 are provided in total at the left and right positions at the bottom of the side wall 851. . These bushes 852 are for fixing the weight 86 to the casing 85.

  The weight 86 is attached to the casing 85 integrally to change the natural frequency of the drive transmission system 8, thereby reducing the rotation unevenness of the photosensitive drum 71. The weight 86 is formed of a so-called heavy metal having a large specific gravity such as lead, and the weight 86 is fixed to the casing 85, thereby effectively changing the natural frequency of the drive transmission system 8. Can do.

  In this embodiment, such a weight 86 is set in a vertically long rectangular shape in accordance with the shape of the side wall 851 of the casing 85. A through-hole 861 for penetrating the screw B is formed at a position corresponding to each bush 852. Therefore, as shown in FIG. 6A, with the weight 86 facing the casing 85, the screws B are inserted into the respective through holes 861, and screwed into the corresponding bushes 852 to be fastened. The weight 86 is fixed to the casing 85 as shown in FIG.

If the rotation unevenness of the photosensitive drum 71 exceeds the reference rotation unevenness Y _b (FIG. 5), the natural frequency of the drive transmission system 8 can be changed by fixing the weight 86 to the casing 85. Accordingly, as described above with reference to FIG. 5, the rotation unevenness of the photosensitive drum 71 can be reduced.

  Hereinafter, an action for reducing rotation unevenness of the photosensitive drum 71, which is executed based on the control by the control unit 31, will be described with reference to FIG. FIG. 7 is a flowchart showing an action flow for reducing rotation unevenness of the photosensitive drum 71.

During operation of the color printer 1, the rotation state detection unit 32 detects data relating to the rotation state of the photosensitive drum 71, and the control unit 31 calculates rotation unevenness (step S1). Next, it is determined whether or not the rotation state of the photosensitive drum 71 is within specifications (step S2). Specifically, it is determined whether or not the rotation unevenness Y exceeds the allowable range (reference rotation unevenness Y _b shown in FIG. 5), and if the specification does not exceed the allowable range (YES in step S2), Step S3 is executed, the rotation state detection unit 32 detects the data about the rotation speed ω and the rotation unevenness Y calculated by the rotation accuracy analysis unit 31b, and the data is stored in the storage unit 33, and the control ends.

In contrast, if not within specification irregular rotation Y of the photosensitive drum 71 exceeds the reference rotation unevenness Y _b at step S2 (NO in step S2), the change in the rotational speed ω of the photosensitive drum 71 in step S4 in or can respond (i.e., whether it is possible to suppress the uneven rotation Y below the reference rotational irregularity Y _b by changing the rotational speed ω of the photosensitive drum 71) is determined. And if correspondence is possible (YES in step S4), while irregular rotation Y is within the specified range (i.e. uneven rotation Y is less than the reference rotation unevenness Y _b) is changed to the rotation speed omega, photoreceptor If the change in the rotational speed ω of the drum 71 cannot be handled (NO in step S4), step S6 is executed.

In step S 6, it is determined whether or not a response can be made by a change in rigidity of the natural frequency changing unit 84. This determination is in the storage unit 33 in order to perform and adaptable range is stored in advance relates improve the current rotational irregularity Y ₀ detected by the rotational state detection portion 32, the rotation precision analyzer 31b was actually calculated It is possible to determine whether or not the value of the rotation unevenness Y is within the applicable range.

If the change can be dealt with by the change in rigidity (YES in step S6), the display control unit 31c controls the display unit 34 to output a character so as to call a serviceman, and based on the data accumulated in the past. The optimal stiffness value calculated by (the weight of the weight 86) is stored in the storage unit 33 (step S7). Thereafter, the control by the control unit 31 ends. The weight of the weight 86 stored in the storage unit 33 is output to the display unit 34 when the serviceman arrives at the site later. Then, the weight 86 having the weight is attached to the casing 85 of the natural frequency changing unit 84. As a result, the curve of the graph showing the relationship between the rotation speed ω and the rotation unevenness Y shown in FIG. 5 moves, so that even if the rotation speed ω of the photosensitive drum 71 remains the current rotation speed ω ₀ , the current rotation rotation unevenness Y ₁ corresponding to the velocity omega ₀ will be below the reference rotational unevenness Y _b. The rotation unevenness Y ₁ is, if you do not fall below the reference rotational unevenness Y _b, and replaced with another heavy weight 86 to below, the so-called trial and error are repeated.

  On the other hand, when the change in rigidity of the natural frequency changing unit 84 cannot cope with the change (NO in step S6), the display unit 34 indicates that the color printer 1 is out of order or has a life and maintenance is required. The comment is displayed as a character output (step S8), and then the control by the control unit 31 ends.

  By the way, the display unit 34 has a light emitting member 37 made of, for example, an LED (Light Emitting Diode) in addition to an LCD (Liquid Crystal Display) used for character output when necessary in the flow in the flowchart of FIG. Depending on whether or not the light emitting member 37 is lit, it is displayed which of the photosensitive drums 71 in the units 7K, 7Y, 7C, and 7M has a malfunction. Yes.

  FIG. 8 is an explanatory diagram for explaining display by the light emitting members 37. FIG. 8A shows a case where all the light emitting members 37 are turned on and the rotation state of each photosensitive drum 71 is good. 8 (B) shows a case where there is a photosensitive drum 71 having a problem in the rotation state.

  As shown in FIG. 8, the light emitting member 37 includes a black issuing member 37K corresponding to the photosensitive drum 71 of the black unit 7K, a yellow issuing member 37Y corresponding to the photosensitive drum 71 of the yellow unit 7Y, A cyan issue member 37C corresponding to the photosensitive drum 71 of the cyan unit 7C and a magenta issue member 37M corresponding to the photosensitive drum 71 of the magenta unit 7M are employed.

Then, when the photoreceptor drum 71 of each unit 7K, 7Y, 7C, and 7M is targeted and the quality of the rotational state of the photoreceptor drum 71 is determined by the procedure shown in the flowchart of FIG. 7, it is within the specifications in step S2. Is determined, that is, when the rotation unevenness Y is below the reference rotation unevenness Yb (YES in step S2), the light emitting member 37 is turned on. When contrast is determined that the it is out of specification in step S2 (Fig. 7), i.e., when the rotational nonuniformity Y is exceeding the reference rotational unevenness Y _b and are the same or reference uneven rotation Yb are subject The light emitting member 37 is turned off.

  Therefore, the operator can know immediately which light emitting member 37 is extinguished and which one of the photosensitive drums 71 is in trouble.

  Incidentally, in FIG. 8A, since all the light emitting members 37 of the black issue member 37K, the yellow issue member 37Y, the cyan issue member 37C, and the magenta issue member 37M are lit, each unit 7K, 7Y. , 7C, 7M, the rotation state of all the photosensitive drums 71 is normal.

  In contrast, in FIG. 7B, since the black issue member 37K, the yellow issue member 37Y, and the cyan issue member 37C are turned off, the black unit 7K, the yellow unit 7Y, and the cyan unit 7C It can be seen that the photosensitive drum 71 has a rotation failure.

  As described above in detail, according to the color printer 1 of the present embodiment, the drive transmission system 8 that drives the photosensitive drum 71 that is rotatably supported integrally around the drum shaft 711, and the photosensitive drum 71. A rotation state detection unit 32 that detects data related to the rotation state, a display unit 34 that displays items related to rotation of the photosensitive drum 71, and a control unit 31 that performs control related to driving of the photosensitive drum 71 are provided. is there.

  The drive transmission system 8 includes a natural frequency changing unit 84 that can change the natural frequency, and the control unit 31 includes a rotation speed control unit 31a that controls the rotation speed of the photosensitive drum 71, and a rotation state detection. A rotation accuracy analysis unit 31b for deriving a relationship between the rotation speed of the photosensitive drum 71 and the rotation unevenness based on the detection result of the unit 32, and a display control unit 31c for controlling display on the display unit 34 are provided.

Moreover, when the rotational nonuniformity of the rotational speed that is actually performed by the analysis of the rotation precision analyzer 31b exceeds a preset reference rotational unevenness Y _b reference value, the display controller 31c, toward the display unit 34 The natural frequency changing unit 84 outputs a control signal to display that the natural frequency should be changed.

  Therefore, the rotation accuracy analysis unit 31b analyzes the detection result of the rotation state detection unit 32, and based on the relationship between the rotation speed of the photoconductor drum 71 and the rotation unevenness, the rotation of the photoconductor drum 71 that is actually rotating. When the rotation unevenness at the rotation speed exceeds the preset reference rotation unevenness Yb, the display unit 34 causes the natural frequency changing unit 84 to respond to a control signal from the display control unit 31c to the display unit 34. To display that the natural frequency of the drive transmission system 8 should be changed. Therefore, the vibration of the drive transmission system 8 can be suppressed without changing the rotation speed of the photosensitive drum 71 by the operation of changing the natural frequency of the drive transmission system 8 by an operator who has visually recognized this display or a service person who has been called.

  As described above, the relationship between the rotational speed and the rotation unevenness of the photosensitive drum 71 can be easily derived by a simple measure of causing the rotational state detecting unit 32 to detect the rotational state of the photosensitive drum 71, and this derivation. Based on the result, it is possible to easily know the position of the rotational speed of the currently rotating photosensitive drum 71 in relation to the rotation unevenness in order to suppress the vibration of the drive transmission system 8. Therefore, it is not necessary to create a complicated simulation model or calculation formula which is troublesome as in the prior art, and an effective vibration absorbing process for the photosensitive drum 71 is executed by changing the natural frequency of the drive transmission system 8 more easily. The

  Further, since it is not necessary to change the rotational speed of the photosensitive drum 71, there is no inconvenience that the image forming processing capability of the color printer 1 fluctuates when the rotational speed is changed, and it is always stable. Image formation processing capability can be ensured.

  Since the drive transmission system 8 changes the rigidity of the drive transmission system 8 by adding the weight 86, the structure of the drive transmission system 8 is simplified and the operation can be performed with an extremely simple operation. The rigidity of the drive transmission system 8 can be easily changed.

  Further, even if the rotation unevenness Y of the photosensitive drum 71 exceeds the reference rotation unevenness Yb, the rotation unevenness is controlled by the rotation speed control by the rotation speed control unit 31a within the predetermined range of the photosensitive drum 71. When the rotation unevenness Yb can be suppressed, the display control unit 31c prevents the display unit 34 from displaying a display indicating that the natural frequency should be changed. In this way, the slight rotation unevenness Y of the photosensitive drum 71 can be dealt with by changing the rotational speed of the photosensitive drum 71 without changing the natural frequency of the drive transmission system 8. Conveniently, the rotation unevenness Y of the photosensitive drum 71 can be reduced without performing a troublesome operation for changing the number.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the color printer 1 has been described as an example of the image forming apparatus. However, a monochrome printer may be used instead of the color printer 1, and a copier regardless of color or monochrome. Or a facsimile machine.

  (2) In the above embodiment, the photosensitive drum 71 has been described as an example of the image carrier, but an endless belt wound around a pair of rollers instead of the photosensitive drum 71 is used as the image carrier. It may be used. In this case, the term “rotation” of the image carrier according to the present invention is replaced with the term “circulation” of the image carrier.

  (3) In the above embodiment, in addition to fixing the weight 86 to the casing 85 including the speed change gear mechanism, the screw S for fixing the casing 85 to the frame F is any of the plurality of screw seats 853. It is possible to select whether or not to screw the frame F, and thereby adjust the rigidity of the drive transmission system 8.

  (4) In the above embodiment, as shown in FIG. 6, the example in which the weight 86 is fixed to the one side wall 851 of the casing 85 has been shown, but the fixing location of the weight 86 is limited to this. Instead, it may be attached to any surface of the casing 85.

1 is a schematic cross-sectional view showing an overall configuration of an embodiment of a color printer according to the present invention. FIG. 2 is an enlarged explanatory view showing an image forming unit 3 and a fixing unit 4 extracted from the color printer shown in FIG. 1. FIG. 3 is a perspective view for explaining a drive transmission system of a photosensitive drum of the color printer according to the embodiment of the present invention. It is a block diagram for demonstrating control of the rotational speed of the color printer which concerns on embodiment of this invention. 7 is a graph showing the relationship between the rotation speed and rotation unevenness in one photosensitive drum 71, showing a state before the rigidity of the drive transmission system is applied to the drive transmission system by a dotted line, and a high line for the drive transmission system by a solid line. The state after the stiffening process is shown. It is a perspective view which shows one Embodiment of the natural frequency change part for raising the rigidity of a drive transmission system and changing the natural frequency, (A) is a weight mounted to the casing of a transmission gear mechanism. (B) shows a state in which a weight is mounted on the casing of the transmission gear mechanism. It is a flowchart which shows the flow of the action for rotation irregularity reduction of a photoconductive drum. It is explanatory drawing for demonstrating the display by a light emitting member, (A) shows the case where all the light emitting members are lighted and the rotation state of each photoconductive drum is favorable, (B) has a malfunction in a rotation state. A case where a photosensitive drum is present is shown.

Explanation of symbols

1 Color printer (image forming device)
DESCRIPTION OF SYMBOLS 1a Device main body 2 Paper feed part 3 Image formation part 4 Fixing part 5 Paper discharge part 6 Conveyance roller 7 Image formation unit 7K Black unit 7Y Yellow unit 7C Cyan unit 7M Magenta unit 8 Drive transmission system 11 Intermediate transfer belt 12 Next transfer roller 13 Drive roller 14 Driven roller 15 Backup roller 16 Primary transfer roller 17 Cleaning brush 18 Drive source 21 Paper feed cassette 22 Pickup roller 23 Paper feed roller 26 Registration roller 27 Pickup roller 31 Controller 31a Rotational speed controller 31b Rotational accuracy Analysis unit 31c Display control unit 32 Rotation state detection unit 33 Storage unit 34 Display unit 35 Analyzer 36 Rotary encoder 36a Encoder disk 36b Encoder detection unit 37 Light emitting member 37K Black issuing member 3 Y Publishing yellow issuing member 37C cyan member 37M for magenta issuing member 41 heat roller 42 pressing roller 71 the photosensitive drum (image bearing member (rotational load))
72 Developing Device 73 Cleaning Device 74 Charger 75 Charging Device 76 Exposure Device 81 Motor 811 Output Shaft 82 Drive Gear 83 Driven Gear 84 Natural Frequency Change Unit (Natural Frequency Change Means)
85 Casing 851 Side wall 852 Bush 853 Screw seat 86 Weight 861 Through hole 361 Slit B Screw F Frame P Paper S Screw

Claims (3)

A drive transmission system for driving a rotatable image carrier;
A rotation state detector for detecting data relating to the rotation state of the image carrier;
A display unit for displaying matters relating to rotation of the image carrier;
A control unit for controlling the driving of the image carrier;
Natural frequency changing means capable of changing the natural frequency of the drive transmission system,
The controller is a rotational speed controller that controls the rotational speed of the image carrier;
A rotation accuracy analysis unit for deriving a relationship between a rotation speed and rotation unevenness of the image carrier based on a detection result of the rotation state detection unit;
A display control unit that controls display on the display unit,
When the rotation unevenness of the current rotation speed exceeds a preset reference value by the analysis of the rotation accuracy analysis unit, the display control unit changes the natural frequency on the display unit by the natural frequency changing unit. An image forming apparatus, characterized in that a display to the effect is made.   2. The image forming apparatus according to claim 1, wherein the natural frequency changing means changes the rigidity of the drive transmission system by adding a weight.   Even when the rotation unevenness exceeds the reference value, the rotation unevenness can be suppressed within the reference value by controlling the rotation speed by the rotation speed control unit within a predetermined range of the image carrier. The image forming apparatus according to claim 1, wherein the display control unit does not display on the display unit a message indicating that the natural frequency should be changed.

Images