JP2009192596A - Belt transporting apparatus with belt skewing control mechanism and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition with high accuracy in an action for transporting a belt in a belt transporting apparatus converging displacement of the belt in an axial direction by inclining a roller to which the belt is hung. <P>SOLUTION: The belt transporting apparatus is provided with an endless belt and a plurality of rollers to which the belt is hung and the displacement of the belt in the axial direction is converged by inclining one of a plurality of rollers. On starting a prescribed action, when the prescribed action is different from the content of an action immediately before, an idle action which is the same content as the prescribed action is executed before going onto the prescribed action. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a belt shift control mechanism of a belt conveyance device using an endless belt. The present invention also relates to an image forming apparatus such as a printer, a copier, and a fax machine equipped with a belt conveyance device using this control technology.

  Conventionally, endless belts are used in various fields. For example, in an electrophotographic image forming apparatus, endless belts are used as a latent image carrier, an intermediate transfer member, a sheet conveying member, a fixing member, and the like. The endless belt is supported and stretched from the inner surface of the loop by a plurality of stretching rollers, and moves endlessly by the rotational drive of at least one stretching roller. In such endless movement, if the roundness of the stretching roller is not sufficient or the parallelism is slightly deviated between the plurality of stretching rollers, the belt cannot be endlessly moved straight. If the belt meanders or shifts, the belt can be removed from the tension roller, possibly leading to damage to the belt. Further, in an image forming apparatus using an endless belt, there is a risk of image misalignment. Therefore, it is necessary to regulate or correct the deviation of the belt.

  Specifically, in the case of regulation, a rubber stopper or a guide rib such as rubber is provided at the end of the belt, and it is regulated by the end of the stretching roller or the circumferential groove of the roller, or a flange is provided at the end of the roller. Direct regulation of the belt end face. However, these configurations not only increase the cost, but also cause the belt detent member to break if the deviating force exceeds the expected level due to distortion of the unit, and even the belt may be damaged. There are also many problems such as the sticking member that has been affixed to the surface, and the handling of the belt must be handled carefully, and even when replacing the belt, the stopper member cannot be easily and smoothly carried out. It was.

  Also, a method using a mechanical link or the like has been proposed as a method for correcting the belt deviation. What is disclosed in Patent Document 1 is a configuration in which the rib on the back surface of the belt rotates by passing between the contact bodies, and the roller shaft is tilted via the link mechanism. In Patent Document 2, a roller shaft displacement member that displaces a roller shaft in accordance with the movement of the belt in the axial direction of the roller is arranged at the end of the roller, and the end surface of the pulley that functions as a detection member at the belt end surface The configuration of pressing is described. In addition, as described in Patent Document 3, there is a proposal that a detection ring is provided and the roller shaft is tilted by using a driving torque generated when the belt end portion rides up. However, when these low-cost and simple mechanical deviation correction methods are used, the time required for the belt movement in the axial direction to converge is the accuracy of the parts, the parallelism of the unit, the installation status of the device body, etc. There is a drawback that it differs depending on the mode. In addition, there is a problem in terms of durability that the belt is stressed and consequently the belt is damaged.

  In addition, a device that detects the position of a belt using a steering roller and a sensor and applies a displacement to a roller shaft using a driving source has been proposed and commercialized. However, in such a system, the cost of the driving device for moving the steering roller up and down, the above-described sensor, the steering roller, etc. is greatly increased.

  In any case, however, the belt must be moved endlessly in a straight line by preventing or converging the movement / displacement in the direction of the rotation axis of the belt by some measure.

JP 2005-92153 A JP 2006-162659 A JP-A-5-52244

  SUMMARY OF THE INVENTION An object of the present invention is to provide a belt conveyance device that converges the axial displacement of a belt by inclining a roller that wraps around the belt, thereby providing a configuration that makes the belt conveyance operation accurate.

  According to the present invention, there is provided a belt transport configured to have an endless belt and a plurality of rollers for winding the endless belt, and to converge the axial displacement of the belt by inclining one of the plurality of rollers. When the predetermined operation is different from the content of the previous operation, the device can solve the problem by performing the idle operation having the same content as the predetermined operation.

  The belt conveyance device is assumed to be a transfer conveyance belt device of an image forming apparatus or an intermediate transfer belt device. Further, it is assumed that the operation is belt conveyance and the content of the operation is a belt conveyance speed. It is also assumed that the above-described operation is the contact / separation of the roller around the belt with respect to the inner peripheral surface of the belt, and the content of the operation is an entrance angle of the belt with respect to the roller inclined by the contact / separation of the roller with the belt. The content of the above operation is the image forming mode, and the operation content may be changed by switching between the color mode and the single color mode.

  Furthermore, it is also effective to execute the idling operation when the belt is exchanged or to perform the idling operation when the apparatus power source is switched from OFF to ON.

  According to the first aspect of the present invention, the belt has an endless belt and a plurality of rollers for winding the endless belt, and is configured to converge the axial displacement of the belt by inclining one of the plurality of rollers. When a predetermined operation is different from the content of the previous operation, the transport device performs the idling operation having the same content as the above-mentioned predetermined operation. It can be transported with high accuracy.

  If the belt conveyance device is a transfer conveyance belt device of the image forming apparatus, the transfer sheet can be conveyed straight, and skew and color misregistration of the transferred image can be prevented. If the belt conveying device is an intermediate transfer belt device, it is possible to prevent color shift and skew of the composite image. Also, if the above operation is a belt conveyance and the content of the above operation is a belt conveyance speed, even if the belt linear speed is switched and the belt is slightly displaced in the axial direction due to a change in the slip rate of the driving roller, etc. The feeding accuracy of the conveyed product can be maintained, and color misregistration and skew can be prevented in the image forming apparatus. If the above operation is the contact / separation of the roller around the belt with respect to the inner peripheral surface of the roller, and the content of the operation is an entrance angle of the belt with respect to the roller tilted by the contact / separation of the roller with the belt, the balance state of the belt changes Even in this case, it is possible to maintain the feeding accuracy of the conveyed product, and it is possible to prevent color misregistration and skew in the image forming apparatus. The content of the above operation is the image forming mode, and even when the operation content is changed by switching between the color mode and the single color mode, color shift and skew can be prevented.

  Furthermore, if the idle rotation operation is additionally executed when the belt is exchanged, the conveyance accuracy can be ensured even if the balance position of the belt differs due to matching with the apparatus main body. It is also useful for securing the conveyance accuracy to additionally execute the idling operation when the apparatus power is turned off.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an image forming apparatus according to the present invention, which is a tandem indirect (intermediate) transfer type copying machine. An endless belt-like intermediate transfer member 10 is provided in the center of the apparatus main body. The intermediate transfer member 10 may have a multilayer structure or a single layer structure. For a multi-layer structure, the base layer is made of, for example, a fluororesin, PVDF sheet or polyimide resin with little elongation, and the surface is covered with a smooth coat layer such as a fluororesin. Materials such as PC, polyimide are used. In the present invention, it is not particularly necessary to specify the material of the intermediate transfer member. As shown in FIG. 1, the belt is wound around the support rollers 12, 13, 14, and 15 so that the belt can be rotated and conveyed counterclockwise.

  In this illustrated example, an intermediate transfer member cleaning device 19 for removing residual toner remaining on the intermediate transfer member 10 after image transfer is provided on the left side of the support roller 13. A blade-like member such as urethane is used as the cleaning member and abuts in the counter direction with respect to the rotation direction of the intermediate transfer member. Although not shown, the cleaning member may be electrostatically recovered using a conductive brush or roller in addition to the urethane blade. In addition, the toner collected by the blade is conveyed to the back side of the apparatus by a conveying member (not shown) in the cleaning device, and is dropped downward by gravity or the like to be stored in a toner collecting bottle (not shown). Is done. The toner collection bottle is provided with a means for detecting the amount of collected toner, and prevents the toner from overflowing by stopping the apparatus when the bottle is full.

  Further, below the lower side of the belt of the intermediate transfer member 10, four image forming units of magenta, cyan, yellow, and black are arranged side by side along the conveying direction to constitute a tandem image forming apparatus. Yes. An exposure device (not shown) is provided below the tandem image forming apparatus.

  On the other hand, a secondary transfer roller 21 is provided on the side of the intermediate transfer body 10 facing the support roller 12. A fixing device 30 for fixing the transferred image on the transfer sheet is provided on the downstream side of the sheet conveyance of the secondary transfer device including the secondary transfer roller 21. The fixing device 30 is configured by pressing a pressure roller against a fixing roller as usual.

  When a start switch (not shown) is pressed, one of the support rollers 12, 13, 14, and 15 is rotationally driven by a drive motor (not shown), and the other support rollers are driven to rotate to convey and convey the intermediate transfer member 10. . At the same time, in each image forming means, the photoreceptor 1 (1a-1d) is rotated to form magenta, cyan, yellow, and black single-color images on each photoreceptor 1. As the intermediate transfer member 10 moves, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer member 10.

  On the other hand, when the start switch is pressed, the paper feeding roller 26 of the paper feeding device is rotated, the transfer sheet is fed out from the paper feeding cassette 25, and separated one by one by a separation roller (not shown) and put into the paper feeding path. Then, the sheet is conveyed by the conveying roller 27 and guided to the sheet feeding path in the copying machine main body, and is abutted against the registration roller 28 and stopped. Then, the registration roller 28 is rotated in synchronization with the composite color image on the intermediate transfer body 10, the sheet is fed between the intermediate transfer body 10 and the secondary transfer roller 21, and transferred by the secondary transfer roller 21. A color image is recorded on the sheet.

  The sheet after the image transfer is conveyed by the secondary transfer roller 21 and sent to the fixing device 30 where heat and pressure are applied to fix the transferred image, and then the sheet is discharged by the discharge roller 32 and placed on the discharge tray. Stack. On the other hand, the intermediate transfer body 10 after image transfer is prepared for re-image formation by the tandem image forming apparatus by removing residual toner remaining on the belt after the image transfer by the intermediate transfer body cleaning device 19.

  Next, an example of a belt deviation correction mechanism will be described. This is to give a tilt to the steering roller in accordance with the displacement of the belt in the axial direction and to correct the deviation of the belt. An inclination imparting member is provided at the end of the roller that is configured to be inclined when the belt is displaced in the axial direction. The inclination imparting member moves in the axial direction, and the inclination of the roller changes to converge the movement of the belt. To make it happen. An example of a specific configuration for mechanically converging the belt movement is shown in FIGS.

  The steering roller 51 is disposed in a state where the steering roller 51 is slightly tilted from the horizontal position in advance, as indicated by a dashed line in FIG. Then, when the belt 10 starts to rotate in the direction of the arrow in FIG. 3, the belt 10 starts to move in the axial direction (left direction) indicated by the arrow in FIG.

  Further, a side guide 52 is provided at one end of the inner periphery of the belt 10, and a belt movement detection member 53, which is a short roller having the same diameter as the steering roller 51, is disposed on the inner side of the side guide 52. The spring 54 is always in contact with the shift guide 52. A roller shaft displacement member 55 that is integrally formed with the belt movement detection member 53 and that can be displaced in the axial direction has a conical surface (inclined portion) in contact with a guide member 56 that is fixed to a body frame (not shown). When the belt 10 starts to move to the left in the figure, the belt is displaced together with the belt movement detecting member 53 against the spring 54, and the conical surface slides on the guide member 56, so that the steering roller 51 is horizontal (shown by a dotted line). It is lifted in the direction approaching. Then, the force approaching the axial direction of the belt 10 is weakened, and the belt shift converges in a balanced state. In addition, when taking the structure which integrates a cleaning apparatus with the steering roller 51, when operating a steering roller, a big offset force may be required. In this case, there is a concern that the steering roller stops with a large shift force and is restricted by the shift guide. Therefore, by adding a spring 57 that assists the operation of the steering roller 51, the steering roller 51 may be moved even with a weak shifting force, and shift correction with excellent shift durability may be realized. At this time, the assisting direction may be reversed depending on the tension applied to the belt in some cases. The correction direction and the strength of the force are adjusted to optimum positions in various configurations of the belt driving device.

  Then, as in this example, when a method of tilting a roller using the moving force of the belt is used, the moving force of the belt varies depending on the unit, the installation state of the main body, and dimensional variations. That is, in the case of the mechanical type, the time until convergence is changed depending on the state at that time. If, for example, a printing operation is performed before the movement / displacement of the belt converges, an image is printed on the belt while the belt is moving in the axial direction, which causes color shift and skew. In other words, the printing operation is ideally performed after the belt movement has completely converged. The result of measuring the actual movement of the belt in the axial direction is shown in FIG. FIG. 4 shows data obtained by experimenting by changing the roller parallelism and the upper and lower limits of the linear velocity in each of the black and color modes.

  From this result, it can be seen that the time and position until the movement of the belt in the axial direction converges are different depending on the mode such as the full color mode and the black mode even if the same apparatus is used. In the case of the mechanical type, it is difficult to control the convergence time because the principle is that the movement / displacement converges when the force is finally balanced. Therefore, it is necessary to start the printing operation after convergence. It is desirable that this idle turning operation for convergence should be performed whenever the mode to be implemented is different from the previous mode. However, based on the basic data shown in FIG. 4, it may be designed so as to determine which mode switching operation requires the idling operation and set the time or the like.

  The amount of deviation of the belt is basically determined by the angle of approach to the roller on which the belt is wound. That is, when the arrangement of the rollers on which the belt is wound differs depending on the mode as shown in FIG. 5 (full color mode) and FIG. 6 (single color mode), the belt convergence position and convergence time are likely to change. This is because the convergence position and the convergence time greatly contribute to the parallelism of the roller on which the belt is wound, the parallelism of the photoconductor in contact with the surface, and the tension deviation before and after the tension. Therefore, when switching the mode in which the convergence position or the convergence time changes as described above, it is desirable to enter the present mode (printing operation) after performing a certain period of idling operation. An example of the operation sequence is shown in FIG.

  Here, the previous printing operation is completed in the color mode (the state shown in FIG. 5), the apparatus main body is temporarily stopped, the subsequent print effective data is sent to the apparatus main body, and the next operation mode is the black mode ( It is an example of the sequence in the case of (state shown in FIG. 6). If the mode is different before and after the machine stop period as in this example, the belt convergence position and convergence time may change as described above, so `` After running idle in almost the same state as the next operation '' The printing operation is started. The same state means that the positional relationship of at least the rollers is the same. Preferably, the bias application conditions are also matched. However, since the belt shift is almost determined by the geometric condition, the “positional relationship” is a problem as a necessary condition.

  The idling time at this time is set as a time until the belt movement is sufficiently converged or an abnormal image (color shift, skew) does not occur. This time is determined from the measurement data as shown in FIG.

  Here, examples of color mode and black mode are described in detail for mode switching, but mode switching that requires the control of the present invention is also assumed. For example, it can be considered when the linear velocity changes greatly, when the secondary transfer roller comes in contact with or separates, when the power is turned OFF / ON (after leaving for a long time), or when the unit is replaced. In any case, it is necessary to determine the necessity of this control after measuring data as shown in FIG. 4 under the critical acceleration condition from the combination of mode switching assumed at that time.

  Note that the present invention has the core in maintaining the quality so as not to be affected by the deviation of the belt by turning on the idling control, and can be widely used as long as it is a belt conveyance device regardless of the image forming apparatus. Technology.

1 is a schematic configuration diagram of an image forming apparatus. It is a figure which shows the structural example of a belt deviation | shift correction mechanism. FIG. 3 is a partial perspective view corresponding to the belt deviation correction mechanism of FIG. 2. It is a graph which shows the relationship between the convergence time measured until the axial displacement of the belt at the time of mechanical shift control converges and the convergence position. It is a conceptual diagram which shows arrangement | positioning of the roller in connection with the belt in a full color mode. It is a conceptual diagram which shows arrangement | positioning of the roller in connection with the belt in a monochrome mode. It is a figure which shows an example for the schematic description of a certain mode switching sequence.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Belt 51 Steering roller 52 Shift guide 53 Belt movement detection member 54 Spring 55 Roller shaft displacement member 56 Guide member 57 Auxiliary spring

Claims (9)

  A belt conveying device having an endless belt and a plurality of rollers for winding the endless belt and converging the axial displacement of the belt by inclining one of the plurality of rollers. When entering, if the predetermined operation is different from the content of the previous operation, an idle rotation operation having the same content as the predetermined operation is performed.   The belt conveyance device according to claim 1, wherein the belt conveyance device is a transfer conveyance belt device of an image forming apparatus.   The belt conveyance device according to claim 1, wherein the belt conveyance device is an intermediate transfer belt device of an image forming apparatus.   The belt conveyance device according to any one of claims 1 to 3, wherein the operation is belt conveyance, and the content of the operation is a belt conveyance speed.   The operation is a contact / separation of a roller that wraps around the belt with respect to an inner peripheral surface of the belt, and the content of the operation is an entrance angle of the belt with respect to the roller that is inclined by the contact / separation of the roller with the belt. The belt conveyance device according to any one of 3.   4. The belt conveying apparatus according to claim 2, wherein the content of the operation is an image forming mode, and the operation content is changed by switching between a color mode and a single color mode.   The belt conveying device according to any one of claims 1 to 3, wherein an idling operation is executed when the belt is exchanged.   The belt conveying device according to any one of claims 1 to 3, wherein an idling operation is performed when the device power source is switched from OFF to ON.   An image forming apparatus comprising the belt conveyance device according to claim 1.

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