JP5282452B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt mechanism and an image forming device which can correct the deflected running endless belt even when there are variations in component precisions. <P>SOLUTION: In the belt mechanism having at least a drive roller 14, a steering roller 15, an entrance roller 16, and an intermediate transfer belt 10 stretched around these rollers wherein the intermediate transfer belt 10 runs as the drive roller 14 turns, the intermediate transfer belt 10 is set deflecting only to a predetermined side in advance, and a belt deflection corrector is provided at an end of the endless belt thus set up. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention includes a belt device having at least three or more rollers and an endless belt wound around the rollers, wherein one of the rollers is a driving roller, and the endless belt travels by rotation of the roller. The present invention relates to an image forming apparatus to be used .

  A belt device using an endless belt that is wound around a plurality of rollers and driven to travel, in particular, a wide endless belt, is known. In image forming apparatuses such as copiers, printers, and facsimiles, sheet conveying devices and photosensitive members are also known. Used in belt units, fixing devices and the like. In such a belt device, when the belt is deviated, there is a risk of causing a problem such as an image misalignment. For this reason, it is necessary to regulate or correct the deviation of the belt.

  Specifically, when the deviation is restricted, tape is applied to both ends of the belt in the width direction on the back of the belt to form guide ribs, and the guide ribs are restricted by roller ends or grooves, or the belt end faces are provided directly at the roller ends. There is a belt misalignment correction means that provides a flange and directly regulates it.

  Patent Document 1 discloses a method for mechanically detecting and correcting a belt shift. According to the method described in Patent Document 1, the steering roller is steered from a member (detection member) that directly contacts the belt end surface and detects that the belt has actually approached via the displacement member, I am trying to correct.

  The belt deviation correction method proposed in Patent Document 1 is a method in which deviation is detected by a conventional optical sensor and the roller is steered by a motor, or a method in which a deviation correction guide tape is attached to the end of the belt as described above. Compared with cost, etc.

  However, in Patent Document 1, it is inconvenient if the belt approaches the direction opposite to the direction in which the steering roller wants to control. For this reason, the apparatus is established by tilting one side of the steering roller in advance and moving the belt in the intended direction. However, depending on variations in component accuracy, the belt may not move in the intended direction.

JP 2006-162659 A

The present invention is to solve the conventional problems described above, and an object thereof is to provide the images forming apparatus that can be more correct reliably the endless belt even variations in parts precision.

In order to achieve the above object, the present invention has at least three or more rollers and an endless belt wound around the rollers, and one of the rollers is a driving roller, and the endless belt is rotated by the rotation of the rollers. In an image forming apparatus using a belt device in which a belt travels as an intermediate transfer belt device, the endless belt is set so as to approach only one end side predetermined by normal rotation, which is a rotation direction during printing, and the endless belt is wound. A belt deviation correction means for correcting the belt deviation by contacting the endless belt which is one of the hung rollers and approaching in the normal rotation direction, and stops when the print job ends. the endless belt of the belt apparatus, wherein by rotating the normal rotation and reverse direction, reverse rotation of the endless belt may not be an integral multiple of the belt circumference It proposes an image forming apparatus, characterized in that the rotation amount.
In order to achieve the above object, the present invention has at least three or more rollers and an endless belt wound around the rollers, and one of the rollers is a driving roller. In an image forming apparatus using a belt device on which the endless belt travels as a fixing belt device, the endless belt is set so as to approach only one end side determined in advance by normal rotation that is a rotation direction during printing, and the endless belt is A belt deviation correcting means for correcting the belt deviation by contacting an endless belt that is one of the wound rollers and approaching the end in the normal rotation is provided. such becoming an endless belt stopped the belt device, the normal is rotated in the rotational direction opposite rotation of the reverse direction of the endless belt to an integral multiple of the belt circumference We propose an image forming apparatus, characterized by the amount of rotation.
Furthermore, in order to achieve the above object, the present invention has at least three or more rollers and an endless belt wound around the rollers, and one of the rollers is a driving roller, and the rotation of the rollers. In the image forming apparatus using the belt device on which the endless belt travels as a transfer material conveying belt device, the endless belt is set so as to approach only one end side determined in advance by normal rotation that is a rotation direction during printing, One of the rollers around which the endless belt is wound, and provided with belt deviation correcting means for correcting the belt deviation by contacting the endless belt that has approached the end of the normal rotation, and printing the endless belt of the belt system is stopped by the job end, the rotated normal rotation and reverse direction, integer reverse rotation of the endless belt of the belt circumference We propose an image forming apparatus, characterized by a rotation amount which is not doubled.

  In the belt device of the present invention, it is advantageous that the roller operated by the belt deviation correcting means is a driven roller having a maximum winding angle of the endless belt.

  Further, in the belt device of the present invention, the position of the roller is adjusted so that the endless belt approaches only one end side in advance, and the adjusting roller and the roller operated by the belt deviation correcting means are provided. It is advantageous if the rollers are different.

Furthermore, in the belt device of the present invention, the belt deviation correction means is provided with a detection member for detecting the deviation of the endless belt on the same axis of the roller, and the detection member is provided with a boss portion facing the roller, It is advantageous to make the outer diameter of the boss part smaller than the outer diameter of the roller to which it is attached.

  Furthermore, in the image forming apparatus of the present invention, it is advantageous that the reverse rotation of the endless belt is longer than one belt revolution.

  According to the present invention, the deviation direction of the belt is set in consideration of the variation of the roller around which the belt is wound and the variation in its attachment, so that the deviation can be reliably detected and the deviation correction device can be operated. Stability and reliability can be improved. In addition, since the member that detects the belt deviation can be reliably moved, the belt deviation correction can be stably performed.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a color copying machine as an example of an image forming apparatus according to the present invention. In this color copying machine, a copying machine main body 100 is arranged at the center, and a sheet feeding unit 200 configured in a table shape is arranged below the copying machine main body 100. A scanner 300 is disposed above the copying machine main body 100, and an automatic document feeder 400 is disposed above the scanner 300. It is the composition which arranged.

  The copying machine main body 100 is provided with an intermediate transfer belt 10 as an image carrier constituted by a flexible endless belt wound around a plurality of rollers 14, 15, 16. The intermediate transfer belt 10 is constituted by a driving roller in which the roller 15 among a plurality of rollers 14, 15, 16 is rotationally driven by a driving device (not shown), and the intermediate transfer belt 10 is indicated by an arrow by the roller 15. The other rollers 14 and 16 are driven to rotate in the direction. Black, cyan, magenta, and yellow image forming units 18 are arranged side by side on the upper traveling side of the intermediate transfer belt 10 that travels in this way. That is, the tandem image forming apparatus 20 is configured by arranging four image forming means 18 on the running side between the roller 14 and the roller 15.

  The four image forming units 18 include a photosensitive drum 40 as a latent image carrier in contact with the intermediate transfer belt 10. Around the photosensitive drum 40, a charging device, a developing device, a cleaning device, a static eliminator, and the like are disposed. Further, a transfer device is disposed inside the intermediate transfer belt 10 at a position where the photosensitive drum 40 contacts the intermediate transfer belt 10. 62 is provided. In the present embodiment, the four image forming units 8 have the same structure, but the color of the toner of the developing device is divided into four colors of black, cyan, magenta, and yellow. Further, an exposure device 21 for irradiating the surface of each photosensitive drum with light-modulated laser light is disposed above each image forming unit 18, and this laser light is applied to the photosensitive drum between the charging device and the developing device. To do. Although the exposure apparatus 21 may be provided for each image forming unit 18, using the common exposure apparatus 21 is advantageous in terms of cost.

  On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer belt 10 from the tandem image forming device 20. The secondary transfer device 22 is arranged so that a secondary transfer belt 24, which is an endless belt, is wound between rollers 23, and the belt is pressed against the roller 16 via the intermediate transfer belt 10.

  In FIG. 1, a fixing device 25 for fixing a transfer image carried on a sheet is provided on the left side of the secondary transfer device 22. The fixing device 25 of this embodiment includes a pressure roller 27 and a fixing belt 26 that is an endless belt pressed against the pressure roller 27.

  The secondary transfer device 22 described above is also provided with a sheet transport function for transporting the image-transferred sheet to the fixing device 25. Of course, a non-contact charger may be disposed as the secondary transfer device 22. In such a case, it is necessary to separately provide a sheet conveying device for conveying the transferred sheet to the fixing device 25.

  In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. It has.

  Now, when making a copy using a color copying machine having such a configuration, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. When this happens, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  Further, when a start switch (not shown) is pressed, the intermediate transfer belt 10 is rotated, and at the same time, the photosensitive member 40 is rotated by the individual image forming means 18 so that the black, yellow, A magenta / cyan monochrome image is formed. Then, as the intermediate transfer belt 10 travels, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

  On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed unit 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped.

  Alternatively, when manual feeding is selected, the sheet feeding roller 50 is rotated to feed out the sheets on the manual tray 51, separated one by one by the separation roller 52, and put into the manual feeding path 53. Stop by hitting.

  Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. Full color images are recorded on the sheet at once.

  The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image. Are discharged and stacked on the discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.

  On the other hand, the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after image transfer, and is prepared for re-image formation by the tandem image forming apparatus 20.

  Incidentally, in the image forming apparatus, the intermediate transfer belt 10 is constituted by a wide endless belt. If a belt shift occurs in the intermediate transfer belt 10, image misalignment is caused and image quality is deteriorated.

At this time, means for correcting the belt shift of the intermediate transfer belt 10 is provided. However, if the direction in which the belt moves is set in advance, correction control can be easily performed.
The present inventor has made various studies on the belt misalignment, and in the belt device in which three or more stretched rollers are installed, when the misalignment correction is performed by the steering roller, the geometric relationship between the stretch rollers is important. I found out that In general, the cause of the movement of the belt depends on the geometric inclination (shift in parallelism) of each roller with respect to the reference roller, and as shown in FIG. Later, it was found that the belt approached because an angle difference occurred due to the inclination of the roller.

  Therefore, in the present invention, the belt is set so as not to move in the opposite direction to the direction in which the belt shift is desired to be controlled, and the belt shift correction is surely performed, as in the intermediate transfer belt 10 in FIG. In the following, an example in which the roller is wound around three rollers 14, 15, 16 will be described.

  3 to 5, the three rollers are the driving roller 14, the steering roller 15, and the entrance roller 16, and the driving roller 14 is used as a reference for the other two rollers 15 and 16. It is assumed that the roller axis is twisted by shifting the entrance roller 16 with respect to the driving roller 14 serving as a reference, with the back side as a fulcrum and the front side in the direction of “−X”. If the conveying direction of the intermediate transfer belt 10 at this time is clockwise, the belt is shifted toward the front side at the steering roller 15.

  On the other hand, when the entrance roller 16 is shifted with respect to the driving roller 14 and the roller axis is twisted by shifting the front side in the direction of “+ X”, the belt in the steering roller 15 is rotated when the conveyance direction of the intermediate transfer belt 10 is clockwise. In the back direction, a shift occurs. As described above, the position of the entrance roller 16 is adjusted to set the direction of the intermediate transfer belt 10, and the entrance roller 16 is configured as a roller for adjusting the position.

  Therefore, the twist direction of the entrance roller 16 is important depending on whether the steering roller 15 performs control (shift correction) by moving the belt 10 toward the front side or controls the belt 10 toward the back side.

  Next, a specific example of the belt deviation correcting means for correcting the deviation used for the steering roller 15 will be described. This gives a tilt to the steering roller 15 as the belt is displaced in the axial direction, and corrects the deviation of the belt.

  6 and 7, a shift guide 72 is provided at one end of the inner periphery of the intermediate transfer belt 10, and a belt movement detection member that is a short roller having the same diameter as the steering roller 15 is provided inside the shift guide 72. 73 is disposed, and is always brought into contact with the shift guide 72 using an inner spring 74. A roller shaft displacement member 75 that is integrally formed with the belt movement detection member 73 and that can be displaced in the axial direction has a conical surface (inclined portion) in contact with a guide member 76 that is fixed to a body frame (not shown). When the intermediate transfer belt 10 starts to move in the left direction in the figure, the belt is moved together with the belt movement detecting member 73 against the action of the spring 74, and the conical surface slides on the guide member 76. It is lifted in a direction approaching (indicated by a dotted line). As a result, the force in the axial direction of the intermediate transfer belt 10 is weakened, and the belt shift eventually converges in a balanced state. In addition, when taking the structure which integrates the cleaning apparatus 17 with the steering roller 15, when the steering roller 15 is operated, a big shift force may be required. In that case, there is a concern that the steering roller 15 stops with a large shift force and is restricted by the shift guide 72. Therefore, by adding a spring 77 that assists the operation of the steering roller 15, the steering roller 15 can be moved even with a weak shifting force, and shift correction with excellent shift durability may be realized.

  When such a belt shift correction means is used, if the intermediate transfer belt 10 is set so as to approach the side where the belt movement detection member 73 is provided in advance at the position of the steering roller 15, the shift correction control can be performed stably and reliably. Can do.

  Therefore, the twisting allowable direction of the inlet roller 16 is set in advance so that the intermediate transfer belt 10 belt moves toward the control direction of the steering roller 15. At this time, the intermediate transfer belt 10 is designed so as to be shifted in the direction controlled by the steering roller 15 in consideration of variations in components and installation.

Next, a steering roller provided with belt deviation correction means was considered.
For example, in the case of the intermediate transfer belt device shown in FIG. 1, there are three rollers: a driving roller 14, a driven roller 15 (steering roller 15), and an entrance roller 16. Since the steering roller tilts its axis, the driving roller 14 that is drivingly connected to the driving device is not preferable. Therefore, the steering roller is either the driven roller 15 or the entrance roller 16.

  8 and 9 show the relationship between the amount of winding (winding angle) and the amount of deviation between the roller and the belt. As is apparent from the graph of FIG. 9, when the winding angle of the belt with respect to the roller is large, it becomes easy to control the belt shift. This is because the amount of displacement increases due to the long time wound around the roller.

  Therefore, in the roller shown in FIG. 8A and the roller shown in FIG. 8B, the most suitable roller for the steering roller 15 is a roller having a large belt winding amount (winding angle θ).

  By the way, as the belt deviation correcting means, it is possible to adopt a system in which the belt movement detecting member 73 detects the belt deviation by contacting the belt end surface. In this method, the belt end face is surely brought into contact with the belt movement detecting member 73, so that the detection accuracy can be further improved and a more stable device can be obtained.

  Therefore, in the case of such a belt shift correcting means, the belt 10 is detected by making the outer diameter C of the boss 73a of the belt movement detecting member 73 smaller than the outer diameter B of the steering roller 15 as shown in FIG. It becomes possible to reliably contact the end portion with the A surface of 73. If the outer diameter C is equal to or larger than B, the belt will rub against the surface indicated by the outer diameter C instead of the A surface of the detection member, so that the deviation amount of the belt 10 cannot be detected correctly, and the steering roller 15 It becomes difficult to rotate the to the required angle.

  By the way, in the method of detecting the belt shift by contacting the belt movement detecting member 73 to the end face, the end face of the intermediate transfer belt 10 is always stressed.

In particular, if a stress is always applied while the machine print job is finished and stopped, depending on the belt material, permanent distortion may be caused.
Therefore, the belt can be slightly separated from the belt movement detecting member 73 by reversely rotating the intermediate transfer belt 10 after the print job is completed.

  In the above-described intermediate transfer belt device, the shifting direction is determined by the rotation direction of the intermediate transfer belt 10, so that when the reverse transfer is performed, the intermediate transfer belt 10 can move in a direction different from that during normal rotation.

  Even if the balance between the rollers is maintained and the belt is in a state of being settled, the direction in which the intermediate transfer belt 10 tries to move is reversed. Since the stress from the belt movement detecting member 73 is reduced even if the intermediate transfer belt 10 is not separated from the belt movement detecting member 73 even if it is rotated in the reverse direction, the durability of the intermediate transfer belt 10 can be improved.

  At this time, the reverse rotation amount of the belt is desirably one or more rounds of the belt (in order to surely eliminate stress), but it is important not to make it an integral multiple of one round length. That is, when the belt is rotated by an integral multiple of the circumference of the belt, the same portion of the intermediate transfer belt 10 comes into contact with the belt movement detecting member 73 and stops, so even the slightest stress can be applied to the same portion. There is an aim to disperse the stress portions by making the stop position of the intermediate transfer belt 10 random rather than giving it.

  Although the preferred embodiments of the present invention have been described above, the belt device of the present invention is not limited to the intermediate transfer belt device, but is applied to belt devices such as a fixing device using a fixing belt and a transfer material conveying device using a conveying belt. Can do.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus to which the present invention is applied. It is explanatory drawing which shows a belt side. It is explanatory drawing explaining the setting of the belt side of this invention. It is a top view of the belt apparatus of FIG. FIG. 4 is a perspective view of the belt device of FIG. 3. It is a side view showing an example of belt deviation correction means. It is a perspective view which shows an example of the belt | deviation correction | amendment means of FIG. (A), (b) is explanatory drawing which shows the roller from which the winding angle of a belt differs. It is a graph which shows the relationship between the winding angle | corner of a belt, and the amount of belt slippage. It is sectional explanatory drawing which shows other embodiment of a belt deviation | shift correction means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 14 Driving roller 15 Steering roller 16 Entrance roller 73 Belt movement detection member

Claims (7)

An intermediate transfer belt device comprising at least three or more rollers and an endless belt wound around the rollers, wherein one of the rollers is a driving roller, and the endless belt travels by rotation of the roller. In the image forming apparatus used for
The endless belt is set so as to approach only one end side determined in advance by normal rotation, which is the rotation direction during printing,
Belt offset correction means for correcting the belt offset by one of the rollers around which the endless belt is wound and the endless belt that has approached the end in the direction of the normal rotation comes into contact;
The endless belt of the belt device stopped by the end of the print job is rotated in the opposite direction to the normal rotation, and the rotation amount in the reverse direction of the endless belt is set to a rotation amount that does not become an integral multiple of the belt circumferential length. Image forming apparatus. A fixing belt device having at least three rollers and an endless belt wound around the roller, wherein one of the rollers is a driving roller, and the endless belt travels by rotation of the roller. In the image forming apparatus used,
The endless belt is set so as to approach only one end side determined in advance by normal rotation, which is the rotation direction during printing,
Belt offset correction means for correcting the belt offset by one of the rollers around which the endless belt is wound and the endless belt that has approached the end in the direction of the normal rotation comes into contact;
The endless belt of the belt device stopped by the end of the print job is rotated in the opposite direction to the normal rotation, and the rotation amount in the reverse direction of the endless belt is set to a rotation amount that does not become an integral multiple of the belt circumferential length. Image forming apparatus. A transfer material conveying belt having at least three or more rollers and an endless belt wound around the rollers, wherein one of the rollers is a driving roller, and the endless belt travels by rotation of the roller; In an image forming apparatus used in the apparatus,
The endless belt is set so as to approach only one end side determined in advance by normal rotation, which is the rotation direction during printing,
Belt offset correction means for correcting the belt offset by one of the rollers around which the endless belt is wound and the endless belt that has approached the end in the direction of the normal rotation comes into contact;
The endless belt of the belt device stopped by the end of the print job is rotated in the opposite direction to the normal rotation, and the rotation amount in the reverse direction of the endless belt is set to a rotation amount that does not become an integral multiple of the belt circumferential length. Image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the roller operated by the belt deviation correcting unit is a driven roller having a maximum winding angle of the endless belt.   5. The image forming apparatus according to claim 1, wherein the position of the roller is adjusted to set the endless belt so as to approach only one end side in advance, and the roller to be adjusted and the belt deviation correction unit An image forming apparatus characterized in that the roller operated by the roller is a different roller. 6. The image forming apparatus according to claim 1, wherein the belt deviation correction means includes a detection member that detects the deviation of the endless belt on the same axis of the roller, and the detection member faces the roller. An image forming apparatus, characterized in that a boss portion is provided and the outer diameter of the boss portion is smaller than the outer diameter of a roller to which the boss portion is attached.   4. The image forming apparatus according to claim 1, wherein the rotation of the endless belt in the reverse direction is longer than one revolution of the belt.

Images