JP2005344750A - Belt drive mechanism and electronic photographing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt drive mechanism having improved power transmitting efficiency by constructing a driving roller and a driven roller to avoid the offset, skewing and meandering of an endless belt with the rotation of the rollers. <P>SOLUTION: The mechanism comprises a plurality of parallel grooves provided in the outer peripheral faces of one or both of the driving roller and the driven roller symmetrically at the axial centers in inclination from the axial centers of the rollers on the upstream side in the rotating directions to the ends on the downstream sides in the rotating directions. With the rotation of the rollers, mutually opposite and crosswise symmetrical force is generated to pull the endless belt from the axial centers of the rollers to both crosswise ends. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a belt driving device for driving an endless belt and electrophotographic apparatuses such as a copying machine, a printer, a facsimile, and a composite machine using the belt driving device. A belt driving device that can be driven without meandering, and an endless belt such as a photosensitive belt, an intermediate transfer belt, and a transfer material (recording medium) conveying belt used in an electrophotographic apparatus by using the belt driving device. The present invention relates to an electrophotographic apparatus.

  Endless belts and their driving devices are used in a variety of devices. For example, in copiers, printers, facsimiles, and complex machines using electrophotography, a photoconductor that forms toner images by electrophotography, After the toner image formed on the photoreceptor is primarily transferred, the photoreceptor is carried on an intermediate transfer body for secondary transfer to a transfer material (recording medium) or a transferred transfer material (recording medium). 2. Description of the Related Art A transfer material (recording medium) carrier for directly transferring an existing toner image is formed of an endless belt and is stretched around a plurality of driving rollers and driven rollers.

  However, in devices such as an electrophotographic apparatus using an endless belt, the difference between the peripheral length of the endless belt, subtle film thickness unevenness, a biased load from the outside, the axis of the driving roller and the driven roller In some cases, the endless belt may be displaced in the axial direction of the roller due to misalignment or parallel alignment, and skew or meander may occur. That is, even if the skew degree (axiality) of the roller is deviated by 0.1 mm, the belt is skewed. Even if the accuracy / axiality of the roller is not a problem, there is no variation in the left and right circumferential length of the belt. If it is 5%, skew will occur.

  However, when skew or meandering occurs, for example, in a color electrophotographic apparatus that superimposes a plurality of colors, the superimposed toner images of each color are displaced and color misalignment occurs.

  Conventionally, for example, Patent Document 1 discloses a method for coping with skew and meandering in devices such as an electrophotographic apparatus using an endless belt, and slipping between an endless belt and a driving roller or driven roller. The width of the endless belt is longer than the axial length of the drive roller or driven roller, both ends of the inner peripheral surface are high friction coefficient surfaces, the center is a low friction coefficient surface, and the endless belt is skewed. An image forming apparatus is shown in which a force for returning an endless belt to a normal position works by utilizing a change in an area where a driving roller or a driven roller and a high friction coefficient surface contact when meandering. .

  In the image forming apparatus, toner or paper dust enters between the end of the endless belt and the driving roller or the driven roller, and the frictional force is reduced to cause slipping. In order to prevent this, in Patent Document 2, a spiral groove is provided on the driving roller or the driven roller so as to incline from the roller center toward the end in the rotational direction from the downstream side to the upstream side. An image forming apparatus in which foreign matter entering between belts is moved in the roller axis direction is shown. Further, Patent Document 3 communicates with a driving roller and a driven roller from one end of the roller shaft to the other end to form a recess. An image forming apparatus is shown in which a groove is provided so that foreign matter that enters between the roller and the belt when the endless belt is driven can be blocked by the edge of the groove.

  Further, in Patent Document 4, in a color image forming apparatus using a photosensitive belt, an intermediate transfer belt, or the like, if there is slippage between the driving roller and the belt, the images of the respective colors cannot be accurately superimposed. The image forming apparatus in which an adhesive or a high friction coefficient resin is applied to a part or the entire surface of the belt contacting the driving roller or a part or the entire surface of the driving roller is shown. Yes.

JP 2000-255821 A JP 2002-130252 A JP 2002-130254 A JP-A-8-152812

  However, the technique disclosed in Patent Document 1 uses both ends of the inner peripheral surface of the endless belt as high friction coefficient surfaces. However, when toner or paper dust enters from the end of the endless belt, When the endless belt is skewed or meandered, the force for returning the endless belt to the normal position does not work. In addition, the devices disclosed in Patent Documents 2 and 3 prevent the occurrence of an image defect due to slippage caused by toner or paper dust that enters between the end of the endless belt and the driving roller and the driven roller. However, it is not for preventing the endless belt from skewing and meandering as in the present application.

  Furthermore, the device disclosed in Patent Document 4 is a driving roller in which an adhesive or a high friction coefficient resin is applied to a part or the entire surface of the belt in contact with the driving roller, or a part or the entire surface of the driving roller. To prevent slippage between the belt and the belt, and not to prevent the endless belt from skewing or meandering as in the present application. If it enters, this applied adhesive or high friction coefficient resin will have a low coefficient of friction.

  Therefore, in the present invention, the endless belt driving device composed of the driving roller and the driven roller is configured so that the endless belt is not displaced, skewed or meandered, and the power transmission efficiency is improved. It is an object to provide a driving device and an electrophotographic apparatus using the belt driving device.

In order to solve the above problems, a belt driving device according to the present invention is provided.
In a belt driving device in which an endless belt is stretched around at least one rotation driving roller and a roller such as a driven roller, and the endless belt is driven along a predetermined path by rotation of the driving roller.
A plurality of parallel rollers inclined toward the downstream end in the rotational direction from the axial center on the upstream side in the rotational direction of the roller, symmetrically with respect to the axial direction center on the outer peripheral surface of one or both of the driving roller and the driven roller The groove is provided, and by the rotation of the roller, symmetrical forces in the width direction are generated in opposite directions so as to pull the endless belt from the roller axial center side toward both ends in the width direction.
The electrophotographic apparatus according to the present invention is
Such a belt driving device is a photosensitive belt on which a toner image is formed on the surface by an electrophotographic system, or an intermediate transfer belt that primarily transfers a toner image on the photosensitive body and then secondary-transfers it to a transfer material (recording medium). Alternatively, it is used as a belt driving device that drives any one of the conveying belts that convey the transfer material.

  And the said groove | channel is formed in linear form or a curvilinear form toward the edge part from the axial direction center in the said roller.

  Further, the groove in one or both of the drive roller and the driven roller is formed by dividing the groove in the axial direction, or either one or both of the drive roller or the driven roller is symmetrical with respect to the axial center. And may be formed so as to be connected via a shaft portion.

  In this way, on the outer peripheral surface of one or both of the driving roller and the driven roller in the belt driving device, symmetrically with respect to the axial center, from the axial center on the upstream side in the rotational direction to the downstream end on the downstream side in the rotational direction. By providing a plurality of parallel grooves inclined toward the surface, an uneven portion is formed on the outer peripheral surface of the driving roller or the driven roller, and the friction coefficient of the contact portion between the outer peripheral surface and the inner surface of the endless belt is large. As a result, the frictional force increases and the transmission efficiency of the driving force by the belt is improved.

  In addition, this groove allows the endless belt to have a symmetrical force in the width direction opposite to each other such that the endless belt is pulled between the both ends in the width direction by rotation of the rollers from the center in the axial direction toward the both ends in the width direction. Therefore, the endless belt is stretched in the width direction by the force symmetrical in the width direction and does not sag, and always comes into contact with the roller in a state of uniform tension. For this reason, if a slight deviation or meandering occurs, the balance of the symmetric force is lost, and the force to return to the state before the deviation or meandering is activated. Can be avoided.

  Further, if the groove is divided into a plurality of parts in the axial direction, or one or both of the driving roller and the driven roller are divided and connected via a shaft part so as to be symmetric with respect to the axial center, Without processing multiple grooves with different orientations into one roller, it can be processed separately for each divided part or processed for each of multiple rollers, simplifying the processing of the grooves and reducing the number of processing steps Reduced.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is an external view of a driving roller or a driven roller used in a belt driving apparatus according to a first embodiment of the present invention, FIG. 2 is an external view of a driving roller or a driven roller according to a second embodiment of the present invention, and FIG. FIG. 4 is an external view of a driving roller or a driven roller according to a third embodiment of the present invention, FIG. 4 is an external view of a driving roller or a driven roller according to the fourth embodiment of the present invention, and FIG. 5 is the first to fourth embodiments. 1 is a cross-sectional view of a portion indicated by AA in FIGS. 1 to 4, and FIG. 6 is a perspective view illustrating a schematic configuration of a belt device according to the first to fourth embodiments. 7 and 7 are schematic sectional views of an electrophotographic apparatus using the belt driving device according to the present invention.

  First, the electrophotographic apparatus using the belt driving apparatus according to the present invention will be briefly described with reference to FIG. 7. The electrophotographic apparatus 1 shown here is a photosensitive in each electrophotographic process unit corresponding to a plurality of different colors. A tandem color image in which the toner image formed on the body 3 is overlaid on a recording medium conveyed by a recording medium conveying belt 5 wound around a driving roller 11 and a driven roller 12 connected to a driving motor (not shown). An image forming apparatus. In the following description, the present invention will be described by taking a color tandem type electrophotographic apparatus using the recording medium conveying belt 5 as an example. However, an endless belt has a toner image formed on the surface thereof by the electrophotographic apparatus. Used for various parts such as a photosensitive belt or an intermediate transfer belt to which a toner image on the photosensitive member is transferred. The electrophotographic apparatus is not only a tandem type electrophotographic apparatus but also a belt-like one. It is apparent that the present invention can be applied to any type of electrophotographic apparatus as long as the electrophotographic apparatus uses any one of a photosensitive member, an intermediate transfer member, a recording medium conveying belt, and the like.

  In the figure, 2 is a developing device, 3 is a photosensitive member, 4 is an exposure unit using an LED, 5 is an endless belt for conveying a recording medium, 6 is a developer container, 7 is a paper feed cassette containing a recording medium, 8 is a charger for charging the photoreceptor 3, 9 is a transfer device for transferring a toner image formed on the photoreceptor 3 to a recording medium by a transfer bias, and 10 is a toner image fixing device. The apparatus 2, the photoreceptor 3, the exposure unit 4, the developer container 6, the charger 8, and the transfer device 9 are provided corresponding to colors such as yellow, cyan, magenta, and black used for color image formation.

  Now, when a print start signal is received from a control circuit (not shown), the photosensitive member 3 is first charged by the charger 8 and then a latent image is formed by exposure by the exposure unit 4. The latent image is developed by the developing device 2 to become a toner image, and the recording medium is taken out from the paper feed cassette 7 and conveyed by the conveying belt 5 at the timing when the toner image reaches the transfer position. The image is transferred to a recording medium by a transfer bias by a transfer device 9 installed at a transfer position for each color. When the toner images of the respective colors are sequentially transferred to the recording medium and reach the fixing device 10, the toner images are fixed and discharged by the fixing device 10.

  In the electrophotographic apparatus 1 configured as described above, the endless belt 5 such as the recording medium conveying belt described above is formed of, for example, a polyimide resin or polycarbonate film, a fluororesin, a fluororubber, or the like. As shown by 50 in FIG. 6, the belt is driven by a belt driving device comprising a driving roller 11 and a driven roller 12, and the endless belt 5 links the driving roller 11 and the two driven rollers 12 together. The drive device 50 is configured. In the drawing, B is the belt width of the endless belt 5 and is formed to have substantially the same length as the length of the outer cylindrical portion 112 of the driving roller 11 and the driven roller 12. In the example shown in FIG. 5, an example in which three rollers are arranged is shown. However, if at least one of the rollers is a driving roller, the endless belt 5 may be stretched by any number of rollers. It is obvious that it is good, and it is also obvious that the back material is not limited to the above.

  As shown in FIG. 1, the driving roller 11 or the driven roller 12 (hereinafter simply referred to as a roller) is symmetric with respect to the axial center 116 on the outer peripheral surface 112a of the outer cylindrical portion 112 formed in a hollow cylindrical shape. A plurality of parallel grooves 20 inclined in opposite directions from the axial center 116 on the upstream side with respect to the rotational direction N of the roller toward the downstream end portion in the rotational direction are provided along the circumferential direction. When the roller rotates, a symmetrical force in the width direction is generated in the opposite directions so as to pull the endless belt 5 from the axial center 116 side of the roller toward the both ends in the width direction.

  In addition, as shown in FIG. 5, the inner cylinder connected by a plurality of ribs 114 (in this example, the number of ribs is three, but this number is not limited to three) inside the roller. The portion 113 is provided with a center hole 113a, and the shaft portion 111 (FIG. 1) is press-fitted and fixed to both ends of the center hole 113a.

  The inclination angle α (see FIG. 1) of the groove 20 with respect to the drive roller shaft center 11d is preferably about 3 ° to 15 °. When the inclination angle α is less than 3 ° and exceeds 15 °, The effect of the symmetrical force in the width direction that pulls the endless belt 5 from the axial center 116 side toward the both ends in the width direction due to the groove 20 is reduced.

  Further, the circumferential pitch p (see FIG. 5) of the grooves 20 is preferably 0.5 mm to 5 mm. If the pitch 20 is less than 0.5 mm, the uneven portion formed by the engraving of the grooves 20 becomes too fine, and the outer peripheral surface 112a. The friction coefficient of the contact portion between the endless belt 5 and the inner surface of the endless belt 5 becomes the same as the case where the groove 20 is not engraved, and the meaning of engraving the groove 20 is lost. On the other hand, when the pitch p exceeds 5 mm, the contact projected area between the groove 20 and the endless belt 5 becomes small, and the effect of the symmetrical force in the width direction due to the formation of the groove 20 becomes small.

  Further, if the width of the groove 20 is 0.1 mm or more, it is combined with the range of the inclination angle α in the range of 3 ° to 15 ° and the range of the circumferential pitch p in the range of 0.5 mm to 5 mm. The effect of can be demonstrated. However, if the width exceeds 50% of the circumferential pitch p, the contact area between the roller and the endless belt 5 becomes too small, and the power transmission efficiency of the belt decreases, so the width is equal to the circumferential pitch. It is preferable to be 50% or less of p.

  The grooves 20 formed on the outer peripheral surface 112a of the drive roller 11 are preferably machined, but may be chemically processed by etching. The groove 20 is provided at least on the driving roller 11 on the driving side of power transmission, and it is more effective if provided on both the driving roller 11 and the driven roller 12. However, only the driven roller 12 is necessary if necessary. It is also possible to provide a groove 20 on the surface.

  In the belt driving device 50 configured as described above, when the driving force from a driving motor (not shown) is transmitted to the driving roller 11 provided with, for example, the groove 20 constituting the belt driving device 50, the rotational force of the driving roller 11 is It is transmitted from the groove 20 provided on the outer peripheral surface 112a of the roller outer cylinder portion 112 to the inner surface of the endless belt 5, and further transmitted from the inner surface of the endless belt 5 to the outer peripheral surface 112a of the driven roller 12 having the groove 20, for example. The driven roller 12 is also rotationally driven.

  At this time, in the roller in which a plurality of grooves 20 are engraved along the circumferential direction, the uneven portion formed by the engraving of the grooves 20 causes the contact portion between the outer peripheral surface 112a and the inner surface of the endless belt 5 to be The friction coefficient is increased, the frictional force is increased, and the transmission efficiency of the driving force by the belt is improved. Further, as described above, the grooves 20 are symmetrical with respect to the axial center 116 of the roller, and are opposite to each other from the upstream axial center 116 toward the downstream end of the rotational direction with respect to the rotational direction N of the roller. When the roller rotates, it is symmetrical with respect to the width direction in opposite directions such as pulling the endless belt 5 from the axial center 116 side of the roller toward the both ends of the width direction. Power is generated.

  For this reason, the endless belt 5 is tensioned in the width direction and does not sag, and is always in contact with the roller in a state where the uniform tension is applied. The balance is lost, and the force to return to the state before the deviation or meandering works, so that the deviation or meandering can be surely avoided.

  FIG. 2 is an external view of the roller 11 according to the second embodiment of the present invention. In the first embodiment, the groove 20 is symmetrical with respect to the axial center 116 and is opposite to the axial center 116. Although shown as being formed so as to extend seamlessly toward both ends of the drive roller 11, the grooves in the second embodiment are symmetrical with respect to the axial center 116 as in the first embodiment, and the axial center. 116 are engraved in opposite directions toward both ends of the driving roller 11, but a cut 21 is provided in the middle to form a plurality (two in this example) of groove groups 22.

When the roller is configured in this way, the groove 20 is divided into a plurality of groove groups 22, so the length in one groove group 21 is shorter than the groove 20 in the first embodiment, and the processing of the groove 20 is easy. become. The other configurations and operational effects are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

  FIG. 3 is an external view of the roller 11 according to the third embodiment of the present invention. In the first and second embodiments, the grooves 20 are symmetrical with respect to the axial center 116 and are mutually separated from the axial center 116. Although shown as being formed in a straight line toward both ends of the drive roller 11 in the opposite direction, the grooves in the third embodiment are formed to be inclined in a curved shape in the axial direction, one in the axial direction. Alternatively, as in the second embodiment, a cut 23 is provided in the middle to provide a plurality (one in each example) of groove groups 24.

  When the roller is configured in this manner, the degree of change in the inclination angle of the groove 20 is small near the axial center 116 and increases as it approaches both ends, and the widthwise symmetric force can be rapidly increased at the portions near both ends. The effect of preventing the deviation and meandering due to the widthwise symmetry force of the endless belt 5 is increased. Further, when the curved groove 20 is divided into a plurality of groove groups 24, the groove length in one groove group 24 is shorter than that in the first embodiment, so that the processing of the grooves 24 is simplified. The curved groove group 24 may be a single groove similar to the first embodiment without being divided into a plurality of groove groups.

  FIG. 4 is an external view of a roller according to a fourth embodiment of the present invention. In the first to third embodiments, the rollers 11 are all single rollers. In this fourth embodiment, FIG. The roller 11 is connected via the shaft 111 as rollers 11a, 11b, and 11c that are concentrically divided into three (three in this example) along the axial direction of the shaft 111, and the groove is connected to the roller 11b. The grooves 25 are formed symmetrically with respect to the axial center 116 positioned and extend from the axial center 116 in opposite directions to both ends of the rollers 11a and 11c.

  If the rollers are configured in this way, the grooves 25 can be processed by forming each of the plurality of rollers 11a, 11b, and 11c without processing a large number of grooves 25 having different directions into a single roller. It becomes simple and processing man-hours are reduced. In addition, although this groove | channel 25 was made into the curved shape in the example of illustration, it is needless to say that it may be linear.

  As described above, according to the present invention, the rotation of the roller symmetrically with respect to the axial center 116 on the outer peripheral surface 112a of one or both of the driving roller 11 and the driven roller 12 in the belt driving device 50. By providing a plurality of grooves 20 that are inclined from the axial center 116 on the upstream side in the direction toward the downstream end portion in the rotational direction and provided with a plurality of grooves 20 in parallel, there are irregularities on the outer peripheral surface 112a of the drive roller 11 or the driven roller 12. The friction coefficient of the contact portion between the outer peripheral surface 112a and the inner surface of the endless belt 5 is increased, the frictional force is increased, and the driving force transmission efficiency by the belt is improved.

  In addition, the groove 20 causes the endless belt 5 to rotate in the width direction in opposite directions so as to pull the endless belt 5 from both ends in the width direction toward the both ends in the width direction by rotation of the roller. Therefore, the endless belt 5 is stretched in the width direction by the force symmetric in the width direction and does not sag, and always comes into contact with the roller with a uniform tension. For this reason, if a slight deviation or meandering occurs, the balance of the symmetric force is lost, and the force to return to the state before the deviation or meandering is activated. Can be avoided.

  Further, the groove 20 is formed by being divided into a plurality of parts in the axial direction, or one or both of the driving roller 11 and the driven roller 12 are divided, and the shaft 20 is symmetrical with respect to the axial center 116. If connected, multiple grooves with different orientations can be processed separately for each divided part without being processed into one roller, or can be processed and formed for multiple rollers, making the groove processing easy. The processing man-hour is reduced.

  According to the present invention, the driving roller or the driven roller of the belt driving device is pulled in the width direction between the both ends in the width direction of the endless belt by the rotation of the roller from the axial center to the both ends in the width direction. By configuring so as to generate a symmetric force, it is possible to provide a belt driving device that avoids the occurrence of deviation, skew or meandering of the endless belt, and improves the power transmission efficiency.

FIG. 3 is an external view of a driving roller or a driven roller used in the belt driving device according to the first embodiment of the present invention. It is an external view of the drive roller or driven roller which concerns on 2nd Example of this invention. It is an external view of the drive roller or driven roller which concerns on 3rd Example of this invention. It is an external view of the drive roller or driven roller which concerns on 4th Example of this invention. FIG. 5 is a cross-sectional view of a driving roller or a driven roller according to the first to fourth embodiments, and is a cross-sectional view of a portion indicated by AA in FIGS. 1 to 4. It is a perspective view which shows schematic structure of the belt apparatus based on the said 1st thru | or 4th Example. It is a schematic sectional drawing of the electrophotographic apparatus using the belt drive device which becomes this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic apparatus 5 Endless belt 11 Drive roller 11a, 11b, 11c Split drive roller 12 Driven roller 20 Groove 50 Belt drive device 111 Shaft part 112 Outer cylinder part 113 Inner cylinder part 116 Axial center

Claims (6)

In a belt driving device in which an endless belt is stretched around at least one rotation driving roller and a roller such as a driven roller, and the endless belt is driven along a predetermined path by rotation of the driving roller.
A plurality of parallel rollers inclined toward the downstream end in the rotational direction from the axial center on the upstream side in the rotational direction of the roller, symmetrically with respect to the axial direction center on the outer peripheral surface of one or both of the driving roller and the driven roller , And the rotation of the roller generates a symmetrical force in the width direction opposite to each other, such as pulling the endless belt from the roller axial center side toward both ends of the width direction. Drive device.   The belt driving device according to claim 1, wherein the groove is formed in a straight line from an axial center to an end portion of the roller.   The belt driving device according to claim 1, wherein the groove is formed in a curved shape from an axial center to an end portion of the roller.   The belt driving device according to claim 2 or 3, wherein the groove in one or both of the driving roller and the driven roller is divided into a plurality of portions in the axial direction.   5. Either or both of the driving roller and the driven roller are divided so as to be symmetric with respect to the center in the axial direction and are connected via a shaft portion. Belt drive.   6. The belt driving device according to claim 1, wherein a toner image is formed on a surface of the photosensitive belt by electrophotography, or a toner image on the photosensitive member is primarily transferred to a transfer material (recording medium). An electrophotographic apparatus characterized by being used as a belt driving device of either an intermediate transfer belt for secondary transfer or a conveyance belt for conveying a transfer material.

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