JP2007272189A - Image transfer device, image forming apparatus, image transfer method and deflection generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image transfer device for transferring an image carried on an image carrier device through an endless belt device while transferring it at a first transfer nip position and a second transfer nip position, wherein fluctuation in torque of the endless belt generated at either transfer nip position is effectively prevented from influencing the other transfer nip position without increasing size and weight or without causing cost rise. <P>SOLUTION: The endless belt 30 of the endless belt device 300 is turned between rollers 31/32 and the endless belt is individually driven at the first transfer nip n1 position formed by the endless belt device 300 and an intermediate transfer device (image carrier device) 200 and the second transfer nip n2 position formed by the endless belt device 300 and a secondary transfer device 400 by drive sources 34/35 so as to generate deflection (t) between the first transfer nip n1 position and the second transfer nip n2 position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, an image carried by an image carrying device is primarily transferred to an endless belt device at a first transfer nip position, and an image held by the endless belt device is transferred to a recording material or a transferred image carrying device at a second transfer nip position. The present invention relates to an image transfer apparatus and an image transfer method for next transfer. In addition, the present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine thereof that includes such an image transfer apparatus and transfers an image. The present invention also relates to a deflection creating method for forming a deflection in an endless belt.

  For example, in an electrophotographic image forming apparatus, an electrostatic latent image is formed by charging and writing on a photosensitive member such as a drum-like or belt-like photosensitive member, and then a developing device. A toner image is formed by attaching a toner to form a toner image, and the toner image is primarily transferred to an endless belt-shaped intermediate transfer member, and then indirectly transferred through the intermediate transfer member to be conveyed. There are some which record an image on a recording medium such as a paper sheet or an OHP film.

  For example, as shown in FIG. 12, the image carried on the image carrying belt 1 of the image carrying device A is primarily applied to the endless belt (intermediate transfer member) 2 of the intermediate transfer device which is the endless belt device B at the first transfer nip position a. The image transferred and held by the endless belt 2 is secondarily transferred to the recording material 3 conveyed in the direction of the arrow by the secondary transfer device C at the second transfer nip position b, and transferred from the image carrier belt 1 to the recording material 3. There is something that transfers the image.

  In such an image forming apparatus, since it is expensive to use a seamless endless belt 2, it is desired to reduce the cost by using the endless belt 2 having the seam 4. . However, since the seam 4 is convex, when the endless belt 2 having the seam 4 is used, load fluctuation occurs when the seam 4 passes the first transfer nip position a or the second transfer nip position b. Thus, the traveling speed of the endless belt 2 changes, and the stable traveling of the endless belt 2 is hindered.

  Further, when the leading edge of the recording material 3 enters the second transfer nip position b or the trailing edge moves out of the second transfer nip position b, the load speed is similarly generated and the traveling speed of the endless belt 2 changes. Then, the stable running of the endless belt 2 is hindered. Then, the disturbance of the stable running is transmitted to the first transfer nip position a through the endless belt 2 to cause the transfer disturbance, and image distortion such as so-called shock jitter is generated.

  In order to solve such a problem, it is conceivable to increase the output of the drive source that drives the endless belt device B or to increase the drive transmission rigidity of the speed reducer that transmits the drive force of the drive source. Further, in a conventional image forming apparatus, the endless belt 2 is wound around a tension roller that is urged by a spring or the like, and the position of the tension roller is moved to absorb torque fluctuations and reduce the shock. Has been done.

Japanese Patent No. 3294342 Japanese Patent Application Laid-Open No. 6-115752

  However, when the output of the drive source is increased or the drive transmission rigidity of the reduction gear is increased, the size and weight are increased, which may increase the cost. Further, in the case where the endless belt 2 is wound around the tension roller, if the mass of the member that absorbs the shock is increased, the responsiveness is deteriorated, and a rapid load fluctuation with a high frequency cannot be dealt with immediately, Sufficient improvement was not obtained.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide an image transfer apparatus for transferring an image carried by an image carrying apparatus through an endless belt apparatus while transferring the image carried at the first transfer nip position and the second transfer nip position. The object is to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without increasing the weight or the cost.

  A second object of the present invention is to form a second transfer nip with an endless belt device and arrange a secondary transfer device, and pass the image carried on the endless belt by the secondary transfer device through the second transfer nip. In an image transfer apparatus that performs secondary transfer to a recording material to be transferred, torque fluctuations of the endless belt generated at the second transfer nip position without increasing the size, weight, etc., or incurring high costs, are transferred to the first transfer. This is to effectively prevent the influence on the nip position.

  A third object of the present invention is to provide a heating means for heating an image carried by an endless belt around an endless belt device, and transferring the image heated by the heating means to a recording material by a secondary transfer device. Similarly, in a fixing type image transfer apparatus, the torque fluctuation of the endless belt generated at the second transfer nip position affects the first transfer nip position without increasing the size or weight or incurring high costs. It is to effectively prevent you from doing.

  A fourth object of the present invention is to increase the size and weight of an image transfer apparatus of a type in which an image carried by an endless belt is secondarily transferred to a transfer image carrying apparatus at a second transfer nip position. It is intended to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without inviting.

  A fifth object of the present invention is, in an image transfer apparatus of the type provided with an image forming apparatus for forming an image on an image carrier as an image holding apparatus, similarly, the size and weight are increased and the cost is increased. In other words, the torque fluctuation of the endless belt generated at one transfer nip position is effectively prevented from affecting the other transfer nip position.

  A sixth object of the present invention is to provide an image transfer apparatus of the type provided with an intermediate transfer apparatus that supports an image with an intermediate transfer member as the image support apparatus. In other words, the torque fluctuation of the endless belt generated at one transfer nip position is effectively prevented from affecting the other transfer nip position.

  A seventh object of the present invention is to provide an image transfer apparatus having a seam in an endless belt of an endless belt apparatus. Similarly, the transfer of one of the endless belt apparatuses does not increase in size, weight, etc., or increase in cost. The object is to effectively prevent the torque fluctuation of the endless belt generated at the nip position from affecting the other transfer nip position.

  An eighth object of the present invention is to provide an image transfer apparatus of a type that travels on an endless belt by driving a roller as a belt support member with a drive source dedicated to the endless belt apparatus. The object is to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without incurring high costs.

  A ninth object of the present invention is the same in an image transfer apparatus of a type that travels an endless belt that is wound around a roller or other belt support member by transmitting a driving force from the outside with a drive source provided outside the endless belt apparatus. In addition, it is possible to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without increasing the size or weight or increasing the cost. is there.

  A tenth object of the present invention is to control a driving source that travels an endless belt so as to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position. There is.

  According to an eleventh object of the present invention, it is always effective that the torque fluctuation of the endless belt generated at one transfer nip position affects the other transfer nip position even when the torque fluctuation is continuously generated in the endless belt. It is to prevent.

  A twelfth object of the present invention is an image transfer apparatus of a type in which an image carried by an endless belt is secondarily transferred to a recording material that passes through a second transfer nip. This is to effectively prevent the torque fluctuation of the endless belt that occurs when the recording material passes through the second transfer nip without affecting the position of the first transfer nip.

  According to a thirteenth object of the present invention, in an image transfer apparatus of a type in which an image carried by an endless belt is secondarily transferred to a recording material passing through the second transfer nip, when the recording material enters the second transfer nip. In addition, when the recording material comes out of the second transfer nip, the torque fluctuation of the endless belt at the second transfer nip position does not increase in size, weight, etc., or increase the cost. It is to prevent effectively from affecting.

  A fourteenth object of the present invention is an image forming apparatus that includes an image transfer device and transfers an image carried by the image carrying device via an endless belt device while transferring the image at the first transfer nip position and the second transfer nip position. In this case, it is effective that the torque fluctuation of the endless belt generated at one transfer nip position affects the other transfer nip position without increasing the size or weight of the image transfer device or increasing the cost. It is to stop.

  According to a fifteenth object of the present invention, in an image forming apparatus of a type in which an image carried by an endless belt is secondarily transferred to a recording material at a second transfer nip position, the size and weight of the image transfer apparatus is increased, It is to effectively prevent the torque fluctuation of the endless belt generated at the second transfer nip position from affecting the first transfer nip position without incurring high costs.

  A sixteenth object of the present invention is an image forming apparatus of a type in which an image carried by an endless belt is secondarily transferred to a transfer image carrying device at a second transfer nip position, and the size and weight of the image transfer device are increased. In other words, it is possible to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without incurring high costs.

  According to a seventeenth object of the present invention, there is provided a heating means for heating an image carried by the endless belt around the endless belt device, and transferring the image heated by the heating means to a recording material by a secondary transfer device. In the fixing type image forming apparatus, the torque fluctuation of the endless belt generated at the second transfer nip position is caused by the size and weight of the image transfer apparatus and the cost is not increased. It is to prevent effectively from affecting.

  An eighteenth object of the present invention is an image transfer method in which a roller as a belt support member is driven by a drive source dedicated to an endless belt device and travels on an endless belt. This is to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position.

  A nineteenth object of the present invention is to drive a roller as a belt support member by a drive source dedicated to an endless belt device to run the endless belt at one transfer nip position, and to drive outside by an external drive source of the endless belt device. Is generated at one transfer nip position without increasing the size, weight, etc., or increasing the cost. Another object is to effectively prevent the endless belt torque fluctuation from affecting the other transfer nip position.

  A twentieth object of the present invention is an image transfer method in which a driving force is transmitted from the outside by an external driving source of an endless belt device and travels on an endless belt. It is intended to effectively prevent the torque fluctuation of the endless belt generated at one transfer nip position from affecting the other transfer nip position without inviting.

Therefore, in order to achieve the first object described above, the invention described in claim 1 constitutes an endless belt device by wrapping an endless belt around a belt support member such as a roller or a fixed nip forming member, A first transfer nip is formed between the endless belt device and an image carrying device, and an image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, In the image transfer apparatus for secondary transfer of the image carried by the endless belt at the second transfer nip position,
The endless belt is wound around the belt support member so that the endless belt is deflected between the first transfer nip position and the second transfer nip position, and the endless belt is moved from the first transfer nip position to the first transfer nip position. The second drive nip position is individually driven.

  Then, the travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position where the image on the endless belt is secondarily transferred are set as appropriate, and the first transfer nip position The endless belt always bends between the first transfer nip position and the second transfer nip position so that the torque fluctuation generated at one transfer nip position does not affect the other transfer nip position.

  According to a second aspect of the present invention, in order to achieve the second object described above, in the image transfer apparatus according to the first aspect, the second transfer nip is formed with the endless belt device to form a secondary transfer apparatus. And an image carried on the endless belt by the secondary transfer device is secondarily transferred to a recording material passing through the second transfer nip.

  Then, the traveling speed of the endless belt at the first transfer nip position and the traveling speed of the endless belt at the second transfer nip position where the image on the endless belt is secondarily transferred to the recording material are set as appropriate. The endless belt always bends at the downstream position of the transfer nip.

  According to a third aspect of the present invention, in order to achieve the third object described above, in the image transfer apparatus according to the second aspect, heating for heating an image carried by the endless belt around the endless belt device. And an image heated by the heating means is transferred and fixed onto a recording material by the secondary transfer device.

  Then, the travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position where the image on the endless belt is transferred and fixed to the recording material are set as appropriate. The endless belt always bends at the downstream position of the nip.

  According to a fourth aspect of the present invention, there is provided the image transfer apparatus according to the first aspect, wherein the image carried on the endless belt is transferred at the second transfer nip position in order to achieve the fourth object. Secondary transfer.

  The travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position where the image on the endless belt is secondarily transferred to the transfer image carrying device are appropriately set. The endless belt always bends between the first transfer nip position and the second transfer nip position.

  According to a fifth aspect of the present invention, in order to achieve the fifth object described above, in the image transfer apparatus according to any one of the first to fourth aspects, a drum-shaped or belt-shaped image is used as the image carrier. An image forming device for forming an image on a carrier is provided.

  Then, the travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position where the image on the endless belt is secondarily transferred are set as appropriate, and the first transfer nip position And the endless belt always bends between the second transfer nip position.

  According to a sixth aspect of the present invention, in order to achieve the sixth object described above, in the image transfer apparatus according to any one of the first to fourth aspects, a drum-shaped or belt-shaped intermediate is used as the image carrier. An intermediate transfer device that carries an image on a transfer body is provided.

  Then, the travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position where the image on the endless belt is secondarily transferred are set as appropriate, and the first transfer nip position And the endless belt always bends between the second transfer nip position.

  According to a seventh aspect of the present invention, in order to achieve the seventh object described above, in the image transfer apparatus according to any one of the first to sixth aspects, the endless belt has a seam.

  Then, the travel speed of the endless belt at the first transfer nip position and the travel speed of the endless belt at the second transfer nip position are appropriately set, and the endless belt is between the first transfer nip position and the second transfer nip position. Will always cause deflection.

  According to an eighth aspect of the present invention, in order to achieve the eighth object described above, in the image transfer apparatus according to any one of the first to seventh aspects, a roller is used as the belt support member, and the roller is driven. And a drive source dedicated to the endless belt device that travels the endless belt.

  A drive source dedicated to the endless belt device is provided, and a roller as a belt support member is driven by the drive source to travel the endless belt. The travel speed of the endless belt at the first transfer nip position and the second transfer nip position The running speed of the endless belt is set appropriately, and the endless belt always bends between the first transfer nip position and the second transfer nip position.

  According to a ninth aspect of the present invention, in order to achieve the ninth object described above, in the image transfer device according to any one of the first to seventh aspects, the driving force is transmitted from the outside, and the belt support member is provided. A drive source for running the endless belt that is wound around is provided outside the endless belt device.

  Then, the driving force provided from the outside of the endless belt device is transmitted from the outside to travel the endless belt that is hung on the belt support member, and the traveling speed of the endless belt at the first transfer nip position and the second transfer nip. The running speed of the endless belt at the position is appropriately set, and the endless belt is always bent between the first transfer nip position and the second transfer nip position.

  According to a tenth aspect of the present invention, in order to achieve the tenth object described above, in the image transfer apparatus according to the eighth or ninth aspect, the endless drive is performed at the first transfer nip position by being driven by the drive source. The traveling speed of traveling the endless belt at the second transfer nip position is made faster than the traveling speed of traveling the belt.

  Then, the drive source is controlled so that the travel speed of the endless belt at the second transfer nip position is higher than the travel speed of the endless belt at the first transfer nip position, and the endless belt is always moved downstream of the second transfer nip. Causes deflection.

  According to an eleventh aspect of the invention, in order to achieve the eleventh object described above, in the image transfer apparatus according to any one of the eighth to tenth aspects, a deflection amount detecting means for detecting a deflection amount of the endless belt. And drive control means for feedback-controlling the drive source based on an output signal of the deflection amount detection means.

  Then, the deflection amount of the endless belt is detected by the deflection amount detection means, the drive source is feedback controlled by the drive control means based on the output signal of the deflection amount detection means, and the running speed of the endless belt at the first transfer nip position is detected. And the traveling speed of the endless belt at the second transfer nip position are different from each other, and a constant deflection is always generated in the endless belt between the first transfer nip position and the second transfer nip position.

  According to a twelfth aspect of the present invention, in order to achieve the twelfth object described above, in the image transfer apparatus according to any one of the eighth to tenth aspects, a recording material passing through the second transfer nip is detected. It is characterized by comprising a recording material detection means and a drive control means for feedback controlling the drive source based on an output signal of the recording material detection means.

  When the recording material detection unit detects the recording material passing through the second transfer nip, the drive source is feedback-controlled by the drive control unit based on the output signal of the recording material detection unit, and the endless member at the first transfer nip position is detected. By varying the belt traveling speed and the traveling speed of the endless belt at the second transfer nip position, the amount of deflection of the endless belt generated at the downstream position of the second transfer nip is adjusted.

  According to a thirteenth aspect of the present invention, in order to achieve the thirteenth object described above, in the image transfer apparatus according to the twelfth aspect, when the recording material is detected by the recording material detecting means, the first transfer nip position is detected. The traveling speed of traveling the endless belt is equal to the traveling speed of traveling the endless belt at the second transfer nip position, or the latter is made slower than the former.

  When the recording material detection unit detects the recording material passing through the second transfer nip, the drive control unit feedback-controls the drive source based on the output signal of the recording material detection unit, and the endless belt is at the first transfer nip position. Is equal to the traveling speed of traveling the endless belt at the second transfer nip position, or the latter is made slower than the former, and the endless belt is bent at the upstream position of the second transfer nip.

  According to the fourteenth aspect of the present invention, in order to achieve the first object described above, an endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device. An image carrying device is formed and the image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is transferred to the second transfer nip. In the image transfer apparatus that performs secondary transfer at a position, the first transfer nip position and the second transfer nip position are set so that torque fluctuation generated at one transfer nip position does not affect the other transfer nip position when the endless belt is running. The endless belt is bent between the transfer nip positions.

  According to a fifteenth aspect of the present invention, in order to achieve the above first object, an endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device. An image carrying device is formed and the image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is transferred to the second transfer nip. In an image transfer apparatus that performs secondary transfer at a position, when the endless belt travels, a deflection that can absorb a torque fluctuation generated at one transfer nip position is caused between the first transfer nip position and the second transfer nip position. It occurs in the endless belt.

  According to the sixteenth aspect of the present invention, in order to achieve the above first object, an endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device. An image carrying device is formed and the image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is transferred to the second transfer nip. In the image transfer apparatus that performs secondary transfer at a position, when the endless belt travels, the endless belt is moved between the transfer nip position and the other transfer nip position to such an extent that torque fluctuations generated at one transfer nip position can be absorbed. The belt length is different between the upstream side and the downstream side in the endless belt traveling direction at the transfer nip position.

  The invention described in claim 17 is characterized in that the endless belt has a three-layer structure in which the base layer is polyimide or metal, the base layer is a silicon rubber layer, and the surface layer is a fluororesin.

  According to an eighteenth aspect of the present invention, in order to achieve the fourteenth object described above, the image forming apparatus includes the image transfer apparatus according to the first aspect.

  In the image forming apparatus including the image transfer device, the running speed of the endless belt at the first transfer nip position of the image transfer device and the endless belt at the second transfer nip position for secondary transfer of the image on the endless belt. The traveling speed is set appropriately, and the endless belt is always bent between the first transfer nip position and the second transfer nip position.

  According to a nineteenth aspect of the present invention, in order to achieve the fifteenth object described above, in the image forming apparatus according to the eighteenth aspect, an image carried by the image carrying device is transferred to the endless belt at the first transfer nip position. A primary transfer is performed on the endless belt of the apparatus, and an image carried on the endless belt is secondarily transferred onto a recording material at the second transfer nip position.

  In the image forming apparatus including the image transfer device, the running speed of the endless belt at the first transfer nip position of the image transfer device and the second transfer nip position at which the image on the endless belt is secondarily transferred to the recording material. The running speed of the endless belt is appropriately set, and the endless belt is always bent at the downstream position of the second transfer nip.

  According to a twentieth aspect of the invention, in order to achieve the sixteenth object described above, in the image forming apparatus of the eighteenth aspect, an image carried by the image carrying device is transferred to the endless belt at the first transfer nip position. A primary transfer is performed on the endless belt of the apparatus, and an image carried by the endless belt is secondarily transferred to the transfer image carrying apparatus at the second transfer nip position.

  In the image forming apparatus including the image transfer device, the running speed of the endless belt at the first transfer nip position of the image transfer device and the second transfer nip position for secondary transfer of the image on the endless belt to the transfer image carrier device The running speed of the endless belt is set appropriately, and the endless belt always bends between the first transfer nip position and the second transfer nip position.

  According to a twenty-first aspect of the invention, in order to achieve the seventeenth object described above, in the image forming apparatus according to the eighteenth aspect, heating for heating an image carried by the endless belt around the endless belt device. And an image heated by the heating means is transferred and fixed onto a recording material by the secondary transfer device.

  In the image forming apparatus including the image transfer device, the running speed of the endless belt at the first transfer nip position of the image transfer device and the endless position at the second transfer nip position for transferring and fixing the image on the endless belt to the recording material. The belt traveling speed is set appropriately, and the endless belt is always bent at the downstream position of the second transfer nip.

  According to a twenty-second aspect of the present invention, there is provided an image transfer method for achieving the eighteenth object described above, wherein the first transfer nip is formed by the endless belt device and the image carrier device, while the first device is used by the other device. A belt support member that forms two transfer nips and hangs the endless belt of the endless belt device separately from both the first transfer nip position and the second transfer nip position by a drive source dedicated to the endless belt device. Driving a certain roller to travel the endless belt, and the traveling speed of traveling the endless belt at the first transfer nip position is different from the traveling speed of traveling the endless belt at the second transfer nip position, The endless belt is deflected between the first transfer nip position and the second transfer nip position, and an image carried by the image carrying device is transferred to the endless belt at the first transfer nip position. The endless belt to transfer primary winding devices, characterized in that the image carrying at its endless belt is secondarily transferred at the second transfer nip position.

  According to a twenty-third aspect of the present invention, in order to achieve the nineteenth object, the image transfer method forms a first transfer nip with the endless belt device and the image carrier device, while the other device performs the first operation. A belt support member that forms two transfer nips and hangs the endless belt of the endless belt device by a drive source dedicated to the endless belt device at either the first transfer nip position or the second transfer nip position. A roller is driven to travel the endless belt, and on the other hand, a driving force is transmitted from the outside by a driving source external to the endless belt device to travel the endless belt, and at the first transfer nip position. The travel speed of traveling the endless belt and the travel speed of traveling the endless belt at the second transfer nip position are made different so that the first transfer nip position and the second transfer nip position The endless belt is bent in the meantime, the image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is second transferred. Secondary transfer is performed at the nip position.

  According to a twenty-fourth aspect of the present invention, in order to achieve the twentieth object, the image transfer method forms a first transfer nip with the endless belt device and the image carrier device, while the other device performs the first operation. Two transfer nips are formed, and the driving force is transmitted from the outside by a drive source external to the endless belt device separately at both the first transfer nip position and the second transfer nip position. The traveling speed of traveling the endless belt at the first transfer nip position and the traveling speed of traveling the endless belt at the second transfer nip position are different from each other. The endless belt is deflected between the second transfer nip positions, and an image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position. Wherein the image bearing at the endless belt is secondarily transferred at the second transfer nip position.

  According to a twenty-fifth aspect of the invention, in order to achieve the first object described above, an image formed between the image carrying device and the endless belt device and carrying the image carried by the image carrying device is endless of the endless belt device. A travel speed for traveling the endless belt at a first transfer nip position for primary transfer to the belt, and a travel speed for traveling the endless belt at a second transfer nip position for secondary transfer of an image on the endless belt. In this bending method, the deflection is formed in the endless belt between the first transfer nip position and the second transfer nip position.

  According to the first aspect of the present invention, the first transfer nip position and the second transfer nip position are deflected so that the torque fluctuation generated at one transfer nip position does not affect the other transfer nip position. The endless belt is hung on the belt support member, and the traveling speed at the first transfer nip position and the traveling speed at the second transfer nip position need only be set appropriately. There is no need to increase the size or increase the drive transmission rigidity of the speed reducer that transmits the drive force of the drive source, thereby eliminating the possibility of increasing the size, weight, etc., or incurring high costs. In addition, endless belt torque fluctuations that occur when the endless belt seam passes the transfer nip position, the recording material enters the second transfer nip position, or passes through the second transfer nip position, and the like. Absorbs the deflection generated in the belt, and the torque fluctuations change the running speed of the endless belt, effectively preventing the change from affecting the other transfer nip position and eliminating the occurrence of image distortion such as so-called shock jitter. be able to.

  According to the second aspect of the present invention, the endless belt torque fluctuation that occurs particularly when the recording material enters the second transfer nip position or exits the second transfer nip position is generated in the endless belt. Absorbing by deflection, it is possible to effectively prevent the travel speed of the endless belt from changing due to the torque fluctuation and the change from affecting the first transfer nip position.

  According to the third aspect of the present invention, particularly in an image transfer apparatus of a transfer and fixing type, an endless belt formed when the recording material enters or exits the second transfer nip position. The torque fluctuation is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt is changed by the torque fluctuation, and the change can effectively prevent the change from affecting the first transfer nip position.

  According to the fourth aspect of the present invention, particularly in an image transfer apparatus of a type that is secondarily transferred to the transfer image carrying apparatus at the second transfer nip position, an endless process that occurs when a joint of the endless belt passes through the transfer nip position. The belt torque fluctuations are absorbed by the deflection generated in the endless belt, and the running speed of the endless belt is changed by the torque fluctuation, and the change can be effectively prevented from affecting the other transfer nip position.

  According to the fifth aspect of the present invention, in an image transfer apparatus of the type including an image forming apparatus that forms an image on an image carrier, particularly as an image carrier, the joint of the endless belt passes through one transfer nip position. Or the endless belt torque fluctuation that occurs when the recording material enters the second transfer nip position or exits the second transfer nip position is absorbed by the deflection generated in the endless belt. It is possible to effectively prevent the belt traveling speed from changing and the change from affecting the other transfer nip position.

  According to the sixth aspect of the present invention, in an image transfer apparatus of the type including an intermediate transfer apparatus that supports an image with an intermediate transfer member, in particular, as the image support apparatus, the joint of the endless belt passes through one transfer nip position. Or the endless belt torque fluctuation that occurs when the recording material enters the second transfer nip position or exits the second transfer nip position is absorbed by the deflection generated in the endless belt. It is possible to effectively prevent the belt traveling speed from changing and the change from affecting the other transfer nip position.

  According to the seventh aspect of the present invention, particularly in an image transfer apparatus having a seam in the endless belt of the endless belt device, the endless belt generated when the seam of the endless belt passes through one transfer nip position or the like. The torque fluctuation is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt is changed by the torque fluctuation and the change can be effectively prevented from affecting the other transfer nip position.

  According to the eighth aspect of the present invention, in an image transfer apparatus of a type that travels on an endless belt by driving a roller as a belt support member with a drive source dedicated to the endless belt apparatus, the torque variation of the endless belt is detected. It is possible to effectively prevent the movement speed of the endless belt from changing due to the torque fluctuation and the change from affecting the other transfer nip position.

  According to the ninth aspect of the present invention, in an image transfer apparatus of a type that travels an endless belt that is applied to a belt support member by transmitting a driving force from the outside with a drive source provided outside the endless belt apparatus. The torque fluctuation is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt is changed by the torque fluctuation and the change can be effectively prevented from affecting the other transfer nip position.

  According to the tenth aspect of the present invention, the drive source that travels the endless belt is controlled so that the endless belt is surely bent at the downstream position of the second transfer nip, and the deflection is particularly caused by the second recording material. Absorbing the torque fluctuation of the endless belt when entering the transfer nip, it is possible to effectively prevent the running speed of the endless belt from changing due to the torque fluctuation and affecting the first transfer nip position. . Since the torque fluctuation of the endless belt when entering the second transfer nip is larger than when the recording material comes out of the second transfer nip, this is the case when the torque fluctuation of the former can be ignored compared to the latter. This configuration is particularly effective.

  According to the eleventh aspect of the present invention, the torque fluctuation generated in the endless belt is absorbed by the deflection generated in the endless belt, and even if the deflection amount of the endless belt decreases, the decrease is detected by the deflection amount detecting means. In addition, when the recording material passes through the second transfer nip position, even when the running speed of the endless belt becomes unstable and the amount of deflection is disturbed, the amount of deflection is detected by the deflection amount detecting means and driven by the drive control means. By performing feedback control of the source, the deflection amount is restored to the original value so that the torque fluctuation is absorbed even when the next torque fluctuation occurs. It is always possible to effectively prevent the torque fluctuation of the endless belt generated at the nip position from affecting the other transfer nip position.

  According to the twelfth aspect of the present invention, when the recording material passes through the second transfer nip, the drive source is feedback-controlled in accordance with the passage of the recording material, and the deflection amount of the endless belt is adjusted, and the endless belt is adjusted by the deflection amount. Thus, it is possible to effectively prevent the change in the traveling speed of the endless belt due to the torque variation and the change from affecting the first transfer nip position.

  According to the thirteenth aspect of the present invention, before the recording material enters the second transfer nip position, the endless belt is deflected at the downstream position of the second transfer nip, and the recording material reaches the second transfer nip position. When the recording material passing through the second transfer nip is detected while absorbing the torque fluctuation of the endless belt when entering, the deflection of the endless belt is generated at the upstream position of the second transfer nip, and the recording material is second. The torque fluctuation of the endless belt when it passes through the transfer nip position can be absorbed, and it can be effectively prevented that the running speed of the endless belt changes due to the torque fluctuation and the change affects the first transfer nip position.

  According to the fourteenth aspect of the present invention, the first transfer nip position and the second transfer nip position are set so that the torque fluctuation generated at one transfer nip position does not affect the other transfer nip position when the endless belt runs. It is only necessary to generate deflection in the endless belt, so there is no need to increase the output of the drive source of the image transfer device or increase the drive transmission rigidity of the speed reducer that transmits the drive force of the drive source. It is possible to eliminate the risk of increasing the weight and the like and incurring high costs. In addition, endless belt torque fluctuations that occur when the endless belt seam passes the transfer nip position, the recording material enters the second transfer nip position, or passes through the second transfer nip position, and the like. Absorbs the deflection generated in the belt, and the torque fluctuations change the running speed of the endless belt, effectively preventing the change from affecting the other transfer nip position and eliminating the occurrence of image distortion such as so-called shock jitter. be able to.

  According to the fifteenth aspect of the present invention, when the endless belt travels, the endless belt is bent between the first transfer nip position and the second transfer nip position so that the torque fluctuation generated at one transfer nip position can be absorbed. Therefore, it is not necessary to increase the output of the drive source of the image transfer device or increase the drive transmission rigidity of the reducer that transmits the drive force of the drive source, increasing the size and weight, etc. The possibility of incurring high costs can be eliminated. In addition, endless belt torque fluctuations that occur when the endless belt seam passes the transfer nip position, the recording material enters the second transfer nip position, or passes through the second transfer nip position, and the like. Absorbs the deflection generated in the belt, and the torque fluctuations change the running speed of the endless belt, effectively preventing the change from affecting the other transfer nip position and eliminating the occurrence of image distortion such as so-called shock jitter. be able to.

  According to the sixteenth aspect of the present invention, the belt length of the endless belt between the transfer nip position and the other transfer nip position is such that the torque fluctuation generated at one transfer nip position can be absorbed when the endless belt runs. It is only necessary to make the difference between the transfer nip position upstream and downstream of the endless belt running direction, so the output of the drive source of the image transfer device can be increased or the drive transmission of the speed reducer that transmits the drive force of the drive source There is no need to increase the rigidity, and there is no possibility of increasing the size or weight or incurring high costs. In addition, endless belt torque fluctuations that occur when the endless belt seam passes the transfer nip position, the recording material enters the second transfer nip position, or passes through the second transfer nip position, and the like. Absorbs the deflection generated in the belt, and the torque fluctuations change the running speed of the endless belt, effectively preventing the change from affecting the other transfer nip position and eliminating the occurrence of image distortion such as so-called shock jitter. be able to.

  According to the invention described in claim 17, since the endless belt has a three-layer structure in which the base layer is polyimide or metal, the base layer is a silicon rubber layer, and the surface layer is a fluororesin, the image carrying property and the image transfer property are improved. An image transfer apparatus having an excellent endless belt can be provided.

  According to the invention described in claim 18, in the image forming apparatus including the image transfer device, the travel speed of the endless belt at the first transfer nip position of the image transfer device and the travel of the endless belt at the second transfer nip position. Since it is only necessary to change the speed, it is not necessary to increase the output of the drive source of the image transfer device or to increase the drive transmission rigidity of the speed reducer that transmits the drive force of the drive source. There is no risk of increasing the weight or incurring high costs. In addition, endless belt torque fluctuations that occur when the endless belt seam passes the transfer nip position, the recording material enters the second transfer nip position, or passes through the second transfer nip position, and the like. Absorbs the deflection generated in the belt, and the torque fluctuations change the running speed of the endless belt, effectively preventing the change from affecting the other transfer nip position and eliminating the occurrence of image distortion such as so-called shock jitter. be able to.

  According to the nineteenth aspect of the present invention, in the image forming apparatus including the image transfer device, particularly when the recording material enters or exits the second transfer nip position of the image transfer device. It is effective that the endless belt torque fluctuation of the endless belt device is absorbed by the deflection generated in the endless belt and the travel speed of the endless belt changes due to the torque fluctuation and the change affects the first transfer nip position. Can be prevented.

  According to the twentieth aspect of the invention, in the image forming apparatus including the image transfer device, in particular, in the image transfer device of the type that is secondarily transferred to the transfer image carrying device at the second transfer nip position, the joint of the endless belt is transferred. The torque fluctuation of the endless belt that occurs when passing through the nip position is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt changes due to the torque fluctuation, and the change affects the other transfer nip position. This can be effectively prevented.

  According to the twenty-first aspect of the present invention, in an image forming apparatus provided with an image transfer device, particularly in a transfer and fixing type image transfer device, the recording material enters the second transfer nip position, or the second transfer nip position is set. The torque fluctuation of the endless belt that occurs when the endless belt is pulled out is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt changes due to the torque fluctuation, and the change affects the first transfer nip position. It can be effectively blocked.

  According to the twenty-second aspect of the present invention, in an image transfer method in which a roller as a belt support member is driven by a drive source dedicated to the endless belt device and travels on the endless belt, the endless belt is moved between the transfer nip positions. It is effective that the endless belt bends due to the difference in travel speed and the endless belt torque fluctuations are absorbed by the deflection, and that the endless belt travel speed changes due to the torque fluctuation and the change affects the other transfer nip position. Can be prevented.

  According to the twenty-third aspect of the present invention, the roller as the belt support member is driven by the drive source dedicated to the endless belt device to run the endless belt at one transfer nip position, and the drive source outside the endless belt device is used. In the image transfer method in which the driving force is transmitted from the outside to travel the endless belt at the other transfer nip position, the endless belt bends due to the difference in travel speed of the endless belt between the transfer nip positions. It is possible to absorb the torque fluctuation of the endless belt and to effectively prevent the running speed of the endless belt from changing due to the torque fluctuation and affecting the other transfer nip position.

  According to the twenty-fourth aspect of the present invention, in the image transfer method of traveling the endless belt by transmitting a driving force from the outside by a driving source external to the endless belt device, the endless belt travels between the transfer nip positions. It is effective that the endless belt bends due to the speed difference and that endorsed belt absorbs torque fluctuation of the endless belt, and the torque fluctuation changes the running speed of the endless belt and the change affects the other transfer nip position. Can be blocked.

  According to a twenty-fifth aspect of the present invention, the first transfer nip position is formed between the image carrying device and the endless belt device, and the image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device. The first transfer nip position and the second transfer nip position are made different from the traveling speed at which the endless belt travels and the second transfer nip position at which the image on the endless belt is secondarily transferred at the second transfer nip position. Since it is only necessary to form a deflection on the endless belt, it is not necessary to increase the output of the drive source of the image transfer device or increase the drive transmission rigidity of the reducer that transmits the drive force of the drive source. The endless belt seam passes through the transfer nip position, the recording material enters the second transfer nip position, or the second transfer nip position is increased without increasing the weight or the cost. The torque fluctuation of the endless belt that occurs when the endless belt is absorbed is absorbed by the deflection generated in the endless belt, and the running speed of the endless belt changes due to the torque fluctuation, and the change affects the other transfer nip position. It is possible to effectively prevent the occurrence of image distortion such as so-called shock jitter.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows a main configuration of an internal mechanism in an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof.

  In the illustrated image forming apparatus, the toner images formed on the respective photoreceptors 10b, 10c, 10m, and 10y by the plurality of image forming apparatuses 100b, 100c, 100m, and 100y are transferred to the intermediate transfer body 20 of the intermediate transfer apparatus 200. Then, the toner image on the intermediate transfer member 20 is transferred onto the endless belt 30 of the endless belt device 300, and the toner image on the endless belt 30 is transferred to the recording material p such as paper / OHP film by the secondary transfer device 400. Transcript to.

  As the image forming apparatus 100, four black, cyan, magenta, and yellow 100b, 100c, 100m, and 100y are arranged side by side along the extending direction of the belt-shaped intermediate transfer body 20 of the intermediate transfer apparatus 200. Prepare for. Each of the image forming apparatuses 100b, 100c, 100m, and 100y is provided with drum-shaped photoreceptors 10b, 10c, 10m, and 10y arranged in parallel to each other so that they can rotate in the same counterclockwise direction.

  Around the photosensitive members 10b, 10c, 10m, and 10y, charging devices 11b, 11c, 11m, and 11y, developing devices 12b, 12c, 12m, and 12y, transfer devices 13b, 13c, 13m, and 13y, and photosensitive members, respectively. Cleaning devices 14b, 14c, 14m and 14y are arranged. Further, an exposure device 15 is provided on each of the four image forming devices 100.

  The intermediate transfer device 200 is provided with an endless belt-like intermediate transfer member 20 that is wound around one drive roller 22 and a driven roller 23 in the illustrated example so as to be able to run clockwise in the drawing. The transfer devices 13b, 13c, 13m, and 13y described above are in the form of rollers and are provided inside the intermediate transfer body 20, and include the intermediate transfer body 20 between the photoreceptors 10b, 10c, 10m, and 10y. In addition, around the intermediate transfer body 20, in the illustrated example, a transfer body cleaning device 25 that removes residual toner remaining on the intermediate transfer body 20 after transfer is provided on the left side of the driving roller 22. The endless belt device 300 is disposed on the front side.

  The endless belt device 300 is configured by winding an endless belt 30 between a large roller 31 and a small roller 32 that are belt support members. Then, the large roller 31 is pressed against the driven roller 23 via the endless belt 30 and the intermediate transfer member 20, and a first transfer nip n1 is formed between the intermediate transfer device 200 as an image carrier. On the other hand, the pressure roller 40 of the secondary transfer device 400 is pressed from the outside against the small roller 32 via the endless belt 30 to form a second transfer nip n2 between the endless belt device 300 and the secondary transfer device 400. .

  Under the intermediate transfer device 200 and the endless belt device 300 as described above, the recording material tray 50 in which the recording material p is stacked and accommodated, and the uppermost recording of the recording material p stacked in the recording material tray 50. A supply roller 51 that contacts the leading end of the material and separates and feeds the recording material p one by one from the top, a guide member 52 that guides the recording material p fed by the supply roller 51, and guides by the guide member 52 A registration roller 53 that feeds the recording material p to be timed to the position of the second transfer nip n2 is provided.

  Now, when recording a color image on the recording material p using this image forming apparatus, the operation of a start switch (not shown) is used for a copying machine, the image signal from a host is used for a printer, and a facsimile is used. Then, based on the image signal sent through the telephone line, the respective photoreceptors 10 of the respective image forming devices 100, the intermediate transfer member 20 of the intermediate transfer device 200, the endless belt 30 of the endless belt device 300, at an appropriate timing, The supply roller 51 and the like are driven to rotate.

  Then, as each photoconductor 10 rotates, the surface of the photoconductor 10 is uniformly charged by the charging device 11 and then converted into a read signal from the document reading device, an image signal from the host, or an image signal through the telephone line. Based on this, writing is performed by irradiating writing light with the exposure device 15 to form an electrostatic latent image on the photosensitive member 10, and then a separate toner is attached to the developing device 12 to make the electrostatic latent image visible. A single color toner image of black, cyan, magenta, and yellow is formed on each photoconductor 10.

  The single color toner images on the respective photoconductors 10 are respectively transferred in a superimposed manner onto the intermediate transfer body 20 by applying a predetermined transfer bias to the transfer device 13, thereby forming a composite color image on the intermediate transfer body 20. Each photoconductor 10 after image transfer is initialized by removing residual toner with a photoconductor cleaning device 14 to clean the surface, and removing electricity with a static eliminator (not shown) to prepare for image formation again.

  On the other hand, the composite color image on the intermediate transfer body 20 forms a transfer electric field at the position of the first transfer nip n1 by applying a transfer bias, and is electrostatically primary-transferred onto the endless belt 30. At this time, if an alternating current component or a pulse component is superimposed on the transfer bias, the electrostatic force exerted on the toner vibrates, and the vibration can weaken the adhesion force of the toner to facilitate the movement of the toner. The intermediate transfer body 20 after the image transfer is cleaned by removing the residual toner by the transfer body cleaning device 25, and is initialized to prepare for another image transfer.

  On the other hand, along with the rotation of the supply roller 51, the recording material p stacked in the recording material tray 50 is separated one by one from the uppermost recording material p, fed out, guided by the guide member 52, and conveyed by the registration roller 53. The timing is taken to the second transfer nip n2. Then, a transfer bias is applied to the pressure roller 40 of the secondary transfer device 400 at the position of the second transfer nip n2, and the toner image held by the endless belt 30 is transferred to the recording material p passing through the second transfer nip n2. And a color image is recorded on the recording material p.

  In the above description, a case where a color image is recorded on the recording material p has been described. However, in the above-described image forming apparatus, some of the image forming apparatuses 100 are appropriately set in accordance with the selected single color mode or multiple color mode. A monochrome image or a color image can be arbitrarily formed by selective use.

  FIG. 2 is an enlarged view of the image transfer apparatus 500 that transfers the toner image carried by the intermediate transfer body 20 of the intermediate transfer apparatus 200 that is an image carrying apparatus to the recording material p via the endless belt 30 of the endless belt apparatus 300. Show.

  In the illustrated image transfer apparatus 500, an endless belt 30 having a seam 33 is used in order to reduce the cost, and the endless belt 30 is wound around the large roller 31 and the small roller 32 with a slack. The endless belt 30 has a three-layer structure in which the base layer is polyimide, the base layer is a silicon rubber layer, and the surface layer is a fluororesin. For the base layer, a metal such as nickel may be used instead of polyimide. The first driving source 34 and the second driving source 35, which are driving sources dedicated to the endless belt device 300, are provided. The first driving source 34 rotates the large roller 31 via the speed reducer 36, and the second driving source. 35, the small roller 32 is rotationally driven via the speed reducer 37, and the traveling speed of the endless belt 30 at the first transfer nip n1 position and the traveling speed at the second transfer nip n2 position are appropriately set. .

  For example, the traveling speed for traveling the endless belt 30 at the second transfer nip position n2 is set slightly faster than the traveling speed for traveling the endless belt 30 at the first transfer nip n1 position.

  The torque variation of the endless belt 30 when the recording material p enters the second transfer nip n2 position is absorbed by the deflection t of the endless belt 30 downstream of the second transfer nip n2, and the second transfer nip n2 position. The torque fluctuation of the endless belt 30 when passing through is absorbed by the deflection t of the endless belt 30 upstream of the second transfer nip n2. Further, since the absorption of the deflection t is larger at the downstream position than the upstream position of the second transfer nip n2, the deflection t of the endless belt 30 at the downstream position gradually decreases at the first transfer nip n1 position. By gradually increasing the traveling speed at which the endless belt 30 travels at the second transfer nip position n2 from the traveling speed at which the endless belt 30 travels, the restoration is gradually performed.

  Thus, the large roller 31 and the small roller are deflected between the first transfer nip n1 position and the second transfer nip n2 position so that the torque fluctuation generated at the one transfer nip position does not affect the other transfer nip position. Since the endless belt 30 is wound around 32 and the traveling speed at the first transfer nip n1 position and the traveling speed at the second transfer nip n2 position need only be set appropriately, the drive source of the image transfer apparatus 500 It is not necessary to increase the output of the motor or to increase the drive transmission rigidity of the speed reducers 36 and 37 that transmit the driving force of those driving sources, which may increase the size, weight, etc., and increase the cost. Can be eliminated.

  Further, when the convex seam 33 of the endless belt 30 passes through the transfer nip positions n1 and n2, the recording material p enters the second transfer nip n2 position, or passes through the second transfer nip n2 position. It is effective to absorb the torque fluctuation of the endless belt 30 caused by the deflection t generated in the endless belt 30 and change the running speed of the endless belt 30 due to the torque fluctuation, and the change affects the other transfer nip position. Therefore, image distortion such as so-called shock jitter can be eliminated.

  In this example, a third drive source 26 is provided in the intermediate transfer device 200 that is an image bearing device, and the drive roller 22 is rotationally driven by the third drive source 26 via a speed reducer 27 so that the intermediate transfer member 20 is moved. Run. On the other hand, the secondary transfer device 400 is not provided with a drive source, and the pressure roller 40 rotates following the traveling of the endless belt 30.

  In the example shown in FIG. 2, the endless belt device 300 includes dedicated drive sources 34 and 35, and the large roller 31 and the small roller 32 are individually driven by the drive sources 34 and 35 to travel the endless belt 30. did. However, as shown in FIG. 3A, the first drive source 34 is eliminated, and the driving force is transmitted to the endless belt 30 by frictional contact with the intermediate transfer member 20 running by the third drive source 26, that is, the endless belt. The third driving source 26 provided outside the apparatus 300 may be used to transmit the driving force from the outside to travel the endless belt 30 at the position of the first transfer nip n1.

  Conversely, as shown in FIG. 3B, the second drive source 35 is eliminated, and a fourth drive source 41 for driving the pressure roller 40 of the secondary transfer device 400 is provided separately. Then, the pressure roller 40 is rotationally driven via the speed reducer 42, and the driving force is transmitted to the endless belt 30 by frictional contact. That is, the driving force is applied from the outside using the fourth driving source 41 provided outside the endless belt device 300. And the endless belt 30 may travel at the position of the second transfer nip n2.

  Further, as shown in FIG. 3 (C), both the dedicated drive sources 34 and 35 of the endless belt device 300 are eliminated, and the third drive source 26 provided outside the endless belt device 300 is used to drive from the outside. The force is transmitted to travel the endless belt 30 at the position of the first transfer nip n1, and the fourth drive source 41 provided outside the endless belt device 300 is used to transmit the driving force from the outside to position the second transfer nip n2. The endless belt 30 may be traveled.

  Here, when the large roller 31 and the small roller 32 are not rotationally driven using the dedicated drive sources 34 and 35, for example, as shown in FIG. 4, instead of the rotating roller, the belt support member is not rotated. It is also possible to use a nip forming member 38 that is fixed and forms the second transfer nip n2.

FIG. 5 shows an enlarged view of another example of the image transfer apparatus 500.
In this example, the driving speed for driving the endless belt 30 is controlled so that the running speed for running the endless belt 30 at the second transfer nip n2 position is higher than the running speed for running the endless belt 30 at the first transfer nip n1 position. The end of the endless belt 30 is always bent at a position downstream of the second transfer nip n2.

  In this way, the endless belt 30 is reliably bent at the downstream position of the second transfer nip n2, and the deflection causes torque fluctuations of the endless belt 30 particularly when the recording material p enters the second transfer nip n2. By absorbing, it is possible to effectively prevent the traveling speed of the endless belt 30 from changing due to the torque fluctuation and the change from affecting the position of the first transfer nip n1.

  In the image transfer apparatus 500 of this example, it is not possible to prevent the torque fluctuation of the endless belt 30 when the recording material p is removed from the second transfer nip n2 from affecting the position of the first transfer nip n1. However, since the torque fluctuation of the endless belt 30 when entering the second transfer nip n2 is larger than when the recording material p exits the second transfer nip n2, the former torque fluctuation can be ignored compared to the latter. In such a case, the configuration as in this example is particularly effective.

FIG. 6 shows an enlarged view of still another example of the image transfer apparatus 500.
In addition to the image transfer apparatus 500 having the configuration shown in FIG. 2, the image transfer apparatus 500 shown in FIG. 6 is provided at a downstream position of the second transfer nip n2 as a deflection amount detecting means for detecting the deflection amount of the endless belt 30. A micro switch 60 and a micro switch 61 provided at an upstream position are provided, and feedback control is performed on, for example, the first drive source 34 and the fourth drive source 41, which are drive sources, based on the output signals of the micro switches 60 and 61. Drive control means 62 is provided.

  Then, the amount of deflection of the endless belt 30 is detected by turning on / off the microswitches 60 and 61, the output signals of these microswitches 60 and 61 are input to the drive control means 62, and the drive control means 62 is based on those output signals. The first drive source 34 and the fourth drive source 41 are feedback-controlled, and the endless belt 30 travels by rotating the large roller 31 and the pressure roller 40 via the speed reducers 36 and 42, and the first transfer nip n1. The traveling speed of the endless belt 30 at the position and the traveling speed of the endless belt 30 at the second transfer nip n2 position are gradually different from each other, and the endless belt 30 is moved between the first transfer nip n1 position and the second transfer nip n2 position. Always generate a certain amount of deflection.

  As a result, the torque fluctuation generated in the endless belt 30 is absorbed by the deflection generated in the endless belt 30, and even if the deflection amount of the endless belt 30 is reduced by absorbing the torque fluctuation, the reduction is detected. This is detected by the microswitches 60 and 61. Further, when the recording material p passes through the position of the second transfer nip n2, even when the running speed of the endless belt 30 becomes unstable and the amount of deflection is disturbed, the disturbance is detected by the micro switches 60 and 61. Then, by performing feedback control of the first drive source 34 and the fourth drive source 41 by the drive control means 62, the deflection amount is gradually returned to the original state, and the torque fluctuation is reliably absorbed even when the next torque fluctuation occurs. In this way, even when torque fluctuations occur continuously in the endless belt 30, it is always possible to effectively prevent the torque fluctuation of the endless belt 30 generated at one transfer nip position from affecting the other transfer nip position.

  In the illustrated example, the micro switches 60 and 61 as the deflection amount detecting means are provided at the downstream position and the upstream position of the second transfer nip n2, but the number is not limited to this, and there may be one or three. There may be more than one.

  By the way, in the above-described example, the toner image carried by the intermediate transfer device 200 that is an image carrying device is primarily transferred to the endless belt 30 of the endless belt device 300 at the first transfer nip n1 position, and the toner carried by the endless belt 30 is transferred. The image transfer apparatus 500 that secondarily transfers an image to the recording material p at the position of the second transfer nip n2 has been described.

FIG. 7 shows an enlarged view of still another example of the image transfer apparatus 500.
In the image transfer apparatus 500 of this example, toner images are formed by the image forming apparatuses 100b, 100c, 100m, and 100y, which are image carrying apparatuses, and the toners carried by the respective drum-shaped photoreceptors 10b, 10c, 10m, and 10y. The image is primarily transferred to the intermediate transfer member 20 of the intermediate transfer device 200 that is an endless belt of the endless belt device by the transfer devices 13b, 13c, 13m, and 13y at the position of the first transfer nip n1, and is carried by the intermediate transfer member 20. The toner image is secondarily transferred onto the recording material p by the pressure roller 40 of the secondary transfer device 400 at the position of the second transfer nip n2.

  Then, the intermediate transfer body 20 is wound around the driving roller 22 and the driven roller 23 which are belt support members so that the intermediate transfer body 20 is always bent between the first transfer nip n1 position and the second transfer nip n2 position. The third drive source 26 and the fifth drive source 65 are driven to rotate the drive roller 22 via the speed reducer 27 and the pressure roller 40 is driven to rotate via the speed reducer 66. Are individually driven at the first transfer nip n1 position and the second transfer nip n2 position to maintain the deflection t.

  As a result, the intermediate transfer member which is an endless belt in the image transfer device 500 of the type including the image forming devices 100b, 100c, 100m, and 100y that form images on the photoreceptors 10b, 10c, 10m, and 10y, particularly as the image bearing device. The torque fluctuation of the intermediate transfer member 20 that occurs when the joint 20 passes through one transfer nip position, the recording material p enters the second transfer nip n2 position, or passes through the second transfer nip n2 position. Can be absorbed by the deflection t generated in the intermediate transfer member 20, and the change in the traveling speed of the intermediate transfer member 20 due to the torque variation can be effectively prevented from affecting the other transfer nip position. .

  Reference numeral 67 in the drawing schematically shows toner adhering to the intermediate transfer body 20 and forms a toner image carried by the intermediate transfer body 20.

  Now, in the image transfer apparatus 500 as shown in FIG. 7, the amount of deflection of the intermediate transfer body 20 decreases each time the recording material p passes through the second transfer nip n2, so that the recording material p is transferred to the second transfer nip n2. When not passing through the nip n2, the fifth drive source 65 is driven to rotate the pressure roller 40 of the secondary transfer device 400, and the deflection amount is returned to the original and held constant. Since there is no recording material p in the second transfer nip n2, the amount of deflection can be returned to the original by reliably running the intermediate transfer member 20 without causing slippage.

FIG. 8 shows a modification of the image transfer apparatus 500 shown in FIG.
In this example, a pair of rollers 68 is provided between the second transfer nip n2 position of the image transfer apparatus 500 configured as shown in FIG. 7 and the first transfer nip n1 position of the photosensitive member 10y to sandwich the intermediate transfer member 20, The range in which the deflection t is formed is limited.

FIG. 9 shows an enlarged view of still another example of the image transfer apparatus 500.
In the image transfer apparatus 500 of this example, toner images are formed by the image forming apparatuses 100b, 100c, 100m, and 100y, and the toner images carried by the respective drum-shaped photoreceptors 10b, 10c, 10m, and 10y are image-bearing. The toner image transferred to the intermediate transfer member 20 of the intermediate transfer device 200, which is the device, and the toner image carried on the intermediate transfer member 20 is transferred and fixed at the first transfer nip n1 position by the transfer fixing device 700 which is an endless belt of the endless belt device The image is primarily transferred to the belt 70, and the toner image carried on the transfer fixing belt 70 is secondarily transferred to the recording material p by the pressure roller 40 of the secondary transfer device 400 at the second transfer nip n2.

  In the transfer fixing device 700, the transfer fixing belt 70 is wound around the small roller 71 and the large roller 72 with a slack t, and the small roller 71 is interposed between the transfer fixing belt 70 and the intermediate transfer body 20. On the other hand, the large roller 72 is pressed against the pressure roller 40 of the secondary transfer device 400 via the transfer fixing belt 70.

  Around the transfer fixing device 700, which is an endless belt device, there is provided a heating means 73 for heating the toner image carried on the transfer fixing belt 70. The toner 67 is heated by the heating means 73, and the heated toner image is heated. Is transferred to the recording material p by the pressure roller 40 of the secondary transfer device 400 and fixed simultaneously. The heating unit 73 includes, for example, a halogen heater 74 that heats the toner image, and a reflection plate 75 that reflects the heat of the halogen heater 74 toward the transfer fixing belt 70.

  Further, in this example, the driving force of the sixth driving source 76 is transmitted to the driving roller 23 via the speed reducer 77, and the intermediate transfer member 20 that is wound around the driven roller 23 travels in the direction of the arrow. At the first transfer nip n1, the transfer fixing belt 70 is brought into frictional contact with the intermediate transfer member 20, while the driving force of the seventh drive source 78 is transmitted to the large roller 72 via the speed reducer 79 to be second. The transfer fixing belt 70 travels in the direction of the arrow at the transfer nip n2 position, and the pressure roller 40 that frictionally contacts the transfer fixing belt 70 at the second transfer nip n2 position is rotated in the direction of the arrow. In a normal state, the traveling speed of traveling the transfer fixing belt 70 at the second transfer nip n2 position is made faster than the traveling speed of traveling the transfer fixing belt 70 at the first transfer nip n1 position. A deflection t is formed at the downstream position.

  Incidentally, a recording material detection means 80 such as a photosensor for detecting the recording material p passing through the second transfer nip n2 is provided at the upstream position of the second transfer nip n2 in the conveyance direction of the recording material p. Then, drive control means 81 for inputting the output signal of the recording material detection means 80 is provided, and the sixth drive source 76 and the seventh drive source 78 are feedback-controlled based on the output signal. Specifically, in the drive control unit 81, when the recording material p is detected by the recording material detection unit 80, the driving speed at which the transfer fixing belt 70 travels at the first transfer nip n1 position and the second transfer nip n2 position. The traveling speed of traveling on the transfer fixing belt 70 is made equal, or the latter is made slower than the former.

  As a result, before the recording material p enters the second transfer nip n2, the deflection of the transfer fixing belt 70 occurs at the downstream position of the second transfer nip n2, and the recording material p enters the second transfer nip n2. The torque fluctuation of the transfer fixing belt 70 when absorbing is absorbed. On the other hand, when the recording material p passing through the second transfer nip n2 is detected, the sixth drive source 76 and the seventh drive source 78 are feedback-controlled to bend the transfer fixing belt 70 at the upstream position of the second transfer nip n2. And the torque fluctuation of the transfer fixing belt 70 when the recording material p has passed through the second transfer nip n2 position is absorbed, and the running speed of the transfer fixing belt 70 is changed by the torque fluctuation, and the change is the first transfer. It is possible to effectively prevent the nip n1 position from being affected.

  That is, when the recording material p enters the second fixing nip n2, the traveling speed of the transfer fixing belt 70 becomes slow, and speed fluctuation occurs. At this time, since the transfer and fixing belt 70 is bent at the downstream position of the second transfer nip n2, even if the traveling speed of the transfer and fixing belt 70 is slowed, the amount of deflection only changes and the position of the first transfer nip n1 is reached. There is no influence on the running speed of the transfer and fixing belt 70.

  Further, the transfer fixing belt 70 is bent at the upstream position of the second transfer nip n2 by slowing the traveling speed of the transfer fixing belt 70 before and after the recording material p enters the second fixing nip n2. In this state, when the trailing edge of the recording material p comes out of the second transfer nip n2, the traveling speed of the recording material p increases and speed fluctuation occurs, but the transfer fixing belt 70 is positioned upstream of the second transfer nip n2. Therefore, even if the traveling speed of the transfer fixing belt 70 increases, the amount of deflection only changes, and the traveling speed of the transfer fixing belt 70 at the position of the first transfer nip n1 is not affected at all.

  In the above-described example, all the images carried by the image bearing device are primarily transferred to the endless belt of the endless belt device at the first transfer nip n1 position, and the images carried by the endless belt are recorded at the second transfer nip n2 position. Although the case where the secondary transfer is performed on the material p has been described, the image carried by the endless belt may be secondarily transferred to a transfer image carrying device carrying the transfer image instead of the recording material.

FIG. 10 shows still another example of the image transfer apparatus 500 in an enlarged manner.
In this image transfer device 500, the toner images on the photoreceptors 10b, 10c, 10m, and 10y of the image forming devices 100b, 100c, 100m, and 100y are primarily transferred to the intermediate transfer member 20 of the intermediate transfer device 200, and the intermediate transfer member. The toner image carried at 20 is secondarily transferred to a transfer fixing roller 84 incorporating a heater 83, and the toner image carried by the transfer fixing roller 84 is transferred onto the recording material p by the transfer roller 85 and fixed simultaneously. is there.

  The recording material p is fed from the recording material tray 50 by the supply roller 51, guided by the guide member 52 and conveyed by the conveying roller 54, and sent by the registration roller 53 to the third transfer nip n 3 position with timing.

  Then, the traveling speed of the intermediate transfer member 20 that is an endless belt at the position of the first transfer nip n1 and the second transfer nip that secondarily transfers the image on the intermediate transfer member 20 to a transfer fixing roller 84 that is a transfer image carrying device. By appropriately setting the traveling speed of the intermediate transfer member 20 at the n2 position, the intermediate transfer member 20 always bends between the first transfer nip n1 position and the second transfer nip n2 position.

  In this way, in the image transfer apparatus 500 of the type that is secondarily transferred to the transfer fixing roller 84 that is the transfer image carrying apparatus, particularly at the position of the second transfer nip n2, the seam of the intermediate transfer body 20 that is an endless belt is the transfer nip. The torque fluctuation of the intermediate transfer body 20 that occurs when passing the position is absorbed by the deflection generated in the intermediate transfer body 20, and the running speed of the intermediate transfer body 20 changes due to the torque fluctuation, and the change is transferred to the other transfer body. It is possible to effectively prevent the nip position from being affected.

FIG. 11 shows still another example of the image transfer apparatus 500 in an enlarged manner.
In this image transfer device 500, the toner image on the photoconductor 10 of the color image forming device 800 is primarily transferred to the transfer fixing belt 70 of the transfer fixing device 700 at the position of the first transfer nip n1, and is carried by the transfer fixing belt 70. The toner image to be transferred is secondarily transferred to the recording material p by the pressure roller 40 of the secondary transfer device 400 at the second transfer nip n2 position and fixed simultaneously.

  In the color image forming apparatus 800 that is an image bearing apparatus, a belt may be used, but in the illustrated example, four developing devices 12y, 12c, 12m, and 12b of yellow, cyan, magenta, and black are provided around the photosensitive member 10 of the drum. . When a full-color image is recorded on the recording material p, as the photosensitive member 10 rotates in the direction indicated by the arrow in the drawing, the first charging is performed by a charging device (not shown), and writing is performed by the exposure device, thereby writing the first on the photosensitive member 10. An electrostatic latent image of color is formed, and development is performed by a first color developing device to form a toner image of the first color on the photoreceptor 10.

  Next, after one rotation, similarly, a second-color electrostatic latent image is formed on the photoreceptor 10 by charging with a charging device (not shown) and writing with an exposure device, and developing with the second-color developing device. Then, a second color toner image is formed on the photoconductor 10 so as to overlap the first color toner image. Similarly, a full-color image is formed on the photoreceptor 10 by forming toner images of the third color and the fourth color. Reference numeral 86 in the drawing schematically shows toner that forms a full-color image.

  In the transfer fixing device 700 which is an endless belt device, a transfer fixing belt 70 having an induction heating layer is wound around a large roller 31 and a small roller 32 which are belt support members, and an induction coil is provided around the belt. A heating device 87 is provided. Then, the induction heating layer of the transfer fixing belt 70 that rotates in the direction of the arrow in the drawing generates heat by the induction coil of the induction heating device 87, and the transfer heating belt 70 of the transfer fixing device 700 is primary at the first transfer nip n1 position. Heat the transferred full-color image.

  Although not shown, for example, similarly, the recording material p fed from the recording material tray by the supply roller is sent to the second transfer nip n2 at the timing by the registration roller. Then, the heated full-color image is secondarily transferred and pressed on the recording material p by the pressure roller 40 of the secondary transfer device 400 at the second transfer nip n2 position, and is fixed simultaneously with the transfer.

  Also in this image transfer apparatus 500, the traveling speed of the transfer fixing belt 70 that is an endless belt at the first transfer nip n1 position and the traveling speed of the transfer fixing belt 70 at the second transfer nip n2 position are appropriately set. The intermediate transfer body 20 is always bent between the first transfer nip n1 position and the second transfer nip n2 position.

  In this way, in particular, the image carried on the photoreceptor 10 of the color image forming device 800 which is an image carrying device is transferred to the transfer fixing belt 70 of the transfer fixing device 700 which is an endless belt of the endless belt device at the first transfer nip n1 position. In the image transfer apparatus 500 of the type in which the image is transferred to the recording material p at the second transfer nip n2 position, the joint of the transfer fixing belt 70 passes through the transfer nip position. The torque fluctuation of the transfer fixing belt 70 that occurs when the transfer fixing belt 70 is absorbed is absorbed by the deflection generated in the transfer fixing belt 70, and the running speed of the transfer fixing belt 70 is changed by the torque fluctuation, and the change is transferred to the other transfer nip position. It is possible to effectively prevent the influence.

FIG. 3 is a configuration diagram of a main part of an internal mechanism in the image forming apparatus. FIG. 2 is an enlarged configuration diagram of an image transfer apparatus provided in the image forming apparatus. (A) thru | or (C) are the expansion block diagrams of the modification of the image transfer apparatus shown in FIG. 2, respectively. FIG. 10 is an enlarged configuration diagram of still another modified example of the image transfer apparatus illustrated in FIG. 2. It is an enlarged block diagram of the other example of an image transfer apparatus. It is an expanded block diagram of the further another example of an image transfer apparatus. FIG. 10 is an enlarged configuration diagram of still another example of the image transfer apparatus. It is an enlarged block diagram of the modification of the image transfer apparatus shown in FIG. FIG. 10 is an enlarged configuration diagram of still another example of the image transfer apparatus. FIG. 10 is an enlarged configuration diagram of still another example of the image transfer apparatus. FIG. 10 is an enlarged configuration diagram of still another example of the image transfer apparatus. It is an enlarged block diagram of the conventional image transfer apparatus.

Explanation of symbols

10, 10b, 10c, 10m, 10y photoconductor (image carrier)
20 Intermediate transfer member 26 Third drive source 30 Endless belt 31 Large roller (belt support member)
32 Small roller (belt support member)
33 Joint 34 First drive source 35 Second drive source 38 Nip forming member (belt support member)
40 Pressure roller 41 Fourth drive source 60 Deflection amount detection means 61 Deflection amount detection means 62 Drive control means 65 Fifth drive source 70 Transfer fixing belt (endless belt)
73 Heating means 76 Sixth drive source 78 Seventh drive source 80 Recording material detection means 81 Drive control means 84 Transfer fixing roller (transfer image carrying device)
100, 100b, 100c, 100m, 100y Image forming device (image carrying device)
200 Intermediate transfer device (image carrier)
300 Endless Belt Device 400 Secondary Transfer Device 500 Image Transfer Device 700 Transfer Fixing Device (Endless Belt Device)
800 color imager (image carrier)
p Recording material n1 First transfer nip n2 Second transfer nip t Deflection

Claims (25)

An endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device and an image carrying device, and an image carried by the image carrying device is stored in the first carrying nip. In the image transfer apparatus for primary transfer to the endless belt of the endless belt apparatus at one transfer nip position and secondarily transferring the image carried by the endless belt at the second transfer nip position,
The endless belt is wound around the belt support member so that the endless belt is deflected between the first transfer nip position and the second transfer nip position, and the endless belt is moved from the first transfer nip position to the first transfer nip position. An image transfer apparatus that is individually driven at a second transfer nip position.   A second transfer nip is formed by forming the second transfer nip with the endless belt device, and an image carried by the endless belt is transferred to the recording material passing through the second transfer nip by the secondary transfer device. The image transfer apparatus according to claim 1, wherein next transfer is performed.   A heating means for heating an image carried by the endless belt is provided around the endless belt device, and the image heated by the heating means is transferred and fixed onto a recording material by the secondary transfer device. Item 3. The image transfer apparatus according to Item 2.   The image transfer apparatus according to claim 1, wherein an image carried by the endless belt is secondarily transferred to a transfer image carrying apparatus at the second transfer nip position.   The image transfer apparatus according to claim 1, further comprising an image forming apparatus that forms an image on a drum-shaped or belt-shaped image bearing member.   5. The image transfer apparatus according to claim 1, further comprising an intermediate transfer apparatus that supports an image with a drum-shaped or belt-shaped intermediate transfer body as the image bearing apparatus.   The image transfer apparatus according to claim 1, wherein the endless belt has a seam.   8. The apparatus according to claim 1, further comprising a drive source dedicated to the endless belt device, wherein a roller is used as the belt support member and the endless belt is driven by driving the roller. 9. Image transfer device.   8. The drive source for driving the endless belt that transmits a driving force from the outside and hangs around the belt support member is provided outside the endless belt device. 8. Image transfer device.   The driving speed of driving the endless belt at the second transfer nip position is faster than the driving speed of driving the endless belt at the first transfer nip position by driving with the driving source. Item 10. The image transfer device according to Item 8 or 9.   11. A deflection amount detection means for detecting a deflection amount of the endless belt, and a drive control means for feedback-controlling the drive source based on an output signal of the deflection amount detection means. The image transfer apparatus according to any one of the above.   The recording material detecting means for detecting a recording material passing through the second transfer nip, and a drive control means for feedback controlling the drive source based on an output signal of the recording material detecting means. The image transfer apparatus according to any one of 8 to 10.   Whether the traveling speed of traveling the endless belt at the first transfer nip position is equal to the traveling speed of traveling the endless belt at the second transfer nip position when the recording material detection unit detects the recording material The image transfer apparatus according to claim 12, wherein the latter is slower than the former. An endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device and an image carrying device, and an image carried by the image carrying device is stored in the first carrying nip. In the image transfer apparatus for primary transfer to the endless belt of the endless belt apparatus at one transfer nip position and secondarily transferring the image carried by the endless belt at the second transfer nip position,
When the endless belt travels, the endless belt is bent between the first transfer nip position and the second transfer nip position so that the torque fluctuation generated at one transfer nip position does not affect the other transfer nip position. An image transfer apparatus characterized by being generated. An endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device and an image carrying device, and an image carried by the image carrying device is stored in the first carrying nip. In the image transfer apparatus for primary transfer to the endless belt of the endless belt apparatus at one transfer nip position and secondarily transferring the image carried by the endless belt at the second transfer nip position,
When the endless belt travels, the endless belt generates a deflection enough to absorb the torque fluctuation generated at one transfer nip position between the first transfer nip position and the second transfer nip position. Image transfer device. An endless belt device is formed by wrapping an endless belt around a belt support member, and a first transfer nip is formed between the endless belt device and an image carrying device, and an image carried by the image carrying device is stored in the first carrying nip. In the image transfer apparatus for primary transfer to the endless belt of the endless belt apparatus at one transfer nip position and secondarily transferring the image carried by the endless belt at the second transfer nip position,
When the endless belt travels, the endless belt length between the transfer nip position and the other transfer nip position is determined so that the torque fluctuation generated at one transfer nip position can be absorbed. An image transfer apparatus characterized in that the upstream side and the downstream side in the running direction are different.   17. The image transfer apparatus according to claim 1, wherein the endless belt has a three-layer structure in which a base layer is polyimide or metal, a silicon rubber layer is formed on the base layer, and a surface layer is a fluororesin.   An image forming apparatus comprising the image transfer apparatus according to claim 1.   The image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is secondarily transferred to a recording material at the second transfer nip position. The image forming apparatus according to claim 18, wherein:   An image carried by the image carrying device is primarily transferred to the endless belt of the endless belt device at the first transfer nip position, and an image carried by the endless belt is transferred to the transferred image carrying device at the second transfer nip position. The image forming apparatus according to claim 18, wherein secondary transfer is performed.   A heating means for heating an image carried by the endless belt is provided around the endless belt device, and the image heated by the heating means is transferred and fixed onto a recording material by the secondary transfer device. Item 19. The image forming apparatus according to Item 18.   The endless belt device and the image bearing device form a first transfer nip, while the other device forms a second transfer nip, and each of the first transfer nip position and the second transfer nip position separately. The endless belt device is driven by a drive source dedicated to the endless belt device to drive a roller, which is a belt support member that wraps the endless belt of the endless belt device, and travels on the endless belt at the first transfer nip position. The endless belt is deflected between the first transfer nip position and the second transfer nip position by making the speed different from the traveling speed at which the endless belt travels at the second transfer nip position. Is transferred to the endless belt of the endless belt device at the first transfer nip position, and the image carried by the endless belt is transferred to the second transfer nip. Wherein the secondary transfer by location, image transfer method.   A first transfer nip is formed by the endless belt device and the image carrying device, while a second transfer nip is formed by another device, and the endless one of the first transfer nip position and the second transfer nip position. A roller that is a belt support member that wraps the endless belt of the endless belt device is driven by a drive source dedicated to the belt device to travel the endless belt, and on the other hand, by a drive source external to the endless belt device A traveling speed for transmitting the driving force from the outside to travel the endless belt, traveling the endless belt at the first transfer nip position, and a traveling speed for traveling the endless belt at the second transfer nip position. The endless belt is deflected between the first transfer nip position and the second transfer nip position, and the image carried by the image carrying device is transferred to the first transfer nip position. It said endless belt to primary transfer of the endless belt device flop position, characterized by transferring secondary image carrying at its endless belt at the second transfer nip position, the image transfer method.   The endless belt device and the image bearing device form a first transfer nip, while the other device forms a second transfer nip, and each of the first transfer nip position and the second transfer nip position separately. A driving force is transmitted from the outside by a driving source external to the endless belt device to travel the endless belt of the endless belt device, travel the endless belt at the first transfer nip position, and the second transfer. The traveling speed at which the endless belt travels at the nip position is made different to cause the endless belt to bend between the first transfer nip position and the second transfer nip position, and the image carried by the image bearing device is The image is primarily transferred to the endless belt of the endless belt device at one transfer nip position, and the image carried by the endless belt is secondarily transferred at the second transfer nip position. Image transfer method.   A traveling speed at which the endless belt travels at a first transfer nip position formed between the image bearing device and the endless belt device to primarily transfer an image carried by the image bearing device to the endless belt of the endless belt device. And the second transfer nip position at which the image on the endless belt is secondarily transferred, and the traveling speed at which the endless belt travels are made different, so that the endlessness is between the first transfer nip position and the second transfer nip position. A method for creating a deflection, comprising forming a deflection in a belt.

Images