Post-processing apparatus and image forming system using the same

Abstract

To smooth wax on a medium by rubbing the wax while conveying the medium, thereby making the wax on the entire surface of the medium less visible.SOLUTION: A post-processing apparatus 1 includes: at least one conveying system 2 for conveying a medium S, which has passed through fixing means 13 that fixes an image G on the medium S by heating and pressing, by clamping the medium S at a predetermined conveying speed v0; first rubbing means 6 located upstream, in the medium conveying direction, of at least one of the conveying systems 2, for rubbing a surface of the medium S in a direction opposite to the medium conveying direction at a speed v1 different from the conveying speed v0; and second rubbing means 7 located downstream, in the medium conveying direction, of at least one of the conveying systems 2, for rubbing the surface of the medium S in the same direction as the medium conveying direction at a speed v2 higher than the conveying speed v0. An image forming system including the post-processing apparatus 1 is also covered.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a post-processing device and an image forming system using the same. [Background technology]

[0002] Conventionally, image forming systems using toner containing wax or post-processing devices used therein are already known, for example, as described in Patent Documents 1 to 3. Patent Document 1 discloses an image forming apparatus equipped with a cleaning unit that cleans unnecessary matter containing at least wax components from the surface of a recording medium after fixing and before discharge from the apparatus. Patent document 2 discloses an image forming system having a fixing unit that fixes an image formed on a recording medium onto the recording medium, a reading unit that reads the fixed image, a rubbing unit that can rub the image fixed on the recording medium, and a control unit that reads the image rubbed by the rubbing unit with a reading unit to evaluate the fixing state of the toner. Patent Document 3 discloses a wax removal device that removes wax from the surface of a recording medium by bringing a blade into contact with the surface of the recording medium, the surface of which is at a temperature equal to or higher than the melting point of the wax contained in a toner image that has been heated and fixed by a fixing device, but lower than the melting point of the toner material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-91205 A (embodiment of the invention, Fig. 6) [Patent Document 2] JP 2023-87297 A (Form for carrying out the invention, FIG. 10) [Patent Document 3] JP 2005-266079 A (Best Mode for Carrying Out the Invention, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem that the present invention aims to solve is to provide a post-processing device that smooths the wax on the medium by rubbing it while transporting the medium, making the wax less visible over the entire surface of the medium, and an image forming system that uses the same. [Means for solving the problem]

[0005] A first technical feature of the present invention is a post-processing device comprising: one or more conveying means for clamping and conveying a medium, bearing an image formed from an imaging material containing wax, at a predetermined conveying speed after the medium has passed through a fixing means for fixing the image on the medium by applying heat and pressure; a first rubbing means located upstream of one of the conveying means in the medium conveying direction and rubbing the surface of the medium in the opposite direction to the medium conveying direction at a speed different from the conveying speed; and a second rubbing means located downstream of one of the conveying means in the medium conveying direction and rubbing the surface of the medium in the same direction as the medium conveying direction at a speed faster than the conveying speed.

[0006] A second technical feature of the present invention is a post-processing device having the first technical feature, characterized in that it comprises: one conveying means that clamps and conveys a medium, which holds an image made of an imaging material containing wax, at a predetermined conveying speed after the medium has passed through a fixing means that fixes the image on the medium by heating and pressurizing the image; a first rubbing means that is located upstream of the conveying means in the medium conveying direction and rubs the surface of the medium in the opposite direction to the medium conveying direction at a speed different from the conveying speed; and a second rubbing means that is located downstream of the conveying means in the medium conveying direction and rubs the surface of the medium in the same direction as the medium conveying direction at a speed faster than the conveying speed. The third technical feature of the present invention is that in a post-treatment apparatus having the first technical feature, after the medium holding an image formed by an imaging material containing wax passes through a fixing means for fixing the image by heating and pressing, the medium is sandwiched and conveyed by a first conveying means at a predetermined conveying speed, a second conveying means located downstream of the first conveying means in the conveying direction of the medium and sandwiching and conveying the medium at the same speed as the conveying speed, and a first rubbing means located downstream of the first conveying means in the conveying direction of the medium and also upstream of the second conveying means in the conveying direction of the medium, and rubbing the surface of the medium in a direction opposite to the conveying direction of the medium at a speed different from the conveying speed, and a second rubbing means located downstream of the first conveying means in the conveying direction of the medium and also upstream of the first rubbing means in the conveying direction of the medium, and rubbing the surface of the medium in the same direction as the conveying direction of the medium at a speed higher than the conveying speed. The post-treatment apparatus is characterized by comprising these components.

[0007] The fourth technical feature of the present invention is that in a post-treatment apparatus having the second technical feature, the distance between the rubbing portion of the first rubbing means and the rubbing portion of the second rubbing means is shorter than the length in the conveying direction of the medium. The post-treatment apparatus is characterized by this. The fifth technical feature of the present invention is that in a post-treatment apparatus having the fourth technical feature, when the distances between the rubbing portions of the first rubbing means or the second rubbing means and the sandwiching portions of the conveying means are L1 and L2, and the length in the conveying direction of the medium is g, the post-treatment apparatus is characterized by satisfying L1, L2 < g / 2. The sixth technical feature of the present invention is that in a post-treatment apparatus having the third technical feature, the distance between the sandwiching portion of the first conveying means and the sandwiching portion of the second conveying means is shorter than the length in the conveying direction of the medium. The post-treatment apparatus is characterized by this. A seventh technical feature of the present invention is a post-processing device having the first technical feature, characterized in that the conveying means comprises a plurality of rotating bodies arranged opposite each other with respect to the medium, and the first rubbing means and the second rubbing means comprise a plurality of rotating bodies arranged opposite each other with respect to the medium and capable of contacting and separating between a contact position and a non-contact position. An eighth technical feature of the present invention is a post-processing device having the seventh technical feature, characterized in that the frictional force between the plurality of rotating bodies constituting the conveying means and the medium is greater than the frictional force between the plurality of rotating bodies constituting the first rubbing means and the second rubbing means and the medium. A ninth technical feature of the present invention is a post-processing device having the seventh technical feature, characterized in that the conveying means, the first rubbing means, and the second rubbing means have an adjustment unit that adjusts the contact pressure of the multiple rotating bodies.

[0008] A tenth technical feature of the present invention is a post-processing device having the second technical feature, characterized in that it comprises a position detection means for detecting the transport position of the medium, and a control means for controlling the rubbing operation by the first rubbing means and the second rubbing means based on position information from the position detection means. An eleventh technical feature of the present invention is a post-processing device having the tenth technical feature, characterized in that the control means places the first rubbing means at a contact position where it contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the transport means, and starts the rubbing operation by the first rubbing means. A twelfth technical feature of the present invention is a post-processing device having the tenth technical feature, characterized in that the control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means. A thirteenth technical feature of the present invention is a post-processing device having the tenth technical feature, characterized in that the control means places the first rubbing means in a non-contact position away from a contact position where it contacts the surface of the medium immediately after the trailing end of the medium in the transport direction passes the first rubbing means, and stops the rubbing action by the first rubbing means. A fourteenth technical feature of the present invention is a post-processing device having the tenth technical feature, characterized in that the control means places the second rubbing means in a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the transport means, and stops the rubbing action by the second rubbing means.

[0009] A fifteenth technical feature of the present invention is a post-processing device having the third technical feature, characterized in that it comprises a position detection means for detecting the transport position of the medium, and a control means for controlling the rubbing operation by the first rubbing means and the second rubbing means based on position information from the position detection means. A sixteenth technical feature of the present invention is a post-processing device having the fifteenth technical feature, characterized in that the control means places the first rubbing means at a contact position that contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the second transport means, and starts the rubbing operation by the first rubbing means. A seventeenth technical feature of the present invention is a post-processing device having the fifteenth technical feature, characterized in that the control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means. An 18th technical feature of the present invention is a post-processing device having the 15th technical feature, characterized in that the control means places the second rubbing means in a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the first transport means, and stops the rubbing action by the second rubbing means. A 19th technical feature of the present invention is a post-processing device having the 15th technical feature, characterized in that the control means places the first rubbing means in a non-contact position away from a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the first rubbing means, and stops the rubbing action by the first rubbing means.

[0010] A twentieth technical feature of the present invention is a post-processing device having the first technical feature, characterized in that it comprises a discrimination means for discriminating whether the type of medium being used is a predetermined first type of medium or not, and a selection means for selecting to perform a rubbing operation by the first rubbing means and the second rubbing means when the discrimination means determines that the medium is the first type of medium. A 21st technical feature of the present invention is a post-processing device having the 20th technical feature, characterized in that the first type of medium is a type of medium in which wax transferred to the front surface or back surface is visualized. A twenty-second technical feature of the present invention is a post-processing device having the twenty-first technical feature, characterized in that the first type of medium is a film medium having a smooth surface. A 23rd technical feature of the present invention is a post-processing device having the 20th technical feature, characterized in that the selection means selects not to perform the rubbing operation by the first rubbing means and the second rubbing means when the discrimination means determines that the medium is of a type other than the first type.

[0011] A 24th technical feature of the present invention is an image forming system comprising: an image forming means for retaining an image formed on a medium using an image forming material containing wax; a fixing means for fixing the image formed by the image forming means to the medium by applying heat and pressure; and a post-processing device having any of the first to 23rd technical features for post-processing the medium after it has passed through the fixing means. [Effects of the Invention]

[0012] According to the first technical feature of the present invention, the wax on the medium can be rubbed and smoothed while the medium is being transported, making the wax less visible over the entire surface of the medium. According to a second technical feature of the present invention, it is possible to provide a configuration in which the entire surface of the medium is rubbed using one conveying means, a first rubbing means, and a second rubbing means. According to a third technical feature of the present invention, it is possible to provide a configuration in which the entire surface of the medium is rubbed using the first transport means, the second transport means, the first rubbing means, and the second rubbing means. According to the fourth technical feature of the present invention, by appropriately arranging the first rubbing means and the second rubbing means, it is possible to rub the entire surface of the medium. According to the fifth technical feature of the present invention, the transport posture of the medium passing through the first rubbing means, the transport means, and the second rubbing means can be stabilized compared to when L1, L2≧g / 2. According to a sixth technical feature of the present invention, by arranging the first rubbing means and the second rubbing means within the appropriately positioned first conveying means and the second conveying means, the entire surface of the medium can be rubbed. According to the seventh technical feature of the present invention, the representative aspects of the conveying means, the first rubbing means and the second rubbing means can be easily configured. According to the eighth technical feature of the present invention, the rubbing action by the first rubbing means and the second rubbing means can be realized under the same speed condition as the transport speed of the medium by the transport means. According to the ninth technical feature of the present invention, the frictional force between the medium and the multiple rotating bodies constituting the conveying means, and the frictional force between the medium and the multiple rotating bodies constituting the first rubbing means or the second rubbing means can be easily adjusted compared to when no adjustment unit is provided. According to a tenth technical feature of the present invention, in an embodiment equipped with one conveying means, a first rubbing means, and a second rubbing means, the rubbing operations by the first rubbing means and the second rubbing means can be distributed between areas before and after the conveying direction of the medium based on the conveying position of the medium. According to the eleventh technical feature of the present invention, the first rubbing means can perform a rubbing operation on the rear area of ​​the medium in the transport direction without impairing the transportability of the medium by the transport means. According to the twelfth technical feature of the present invention, the second rubbing means can perform a rubbing operation on the front area in the transport direction of the medium without impairing the transportability of the medium by the transport means. According to the thirteenth technical feature of the present invention, preparations can be made in advance for subsequent post-processing of the wax on the medium. According to the fourteenth technical feature of the present invention, when the trailing end of the medium in the transport direction passes through the transport means, it is possible to prevent a mismatch between the rubbing operation speed by the second rubbing means and the transport speed of the medium by the transport means located further downstream. According to the fifteenth technical feature of the present invention, in an embodiment equipped with a first conveying means, a second conveying means, a first rubbing means, and a second rubbing means, the rubbing action by the first rubbing means and the second rubbing means can be distributed between areas before and after the conveying direction of the medium based on the conveying position of the medium. According to the sixteenth technical feature of the present invention, the first rubbing means can perform a rubbing operation on the rear area in the transport direction of the medium without impairing the transportability of the medium by the second transport means. According to the seventeenth technical feature of the present invention, the second rubbing means can perform a rubbing operation on the front area in the transport direction of the medium without impairing the transportability of the medium by the first transport means. According to the 18th technical feature of the present invention, it is possible to eliminate the situation in which the transport speed of the medium increases when the rubbing operation by the second rubbing means is continued after the trailing end of the medium in the transport direction has passed the first transport means. According to the nineteenth technical feature of the present invention, it is possible to prevent the first rubbing means from impairing the transportability of the medium in advance. According to the twentieth technical feature of the present invention, post-processing with wax can be carried out only on media that require post-processing with wax. According to the 21st technical feature of the present invention, even if the wax transferred to the surface of the medium becomes visible, the wax can be spread thinly by rubbing it, making the wax on the medium less visible. According to the twenty-second technical feature of the present invention, in the case of a film medium with a smooth surface, the visualization phenomenon caused by wax transferred to the surface of the medium is prominent, but this can be easily made less visible. According to the twenty-third technical feature of the present invention, for media that do not require wax post-treatment, wax post-treatment can be omitted. According to a 24th technical feature of the present invention, an image forming system can be constructed that includes a post-processing device that can smooth the wax on the medium by rubbing it while transporting the medium, making the wax less visible over the entire surface of the medium. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1A is an explanatory diagram showing an example of an outline of an embodiment of an image forming system including a post-processing device to which the present invention is applied, and FIG. 1B is an explanatory diagram showing the main parts of the post-processing device shown in FIG. [Figure 2] 1A is an explanatory diagram showing the post-processing range of a medium by a first rubbing means of a post-processing device according to the outline of the embodiment shown in FIG. 1; FIG. 1B is an explanatory diagram showing the post-processing range of a medium by a second rubbing means of the same post-processing device; and FIG. 1C is an explanatory diagram showing the changes in wax held on a medium before and after it passes through the post-processing device. [Figure 3] FIG. 1A is an explanatory diagram showing another example of an outline of an embodiment of an image forming system including a post-processing device to which the present invention is applied, and FIG. 1B is an explanatory diagram showing the main parts of the post-processing device shown in FIG. [Figure 4] 4(a) is an explanatory diagram showing the post-processing range of a medium by the second rubbing means of the post-processing device in the outline of the embodiment shown in FIG. 3, and FIG. 4(b) is an explanatory diagram showing the post-processing range of a medium by the first rubbing means of the same post-processing device. [Figure 5] 1 is an explanatory diagram showing the overall configuration of an image forming system according to a first embodiment. [Figure 6] (a) is an explanatory diagram showing an example of the configuration of a fixing device used in the image forming system of Figure 5, (b) is an explanatory diagram showing the state in which a medium carrying an unfixed toner image enters the fixing device, and (c) is an explanatory diagram showing the state in which the wax on the toner surface is transferred to a heating roll, which is a fixing member for heating, when the medium passes through the fixing device. [Figure 7] (a) is an explanatory diagram showing the state in which wax transferred to the heating roll that has slipped through the cleaning mechanism is transferred to the pressure roll, which is the fixing member for applying pressure; (b) is an explanatory diagram showing the state in which wax is transferred from the heating roll and pressure roll, which are the fixing members, to the front and back surfaces of the medium when the subsequent medium passes through the fixing device; and (c) is an explanatory diagram schematically showing the state in which the wax transferred to the surface of the medium has solidified. [Figure 8] FIG. 2 is an explanatory diagram showing a drive control system of the post-processing device according to the first embodiment. [Figure 9] 3 is an explanatory diagram showing an example of the configuration of a transport roll, a first rubbing roll, and a second rubbing roll of the post-processing device according to the first embodiment. FIG. [Figure 10] FIG. 2A is an explanatory diagram showing an example of a support structure for a transport roll, and FIG. 2B is an explanatory diagram showing an example of a retraction mechanism shown in FIG. [Figure 11] FIG. 1(a) is an explanatory diagram showing an example of a support structure for the first or second rubbing roll, FIG. 1(b) is an explanatory diagram showing an example of the first or second nip release mechanism shown in FIG. 1(a), FIG. 1(c) is an arrow view seen from the direction C in FIG. 1(b), and FIG. 1(d) is an explanatory diagram showing an example of the configuration for applying contact pressure when the first or second rubbing roll comes into contact. [Figure 12] 4 is a flowchart showing a control process of the post-processing device according to the first embodiment. [Figure 13] (a) is an explanatory diagram schematically showing the first mode of the post-processing device, (b) is an explanatory diagram schematically showing the second mode of the post-processing device, and (c) is an explanatory diagram schematically showing the third mode of the post-processing device. [Figure 14]10(a) to 10(e) are explanatory diagrams showing the process of post-processing an medium by a post-processing device in which the transport roll is positioned closer to the second rubbing roll than to the first rubbing roll (an example of an arrangement in which L1>L2). [Figure 15] 10(a) to 10(e) are explanatory diagrams showing the process of post-processing an medium by a post-processing device in which the transport roll is positioned closer to the first rubbing roll than the second rubbing roll (an example of an arrangement in which L2>L1). [Figure 16] (a) is an explanatory diagram showing the post-processing range by the first rubbing roll and the second rubbing roll in an example of arrangement where L1>L2 (Figure 14), and (b) is an explanatory diagram showing the post-processing range by the first rubbing roll and the second rubbing roll in an example of arrangement where L2>L1 (Figure 15). [Figure 17] (a) is an explanatory diagram showing a schematic diagram of the change in the state of wax held on the medium before and after passing through the post-processing device of embodiment 1, and (b) is an explanatory diagram showing a schematic diagram of the change in the state of wax held on the medium before and after passing through the post-processing device of comparative embodiment 1. [Figure 18] FIG. 10 is an explanatory diagram showing the main parts of a post-processing device according to a second embodiment and its drive control system. [Figure 19] 10 is an explanatory diagram showing an example of the configuration of a first transport roll, a second transport roll, a first rubbing roll, and a second rubbing roll of a post-processing device according to a second embodiment. FIG. [Figure 20] 10 is a flowchart showing a control process of a post-processing device according to a second embodiment. [Figure 21] (a) is an explanatory diagram schematically showing the first mode of the post-processing device, (b) is an explanatory diagram schematically showing the second mode of the post-processing device, and (c) is an explanatory diagram schematically showing the third mode of the post-processing device. [Figure 22] 10(a) to 10(f) are explanatory diagrams showing the process of post-processing performed on a medium by a post-processing device. [Figure 23] FIG. 3 is an explanatory diagram showing the post-treatment range by the first rubbing roll and the second rubbing roll. [Figure 24] FIG. 10 is an explanatory diagram showing a main part of a post-processing device according to a third embodiment. [Figure 25]FIG. 1(a) is an explanatory diagram showing the state in which media requiring wax post-treatment passes through the post-treatment device, and FIG. 1(b) is an explanatory diagram showing the state in which media not requiring wax post-treatment passes through the post-treatment device. [Figure 26] FIG. 10 is an explanatory diagram showing a main part of a post-processing device according to a fourth embodiment. [Figure 27] (a) is an explanatory diagram showing an example of a microscopic photograph taken of the surface of a medium before post-processing by the post-processing device of Example 1, (b) is an explanatory diagram showing a schematic diagram of the wax adhesion state on the surface of the medium shown in (a), (c) is an explanatory diagram showing an example of a microscopic photograph taken of the surface of a medium after post-processing by the post-processing device of Example 1, and (d) is an explanatory diagram showing a schematic diagram of the wax adhesion state on the surface of the medium shown in (c). DETAILED DESCRIPTION OF THE INVENTION

[0014] Overview of the implementation form FIG. 1(a) shows an outline of an embodiment of an image forming system to which the present invention is applied. In the same figure, the image forming system comprises an image forming means 12 that holds an image G made of an imaging material containing wax on a medium S, a fixing means 13 that fixes the image formed by the image forming means 12 to the medium by applying heat and pressure, and a post-processing device 1 that post-processes the medium S after it has passed through the fixing means 13. In this example, as shown in Figure 1(b), the post-processing device 1 includes one or more conveying means 2 that clamp and convey the medium S at a predetermined conveying speed v0 after it has passed through a fixing means 13 that fixes the image G on the medium S by applying heat and pressure, a first rubbing means 6 that is located upstream of one of the conveying means 2 in the conveying direction of the medium S and rubs the surface of the medium S in the opposite direction to the conveying direction of the medium S at a speed v1 that is different from the conveying speed v0, and a second rubbing means 7 that is located downstream of one of the conveying means 2 in the conveying direction of the medium S and rubs the surface of the medium S in the same direction as the conveying direction of the medium S at a speed v2 that is faster than the conveying speed v0.

[0015] In such technical means, the medium S is not limited to a sheet-like medium cut to a predetermined size, but also includes a continuous medium such as a roll-like medium. Furthermore, the image-forming means 12 may be any means that forms an image G using an image-forming material (e.g., toner) containing wax and retains it on the medium S. Representative examples include, but are not limited to, electrophotography and electrostatic recording methods. The reason the image-forming material contains wax is to ensure releasability between the image G and the fixing member during fixing by the fixing means 13, which applies heat and pressure. Furthermore, the fixing means 13 may be appropriately selected as long as it employs a fixing method that uses heat and pressure. A typical example is a configuration in which a heating fixing member and a pressure fixing member are arranged to apply pressure, and the medium S passes through the contact area between them. In this case, the fixing member may be in the form of a roll, a belt, or the like. The heating method of the heating fixing member may be such that a heat source is incorporated inside the fixing member, or the fixing member may be heated from the outside. Furthermore, the heating fixing member may be provided with a cleaning element that cleans wax, paper dust, and the like that has been transferred to the fixing member. Furthermore, a heat source or cleaning element may be added to the pressure fixing member as needed.

[0016] Furthermore, the post-processing device 1 is incorporated into an image forming unit that includes, for example, an image creating unit 12 and a fixing unit 13. However, the present invention is not limited to this configuration, and the post-processing device 1 may be configured as an independent unit separate from the image forming unit. In this case, the post-processing device 1 may be installed alongside the image forming unit to form an image forming system. Alternatively, the post-processing device 1 may be installed separately from the image forming unit, and post-processing may be performed on the medium S that has been output from the image forming unit. In this example, for the medium S to pass through the post-processing device 1, an element for feeding the medium S and an element for removing the medium S are provided before and after the transport path of the medium S in the post-processing device 1. The transport means 2 may be selected as appropriate as long as it clamps and transports the medium S at a predetermined transport speed v0. The transport speed v0 is selected based on the feed speed of the medium S into the post-processing device 1 or the removal speed of the medium S from the post-processing device 1. The transport means 2 may include multiple transport members that clamp and transport the medium S. Furthermore, the transport means 2 is not limited to a single transport means 2 provided in the transport direction of the medium S, but may also include a multiple transport means 2 provided in parallel along the transport direction of the medium S. In this case, the first scrubbing means 6 may be located upstream of one of the multiple transport means 2 in the transport direction of the medium S. The second scrubbing means 7 may be located downstream of one of the multiple transport means 2 in the transport direction of the medium S.

[0017] Furthermore, the first rubbing means 6 is located upstream of the transport means 2 in the transport direction of the medium S, and is required to rub the surface of the medium S. Here, "surface of the medium S" means not only the front surface of the medium S, but also the back surface. Therefore, the first rubbing means 6 typically rubs both the front and back surfaces of the medium S, but it also includes means that rub either the front or back surface of the medium S. Furthermore, in order for the first rubbing means 6 to perform a rubbing operation on the surface of the medium S, the first rubbing means 6 needs to rub the surface of the medium S in the opposite direction to the transport direction of the medium S at a speed v1 that is different from the transport speed v0. In this case, the medium S is transported between the first rubbing means 6 and the transport means 2 in a state where it is pulled in the transport direction.

[0018] Here, when the medium S is transported by the transport means 2 at a transport speed v0, in order for the first rubbing means 6 to rub the surface of the medium S in the opposite direction to the transport direction of the medium S, the first rubbing means 6 should behave as follows: Specifically, the first rubbing means 6 behaves in one of the following ways: (i) moving in the opposite direction to the transport direction of the medium S, (ii) remaining stationary, or (iii) moving in the same direction as the transport direction of the medium S at a transport speed less than v0 of the medium S. In this regard, if it is assumed that the first rubbing means 6 moves in the same direction as the transport direction of the medium S at the same speed as the transport speed v0 of the medium S, the relative speed between the first rubbing means 6 and the medium S will be the same, and no rubbing will occur between them. Also, if it is assumed that the first rubbing means 6 moves in the same direction as the transport direction of the medium S but faster than the transport speed v0 of the medium S, there is a high possibility that the first rubbing means 6 will unwind the medium S faster than the transport speed v0. For this reason, there is a concern that the transportability of the medium S between the first rubbing means 6 and the transport means 2 will be impaired.

[0019] The second rubbing means 7 is located downstream of the transport means 2 in the transport direction of the medium S, and is required to rub the surface of the medium S. As mentioned above, the "surface of the medium S" here means not only the front surface of the medium S, but also the back surface. Furthermore, in order for the second rubbing means 7 to perform a rubbing operation on the surface of the medium S, the second rubbing means 7 should behave as follows. Specifically, the second rubbing means 7 needs to rub the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0. In this case, the medium S is transported between the transport means 2 and the second rubbing means 7 in a state where it is pulled in the transport direction.

[0020] If we assume that the second scrubbing means 7 moves in the same direction as the transport direction of the medium S at the same speed as the transport speed v0 of the medium S, the relative speed between the second scrubbing means 7 and the medium S will be the same, and rubbing will not occur between them. Also, assume that the second scrubbing means 7 moves in the same direction as the transport direction of the medium S at a speed less than the transport speed v0 of the medium S. In this case, the transport speed v0 of the medium S will decrease as the medium S passes through the second scrubbing means 7, and there is a high possibility that the medium S will buckle and deform in the transport direction between the transport means 2 and the second scrubbing means 7. Furthermore, assume that the second scrubbing means 7 moves in the opposite direction to the transport direction of the medium S. In this case, the transport speed v0 of the medium S will further decrease as the medium S passes through the second scrubbing means 7, and there is an even higher possibility that the medium S will buckle and deform between the transport means 2 and the second scrubbing means 7. This raises the concern that the transportability of the medium S between the transport means 2 and the second scrubbing means 7 may be impaired.

[0021] Here, the following are typical examples of the arrangement of one or more conveying means 2, the first rubbing means 6 and the second rubbing means 7. A first typical example of an arrangement is shown in Figures 1(a) and (b), and includes a first conveying means 2 that clamps and conveys the medium S at a predetermined conveying speed v0 after it has passed through a fixing means 13 that fixes the image G on the medium S by applying heat and pressure, a first rubbing means 6 that is located upstream of the conveying means 2 in the conveying direction of the medium S and rubs the surface of the medium S in the opposite direction to the conveying direction of the medium S at a speed v1 that is different from the conveying speed v0, and a second rubbing means 7 that is located downstream of the conveying means 2 in the conveying direction of the medium S and rubs the surface of the medium S in the same direction as the conveying direction of the medium S at a speed v2 that is faster than the conveying speed v0. As shown in FIGS. 3(a) and 3(b), a second representative example of the arrangement includes a first conveying means 3, which is one of a plurality of conveying means 2, that sandwiches and conveys the medium S at a predetermined conveying speed v0 after the medium S has passed through a fixing means 13 that fixes an image G on the medium S by applying heat and pressure; a second conveying means 4, which is one of a plurality of conveying means 2, that is located downstream of the first conveying means 3 in the conveying direction of the medium S and that sandwiches and conveys the medium S at the same speed as the conveying speed v0; This embodiment includes a first rubbing means 6 located on the downstream side of the first conveying means 3 in the conveying direction of the medium S and upstream of the second conveying means 4, and rubbing the surface of the medium S in the opposite direction to the conveying direction of the medium S at a speed v1 different from the conveying speed v0, and a second rubbing means 7 located downstream of the first conveying means 3 in the conveying direction of the medium S and upstream of the first rubbing means 6 in the conveying direction of the medium S, and rubbing the surface of the medium S in the same direction as the conveying direction of the medium S at a speed v2 faster than the conveying speed v0.

[0022] <Effect of the first representative layout example> 2(a), the medium S passes through the first rubbing means 6 and then reaches the conveying means 2. During this time, the first rubbing means 6 has not yet performed a rubbing operation. Next, when the leading edge of medium S in the transport direction passes transport means 2, transport means 2 clamps medium S and transports it at transport speed v0. In this state, first scrubbing means 6 begins a scrubbing operation, scrubbing the surface of medium S in the opposite direction to the transport direction of medium S at speed v1, which is different from transport speed v0. Therefore, after the leading edge of medium S in the transport direction passes transport means 2, the scrubbing operation by first scrubbing means 6 is performed. Then, the rubbing area R1 formed by the first rubbing means 6 starts to be formed midway in the transport direction of the medium S passing through the first rubbing means 6, and continues to be formed until the trailing end of the medium S in the transport direction passes the first rubbing means 6.

[0023] 2(b), before the leading edge of the medium S in the transport direction reaches the second rubbing means 7, the second rubbing means 7 stands by in a state where it is ready to perform rubbing operation. Then, when the leading edge of the medium S in the transport direction reaches the second rubbing means 7, the second rubbing means 7 starts its rubbing operation, rubbing the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0. Therefore, after the leading edge of the medium S in the transport direction has passed the second rubbing means 7, the second rubbing means 7 performs a rubbing operation. Then, the rubbing area R2 formed by the second rubbing means 7 starts from the leading edge of the medium S in the transport direction and continues to be formed until just before the trailing edge of the medium S in the transport direction passes the transport means 2. Here, the second rubbing means 7 stops the rubbing operation just before the trailing edge of the medium S in the transport direction passes the transport means 2. This is because if the rubbing operation by the second rubbing means 7 were to continue once the leading edge of the medium S in the transport direction has passed the transport means 2, the transportability of the medium S would be impaired.

[0024] In this way, the rubbing area R1 by the first rubbing means 6 is formed in a range from midway in the transport direction of the medium S to the trailing end in the transport direction. On the other hand, the rubbing area R2 by the second rubbing means 7 is formed in a range from the leading end to midway in the transport direction of the medium S. In this case, if R1+R2 is equal to or greater than the transport direction length g of the medium S, the first rubbing means 6 and the second rubbing means 7 will perform a rubbing operation on the entire surface of the medium S. As a result, when wax is transferred to the surface of the medium S that has passed through the fixing means 13, the wax W tends to deform and become round due to surface tension as it cools and solidifies, forming granular lumps Wa, as shown in Figure 2(c). In this case, if a transparent film or similar is used as the medium S, the granular lumps Wa will scatter light, causing them to appear cloudy and white. In this embodiment, the post-processing device 1 rubs the surface of the medium S using the first rubbing means 6 and the second rubbing means 7. This makes it possible to smooth the granular lumps of wax W into a thin film layer Wb. This reduces the visualization of the wax W caused by scattering of transmitted and reflected light from the medium S.

[0025] <Effect of the second typical layout example> In this example, as shown in FIG. 4(a), the medium S enters the first transport means 3 and is transported at a transport speed v0. At this time, before the leading edge of the medium S in the transport direction reaches the second rubbing means 7, the second rubbing means 7 waits in a state where it is ready to perform rubbing operation. Then, when the leading edge of the medium S in the transport direction reaches the second rubbing means 7, the second rubbing means 7 begins its rubbing operation, rubbing the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0. Therefore, after the leading edge of the medium S in the transport direction has passed the second rubbing means 7, the second rubbing means 7 performs a rubbing operation. As a result, the rubbing region R2 formed by the second rubbing means 7 starts from the leading edge of the medium S in the transport direction. The rubbing region R2 is then continuously formed until just before the trailing edge of the medium S in the transport direction passes the first transport means 3. Here, the second rubbing means 7 stops the rubbing operation just before the trailing edge of the medium S in the transport direction passes the first transport means 3. This is because if the rubbing operation by the second rubbing means 7 were to continue once the leading edge of the medium S in the transport direction has passed the first transport means 3, the transportability of the medium S would be impaired.

[0026] 4(b), the medium S passes through the first rubbing means 6 and then reaches the second conveying means 4. During this time, the rubbing operation by the first rubbing means 6 has not yet been performed. Next, when the leading edge of medium S in the transport direction passes second transport means 4, second transport means 4 clamps medium S and transports it at transport speed v0. In this state, first scrubbing means 6 begins a scrubbing operation, scrubbing the surface of medium S in the opposite direction to the transport direction of medium S at speed v1, which is different from transport speed v0. Therefore, after the leading edge of medium S in the transport direction passes second transport means 4, the scrubbing operation by first scrubbing means 6 is performed. Then, the rubbing area R1 formed by the first rubbing means 6 starts to be formed midway in the transport direction of the medium S passing through the second transport means 4. Then, the rubbing area R1 is formed continuously until the trailing end of the medium S in the transport direction passes the second transport means 4.

[0027] Thus, the rubbing area R2 by the second rubbing means 7 is formed in the range from the leading end to the middle in the conveyance direction of the medium S. On the other hand, the rubbing area R1 by the first rubbing means 6 is formed in the range from the middle to the trailing end in the conveyance direction of the medium S. At this time, if R1 + R2 is greater than or equal to the conveyance direction length g of the medium S, the first rubbing means 6 and the second rubbing means 7 will perform a rubbing operation on the entire surface of the medium S. As a result, similar to the first typical arrangement example, it is assumed that the wax on the surface of the medium S that has passed through the fixing means 13 has become granular lumps (clumps). However, in this example, the post-processing device 1 rubs the surface of the medium S by the first rubbing means 6 and the second rubbing means 7. Therefore, it becomes possible to smooth the wax that has become granular lumps. For this reason, the visualization phenomenon caused by the scattering of transmitted light or reflected light on the medium S is reduced.

[0028] Next, a typical aspect or a preferred aspect of the post-processing device according to the present embodiment will be described. First, the preferred positional relationship of the first typical arrangement example (the aspect of FIG. 1(b)) will be described. As a preferred positional relationship between the first rubbing means 6 and the second rubbing means 7, there is an aspect of rubbing the entire surface of the medium S. In this case, as shown in FIG. 1(b), the distance L between the rubbing portion of the first rubbing means 6 and the rubbing portion of the second rubbing means 7 may be made shorter than the conveyance direction length of the medium S. Furthermore, as a preferred positional relationship between the first rubbing means 6, the second rubbing means 7, and the conveyance means 2, there is an aspect of stabilizing the conveyance posture of the medium S. In this case, it is preferable to satisfy L1, L2 < g / 2. Here, the distances between the rubbing portion of the first rubbing means 6 or the second rubbing means 7 and the sandwiching portion of the conveyance means 2 are L1 and L2, and the conveyance direction length of the medium S is g. If L1 or L2 is a distance of g / 2 or more, the distance L1 or L2 between the first rubbing means 6 or the second rubbing means 7 and the conveyance means 2 becomes long. For this reason, the conveyance posture of the medium S is likely to deviate from the proper position, and a guiding member for guiding the medium S or the like is required.

[0029] Next, a preferred positional relationship in the second representative example of arrangement (the embodiment shown in FIG. 3(b)) will be described. The following is an example of a preferred positional relationship between the first conveying means 3 and the second conveying means 4. In this example, the distance D between the clamping portion of the first conveying means 3 and the clamping portion of the second conveying means 4 is shorter than the length g of the medium S in the conveying direction. In this example, the medium S is conveyed by the first conveying means 3 and reaches the second conveying means 4 before passing through the first conveying means 3. Therefore, the conveyability of the medium S by the first conveying means 3 and the second conveying means 4 is maintained good. The first rubbing means 6 and the second rubbing means 7 are disposed between the first transport means 3 and the second transport means 4. Therefore, it is desirable that the distance between the first rubbing means 6 and the second rubbing means 7 is shorter than the length g of the medium S in the transport direction.

[0030] 1(b) or 3(b), the following are representative embodiments of the conveying means 2 (or the first conveying means 3 or the second conveying means 4), and the first rubbing means 6 and the second rubbing means 7. The conveying means 2 (or the first conveying means 3 or the second conveying means 4) may be formed of a plurality of rotating bodies 2a, 2b (or 3a, 3b or 4a, 4b) arranged opposite each other with respect to the medium S. The first rubbing means 6 and the second rubbing means 7 may be formed of a plurality of rotating bodies 6a, 6b and 7a, 7b arranged opposite each other with respect to the medium S and capable of contacting and separating between a contact position and a non-contact position. The rotating body referred to here is typically a roll-shaped member, but also includes a belt-shaped member stretched over a plurality of tension members. In this example, a preferable aspect of the conveying means 2 (or the first conveying means 3 or the second conveying means 4), the first rubbing means 6, and the second rubbing means 7 is the magnitude relationship of the frictional force with the medium S. In this case, it is only necessary to consider realizing the rubbing action by the first rubbing means 6 and the second rubbing means 7 under the condition that the conveying speed v0 of the medium S by the conveying means 2 (or the first conveying means 3 or the second conveying means 4) is maintained. In light of this, it is preferable that the frictional force between the medium S and the multiple rotating bodies 2a, 2b (or 3a, 3b, or 4a, 4b) constituting the conveying means 2 (or the first conveying means 3 or the second conveying means 4) is greater than the frictional force between the medium S and the multiple rotating bodies 6a, 6b and 7a, 7b constituting the first rubbing means 6 and the second rubbing means 7.

[0031] Furthermore, a preferred mode for setting the magnitude relationship of the frictional forces is one in which the frictional forces can be easily adjusted. In this case, it is necessary to take into consideration that the frictional force depends on the drag force acting vertically on the medium S and the dynamic friction coefficient between the contacting portions. In other words, since the dynamic friction coefficient is uniquely determined by the material between the contacting portions, it is necessary to make the drag force adjustable. In light of this, it is preferable that the conveying means 2 (or the first conveying means 3 or the second conveying means 4), the first rubbing means 6, and the second rubbing means 7 have an adjustment unit that adjusts the contact pressure of the multiple rotating bodies 2a, 2b (or 3a, 3b, or 4a, 4b), the multiple rotating bodies 6a, 6b, and the multiple rotating bodies 7a, 7b.

[0032] Furthermore, in the first representative arrangement example (see FIGS. 1(a) and 1(b)), it is preferable to allocate and perform the rubbing operations by the first rubbing means 6 and the second rubbing means 7 based on the transport position of the medium S. To realize this embodiment, it is sufficient to provide a position detection means 8 that detects the transport position of the medium S, and a control means 9 that controls the rubbing operations by the first rubbing means 6 and the second rubbing means 7 based on position information from the position detection means 8. Here, the following can be mentioned as an example of a mode for effectively performing the rubbing operation on the rear region in the transport direction of the medium S. In this case, the control unit 9 may be configured to position the first rubbing unit 6 at a contact position where it comes into contact with the surface of the medium S immediately after the leading edge of the medium S in the transport direction enters the transport unit 2, and to start the rubbing operation by the first rubbing unit 6.

[0033] The following is an example of a mode for effectively performing the rubbing operation on the front region in the transport direction of the medium S. In this case, the control unit 9 may position the second rubbing unit 7 at a contact position where it comes into contact with the surface of the medium S before the leading edge of the medium S in the transport direction reaches the second rubbing unit 7, and start the rubbing operation by the second rubbing unit 7. Furthermore, the following can be mentioned as an example of a manner in which wax post-treatment can be performed smoothly on the subsequent medium S. In this case, the control means 9 may place the first rubbing means 6 at a non-contact position away from the contact position where it contacts the surface of the medium S immediately after the trailing end of the medium S in the transport direction passes the first rubbing means 6, and stop the rubbing operation by the first rubbing means 6. Furthermore, the following can be mentioned as an example of a mode for maintaining good transportability of the medium S discharged from the post-processing device 1. In this case, the control unit 9 may place the second rubbing unit 7 at a non-contact position away from the contact position where it contacts the surface of the medium S just before the trailing end of the medium S in the transport direction passes through the transport unit 2, and stop the rubbing operation by the second rubbing unit 7.

[0034] Also, in the second representative arrangement example (see FIGS. 3(a) and 3(b)), it is preferable to allocate and perform the rubbing operations by the first rubbing means 6 and the second rubbing means 7 based on the transport position of the medium S. To realize this embodiment, it is necessary to provide a position detection means 8 that detects the transport position of the medium S, and a control means 9 that controls the rubbing operations by the first rubbing means 6 and the second rubbing means 7 based on position information from the position detection means 8. Here, the following can be mentioned as an example of a mode for effectively performing the rubbing operation on the rear region in the transport direction of the medium S. In this case, the control unit 9 may position the first rubbing unit 6 at a contact position where it comes into contact with the surface of the medium S immediately after the leading edge of the medium S in the transport direction enters the second transport unit 4, and start the rubbing operation by the first rubbing unit 6.

[0035] The following is an example of a mode for effectively performing the rubbing operation on the front region in the transport direction of the medium S. In this case, the control unit 9 may position the second rubbing unit 7 at a contact position where it comes into contact with the surface of the medium S before the leading edge of the medium S in the transport direction reaches the second rubbing unit 7, and start the rubbing operation by the second rubbing unit 7. Furthermore, the following is a preferred mode for preventing an increase in the transport speed of the medium S. In this case, the control unit 9 may place the second rubbing unit 7 at a non-contact position away from the contact position where it contacts the surface of the medium S just before the trailing end of the medium S in the transport direction passes the first transport unit 3, and stop the rubbing operation by the second rubbing unit 7. Furthermore, the following is a preferred mode for preventing the first rubbing means 6 from impairing the transportability of the medium S in advance. In this case, the control means 9 may position the first rubbing means 6 at a non-contact position away from the contact position where it contacts the surface of the medium S before the leading edge of the medium S in the transport direction reaches the first rubbing means 6, and stop the rubbing operation by the first rubbing means 6.

[0036] The following is an example of a mode in which wax post-treatment is performed only on media S that require wax post-treatment. In this case, the post-treatment device 1 may include, as shown in Fig. 1(a) (or Fig. 3(a)), a discrimination means 10 that determines whether the type of media S being used is a predetermined first type of media, and a selection means 11 that performs a rubbing operation by the first rubbing means 6 and the second rubbing means 7 when the discrimination means 10 determines that the media is the first type of media. In this embodiment, a preferred embodiment of the first type of medium is a medium in which the wax transferred to the front or back surface is visualized. A typical medium in which the visualization phenomenon is prominent is a film medium with a transparent surface. Furthermore, the following is a preferred embodiment for the medium S that does not require post-wax treatment. In this case, the selection means 11 may be configured to disable the rubbing operations by the first rubbing means 6 and the second rubbing means 7 when the discrimination means 10 determines that the medium is a medium other than the first type.

[0037] Embodiment 1 FIG. 5 shows the overall configuration of the image forming system according to the first embodiment. -Overall configuration of image formation system- In the figure, an image forming system 20 has a unit housing 21 having a required external shape. The internal space of this unit housing 21 houses main elements such as an image forming engine 22, a medium transport system 23, a fixing device 24, and a post-processing device 25.

[0038] -Imaging engine- In this example, the image forming engine 22 corresponds to the image forming means 12 shown in FIG. In Figure 5, the image creation engine 22 includes a plurality of (four in this example) image forming units 30 (specifically, 30a to 30d) that form images of a plurality of (four in this example) color components, an intermediate transfer body 40 that sequentially transfers and holds the images of each color component formed by the plurality of image forming units 30, and then transports them to a position where they are transferred to a medium, and a transfer device 50 that secondarily (collectively) transfers the images of each color component held on the intermediate transfer body 40 to the medium. In this example, each image forming unit 30 (30a-30d) forms an image of each color component: yellow (Y), magenta (M), cyan (C), and black (K). The arrangement of the image forming units 30 may be changed as appropriate, and the multiple image forming units 30 may, of course, include units that form images of other color components (such as white, transparent, or special color components). In this example, the image forming units 30 are configured to form images of multiple color components, but they may also form monochrome images of, for example, black (K) only. Furthermore, in this example, the imaging engine 22 forms an image on a medium via the intermediate transfer body 40, but it may also form an image directly on a medium without using the intermediate transfer body 40.

[0039] <Image forming section> In the figure, each image forming unit 30 (30a to 30d) employs an electrophotographic system. In this example, each image forming unit 30 (30a to 30d) has a photoconductor 31 that rotates in a predetermined direction. Around the photoconductor 31, devices such as a charger 32, an exposure unit 33, a developing unit 34, and a cleaning unit 35 are sequentially arranged. Here, the photoreceptor 31 is configured, for example, in the shape of a drum, and has a photosensitive layer on its surface that serves as an image forming surface and an image holding surface. The charger 32 charges the outer surface of the photoreceptor 31 to a required surface potential. The charger 32 may be, for example, a non-contact charging method using corona discharge or a contact charging method using a charging roll. Furthermore, the exposure unit 33 irradiates the outer peripheral surface of the photosensitive member 31 with light according to image information to form electrostatic latent images for each color component image. A light irradiation device such as a laser scanner or an LED array is used as the exposure unit 33. In this example, the exposure unit 33 is provided individually for each image forming unit 30 (30a to 30d), but some or all of the exposure units may be shared.

[0040] The developing units 34 use a developer containing toner of each color component as an example of an image-forming material, and develop each electrostatic latent image on the photoreceptor 31 into an image using the toner of each color component. The toner in the developer contains an appropriate amount of wax. This wax is mainly used to ensure releasability between the fixing member of the fixing device 24 and the image on the medium. Furthermore, a toner supply mechanism 36 is provided in the space above the developing units 34 of each image forming unit 30, and is connected to and communicates with each developing unit 34. Each toner supply mechanism 36 is provided with a detachable toner cartridge 37 containing replenishment toner. The cleaner 35 is provided on the photoreceptor 31 downstream in the rotation direction of the photoreceptor 31 from the primary transfer position onto the intermediate transfer body 40. The cleaner 35 cleans off toner and other residues remaining on the photoreceptor 31 after the primary transfer. In this example, an electrophotographic method using a photosensitive member 31 and an exposure device 33 is adopted, but this is not limited to this, and it is of course also possible to adopt an electrostatic recording method using a dielectric and an ion flow writer.

[0041] <Intermediate transfer body> In this example, the intermediate transfer body 40 is an endless belt member made of, for example, polyimide resin. The intermediate transfer body 40 is stretched over multiple (six in this example) tension rolls 41 (specifically, 41a to 41f). In this example, of the multiple tension rolls 41, for example, tension roll 41a is used as a drive roll, and the other tension rolls 41b to 41f are used as driven rolls. In this example, the photosensitive elements 31 of each image forming unit 30 are arranged at predetermined intervals, facing a horizontal portion 40h of the intermediate transfer body 40 stretched between tension rolls 41a and 41b.

[0042] A primary transfer device 42 is provided on the rear surface of the horizontal portion 40h of the intermediate transfer body 40, facing the photosensitive body 31 of each image forming unit 30. Each primary transfer device 42 electrostatically transfers an image formed in each image forming unit 30 onto the intermediate transfer body 40. Any primary transfer device 42 may be selected as long as it generates a transfer electric field that attracts the image on the photosensitive body 31 toward the intermediate transfer body 40. For example, a transfer member (such as a transfer roll or a discharge wire for generating corona discharge) may be provided facing the photosensitive body 31, and a transfer voltage for primary transfer may be applied to this transfer member. Furthermore, an intermediate transfer body cleaner 45 is provided on the outer peripheral surface of the intermediate transfer body 40 that is stretched over the tension roll 41a. This intermediate transfer body cleaner 45 cleans off any toner, paper dust, and other residues remaining on the intermediate transfer body 40 after the image has been transferred to the medium.

[0043] <Transfer device> In this example, the transfer device 50 is mounted on the outer peripheral surface of the intermediate transfer body 40, stretched over the tension roll 41e. This transfer device 50 electrostatically transfers the image held on the intermediate transfer body 40 to the medium. Any suitable transfer device 50 may be used as long as it generates a transfer electric field that attracts the image on the intermediate transfer body toward the medium. For example, a transfer member 51 may be placed opposite the tension roll 41e of the intermediate transfer body 40, and a transfer voltage for secondary transfer may be applied to the transfer member 51 or the tension roll 41e to form a transfer electric field for secondary (collective) transfer between the transfer member 51 and the tension roll 41e. In this example, a transfer belt module 52 is used as the transfer member 51. This transfer belt module 52 has a transfer belt 52c stretched between a transfer roll 52a and a peel roll 52b. In this example, a transfer electric field is formed between the transfer roll 52a and the tension roll 41e, and the area of ​​effect of this transfer electric field serves as the transfer zone TR. Then, the medium S undergoes an image transfer operation in the transfer area TR, passes through the transfer area TR, is guided along the transfer belt 52c, and is peeled off by the peeling roll 52b. The transfer member 51 is not limited to the transfer belt module 52, but may be any suitable member such as a transfer roll alone or a discharge wire utilizing corona discharge.

[0044] -Media transport system- In this example, the medium transport system 23 is equipped with a medium supply device 60 that supplies the medium S. In this example, the medium S is in the form of sheets cut to a predetermined size. This medium supply device 60 stores the medium S in a storage container 61, and feeds the medium S one by one using a feeder 62. In this example, one storage container 61 is provided, but multiple storage containers 61 may be provided. Also provided within the unit housing 21 is a vertical transport path 63 that transports the medium S supplied from the medium supply device 60 in a substantially vertical direction. Above this vertical transport path 63 is a horizontal transport path 64 that transports the medium S in a substantially horizontal direction. Here, the horizontal transport path 64 extends to a discharge outlet 21a opened in a side wall of the unit housing 21. Then, outside the discharge outlet 21a of the unit housing 21, a discharge receiver (not shown) that receives the discharged medium S is provided. Also, an appropriate number of transport rolls 65 (specifically 65a to 65d) are provided on the vertical transport path 63 and the horizontal transport path 64. Note that the transport roll 65d provided immediately before the discharge outlet 21a functions as a discharge roll that discharges the medium S to the discharge receiver. Furthermore, an alignment roll 66 is provided on the horizontal transport path 64 upstream of the transfer zone TR of the transfer device 50 in the transport direction of the medium S. This alignment roll 66 aligns the leading edge of the medium S supplied from the medium supply device 60, and then sends the medium S toward the transfer zone TR at an appropriate timing. A guide member 67 is provided between the alignment roll 66 and the transfer zone TR to guide the medium S toward the transfer zone TR.

[0045] A conveyor belt 68 is provided on the horizontal conveyance path 64 downstream of the transfer device 50 in the conveyance direction of the medium S. The conveyor belt 68 stably holds and conveys the medium S carrying an unfixed image in a state of electrostatic attraction. Furthermore, a fixing device 24 is provided on the horizontal conveying path 64 downstream of the conveying belt 68 in the conveying direction of the medium S. A post-processing device 25 is provided on the horizontal conveying path 64 downstream of the fixing device 24 in the conveying direction of the medium S. In this example, the medium transport system 23 includes only the vertical transport path 63 and the horizontal transport path 64, but is not limited to this. For example, a reversible branch transport path (not shown) that branches downward from the horizontal transport path 64 between the fixing device 24 and the post-processing device 25 may be provided. In an embodiment with such a branch transport path, the medium inverted on the branch transport path may be returned from the vertical transport path 63 to the horizontal transport path 64 via a return transport path. In this case, an image can be transferred to the reverse side of the inverted medium in the transfer zone TR. Alternatively, a branch return transport path that branches off from the branch transport path may be provided so that the inverted medium is discharged to a medium discharge receptacle outside the unit housing 21. Furthermore, in this example, the medium transport system 23 is configured to transport sheet-like media S, but this is not limited to this, and it is of course also possible to use a system that transports continuous media.

[0046] -Fixing device- In this example, as shown in FIG. 6( a), the fixing device 24 fixes an image on the medium S by applying heat and pressure. The fixing device 24 includes a heating roll 71 as a fixing member for heating, and a pressure roll 72 as a fixing member for applying pressure. The heating roll 71 is disposed in contact with the image bearing surface of the medium S, and rotates by receiving a driving force from a driving source (not shown). On the other hand, the pressure roll 72 is disposed opposite and pressurized to the heating roll 71, and rotates following the heating roll 71. Therefore, the fixing device 24 passes the toner image G held on the medium S through a fixing zone FR between the heating roll 71 and the pressure roll 72, and fixes the image G by applying heat and pressure.

[0047] In this example, the heating roll 71 is configured such that a heater 71b is built into a roll body 71a made of metal with good thermal conductivity. However, the heating method of the heating roll 71 is not limited to this, and the roll body 71a may be heated by bringing an external heater (not shown) into contact with the outer circumferential surface of the roll body 71a. On the other hand, the pressure roll 72 has a heat-resistant elastic layer 72b laminated around a metal core 72a, and the surface of the elastic layer 72b is covered with a protective layer 72c. A heater may be added to the pressure roll 72 as needed. In this example, the medium S passes through the fixing zone FR between the heating roll 71 and the pressure roll 72 while being sandwiched by the elastic deformation of the pressure roll 72, and the image G on the medium S is heated and pressurized. In this example, the fixing device 24 is configured as a pair of rolls, but is not limited to this, and instead of the heating roll 71, it may be configured as an appropriate device, such as a heating belt that uses an electromagnetic induction heating method.

[0048] <Cleaning mechanism> In this embodiment, the heating roll 71 of the fixing device 24 is provided with a cleaning mechanism 73. This cleaning mechanism 73 mainly serves to reduce the wax component in the toner adhering to the heating roll 71. Here, the reason why wax components adhere to the heating roll 71 will be briefly explained. Generally, the toner used in the developing device 34 of the image forming unit 30 contains wax. Therefore, as shown in FIG. 6(a), the image G formed by the toner transferred to the medium S contains a wax component. In this state, as shown in FIGS. 6(b) and 6(c), when the medium S carrying the image G passes through the fixing zone FR of the fixing device 24, the image G is fixed onto the medium S by heat and pressure in the fixing zone FR. At this time, the heat causes a situation in which part of the wax W on the toner surface separates from the image G portion and is transferred to the heating roll 71.

[0049] In this example, as shown in FIG. 6( a), the cleaning mechanism 73 employs a system in which a cleaning member is pressed against and rubbed against the surface of the heating roll 71. Specifically, the cleaning mechanism 73 includes a cleaning web 74, a payout roll 75, a take-up roll 76, and a pressure roll 77. Here, the cleaning web 74 is an example of a cleaning member made of, for example, a heat-resistant nonwoven fabric. The payout roll 75 is an example of a payout member around which the cleaning web 74 is wound in a braked state so that it can be paid out. The take-up roll 76 is an example of a take-up member around which a used portion of the cleaning web 74 can be taken up. Furthermore, the pressure roll 77 is an example of a pressurizing member that presses the cleaning web 74, which is wound between the payout roll 75 and the take-up roll 76, against the heating roll 71. According to the cleaning mechanism 73 of this example, the cleaning web 74 is pressed against and rubs against the surface of the heating roll 71. At this time, since the cleaning web 74 is made of a heat-resistant nonwoven fabric or the like, the wax W liquefied on the surface of the heating roll 71 is absorbed by capillary action. In this example, gradually winding the cleaning web 74 is effective in increasing the absorption life of the cleaning web 74.

[0050] <Challenges with cleaning mechanisms> The cleaning mechanism 73 of this example has the following problems. In the cleaning mechanism 73 of this example, the cleaning web 74 is designed to come into contact with the rotating heating roll 71 only once, in principle. Therefore, there is a concern that the cleaning web 74 may not be able to sufficiently absorb the wax W by capillary action if it comes into contact with the wax W, which remains viscous even after liquefaction, only once. At this time, as shown in FIG. 7(a), assume a situation where the preceding medium Sf has left the fixing zone FR of the fixing device 24 and the following medium Sr has not yet entered the fixing zone FR of the fixing device 24. In the inter-image area (the area between the media S) between the preceding medium Sf and the following medium Sr, the heating roll 71 and the pressure roll 72 come into direct contact in the fixing zone FR. In this state, some of the wax W transferred to the heating roll 71 slips through without being cleaned by the cleaning mechanism 73 (see FIG. 6(a)). This leads to a situation where the wax W is transferred from the heating roll 71 to the pressure roll 72.

[0051] After this, as shown in FIG. 7(b), when the succeeding medium Sr passes through the fixing zone FR, the wax W transferred to the heating roll 71 and the pressure roll 72 is transferred back to the front and back surfaces of the medium S. For this reason, there is a concern that wax W may remain on the surface of the medium S even after fixing by the fixing device 24. At this time, as shown in FIG. 7(c), the wax W remaining on the medium S aggregates into granules and solidifies as the medium S cools, turning into granular lumps Wa. In this state, if the medium S is a smooth film medium, for example, the granular lumps Wa scatter the light reflected from or transmitted through the medium S, resulting in the wax marks becoming visible. If the wax marks become visible in this way, they will become apparent as dirt on the medium S or image defects.

[0052] To solve this problem, it is conceivable to increase the number of times the heating roll 71 comes into contact with the cleaning web 74 of the cleaning mechanism 73. However, this measure requires the heating roll 71 to continue rotating for a long period of time, during which time the fixing process by the fixing device 24 must wait, and therefore is not a desirable measure. In this example, the cleaning mechanism 73 is provided only on the heating roll 71, but it may of course be provided on the pressure roll 72 side. However, even if the cleaning mechanism 73 is provided on both the heating roll 71 and the pressure roll 72, it is difficult to completely remove the wax W that slips through the cleaning mechanism 73 on the heating roll 71 and the pressure roll 72.

[0053] -After-treatment device- In this embodiment, as shown in Figure 5, considering that wax W may remain on the medium S that has passed through the fixing device 24, a post-processing device 25 is provided downstream of the fixing device 24 in the transport direction of the medium S. In this example, the post-processing device 25 performs post-processing to change the wax remaining on the medium S from a visible state (granular lumps) to a less visible state (smoothing). This suppresses the light scattering phenomenon caused by the granular lumps Wa by stretching and smoothing the granular lumps Wa through a rubbing operation.

[0054] <Basic configuration of post-processing device> 8, the post-processing device 25 includes a transport roll 80 as a transport means that clamps and transports the medium S after passing through the fixing device 24 at a predetermined transport speed v0, a first rubbing roll 91 as a first rubbing means that is located upstream of the transport roll 80 in the transport direction of the medium S and rubs the surface of the medium S in the opposite direction to the transport direction of the medium S at a speed v1 that is different from the transport speed v0, and a second rubbing roll 92 as a second rubbing means that is located downstream of the transport roll 80 in the transport direction of the medium S and rubs the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0, and these are appropriately arranged and mounted in a housing not shown. The housing not shown has an inlet opening and an outlet opening through which the medium S passes. In this example, the first rubbing roll 91 and the second rubbing roll 92 are configured to rub both the front and back surfaces of the medium S. This is because there is a possibility that the wax W may be transferred to both the front and back surfaces of the medium S that has passed through the fixing device 24.

[0055] -Transport Roll- <Conveyor Roll Configuration Examples and Driving Methods> 8 and 9, the transport roll 80 is made up of a plurality of rotors 80a and 80b that are arranged facing each other with respect to the medium S. The rotors 80a and 80b that make up the transport roll 80 have a structure in which the periphery of a solid shaft 83 made of a metal such as SUS is covered with an elastic layer 84 made of silicone rubber or the like, and a release layer 85 made of PFA or the like is provided on the surface of the elastic layer 84 to prevent wax from adhering. In this example, the multiple rotating bodies 80a, 80b are arranged in pressure contact with each other, and the medium S is sandwiched and transported in the contact area CN0 between them. Here, the transport roll 80 is configured such that, of the multiple rotating bodies 80a, 80b, for example, the lower rotating body 80b serves as a drive roll, and the upper rotating body 80a serves as a driven roll. Driving force from a drive motor 86 is transmitted to the rotating body 80b serving as the drive roll via a drive transmission mechanism 87, such as a drive transmission gear train.

[0056] <Example of transport roll evacuation configuration> In this example, one of the rotating bodies 80a of the transport roll 80 is provided with a retraction mechanism 88 as a retractable retraction means, as shown in FIGS. 8 and 10(a) and 10(b). The retraction mechanism 88 supports both ends of the shaft 83 of the rotating body 80a and releases the nipped state of the transport roll 80 (corresponding to the contact state between the multiple rotating bodies 80a and 80b) when, for example, the medium S becomes jammed. In this example, as shown in FIG. 10(b), the retraction mechanism 88 has support arms 88b that protrude radially from both sides of the rotatable support shaft 88a. The support arms 88b support bearings 89 provided at both ends of the shaft 83 of the rotating body 80a from below. An operating lever 88c that protrudes radially from the support shaft 88a in a direction different from that of the support arms 88b is provided at one end of the support shaft 88a.

[0057] <Transport roll nip pressure setting> 10(a), biasing springs 114 are provided at both ends of one rotating body 80a of the transport roll 80 as biasing means for adjusting the nip pressure of the transport roll 80 (corresponding to the contact pressure of the contact area CN0 of the multiple rotating bodies 80a, 80b). The biasing springs 114 are formed, for example, by compression coil springs, and the biasing force can be variably set by adjusting the amount of compression deformation with an adjustment unit not shown. This sets the nip pressure of the transport roll 80. <Example of using the retract mechanism> In this example, for example, if the medium S jams (is jammed) while passing through the transport rolls 80, the retract mechanism 88 can be operated. Specifically, as shown in FIG. 10(b), an operator manually presses down the operating lever 88c of the retract mechanism 88, causing the support arm 88b to swing upward around the support shaft 88a. At this time, the support arm 88b pushes up the rotating body 80a against the biasing force of the biasing spring 114, and the contact state between the multiple rotating bodies 80a and 80b is released. Note that if the operating lever 88c is returned to its original position, the contact state between the multiple rotating bodies 80a and 80b will return to normal.

[0058] -First scraping roll- <Configuration example of first rubbing roll> In this example, the first rubbing roll 91 is made up of multiple rotors 91a and 91b that are arranged facing each other with respect to the medium S, as shown in Figures 8 and 9. In this example, the rotors 91a and 91b that make up the first rubbing roll 91 have a structure in which the surface of a solid shaft 93 made of a metal such as SUS is covered with a nonwoven fabric 94. Here, the nonwoven fabric 94 is, for example, felt or microfiber cloth with a thickness of 1 mm or less. The nonwoven fabric 94 is fixed to the shaft 93 with adhesive, double-sided tape, or the like. <Drive system for the first rubbing roll> In this example, the first rubbing roll 91 uses both rotating bodies 91a and 91b as drive rolls. That is, the driving force from a drive motor 96 is transmitted to both rotating bodies 91a and 91b via a drive transmission mechanism 97 (specifically, 97a and 97b) such as a drive transmission gear train. Here, the drive transmission mechanisms 97a and 97b may be partially shared, or may be provided separately. In this example, the drive transmission mechanism 97b shares the drive transmission mechanism 97a, and is configured to add a transmission gear for changing the rotation direction with respect to the final transmission gear of the drive transmission mechanism 97a.

[0059] <Speed ​​condition of the first rubbing roll> As shown in FIGS. 8 and 9, the first rubbing roll 91 may be any roll that rubs the surface of the medium S in the opposite direction to the transport direction of the medium S at a speed v1 different from the transport speed v0 of the transport roll 80. In this example, the first rubbing roll 91 is selected so that (i) it rotates in the opposite direction to the transport direction of the medium S in the contact area CN1 of the multiple rotating bodies 91a and 91b. That is, the upper rotating body 91a rotates clockwise, and the lower rotating body 91b rotates counterclockwise. The reason for this selection is based on the viewpoint of increasing the rubbing resistance of the first rubbing roll 91. By selecting in this manner, it is possible to increase the speed difference (v0-v1) between the first rubbing roll 91 and the transport roll 80. Here, the speed v1 of the first rubbing roll 91 may be selected appropriately, but in this example, it is set to about 5 to 10 times v0 in absolute value. In addition to (i), the first rubbing roll 91 can be made to rub the surface of the medium S in the opposite direction to the transport direction of the medium S by (ii) keeping the roll stationary in the contact area CN1, or (iii) rotating in the same direction as the transport direction of the medium S in the contact area CN1 at a speed less than the transport speed v0 of the medium S. However, it should be noted that the methods (ii) and (iii) result in a smaller rubbing resistance from the first rubbing roll 91 than the method (i).

[0060] <Example of contact and separation configuration of first rubbing roll> In this example, as shown in FIGS. 8 and 11(a) and 11(b), one of the rotating bodies 91a of the first rubbing roll 91 is provided with a first nip release mechanism 101 as a contact / separation mechanism that can move between a contact position where it contacts the other rotating body 91b and a non-contact position away from the contact position. The first nip release mechanism 101 supports both ends of the shaft 93 of the rotating body 91a and switches the first rubbing roll 91 between a nip state (corresponding to a contact state of the multiple rotating bodies 91a and 91b) and a release state (corresponding to a non-contact state of the multiple rotating bodies 91a and 91b) based on a control signal. In this example, as shown in FIG. 11(b), the first nip release mechanism 101 has support arms 104 on both sides of the rotatable support shaft 103 that protrude radially from the support shaft 103. The support arms 104 support bearings 95 provided at both ends of the shaft 93 of the upper rotating body 91a from below.

[0061] In this example, bearings 95 provided on both ends of shaft 93 are supported so as to be vertically movable relative to support panel 110. Specifically, elongated holes 111 extending in the vertical direction are formed in support panel 110. Bearings 95 provided on both ends of shaft 93 of rotating body 91a are held in these elongated holes 111 so as to be slidable. Furthermore, a reversible nip release motor 105 is provided directly or via a drive transmission gear train (not shown) on one end of the support shaft 103. As shown in Figures 11(b) and 11(c), this nip release motor 105 rotates the support shaft 103 in the forward and reverse directions, thereby swinging the support arm 104 within a predetermined angular range.

[0062] <Nip pressure setting of the first rubbing roll> In this example, as shown in FIGS. 11(a) and 11(d), the first rubbing roll 91 is provided with a biasing spring 115 as a biasing means for adjusting the nip pressure of the first rubbing roll 91 (corresponding to the contact pressure in the contact area between the multiple rotors 91a and 91b). This biasing spring 115 is configured, for example, by a compression coil spring. This biasing spring 115 is interposed, for example, between the upper edge of the elongated hole 111 and the bearing 95 of the rotor 91a. This biasing spring 115 is also provided with an adjustment portion 116 for adjusting the amount of compressive deformation. This adjustment portion 116 variably sets the biasing force of the biasing spring 115 by adjusting the amount of compressive deformation. This allows the nip pressure of the first rubbing roll 91 to be set.

[0063] <Adjusting the friction force of the first rubbing roll> In this example, the first rubbing roll 91 and the transport roll 80 each come into contact with the moving medium S. When the medium S passes through the contact area CN1 of the first rubbing roll 91, a frictional force f1 is generated between the first rubbing roll 91 and the medium S, as shown in Fig. 9. On the other hand, when the medium S passes through the contact area CN0 of the transport roll 80, a frictional force f0 is generated between the transport roll 80 and the medium S. In this example, the friction force f0 between the multiple rotating bodies 80a, 80b constituting the conveying roll 80 and the medium S must be greater than the friction force f1 between the multiple rotating bodies 91a, 91b constituting the first rubbing roll 91 and the medium S. Here, if the vertical resistance acting on the contact area CN0 of the transport roll 80 is U0, the dynamic friction coefficient between the transport roll 80 and the medium S is μ0, the vertical resistance acting on the contact area CN1 of the first rubbing roll 91 is U1, and the dynamic friction coefficient between the first rubbing roll 91 and the medium S is μ1, then it can be expressed as follows: f0=μ0·U0 f1=μ1·U1 To satisfy the condition f0>f1, the kinetic friction coefficients μ0 and μ1 are values ​​that depend on the material, etc., so the biasing forces of the biasing springs 114 and 115 that affect the vertical drag forces U0 and U1 can be adjusted taking into account the respective kinetic friction coefficients. Here, U0 is selected to optimize the transportability of the medium S, so it is preferable to adjust the biasing force of the biasing spring 115 primarily and appropriately adjust the friction force f1.

[0064] -Second rubbing roll- <Example of second rubbing roll configuration> 8 and 9, the second rubbing roll 92 is made up of a plurality of rotating bodies 92a, 92b arranged opposite each other with respect to the medium S. In this example, the rotating bodies 92a, 92b constituting the second rubbing roll 92 have a structure in which the surface of a solid shaft 93 made of a metal such as SUS is covered with a nonwoven fabric 94, similar to the first rubbing roll 91. <Drive system for the second rubbing roll> Similarly to the first rubbing roll 91, the second rubbing roll 92 also uses both rotating bodies 92a, 92b as drive rolls. That is, the driving force from a drive motor 98 is transmitted to both rotating bodies 92a, 92b via a drive transmission mechanism 99 (specifically, 99a, 99b) such as a drive transmission gear train. Here, the drive transmission mechanisms 99a, 99b may be partially shared, as with the drive transmission mechanism 97, or may be provided separately. In this example, the drive transmission mechanism 99b shares the drive transmission mechanism 99a, and is configured to add a transmission gear for changing the rotation direction with respect to the final-stage transmission gear of the drive transmission mechanism 99a.

[0065] <Speed ​​condition of the second rubbing roll> As shown in FIGS. 8 and 9, the second rubbing roll 92 may be any roll that rubs the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0 of the transport roll 80. In this example, the second rubbing roll 92 is selected so as to rotate in the contact area CN2 of the multiple rotating bodies 92a and 92b in the same direction as the transport direction of the medium S. That is, the upper rotating body 92a rotates counterclockwise, and the lower rotating body 92b rotates clockwise. With this selection, the speed difference (v2-v0) between the second rubbing roll 92 and the transport roll 80 becomes larger than 0. Therefore, the transport roll 80 transports the medium S at a transport speed v0. In this situation, when the medium S passes the second rubbing roll 92, the second rubbing roll 92 ensures a rubbing action against the surface of the medium S. Here, the speed v2 of the second rubbing roll 92 may be selected as appropriate. However, it is preferable to set v2 large in order to increase the rubbing resistance of the second rubbing roll 92. In this example, it is set to an absolute value of about 5 to 10 times v0.

[0066] <Example of contact and separation configuration of second rubbing roll> In this example, the second rubbing roll 92 is equipped with a second nip release mechanism 102, similar to the first nip release mechanism of the first rubbing roll 91. As shown in Fig. 8 and Figs. 11(a) and (b), this second nip release mechanism 102 is provided on one of the rotating bodies 92a of the second rubbing roll 92. Similar to the first nip release mechanism 101, the second nip release mechanism 102 supports both ends of the shaft 93 of the rotating body 92a and switches the second rubbing roll 92 between a nip state (corresponding to a contact state of the multiple rotating bodies 92a, 92b) and a release state (corresponding to a non-contact state of the multiple rotating bodies 92a, 92b) based on a control signal. In this example, the second nip release mechanism 102 has the same components (the support shaft 103 and the support arm 104) as the first nip release mechanism 101, as shown in FIGS. 11(b) and 11(c). Here, support arm 104 supports bearing 95 of rotating body 92a from below. Bearing 95 is slidably held in elongated hole 111 of support panel 110, similar to first nip release mechanism 101. Furthermore, one end of support shaft 103 is provided with nip release motor 105, which is substantially the same as first nip release mechanism 101.

[0067] <Nip pressure setting of the second rubbing roll> 11(a) and 11(d), the second rubbing roll 92, like the first rubbing roll 91, is provided with a biasing spring 117 as a biasing means for adjusting the nip pressure of the second rubbing roll 92 (corresponding to the contact pressure in the contact area between the multiple rotors 92a and 92b). The biasing spring 117 is, for example, a compression coil spring. The biasing spring 117 is interposed, for example, between the upper edge of the elongated hole 111 and the bearing 95 of the rotor 92a. The biasing spring 117 is also provided with an adjustment portion 118 for adjusting the amount of compressive deformation. The adjustment portion 118 adjusts the amount of compressive deformation to variably set the biasing force of the biasing spring 117. This allows the nip pressure of the second rubbing roll 92 to be set.

[0068] <Adjusting the friction force of the second rubbing roll> In this example, the second rubbing roll 92 and the transport roll 80 each come into contact with the moving medium S. When the medium S passes through the contact area CN2 of the second rubbing roll 92, a frictional force f2 is generated between the second rubbing roll 92 and the medium S, as shown in Fig. 9. On the other hand, when the medium S passes through the contact area CN0 of the transport roll 80, a frictional force f0 is generated between the transport roll 80 and the medium S. In this example, the friction force f0 between the multiple rotating bodies 80a, 80b constituting the conveying roll 80 and the medium S must be greater than the friction force f2 between the multiple rotating bodies 92a, 92b constituting the second rubbing roll 92 and the medium S. Here, if the vertical resistance acting on the contact area CN0 of the transport roll 80 is U0, the dynamic friction coefficient between the transport roll 80 and the medium S is μ0, the vertical resistance acting on the contact area CN2 of the second rubbing roll 92 is U2, and the dynamic friction coefficient between the second rubbing roll 92 and the medium S is μ2, then the following can be expressed: f0=μ0·U0 f2=μ2·U2 To satisfy the condition f0>f2, the kinetic friction coefficients μ0 and μ2 are values ​​that depend on the material, etc., so the biasing forces of the biasing springs 114 and 117 that affect the vertical drag forces U0 and U2 can be adjusted taking into account the respective kinetic friction coefficients. Here, U0 is selected to optimize the transportability of the medium S, so it is preferable to adjust the biasing force of the biasing spring 117 primarily and appropriately adjust the friction force f2.

[0069] - Positional relationship between the transport roll and the first and second rubbing rolls - In this example, the positional relationship between the transport roll 80, the first rubbing roll 91, and the second rubbing roll 92 is as follows. As shown in Figure 9, if the distance between the circumferential center of the contact area CN1 of the first rubbing roll 91 and the circumferential center of the contact area CN2 of the second rubbing roll 92 is L, the distance between the circumferential center of the contact area CN1 of the first rubbing roll 91 and the circumferential center of the contact area CN0 of the conveying roll 80 is L1, the distance between the circumferential center of the contact area CN0 of the conveying roll 80 and the circumferential center of the contact area CN2 of the second rubbing roll 92 is L2, and the conveying direction length of the medium S is g (see Figure 14(a)), they are selected to satisfy the following equations (I) and (II). L <g (I) L1, L2 <g / 2 (II) However, L = L1 + L2 The circumferential center of the contact area CN (CN1 or CN2) refers to the intersection of the contact area CN (CN1 or CN2) and a line connecting the axial centers of the multiple rotating bodies 80a, 80b (91a, 91b or 92a, 92b).

[0070] In this example, formula (I) is the condition for rubbing the entire area of ​​both the front and back surfaces of the medium S with the first rubbing roll 91 and the second rubbing roll 92. Moreover, the formula (II) is a condition for the first rubbing roll 91 and the second rubbing roll 92 to rub an area exceeding half of both the front and back surfaces of the medium S. In particular, in formula (II), since L1 and L2 are less than half of the length g of the medium S in the conveying direction, it is possible to maintain the conveying posture of the medium S and transport it stably without providing a guide member or the like in the transport path of the medium S in the post-processing device 25. In this example, a transport roll 65c for feeding the medium S into the post-processing device 25 is disposed on the horizontal transport path 64 on the upstream side of the transport direction of the medium S from the post-processing device 25. On the other hand, a transport roll 65d for receiving the medium S from the post-processing device 25 is disposed on the downstream side of the transport direction of the medium S from the post-processing device 25. Here, in order for the feeding transport roll 65c, the transport roll 80 and the receiving transport roll 65d to transport the medium S at a transport speed v0, it is necessary that the distance between each of the feeding transport roll 65c, the transport roll 80 and the receiving transport roll 65d (specifically, the distance between the circumferential centers of the contact areas of adjacent rolls) be set shorter than the transport direction length g of the medium S.

[0071] -Aftertreatment device control system- In this embodiment, as shown in FIG. 8, a control device 120 is provided that controls each element of the image forming system 20 (image creation engine 22, medium transport system 23, fixing device 24, post-processing device 25, etc.). The control device 120 is configured with a microcomputer including various processors. The term "processor" here refers to a processor in a broad sense, including general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.). In this example, a position sensor 130 serving as a position detection means is provided on the horizontal conveyance path 64 upstream of the post-processing device 25 in the conveyance direction of the medium S. Here, the position sensor 130 may be appropriately selected as long as it detects the timing when the leading edge of the medium S passes by. Specific examples of the position sensor 130 include a mechanical switch such as a limit switch, or an optical sensor having a light-emitting element and a light-receiving element.

[0072] In this example, the control device 120 has necessary programs installed in advance in a memory (not shown), such as an image creation program for the image forming system 20 and a control processing program (see FIG. 12) for the post-processing device 25. When a start switch (not shown) is turned on, the control device 120 executes the image creation program and sends control signals required for image creation processing to the image creation engine 22, the medium transport system 23, and the fixing device 24. Furthermore, it is now assumed that the leading edge of the medium S that has passed through the fixing device 24 has now passed through the position sensor 130. At this time, the control device 120 inputs the detection information from the position sensor 130 into the processor and executes the control processing program for the post-processing device 25. The control device 120 then sends a nip release control signal to the first nip release mechanism 101 and the second nip release mechanism 102. The control device 120 also sends drive control signals to the drive motors 86, 96, and 98 of the transport roll 80, the first rubbing roll 91, and the second rubbing roll 92.

[0073] - Aftertreatment device operation - In this example, the control device 120 executes a control process for the post-processing device 25 as shown in FIG. 12, the control device 120 determines whether the leading edge of the medium S that has passed through the fixing device 24 has passed a predetermined reference position P0. In this example, the control device 120 determines that the leading edge of the medium S has passed the reference position P0 based on a detection signal from the position sensor 130. Then, the control device 120 starts the counting operation of an internal time counter, and uses this to determine the transport position of the medium S. <First mode> After this, the control device 120 determines whether the first rubbing roll 91, the second rubbing roll 92, and the transport roll 80 are arranged in the first mode. The "first mode" here refers to the operating behavior shown in FIG. 13(a). In this case, the first rubbing roll 91 is arranged in the release position, and the transport roll 80 and the second rubbing roll 92 are arranged in the nip position. Furthermore, the transport roll 80 and the second rubbing roll 92 in the nip position are driven. In this example, if the first mode is configured, the first mode is implemented. If the first mode is not configured, the control device 120 configures the first mode and then implements the first mode. In this state, the transport roll 80 rotates idly at a predetermined transport speed v0 at the nip position. The second rubbing roll 92 rotates idly at a speed v2 (v2>v0) at the nip position in the same direction as the transport roll 80. In contrast, the first rubbing roll 91 stops driving at the release position and is on standby. Meanwhile, the medium S passes through the position sensor 130 by the infeed transport roll 65c (see FIG. 5) and is transported into the post-processing device 25. The medium S then passes directly past the first rubbing roll 91 and heads toward the transport roll 80.

[0074] <Switching to the second mode> Next, the control device 120 determines whether the leading edge of the medium S has passed the transport roll 80. If it is determined that the leading edge of the medium S has passed the transport roll 80, the control device 120 switches to the second mode. The "second mode" here refers to the operating behavior shown in FIG. 13(b). In this case, unlike the first mode, the first rubbing roll 91 is switched to the nip position and starts driving. The transport roll 80 and the second rubbing roll 92 are the same as in the first mode. In this state, immediately after the medium S enters the transport rolls 80, the first rubbing rolls 91 pinch the medium S midway in the transport direction and rotate in the opposite direction to the transport rolls 80 at a speed v1 (|v1|>v0).

[0075] Therefore, between the first rubbing roll 91 and the conveying roll 80, the medium S is conveyed in a state of being tensioned in the conveying direction. At this time, the relationship between the frictional force f1 between the first rubbing roll 91 and the medium S and the frictional force f0 between the conveying roll 80 and the medium S is f1 < f0. Therefore, the medium S will be conveyed at the conveying speed v0 by the conveying roll 80. In this state, when the first rubbing roll 91 rotates in the opposite direction at the speed v1 in the contact area CN1, the surface of the medium S is rubbed in the opposite direction to the conveying direction of the medium S. As a result, the rubbing operation by the first rubbing roll 91 continues until the rear end in the conveying direction of the medium S passes through the first rubbing roll 91. Therefore, the rubbing area R1 by the first rubbing roll 91 becomes the latter half area of the medium S from the middle in the conveying direction of the medium S to the rear end in the conveying direction of the medium S (see FIGS. 14 to 16).

[0076] Also, in the second mode, when the leading end of the medium S reaches the second rubbing roll 92, the following behavior occurs. In this example, when the medium S enters the second rubbing roll 92, the second rubbing roll 92 sandwiches the leading end of the medium S and rotates in the same direction as the conveying roll 80 at the speed v2 (v2 > v0). Therefore, between the conveying roll 80 and the second rubbing roll 92, the medium S is conveyed in a state of being tensioned in the conveying direction. At this time, the relationship between the frictional force f2 between the second rubbing roll 92 and the medium S and the frictional force f0 between the conveying roll 80 and the medium S is f2 < f0. Therefore, the medium S will be conveyed at the conveying speed v0 by the conveying roll 80. In this state, when the second rubbing roll 92 rotates in the same direction at the speed v2 in the contact area CN2, the surface of the medium S is rubbed in the same direction as the conveying direction of the medium S. As a result, the rubbing operation by the second rubbing roll 92 continues from the leading end of the medium S until immediately before the medium S passes through the conveying roll 80. Therefore, the rubbing area R2 by the second rubbing roll 92 becomes the first half area of the medium S from the leading end of the medium S to the middle in the conveying direction of the medium S (see FIGS. 14 to 16).

[0077] <Switching to the First Mode> Next, the control device 120 determines whether the trailing end of the medium S has passed the first rubbing roll 91. At this time, if the control device 120 determines that the trailing end of the medium S has passed the first rubbing roll 91, the control device 120 switches to the first mode. As a result, the first rubbing roll 91 is placed in the release position and its driving is stopped. This is because when the trailing end of the medium S passes the first rubbing roll 91, there is no more medium S to be rubbed by the first rubbing roll 91. In this example, the mode is switched to the first mode in order to prepare in advance to receive the following medium S.

[0078] <Switching to the third mode> Thereafter, the control device 120 determines whether the trailing end of the medium S has passed the transport roll 80. If it determines that the trailing end of the medium S is about to pass the transport roll 80, the control device 120 switches to the third mode. The "third mode" here refers to the operational behavior shown in FIG. 13(c). In this case, the third mode differs from the first and second modes in that the second rubbing roll 92 is switched to the release position and stops driving. At this time, the first rubbing roll 91 and the transport roll 80 may be the same as in either the first mode or the second mode. Note that FIG. 13(c) shows a state in which the first rubbing roll 91 is the same as in the second mode. This third mode is intended to maintain good transportability of the medium S discharged from the post-processing device 25. If the rubbing operation by the second rubbing roll 92 continues even after the rear end of the medium S has passed the transport roll 80, the second rubbing roll 92 will discharge the medium S at a speed v2 (v2>v0) when the transport operation of the medium S by the transport roll 80 stops. In this case, the second rubbing roll 92 will discharge the medium S at a speed v2 that is faster than the predetermined transport speed v0, and the transportability of the medium S will be impaired.

[0079] <Return to initial position> Next, the control device 120 determines whether or not the rear end portion of the medium S has passed through the second rubbing roll 92. In this example, when it is determined that the rear end portion of the medium S has passed through the second rubbing roll 92, the control device 120 stops driving the conveying roll 80 and the first rubbing roll 91, and arranges the first rubbing roll 91 and the second rubbing roll 92 at their initial positions. In this example, the initial positions are selected, for example, as the arrangement in the first mode (the first rubbing roll 91 is at the release position and the second rubbing roll 92 is at the nip position).

[0080] -Specific Example of Wax Rubbing Process by Post-treatment Device- In this example, the distance L1 (see paragraph

[0069] ) between the first rubbing roll 91 and the conveying roll 80 and the distance L2 (see paragraph

[0069] ) between the conveying roll 80 and the second rubbing roll 92 may be appropriately selected as long as they satisfy the formulas (I): L1 + L2 = L < g (the length of the medium S in the conveying direction) and the formula (II): L1, L2 < g / 2. Therefore, typically, the aspect of L1 = L2 can be cited. Hereinafter, specific example 1 and specific example 2 will be taken as examples for explanation.

[0081] ◎Specific Example 1: When L1 > L2 Figs. 14(a) to (e) show the wax rubbing process by the post-treatment device 25 in specific example 1. Fig. 14(a) shows a state where the leading end portion of the medium S enters the conveying roll 80. In this case, since the first mode is implemented, the medium S is conveyed by the conveying roll 65c located on the inlet side of the post-treatment device 25, passes through the first rubbing roll 91 at the release position, and enters the conveying roll 80. Fig. 14(b) shows a state after the leading end portion of the medium S has entered the conveying roll 80. In this case, since the second mode is implemented, the first rubbing roll 91 is arranged at the nip position and driving is started. Then, the rubbing operation by the first rubbing roll 91 is performed from the middle of the conveying direction of the medium S. In Fig. 14(b), R1 indicates the rubbing area (corresponding to the diagonally lower left hatched area in the figure) by the first rubbing roll 91 with respect to the medium S.

[0082] 14(c) shows a state in which the leading edge of the medium S has entered the second rubbing roll 92. In this case, the second mode continues to be performed, and the rubbing operation by the second rubbing roll 92 starts from the leading edge of the medium. Note that the rubbing operation by the first rubbing roll 91 continues. FIG. 14(d) shows the state in which the rear end of the medium S passes the first rubbing roll 91. In this case, the mode is switched to the first mode, the first rubbing roll 91 is placed in the release position, and driving is stopped. During this time, the rubbing operation by the first rubbing roll 91 is performed from midway in the transport direction of the medium S to the rear end of the medium S. In addition, the rubbing operation by the second rubbing roll 92 is performed from the front end of the medium S toward the downstream side in the transport direction of the medium S. In FIG. 14(d), R2 indicates the rubbing area of ​​the medium S by the second rubbing roll 92 (corresponding to the hatched area diagonally downward right in the figure).

[0083] FIG. 14(e) shows the state immediately before the trailing end of the medium S passes the transport roll 80. In this case, the mode switches to the third mode, the second rubbing roll 92 is placed in the release position, and driving is stopped. During this time, the second rubbing roll 92 performs a rubbing operation from the leading end of the medium S to partway along the transport direction of the medium S. The rubbing operation by the second rubbing roll 92 stops when the second rubbing roll 92 is placed in the release position. In FIG. 14(e), the rubbing area R2 by the second rubbing roll 92 is performed in a range of approximately g-L2. On the other hand, the rubbing area R1 by the first rubbing roll 91 is performed in a range of approximately g-L1. Furthermore, when switching to the third mode, the leading edge of the medium S is conveyed while being sandwiched between conveyance rolls 65d located on the exit side of the post-processing device 25. Therefore, the conveyance of the medium S discharged from the post-processing device 25 is maintained favorably.

[0084] Thus, in this example, as shown in Fig. 16(a), the wax post-treatment of the post-treatment device 25 will rub both the front and back surfaces of the medium S in the rubbing area R1 by the first rubbing roll 91 and the rubbing area R2 by the second rubbing roll 92. In this example, since R1 + R2 = 2g - L (g > L) is satisfied, it is understood that the wax post-treatment by the post-treatment device 25 is realized with the entire area of both the front and back surfaces of the medium S as the rubbing target. Also, in this example, the rubbing areas R1 and R2 are in a state of partial overlap in the middle part in the conveyance direction of the medium S, and are achieved by satisfying the relationship R2 > R1.

[0085] ◎ Specific Example 2: When L1 < L2 Figs. 15(a) to (e) show the wax rubbing process by the post-treatment device 25 in Specific Example 2. Figs. 15(a) to (e) are substantially the same as the wax rubbing process by the post-treatment device 25 in Specific Example 1, except that the dimensional relationship of L1 and L2 is different from that in Specific Example 1. In this example, as shown in Fig. 16(b), the wax post-treatment of the post-treatment device 25 will rub both the front and back surfaces of the medium S in the rubbing area R1 by the first rubbing roll 91 and the rubbing area R2 by the second rubbing roll 9s, similar to Specific Example 1. Also in this example, since R1 + R2 = 2g - L (g > L) is satisfied, it is understood that the wax post-treatment by the post-treatment device 25 is realized with the entire area of both the front and back surfaces of the medium S as the rubbing target. Also, in this example, the rubbing areas R1 and R2 are in a state of partial overlap in the middle part in the conveyance direction of the medium S, and are achieved by satisfying the relationship R2 < R1.

[0086] - Morphological Changes of Wax on the Medium Before and After Post-Treatment - Fig. 17(a) shows the morphological changes of the wax W before and after the post-treatment by the post-treatment device 25 when a film medium with a smooth surface is used as the medium S. In the figure, many waxes W on the medium S before the post-treatment were confirmed as granular lumps Wa (lumps with a diameter df of about 5 μm and a height tf of about 0.3 μm, for example). In contrast, after post-processing by the post-processing device 25, the wax W consisting of the granular lumps Wa before post-processing was barely recognizable. In this example, the granular lumps Wa were flattened by the first abrading roll 91 or the second abrading roll 92. As a result, it was confirmed that the form of the wax W had changed from the granular lumps Wa to a thin film-like layer Wb (a circular region with a diameter dr of, for example, 30 μm and a thickness tr of, for example, about 0.1 μm). In this state, it was confirmed that the wax W made of the thin film layer Wb does not scatter light, and its presence on the medium S is not visible to the naked eye.

[0087] Comparison form 1 As shown in Figure 17(b), the post-processing device of this comparative embodiment is similar to Patent Document 1 or Patent Document 3 in that it removes wax W consisting of granular lumps Wa that have been transferred onto the medium S using a removal member such as a blade. In this example, if one were to attempt to completely mechanically remove the wax W that has been transferred onto the medium S, it would be necessary to press a removal member firmly against the surface of the medium S. This raises the concern that the image held on the medium S may be damaged, and is therefore not a desirable measure.

[0088] ◎Deformation mode (1) In this embodiment, when the first rubbing roll 91 (or the second rubbing roll 92) is placed at the release position, the driving of the multiple rotating bodies 91a, 91b (or 92a, 92b) is stopped. However, the first rubbing roll 91 (or the second rubbing roll 92) may be placed at the release position without stopping the driving of the multiple rotating bodies 91a, 91b (or 92a, 92b). (2) In this embodiment, the second mode is first switched to the first mode, and then switched to the third mode. However, it is also possible to switch from the second mode to the third mode without going through the first mode. (3) In this embodiment, the first mode configuration is selected as the initial position of the post-processing device 25, but it is also possible to select the second mode configuration (both the first rubbing roll 91 and the second rubbing roll 92 are in the nip position). (4) In this embodiment, the post-processing device 25 is configured to perform post-processing on sheet-like media S, but this is not limited to this, and it is of course also possible to perform post-processing on continuous media such as roll-like media.

[0089] Embodiment 2 FIG. 18 shows the main part of a post-processing device incorporated in an image forming system according to the second embodiment. In this example, the basic configuration of the image forming system 20 is substantially the same as that of the first embodiment, as shown in Fig. 5. Then, the post-processing device 25, like the first embodiment, performs post-processing to change the wax remaining on the medium S from a visible state (granular lumps) to a less visible state (smoothing). <Basic configuration of post-processing device> 18 and 19, unlike the first embodiment, the post-processing device 25 in this example includes a first transport roll 81, a second transport roll 82, a first rubbing roll 91, and a second rubbing roll 92. These components are appropriately arranged and mounted in a housing (not shown). The housing (not shown) is formed with an inlet opening and an outlet opening through which the medium S passes.

[0090] Here, the first transport roll 81 corresponds to the first transport means 3 shown in FIG. 3 and clamps and transports the medium S after passing through the fixing device 24 at a predetermined transport speed v0. The second transport roll 82 corresponds to the second transport means 4 shown in FIG. 3 and is located downstream of the first transport roll 81 in the transport direction of the medium S and clamps and transports the medium S at the same speed as the transport speed v0. The first rubbing roll 91 is located downstream of the first transport roll 81 in the transport direction of the medium S and upstream of the second transport roll 82 in the transport direction of the medium S. The first rubbing roll 91 rubs the surface of the medium S in the opposite direction to the transport direction of the medium S at a speed v2, which is different from the transport speed v0. Furthermore, the second rubbing roll 92 is located downstream of the first transport roll 81 in the transport direction of the medium S and upstream of the first rubbing roll 91 in the transport direction of the medium S. The second rubbing roll 92 rubs the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0. In this example, the first rubbing roll 91 and the second rubbing roll 92 are configured to rub both the front and back surfaces of the medium S, similar to the first embodiment. However, unlike the first embodiment, the second rubbing roll 92 is disposed upstream of the first rubbing roll 91 in the transport direction of the medium S.

[0091] -First transport roll- <Configuration example and driving method of the first transport roll> 18 and 19, the first transport roll 81 is made up of a plurality of rotating bodies 81a and 81b arranged opposite each other with respect to the medium S. The rotating bodies 81a and 81b constituting the first transport roll 81 have the same structure as the transport roll 80 of the first embodiment (a three-layer structure of a shaft 83, an elastic layer 84, and a release layer 85). In this example, the multiple rotating bodies 81a, 81b are arranged in pressure contact with each other, and the medium S is sandwiched and transported in the contact area CN0 between them. Here, the first transport roll 81 is configured such that, of the multiple rotating bodies 81a, 81b, the lower rotating body 81b serves as a drive roll, and the upper rotating body 81a serves as a driven roll. Driving force from a drive motor 86 is transmitted to the rotating body 81b serving as the drive roll via a drive transmission mechanism 87, such as a drive transmission gear train.

[0092] <Example of retraction configuration of first transport roll> In this example, one rotating body 81a of the first transport roll 81 is provided with a retraction mechanism 88 as a retractable retraction means, as shown in Fig. 18. This retraction mechanism 88 has the same configuration (spindle 88a, support arm 88b, operation lever 88c) as the retraction mechanism 88 used in the transport roll 80 of the first embodiment. <Nip pressure setting of the first transport roll> Similar to the transport roll 80 of the first embodiment, biasing springs 114 are provided at both ends of one of the rotors 81a of the first transport roll 81 as biasing means for adjusting the nip pressure of the first transport roll 81 (corresponding to the contact pressure of the contact area CN0 of the multiple rotors 81a and 81b). The biasing springs 114 are, for example, compression coil springs, and the biasing force can be variably set by adjusting the amount of compressive deformation with an adjustment unit (not shown). This sets the nip pressure of the first transport roll 81.

[0093] -Second transport roll- <Configuration example and driving method of the second transport roll> 18 and 19, the second transport roll 82 is made up of a plurality of rotating bodies 82a and 82b that are arranged facing each other with respect to the medium S. The rotating bodies 82a and 82b that make up the second transport roll 82 have a three-layer structure of a shaft 83, an elastic layer 84, and a release layer 85, similar to the plurality of rotating bodies 81a and 81b that make up the first transport roll 81. In this example, the multiple rotating bodies 82a, 82b are arranged in pressure contact with each other, and the medium S is sandwiched and transported in the contact area CN0 between them. Here, the second transport roll 82 is configured such that, of the multiple rotating bodies 82a, 82b, the lower rotating body 82b serves as a drive roll, and the upper rotating body 82a serves as a driven roll. Driving force from a drive motor 86 is transmitted to the rotating body 82b serving as the drive roll via a drive transmission mechanism 87, such as a drive transmission gear train.

[0094] <Example of retraction configuration of second transport roll> In this example, one of the rotating bodies 82a of the second conveying roll 82 is provided with a retraction mechanism 88 (specifically, a support shaft 88a, a support arm 88b, and an operating lever 88c) as a retractable retraction means, similar to the first conveying roll 81, as shown in Figures 6 and 8(a) and (b). <Nip pressure setting of the second transport roll> Similar to the first conveying roll 81, a biasing spring 114 is provided at both ends of one of the rotating bodies 82a of the second conveying roll 82 as a biasing means for adjusting the nip pressure of the second conveying roll 82 (corresponding to the contact pressure of the contact area CN0 of the multiple rotating bodies 82a, 82b).

[0095] -First scraping roll- <Configuration example of first rubbing roll> 18 and 19, the first rubbing roll 91 is made up of a plurality of rotors 91a and 91b arranged opposite each other with respect to the medium S. In this example, the rotors 91a and 91b constituting the first rubbing roll 91 have a structure in which the surface of a solid shaft 93 made of a metal such as SUS is covered with a nonwoven fabric 94, as in the first embodiment. <Drive system for the first rubbing roll> The first rubbing roll 91 uses both rotating bodies 91a and 91b as drive rolls, as in the first embodiment. That is, the driving force from a drive motor 96 is transmitted to both rotating bodies 91a and 91b via a drive transmission mechanism 97 (specifically, 97a and 97b) such as a drive transmission gear train. Here, the drive transmission mechanisms 97a and 97b may be partially shared, or may be provided separately.

[0096] <Speed ​​condition of the first rubbing roll> As shown in Figures 18 and 19, the first rubbing roll 91 may be any roll that rubs the surface of the medium S in the opposite direction to the transport direction of the medium S at a speed v1 that is different from the transport speed v0 of the second transport roll 82. In this example, as in the first embodiment, the first rubbing roll 91 is selected so that (i) it rotates in the opposite direction to the transport direction of the medium S in the contact area CN1 of the multiple rotating bodies 91a and 91b. That is, the upper rotating body 91a rotates clockwise, and the lower rotating body 91b rotates counterclockwise. The reason for this selection is based on the viewpoint of increasing the rubbing resistance of the first rubbing roll 91. By selecting in this manner, it is possible to increase the speed difference (v0-v2) between the first rubbing roll 91 and the second transport roll 82. Here, the speed v1 of the first rubbing roll 91 may be selected appropriately, but in this example, it is set to about 5 to 10 times v0 in absolute value. In addition to (i), the first rubbing roll 91 can be made to rub the surface of the medium S in the opposite direction to the transport direction of the medium S by (ii) keeping the roll stationary in the contact area CN1, or (iii) rotating in the same direction as the transport direction of the medium S in the contact area CN1 at a speed less than the transport speed v0 of the medium S. However, it should be noted that the methods (ii) and (iii) result in a smaller rubbing resistance from the first rubbing roll 91 than the method (i).

[0097] <Example of contact and separation configuration of first rubbing roll> In this example, the first rubbing roll 91 is equipped with a first nip release mechanism 101, similar to the first embodiment. As shown in Fig. 18 and Figs. 10(a) and (b), this first nip release mechanism 101 is provided on one of the rotating bodies 91a of the first rubbing roll 91. The first nip release mechanism 101 supports both ends of the shaft 93 of the rotating body 91a, and switches the first rubbing roll 91 between a nip state (corresponding to a contact state of the multiple rotating bodies 91a and 91b) and a release state (corresponding to a non-contact state of the multiple rotating bodies 91a and 91b) based on a control signal. In this example, as shown in FIG. 10(b), the first nip release mechanism 101 has the same components (the support shaft 103, the support arm 104, and the nip release motor 105) as those in the first embodiment.

[0098] <Nip pressure setting of the first rubbing roll> 10(a) and 10(d), the first rubbing roll 91 is provided with a biasing spring 115 as a biasing means for adjusting the nip pressure (corresponding to the contact pressure in the contact area between the multiple rotating bodies 91a and 91b) of the first rubbing roll 91, as in the first embodiment. The biasing spring 115 is formed of, for example, a compression coil spring, and the biasing spring 115 is provided with an adjustment section 116 for adjusting the amount of compressive deformation.

[0099] <Adjusting the friction force of the first rubbing roll> In this example, the first rubbing roll 91 and the second transport roll 82 each come into contact with the moving medium S. At this time, when the medium S passes through the contact area CN1 of the first rubbing roll 91, a frictional force f1 is generated between the first rubbing roll 91 and the medium S, as shown in Fig. 19. On the other hand, when the medium S passes through the contact area CN0 of the second transport roll 82, a frictional force f0 is generated between the second transport roll 82 and the medium S. In this example, the friction force f0 between the multiple rotating bodies 82a, 82b constituting the second conveying roll 82 and the medium S must be greater than the friction force f1 between the multiple rotating bodies 91a, 91b constituting the first rubbing roll 91 and the medium S. Here, if the vertical resistance acting on the contact area CN0 of the second conveying roll 82 is U0, the dynamic friction coefficient between the second conveying roll 82 and the medium S is μ0, the vertical resistance acting on the contact area CN1 of the first rubbing roll 91 is U1, and the dynamic friction coefficient between the first rubbing roll 91 and the medium S is μ1, then the following can be expressed: f0=μ0·U0 f1=μ1·U1 To satisfy the condition f0>f1, the kinetic friction coefficients μ0 and μ1 are values ​​that depend on the material, etc., so the biasing forces of the biasing springs 114 and 115 that affect the vertical drag forces U0 and U1 can be adjusted taking into account the respective kinetic friction coefficients. Here, U0 is selected to optimize the transportability of the medium S, so it is preferable to adjust the biasing force of the biasing spring 115 primarily and appropriately adjust the friction force f1.

[0100] -Second rubbing roll- <Example of second rubbing roll configuration> 18 and 19, the second rubbing roll 92 is made up of a plurality of rotating bodies 92a and 92b arranged opposite each other with respect to the medium S. In this example, the rotating bodies 92a and 92b constituting the second rubbing roll 92 have the same structure (shaft 93, nonwoven fabric 94) as the first rubbing roll 91. <Drive system for the second rubbing roll> In this example, the second rubbing roll 92 uses both rotating bodies 92a, 92b as drive rolls, similar to the first rubbing roll 91. That is, the driving force from a drive motor 98 is transmitted to both rotating bodies 92a, 92b via a drive transmission mechanism 99 (specifically, 99a, 99b) such as a drive transmission gear train. Here, the drive transmission mechanisms 99a, 99b may be partially shared, or may be provided separately.

[0101] <Speed ​​condition of the second rubbing roll> As shown in Figures 18 and 19, the second rubbing roll 92 may be any roll that rubs the surface of the medium S in the same direction as the transport direction of the medium S at a speed v2 that is faster than the transport speed v0 of the first transport roll 81. In this example, the second rubbing roll 92 is selected so as to rotate in the contact area CN2 of the multiple rotating bodies 92a and 92b in the same direction as the transport direction of the medium S. That is, the upper rotating body 92a rotates counterclockwise, and the lower rotating body 92b rotates clockwise. By selecting in this manner, the speed difference (v2-v0) between the second rubbing roll 92 and the first transport roll 81 becomes larger than 0. Therefore, the medium S is transported by the first transport roll 81 at a transport speed v0. In this situation, when the medium S passes under the second rubbing roll 92, the second rubbing roll 92 ensures a rubbing action against the surface of the medium S. Here, the speed v2 of the second rubbing roll 92 may be selected as appropriate. However, it is preferable to set v2 large in order to increase the rubbing resistance of the second rubbing roll 92. In this example, it is set to an absolute value of about 5 to 10 times v0.

[0102] <Example of contact and separation configuration of second rubbing roll> In this example, the second rubbing roll 92 is equipped with a second nip release mechanism 102, similar to the first nip release mechanism 101 of the first rubbing roll 91. As shown in FIG. 18 and FIGS. 10(a) and (b), this second nip release mechanism 102 is provided on one of the rotating bodies 92a of the second rubbing roll 92. Similar to the first nip release mechanism 101, the second nip release mechanism 102 supports both ends of the shaft 93 of the rotating body 92a and switches the second rubbing roll 92 between a nip state (corresponding to a contact state of the multiple rotating bodies 92a, 92b) and a release state (corresponding to a non-contact state of the multiple rotating bodies 92a, 92b) based on a control signal. In this example, the second nip release mechanism 102 has the same components as the first nip release mechanism 101 (the support shaft 103, the support arm 104, and the nip release motor 105), as shown in FIG. 10(b).

[0103] <Nip pressure setting of the second rubbing roll> In this example, the second rubbing roll 92 is provided with a biasing spring 117 as a biasing means for adjusting the nip pressure (corresponding to the contact pressure in the contact area of ​​the multiple rotating bodies 92a, 92b) of the second rubbing roll 92, similar to the first rubbing roll 91. The biasing spring 117 is formed, for example, by a compression coil spring, and the biasing spring 117 is provided with an adjustment section 118 for adjusting the amount of compressive deformation. <Adjusting the friction force of the second rubbing roll> In this example, the second rubbing roll 92 and the first transport roll 81 each come into contact with the moving medium S. At this time, when the medium S passes through the contact area CN2 of the second rubbing roll 92, a frictional force f2 is generated between the second rubbing roll 92 and the medium S, as shown in Fig. 19. On the other hand, when the medium S passes through the contact area CN0 of the first transport roll 81, a frictional force f0 is generated between the first transport roll 81 and the medium S. In this example, the friction force f0 between the multiple rotating bodies 81a, 81b constituting the first conveying roll 81 and the medium S must be greater than the friction force f2 between the multiple rotating bodies 92a, 92b constituting the second rubbing roll 92 and the medium S. Here, if the vertical resistance acting on the contact area CN0 of the first conveying roll 81 is U0, the dynamic friction coefficient between the first conveying roll 81 and the medium S is μ0, the vertical resistance acting on the contact area CN2 of the second rubbing roll 92 is U2, and the dynamic friction coefficient between the second rubbing roll 92 and the medium S is μ2, then the following can be expressed: f0=μ0·U0 f2=μ2·U2 To satisfy the condition f0>f2, the kinetic friction coefficients μ0 and μ2 are values ​​that depend on the material, etc., so the biasing forces of the biasing springs 114 and 117 that affect the vertical drag forces U0 and U2 can be adjusted taking into account the respective kinetic friction coefficients. Here, U0 is selected to optimize the transportability of the medium S, so it is preferable to adjust the biasing force of the biasing spring 117 primarily and appropriately adjust the friction force f2.

[0104] -Positional relationship between the first and second conveying rolls and the first and second rubbing rolls- In this example, the positional relationship between the first transport roll 81, the second transport roll 82, the first rubbing roll 91 and the second rubbing roll 92 is as follows. As shown in Figure 19, if the distance between the circumferential center of the contact area CN0 of the first conveying roll 81 and the circumferential center of the contact area CN0 of the second conveying roll 82 is D, the distance between the circumferential center of the contact area CN0 of the first conveying roll 81 and the circumferential center of the contact area CN2 of the second rubbing roll 92 is D1, the distance between the circumferential center of the contact area CN2 of the second rubbing roll 92 and the circumferential center of the contact area CN1 of the first rubbing roll 91 is D2, the distance between the circumferential center of the contact area CN1 of the first rubbing roll 91 and the circumferential center of the contact area CN0 of the second conveying roll 82 is D3, and the conveying direction length of the medium S is g (see Figure 23), they are selected to satisfy the following equations (III) and (IV). D <g (III) D1,D <g / 2 (IV) However, D = D1 + D2 + D3 The circumferential center of the contact area CN0 (CN1 or CN2) refers to the intersection of a straight line connecting the axial centers of the multiple rotating bodies 81a, 81b or 82a, 82b (91a, 91b or 92a, 92b) and the contact area CN0 (CN1 or CN2).

[0105] In this example, formula (III) is a condition for transporting the medium S by the first transport roll 81 and the second transport roll 82 at a transport speed v0. Moreover, the formula (III) also serves as a condition for rubbing the entire area of ​​both the front and back surfaces of the medium S with the first rubbing roll 91 and the second rubbing roll 92. Moreover, formula (IV) is a condition for the first rubbing roll 91 and the second rubbing roll 92 to rub an area exceeding half of both the front and back surfaces of the medium S. In particular, in formula (IV), since D1 and D3 are less than half of the transport direction length g of the medium S, it is possible to maintain the transport posture of the medium S and transport it stably without providing a guide member or the like in the transport path of the medium S in the post-processing device 25. In this example, a transport roll 65c for feeding the medium S into the post-processing device 25 is disposed on the horizontal transport path 64 on the upstream side of the transport direction of the medium S from the post-processing device 25. On the other hand, a transport roll 65d for receiving the medium S from the post-processing device 25 is disposed on the downstream side of the transport direction of the medium S from the post-processing device 25. Here, in order to transport the medium S at a transport speed v0 using the feeding transport roll 65c, the first transport roll 81, the second transport roll 82, and the receiving transport roll 65c, it is necessary that the distance between the feeding transport roll 65c and the first transport roll 81, and the distance between the second transport roll 82 and the receiving transport roll 65d (specifically, the distance between the circumferential centers of the contact areas of adjacent rolls) be set shorter than the transport direction length g of the medium S.

[0106] -Aftertreatment device control system- In this embodiment, as shown in FIG. 18, a control device 120 is provided that controls each element of the image forming system 20 (image creation engine 22, medium transport system 23, fixing device 24, post-processing device 25, etc.). This control device 120 is configured with a microcomputer including various processors, similar to embodiment 1. In this example, a position sensor 130 as a position detection means is provided on the horizontal conveyance path 64 on the upstream side of the post-processing device 25 in the conveyance direction of the medium S.

[0107] In this example, the control device 120 has necessary programs installed in advance in a memory (not shown), such as an image creation program for the image forming system 20 and a control processing program for the post-processing device 25 (see FIG. 20). When a start switch (not shown) is turned on, the control device 120 executes the image creation program and sends control signals required for image creation processing to the image creation engine 22, the medium transport system 23, and the fixing device 24. Furthermore, it is now assumed that the leading edge of the medium S that has passed through the fixing device 24 has now passed through the position sensor 130. At this time, the control device 120 inputs the detection information from the position sensor 130 into the processor and executes the control processing program for the post-processing device 25. The control device 120 then sends a nip release control signal to the first nip release mechanism 101 and the second nip release mechanism 102. Furthermore, the control device 120 sends a drive control signal to the drive motors 86, 96, and 98 of the first transport roll 81, the second transport roll 82, the first rubbing roll 91, and the second rubbing roll 92.

[0108] - Aftertreatment device operation - In this example, the control device 120 executes a control process for the post-processing device 25 as shown in FIG. 20, the control device 120 determines whether the leading edge of the medium S that has passed through the fixing device 24 has passed a predetermined reference position P0. In this example, the control device 120 determines that the leading edge of the medium S has passed the reference position P0 based on a detection signal from the position sensor 130. Then, the control device 120 starts the counting operation of an internal time counter, and uses this to determine the transport position of the medium S.

[0109] <First mode> After this, the control device 120 determines whether the first rubbing roll 91, the second rubbing roll 92, the first transport roll 81, and the second transport roll 82 are arranged in the first mode. The "first mode" here refers to the operating behavior shown in FIG. 21(a). In this case, the first rubbing roll 91 is arranged in the release position, and the first transport roll 81, the second transport roll 82, and the second rubbing roll 92 are arranged in the nip position. Furthermore, the first transport roll 81, the second transport roll 82, and the second rubbing roll 92 in the nip position are driven. In this example, if the first mode is configured, the first mode is implemented. If the first mode is not configured, the control device 120 configures the first mode and then implements the first mode.

[0110] In this state, the first conveying roll 81 and the second conveying roll 82 rotate idly at a predetermined conveying speed v0 at the nip position. The second rubbing roll 92 rotates idly in the same direction as the first conveying roll 81 and the second conveying roll 82 at a speed v2 (v2 > v0) at the nip position. In contrast, the first rubbing roll 91 stops driving at the release position and is waiting. On the other hand, the medium S passes through the position sensor 130 by the feeding conveying roll 65c (see FIG. 5) and is conveyed into the post-processing device 25. Thereafter, the medium S is drawn in by the first conveying roll 81 and heads toward the second rubbing roll 92.

[0111] In the first mode, when the leading end of the medium S reaches the second rubbing roll 92, the following behavior occurs. In this example, when the medium S enters the second rubbing roll 92, the second rubbing roll 92 sandwiches the leading end of the medium S and rotates in the same direction as the first conveying roll 81 at a speed v2 (v2 > v0). Therefore, between the first conveying roll 81 and the second rubbing roll 92, the medium S is conveyed in a state of being tensioned in the conveying direction. At this time, the relationship between the frictional force f2 between the second rubbing roll 92 and the medium S and the frictional force f0 between the first conveying roll 81 and the medium S is f2 < f0. Therefore, the medium S is conveyed at the conveying speed v0 by the first conveying roll 81.

[0112] In this state, when the second rubbing roll 92 rotates in the same direction as the conveying direction of the medium S at a speed v2 in the contact area CN2, it rubs the surface of the medium S in the same direction as the conveying direction of the medium S. As a result, the rubbing operation by the second rubbing roll 92 continues from the leading end of the medium S until immediately before the medium S passes through the first conveying roll 81. Therefore, the rubbing area R2 by the second rubbing roll 92 becomes the front half area of the medium S from the leading end of the medium S to the middle of the conveying direction of the medium S (see FIGS. 22 and 23). Further, when the tip of the medium S passes through the second rubbing roll 92, the medium S is conveyed toward the position of the first rubbing roll 91. At this time, in the first mode, the first rubbing roll 91 is waiting at the release position. Therefore, the medium S conveyed by the first conveying roll 81 passes through the first rubbing roll 91 and heads toward the second conveying roll 82.

[0113] <Switching to the Second Mode> Next, the control device 120 determines whether or not the tip of the medium S has passed through the second conveying roll 82. When it is determined that the tip of the medium S has passed through the second conveying roll 82, the control device 120 switches to the second mode. The "second mode" referred to here indicates the operation behavior shown in Fig. 21(b). In this case, different from the first mode, the first rubbing roll 91 is switched to the nip position and starts driving. The first conveying roll 81, the second conveying roll 82, and the second rubbing roll 92 are the same as in the first mode. In this state, immediately after the medium S enters the second conveying roll 82, the first rubbing roll 91 sandwiches the middle portion of the medium S in the conveying direction and rotates in the opposite direction to the second conveying roll 82 at a speed v1 (|v1| > v0).

[0114] Therefore, between the first rubbing roll 91 and the second conveying roll 82, the medium S is conveyed in a state of being tensioned in the conveying direction. At this time, the relationship between the frictional force f1 between the first rubbing roll 91 and the medium S and the frictional force f0 between the second conveying roll 82 and the medium S is f1 < f0. Thus, the medium S is conveyed at the conveying speed v0 by the second conveying roll 82. In this state, when the first rubbing roll 91 rotates in the opposite direction at a speed v1 in the contact area CN1, the surface of the medium S is rubbed in the opposite direction to the conveying direction of the medium S. As a result, the rubbing operation by the first rubbing roll 91 continues until the rear end in the conveying direction of the medium S passes through the first rubbing roll 91. Therefore, the rubbing area R1 by the first rubbing roll 91 becomes the rear half area of the medium S from the middle in the conveying direction of the medium S to the rear end in the conveying direction of the medium S (see Figs. 22 and 23).

[0115] <Switching to the third mode> Thereafter, the control device 120 determines whether the trailing end of the medium S has passed the first transport roll 81. If it is determined that the trailing end of the medium S is about to pass the first transport roll 81, the control device 120 switches to the third mode. The "third mode" here refers to the operational behavior shown in FIG. 21(c). In this case, the third mode differs from the first and second modes in that the second rubbing roll 92 is switched to the release position and stops driving. At this time, the first transport roll 81, the second transport roll 82, and the first rubbing roll 91 may be the same as in the second mode.

[0116] This third mode is intended to maintain good transportability of the medium S within the post-processing device 25. If the rubbing operation by the second rubbing roll 92 continues even after the rear end of the medium S has passed the first transport roll 81, the medium S will be transported by the second rubbing roll 92 at a speed v2 (v2 > v0) when the transport operation of the medium S by the first transport roll 81 stops. In this case, the medium S is transported at a transport speed v0 by the first rubbing roll 91 and the second transport roll 82. Therefore, within the post-processing device 25, the medium S will be transported fast only by the first rubbing roll 91, and the transportability of the medium S will be impaired.

[0117] <Return to initial position> Next, the control device 120 determines whether the trailing end of the medium S has passed the second transport roll 82. In this example, when it is determined that the trailing end of the medium S has passed the second transport roll 82, the control device 120 stops driving the first transport roll 81, the second transport roll 82, and the first rubbing roll 91, and places the first rubbing roll 91 and the second rubbing roll 92 in their initial positions. In this example, the initial positions are selected, for example, to be the arrangement for the first mode (the second rubbing roll 92 is in the nip position, and the first rubbing roll 91 is in the release position).

[0118] -Example of wax rubbing treatment using post-treatment equipment- In this example, the distance D1 (see paragraph

[0104] ) between the first conveying roll 81 and the second rubbing roll 92, the distance D2 (see paragraph

[0104] ) between the second rubbing roll 92 and the first rubbing roll 91, and the distance D3 (see paragraph

[0104] ) between the first rubbing roll 91 and the second conveying roll 82 may be appropriately selected as long as they satisfy the formulas (III): D1 + D2 + D3 = D < g (the length of the medium S in the conveying direction), and formula (IV): D1, D3 < g / 2. As a specific example below, a mode where D1, D2, and D3 are substantially equally spaced will be described as an example. Figs. 22(a) to (f) show the wax rubbing process by the post-treatment device 25 in a specific example.

[0119] Fig. 22(a) shows a state where the leading end of the medium S enters the first conveying roll 81. In this case, since the first mode (see Fig. 21(a)) is implemented, the medium S is conveyed by the feeding conveying roll 65c located on the inlet side of the post-treatment device 25 and then conveyed by the first conveying roll 81. Fig. 22(b) shows a state after the leading end of the medium S enters the second rubbing roll 92. In this case, since the first mode is implemented, the rubbing operation by the second rubbing roll 92 is performed from the middle of the conveying direction of the medium S. In Fig. 22(b), R2 indicates the rubbing area (corresponding to the diagonally lower left hatched area in the figure) by the second rubbing roll 92 against the medium S. Also, since the first rubbing roll 91 stops driving and waits at the release position, the medium S passes through the first rubbing roll 91 and heads towards the second conveying roll 82.

[0120] Fig. 22(c) shows a state where the leading end of the medium S enters the second conveying roll 82. In this case, since the second mode (see Fig. 21(b)) is implemented, the first rubbing roll 91 starts driving after being arranged at the nip position. Therefore, the rubbing operation by the first rubbing roll 91 starts from the middle of the conveying direction of the medium. Note that the rubbing operation by the second rubbing roll 92 continues to be performed. FIG. 22(d) shows the state in which the rear end of the medium S passes the first transport roll 81. In this case, the mode switches to the third mode (see FIG. 21(c)), the second rubbing roll 92 is placed in the release position, and driving is stopped. During this time, the rubbing operation by the second rubbing roll 92 is performed from the front end of the medium S to halfway in the transport direction of the medium S. In addition, the rubbing operation by the first rubbing roll 91 is performed from halfway in the transport direction of the medium S toward the downstream side in the transport direction of the medium S. In FIG. 22(d), R1 indicates the rubbing area of ​​the first rubbing roll 91 against the medium S (corresponding to the hatched area diagonally downward right in the figure).

[0121] 22(e) shows the state in which the trailing end of the medium S passes the second rubbing roll 92. In this case, the third mode is still being performed. During this time, the rubbing operation by the first rubbing roll 91 is performed from midway in the transport direction of the medium S to the trailing end of the medium S. 22(e), the rubbing area R1 by the first rubbing roll 91 is approximately in the range of g-L3, while the rubbing area R2 by the second rubbing roll 92 is approximately in the range of g-L1. FIG. 22( f ) shows the state immediately after the trailing end of the medium S has passed the second transport roll 82 . In this case, the first conveying roll 81, the second conveying roll 82 and the first rubbing roll 91 stop driving, and the first rubbing roll 91 and the second rubbing roll 92 return to their initial positions (in this example, the first mode arrangement). The leading edge of the medium S that has passed through the post-processing device 25 is conveyed while being sandwiched between receiving conveying rolls 65d located on the exit side of the post-processing device 25. Therefore, the conveyance of the medium S discharged from the post-processing device 25 is maintained good.

[0122] 23, the wax rubbing process by the post-processing device 25 rubs both the front and back surfaces of the medium S in a rubbing area R1 by the first rubbing roll 91 and a rubbing area R2 by the second rubbing roll 92. In this example, since R1 + R2 ≈ 2g - L1 - L3 (g > L) is satisfied, it can be understood that the wax rubbing process by the post-processing device 25 is realized by rubbing the entire area of ​​both the front and back surfaces of the medium S. Also, in this example, the rubbing areas R1 and R2 are partially overlapping in the middle of the transport direction of the medium S, and are achieved by satisfying the relationship R1 ≈ R2.

[0123] ◎Deformation mode (1) In this embodiment, when the first rubbing roll 91 (or the second rubbing roll 92) is placed at the release position, the driving of the multiple rotating bodies 91a, 91b (or 92a, 92b) is stopped. However, the first rubbing roll 91 (or the second rubbing roll 92) may be placed at the release position without stopping the driving of the multiple rotating bodies 91a, 91b (or 92a, 92b). (2) In this embodiment, the arrangement for the first mode is selected as the initial position of post-processing device 25, but a different arrangement may also be used.

[0124] Embodiment 3 FIG. 24 shows the main part of a post-processing device according to the third embodiment. In the figure, the basic configuration of post-processing device 25 is substantially the same as that of embodiment 1, but unlike embodiment 1, this embodiment selectively performs wax rubbing processing depending on the type of medium S. Note that components similar to those in embodiment 1 are assigned the same reference numerals as those in embodiment 1, and detailed description thereof will be omitted here. In the figure, reference numeral 140 denotes a medium type discrimination device that discriminates the type of medium S. This medium type discrimination device 140 discriminates whether the medium S is a first type of medium. Here, the first type of medium S is selected from among the media S that have passed through the fixing device 24, and is a type of medium in which the wax transferred to the front or back surface is visible. A representative embodiment of the first type of medium S is a film medium with a transparent surface. In this example, the media type discrimination device 140 may be configured to discriminate the media specified by the user of the image forming system 20 using a discrimination unit within the control device 120, or may be configured to directly detect the physical properties (smoothness (surface roughness, air permeability), electrical resistance, surface gloss, etc.)) of the media S transported by the media transport system 23 to discriminate the type of media S.

[0125] In this example, the control device 120 determines whether the medium S is a first type of medium based on the discrimination signal from the medium type discriminator 140. If the control device 120 determines that the medium S is the first type of medium, the post-processing device 25 performs the wax rubbing process. On the other hand, if the control device 120 determines that the medium is a medium other than the first type of medium, the post-processing device 25 does not perform the wax rubbing process. Here, when performing the wax rubbing process using the post-processing device 25, as shown in Figure 25(a), the control device 120 controls the conveying roll 80, the first rubbing roll 91, and the second rubbing roll 92, in approximately the same manner as in embodiment 1, and the rubbing operation is performed by the first rubbing roll 91 and the second rubbing roll 92. On the other hand, when the post-processing device 25 does not perform the wax rubbing process, the control device 120 may be configured to perform only the transport operation by the transport roll 80, as shown in FIG. 25(b). At this time, the first rubbing roll 91 and the second rubbing roll 92 may be placed in the release position and stopped from being driven. As a result, the medium S that does not require the wax rubbing process is transported through the post-processing device 25 by the transport roll 80 without being subjected to the rubbing operation by the first rubbing roll 91 and the second rubbing roll 92. In this embodiment, a post-processing device 25 having a configuration substantially similar to that of embodiment 1 is employed, but this is not limited to this, and it is of course possible to employ a post-processing device 25 having a configuration substantially similar to that of embodiment 2, for example.

[0126] Embodiment 4 FIG. 26 is an explanatory diagram showing a main part of a post-processing device according to the fourth embodiment. In the figure, the basic configuration of post-processing device 25 is substantially the same as in embodiment 3, in that wax rubbing processing is selectively performed depending on the type of medium S, but is different from embodiment 3. Note that components similar to those in embodiment 3 are assigned the same reference numerals as in embodiment 3, and detailed description thereof will be omitted here. In the figure, reference numeral 140 denotes a medium type discriminating device similar to that of the third embodiment. In this example, a branched conveying path 150 that branches off from the horizontal conveying path 64 is provided between the fixing device 24 and the post-processing device 25 on the horizontal conveying path 64. After branching off from the horizontal conveying path 64, the branched conveying path 150 extends in a substantially horizontal direction toward the discharge opening 21b on the side wall of the unit housing 21. An appropriate number of conveying rolls 151 for conveying the medium S are provided on the branched conveying path 150. A switching gate 152 is provided as a switching means at the branch point between the horizontal conveying path 64 and the branch conveying path 150. This switching gate 152 switches the conveying path of the medium S between the horizontal conveying path 64 and the branch conveying path 150 by a switching motor 153.

[0127] In this example, the control device 120 determines whether the medium S is a first type of medium based on the discrimination signal from the medium type discriminator 140. If the control device 120 determines that the medium S is the first type of medium, the post-processing device 25 performs the wax rubbing process. On the other hand, if the control device 120 determines that the medium is a medium other than the first type of medium, the post-processing device 25 does not perform the wax rubbing process. Here, when the wax rubbing process is performed by the post-processing device 25, the control device 120 controls the switching motor 153, and the switching gate 152 switches the transport path of the medium S to the horizontal transport path 64. As a result, the medium S is transported to the post-processing device 25, and the post-processing device 25 performs the wax rubbing process. On the other hand, when the wax rubbing process by post-processing device 25 is not to be performed, control device 120 controls switching motor 153 to switch the transport path of medium S to branch transport path 150 using switching gate 152. As a result, medium S is discharged from discharge port 21b of unit housing 21 via branch transport path 150 without passing through post-processing device 25. In this embodiment, a post-processing device 25 having a configuration substantially similar to that of embodiment 1 is employed, but this is not limited to this, and it is of course possible to employ a post-processing device 25 having a configuration substantially similar to that of embodiment 2, for example. [Example]

[0128] Example 1 In Example 1, the wax rubbing process is carried out using the post-processing device 25 of the image forming system 20 according to the first embodiment. FIG. 27(a) shows a photomicrograph (×150) of the surface condition of a medium (transparent film medium) that has passed through the fixing device and before post-processing by the post-processing device 25. FIG. FIG. 27(c) shows a photomicrograph (×150) of the surface condition of a medium (transparent film medium) that has passed through the fixing device and has been post-processed by the post-processing device 25. When evaluating the post-processing performed by the post-processing device 25, the cross-sectional state of the medium S before post-processing, as shown in FIG. 27(a), was confirmed, and the results shown in FIG. 27(b) were obtained. In FIG. 27(b), it was confirmed that the wax W transferred to the medium S was present in large quantities as granular lumps Wa (for example, lumps with a diameter of about 5 μm and a thickness of about 0.3 μm). In this case, the granular lumps Wa scatter the light reflected from or transmitted through the medium S, making it visible. These granular lumps Wa are noticeable as surface stains on the medium S, and there is a concern that they may also lead to image defects in toner images. In contrast, when the cross-sectional state of the medium S after post-processing by the post-processing device 25 was examined as shown in FIG. 27(c), the results shown in FIG. 27(d) were obtained. In FIG. 27(d), it was confirmed that the wax W transferred onto the medium S had been transformed into a thin, smooth layer Wb (for example, a layer of approximately 0.1 μm thickness over a circular area with a diameter of 30 μm) by the rubbing process of the post-processing device 25. In this case, the thin layer Wb does not scatter like the granular lumps Wa, and the wax is difficult to see. This effectively reduces the risk of the wax transferred to the medium S appearing as surface contamination.

[0129] (Addendum) (((1))) one or more conveying means for nipping and conveying the medium at a predetermined conveying speed after the medium has passed through a fixing means for fixing an image formed by an imaging material containing wax by applying heat and pressure to the image; a first rubbing means that is located upstream of any one of the conveying means in the medium conveying direction and that rubs the surface of the medium in the opposite direction to the medium conveying direction at a speed different from the conveying speed; a second rubbing means located downstream of any one of the transport means in the transport direction of the medium, and configured to rub the surface of the medium in the same direction as the transport direction of the medium at a speed faster than the transport speed; A post-processing device comprising: (((2))) In the post-processing device described in (((1))), one conveying means for nipping and conveying the medium at a predetermined conveying speed after the medium has passed through a fixing means for fixing an image formed by an imaging material containing wax by applying heat and pressure to the image; the first rubbing means, which is located upstream of the transport means in the transport direction of the medium and which rubs the surface of the medium in the opposite direction to the transport direction of the medium at a speed different from the transport speed; the second rubbing means, which is located downstream of the transport means in the transport direction of the medium and which rubs the surface of the medium in the same direction as the transport direction of the medium at a speed faster than the transport speed; A post-treatment device characterized by comprising ((3)) In the post-treatment device according to ((1)), a first conveying means for sandwiching and conveying the medium after passing through a fixing means for fixing the image on the medium holding the image formed by an imaging material containing wax by heating and pressing, at a predetermined conveying speed; a second conveying means located on the downstream side in the conveying direction of the medium from the first conveying means, for sandwiching and conveying the medium at the same speed as the conveying speed; a first rubbing means located on the downstream side in the conveying direction of the medium from the first conveying means, and also located on the upstream side in the conveying direction of the medium from the second conveying means, for rubbing the surface of the medium in a direction opposite to the conveying direction of the medium at a speed different from the conveying speed; a second rubbing means located on the downstream side in the conveying direction of the medium from the first conveying means, and also located on the upstream side in the conveying direction of the medium from the first rubbing means, for rubbing the surface of the medium in the same direction as the conveying direction of the medium at a speed higher than the conveying speed; A post-treatment device characterized by comprising ((4)) In the post-treatment device according to ((2)), A post-treatment device, characterized in that the distance between the rubbing portion of the first rubbing means and the rubbing portion of the second rubbing means is shorter than the length in the conveying direction of the medium. ((5)) In the post-treatment device according to ((2)) or ((4)), when the distances between the rubbing portions of the first rubbing means or the second rubbing means and the sandwiching portions of the conveying means are L1 and L2, and the length in the conveying direction of the medium is g, a post-treatment device characterized by satisfying L1, L2 < g / 2. ((6)) In the post-treatment device according to ((3)), A post-treatment device, characterized in that the distance between the sandwiching portion of the first conveying means and the sandwiching portion of the second conveying means is shorter than the length in the conveying direction of the medium. ((7)) In the post-processing device according to any one of (((1))) to (((6))), the conveying means comprises a plurality of rotating bodies arranged opposite to each other with respect to the medium, The post-processing device is characterized in that the first rubbing means and the second rubbing means are arranged opposite each other with respect to the medium and comprise a plurality of rotating bodies that can be moved toward and away from each other between a contact position and a non-contact position. (((8))) In the post-processing device described in (((7))), A post-processing device characterized in that the frictional force between the plurality of rotating bodies constituting the conveying means and the medium is greater than the frictional force between the plurality of rotating bodies constituting the first rubbing means and the second rubbing means and the medium. (((9))) In the post-processing device described in (((7))), 10. The post-processing device, wherein the conveying means, the first rubbing means, and the second rubbing means each have an adjustment unit that adjusts the contact pressure of the plurality of rotating bodies. (((10))) In the post-processing device described in (((2))), a position detection means for detecting a transport position of the medium; a control unit that controls the rubbing operations of the first rubbing unit and the second rubbing unit based on position information from the position detection unit. (((11))) In the post-processing device described in (((10))), The control means positions the first rubbing means at a contact position where it contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the transport means, and starts the rubbing operation by the first rubbing means. (((12))) In the post-processing device according to (((10))) or (((11))), The control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means. (((13))) In the post-processing device according to any one of (((10))) to (((12))), The control means is characterized in that immediately after the trailing end of the medium in the transport direction passes the first rubbing means, the control means positions the first rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium, and stops the rubbing operation by the first rubbing means. (((14))) In the post-processing device according to any one of (((10))) to (((13))), The control means positions the second rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the transport means, and stops the rubbing operation by the second rubbing means. (((15))) In the post-processing device described in (((3))), a position detection means for detecting a transport position of the medium; a control unit that controls the rubbing operations of the first rubbing unit and the second rubbing unit based on position information from the position detection unit. (((16))) In the post-processing device described in (((15))), The post-processing device is characterized in that the control means positions the first rubbing means at a contact position where it contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the second transport means, and starts the rubbing operation by the first rubbing means. (((17))) In the post-processing device according to (((15))) or (((16))), The control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means. (((18))) In the post-processing device according to any one of (((15))) to (((17))), The control means positions the second rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the first transport means, and stops the rubbing action by the second rubbing means. (((19))) In the post-processing device according to any one of (((15))) to (((18))), The control means positions the first rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the first rubbing means, and stops the rubbing operation by the first rubbing means. (((20))) In the post-processing device according to any one of (((1))) to (((19))), a determining means for determining whether the type of medium being used is a predetermined first type of medium; a selection means for selecting whether to perform a rubbing operation by the first rubbing means or the second rubbing means when the discrimination means discriminates that the medium is the first type; A post-processing device comprising: (((twenty one))) In the post-processing device described in (((20))), A post-processing device, wherein the first type of medium is a type of medium in which wax transferred to the front surface or back surface is made visible. (((twenty two))) In the post-processing device described in (((21))), 10. A post-processing device, wherein the first type of medium is a film medium having a smooth surface. (((twenty three))) In the post-processing device according to any one of (((20))) to (((22))), The post-processing device is characterized in that the selection means selects not to perform rubbing operations by the first rubbing means and the second rubbing means when the discrimination means determines that the medium is of a type other than the first type. (((twenty four))) an image forming means for holding an image on a medium using an image forming material containing wax; a fixing unit that fixes the image formed by the image forming unit onto the medium by applying heat and pressure; a post-processing device according to any one of (((1))) to (((23))) that post-processes the medium after it has passed through the fixing device; An image forming system comprising:

[0130] According to the post-processing device of (((1))), the wax on the medium is rubbed off and smoothed while the medium is being transported, making the wax less visible over the entire surface of the medium. According to the post-processing device of (((2))), it is possible to provide a configuration in which the entire surface of the medium is rubbed using one conveying means, a first rubbing means, and a second rubbing means. According to the post-processing device of (((3))), a configuration can be provided in which the entire surface of the medium is rubbed using the first conveying means, the second conveying means, the first rubbing means, and the second rubbing means. According to the post-processing device of (((4))), by appropriately arranging the first rubbing means and the second rubbing means, it is possible to rub the entire surface of the medium. According to the post-processing device of (((5))), the transport posture of the medium passing through the first rubbing means, the transport means, and the second rubbing means can be stabilized compared to when L1, L2≧g / 2. According to the post-processing device of (((6))), the entire surface of the medium can be rubbed by arranging the first rubbing means and the second rubbing means within the appropriately positioned first conveying means and the second conveying means. According to the post-processing device of (((7))), the typical aspects of the conveying means, the first rubbing means and the second rubbing means can be easily configured. According to the post-processing device of (((8))), the rubbing operation by the first rubbing means and the second rubbing means can be realized under the same speed conditions as the medium conveying speed by the conveying means. According to the post-processing device of (((9))), the frictional force between the medium and the multiple rotating bodies constituting the conveying means, and the frictional force between the medium and the multiple rotating bodies constituting the first rubbing means or the second rubbing means can be easily adjusted compared to when the post-processing device does not have an adjustment unit. According to the post-processing device of (((10))), in an aspect equipped with one conveying means, a first rubbing means, and a second rubbing means, the rubbing operations by the first rubbing means and the second rubbing means can be distributed between areas before and after the conveying direction of the medium based on the conveying position of the medium. According to the post-processing device of (((11))), the first rubbing means can perform a rubbing operation on the rear area in the transport direction of the medium without impairing the transportability of the medium by the transport means. According to the post-processing device of (((12))), the second rubbing means can perform a rubbing operation on the front area of ​​the medium in the transport direction without impairing the transportability of the medium by the transport means. According to the post-processing device of (((13))), preparations can be made in advance for post-processing of wax on subsequent media. According to the post-processing device of (((14))), when the trailing end of the medium in the transport direction passes through the transport means, it is possible to prevent a mismatch between the rubbing operation speed by the second rubbing means and the transport speed of the medium by the transport means located further downstream. According to the post-processing device of (((15))), in an aspect equipped with a first conveying means, a second conveying means, a first rubbing means and a second rubbing means, the rubbing operations by the first rubbing means and the second rubbing means can be distributed between areas before and after the transport direction of the medium based on the transport position of the medium. According to the post-processing device of (((16))), the first rubbing means can perform a rubbing operation on the rear area in the transport direction of the medium without impairing the transportability of the medium by the second transport means. According to the post-processing device of (((17))), the second rubbing means can perform a rubbing operation on the front area of ​​the medium in the transport direction without impairing the transportability of the medium by the first transport means. According to the post-processing device of (((18))), it is possible to eliminate the situation in which the medium transport speed increases when the rubbing operation by the second rubbing means is continued after the trailing end of the medium in the transport direction has passed the first transport means. According to the post-processing device of (((19))), it is possible to prevent the first rubbing means from impairing the transportability of the medium in advance. According to the post-processing device of (((20))), post-processing with wax can be performed only on media that require post-processing with wax. According to the post-processing device of (((21))), even if the wax transferred to the surface of the medium becomes visible, the wax can be spread thinly by rubbing it, making the wax on the medium less visible. According to the post-processing device of (((22))), when the surface of a film medium is smooth, the visualization phenomenon caused by wax transferred to the surface of the medium becomes noticeable, but this can be easily made less visible. According to the post-processing device of (((23))), post-processing of wax can be omitted for media that do not require post-processing of wax. According to the image forming system of (((24))), it is possible to construct an image forming system including a post-processing device that can smooth the wax on the medium by rubbing it while transporting the medium, making the wax less visible over the entire surface of the medium. [Explanation of symbols]

[0131] 1... post-processing device, 2... conveying means, 2a, 2b... rotating body, 3... first conveying means, 3a, 3b... rotating body, 4... second conveying means, 4a, 4b... rotating body, 6... first rubbing means, 6a, 6b... rotating body, 7... second rubbing means, 7a, 7b... rotating body, 8... position detection means, 9... control means, 10... discrimination means, 11... selection means, 12... imaging means, 13... fixing means, S... medium, G... image, L... distance between rubbing portion of first rubbing means and rubbing portion of second rubbing means, L1... distance between rubbing portion of first rubbing means and clamping portion of conveying means, L2... distance between rubbing portion of second rubbing means and clamping portion of conveying means, g... length of medium in conveying direction, D... distance between clamping portion of first conveying means and clamping portion of second conveying means

Claims

1. one or more conveying means for nipping and conveying the medium at a predetermined conveying speed after the medium has passed through a fixing means for fixing an image formed by an imaging material containing wax by applying heat and pressure to the image; a first rubbing means located upstream of any one of the transport means in the transport direction of the medium, and configured to rub the surface of the medium in a direction opposite to the transport direction of the medium at a speed different from the transport speed; a second rubbing means positioned downstream of any one of the conveying means in the medium conveying direction, and configured to rub the surface of the medium in the same direction as the medium conveying direction at a speed faster than the conveying speed; A post-processing device comprising:

2. 2. The post-processing device according to claim 1, one conveying means for nipping and conveying the medium at a predetermined conveying speed after the medium has passed through a fixing means for fixing an image formed by an imaging material containing wax by applying heat and pressure to the image; the first rubbing means, which is located upstream of the transport means in the transport direction of the medium and which rubs the surface of the medium in a direction opposite to the transport direction of the medium at a speed different from the transport speed; the second rubbing means, which is located downstream of the transport means in the transport direction of the medium and which rubs the surface of the medium in the same direction as the transport direction of the medium at a speed faster than the transport speed; A post-processing device comprising:

3. 2. The post-processing device according to claim 1, a first conveying means for nipping and conveying the medium at a predetermined conveying speed after the medium has passed through a fixing means for fixing an image formed by an imaging material containing wax by applying heat and pressure to the image; a second conveying means located downstream of the first conveying means in the conveying direction of the medium, and configured to sandwich and convey the medium at the same speed as the conveying speed; the first rubbing means, which is located downstream of the first transport means in the transport direction of the medium and upstream of the second transport means in the transport direction of the medium, and which rubs the surface of the medium in the opposite direction to the transport direction of the medium at a speed different from the transport speed; the second rubbing means, which is located downstream of the first transport means in the transport direction of the medium and upstream of the first rubbing means in the transport direction of the medium, and which rubs the surface of the medium in the same direction as the transport direction of the medium at a speed faster than the transport speed; A post-processing device comprising:

4. 3. The post-processing device according to claim 2, 10. A post-processing device, wherein a distance between the rubbing portion of said first rubbing means and the rubbing portion of said second rubbing means is shorter than a length of said medium in a transport direction.

5. The post-processing device according to claim 4, A post-processing device characterized in that, when the distance between the rubbing portion of the first rubbing means or the second rubbing means and the clamping portion of the conveying means is L1 or L2, and the length of the medium in the conveying direction is g, L1, L2 < g / 2 is satisfied.

6. 4. The post-processing device according to claim 3, 10. A post-processing device, wherein the distance between the clamping portion of the first conveying means and the clamping portion of the second conveying means is shorter than the length of the medium in the conveying direction.

7. 2. The post-processing device according to claim 1, the conveying means comprises a plurality of rotating bodies arranged opposite to each other with respect to the medium, a first rubbing means for rubbing the medium with the second rubbing means; a second rubbing means for rubbing the medium with the first rubbing means; a second rubbing means for rubbing the medium with the second rubbing means;

8. The post-processing device according to claim 7, A post-processing device characterized in that the frictional force between the plurality of rotating bodies constituting the conveying means and the medium is greater than the frictional force between the plurality of rotating bodies constituting the first rubbing means and the second rubbing means and the medium.

9. The post-processing device according to claim 7, 10. The post-processing device, wherein the conveying means, the first rubbing means, and the second rubbing means each have an adjusting unit that adjusts the contact pressure of the plurality of rotating bodies.

10. 3. The post-processing device according to claim 2, a position detection means for detecting a transport position of the medium; a control unit that controls the rubbing operations of the first rubbing unit and the second rubbing unit based on the position information from the position detection unit.

11. The post-processing device according to claim 10, The control means positions the first rubbing means at a contact position where it contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the transport means, and starts the rubbing operation by the first rubbing means.

12. The post-processing device according to claim 10, The control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means.

13. The post-processing device according to claim 10, The control means is characterized in that immediately after the trailing end of the medium in the transport direction passes the first rubbing means, the control means positions the first rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium, and stops the rubbing operation by the first rubbing means.

14. The post-processing device according to claim 10, The control means is characterized in that it positions the second rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the transport means, and stops the rubbing operation by the second rubbing means.

15. 4. The post-processing device according to claim 3, a position detection means for detecting a transport position of the medium; a control unit that controls the rubbing operations of the first rubbing unit and the second rubbing unit based on the position information from the position detection unit.

16. 16. The post-processing device according to claim 15, The post-processing device is characterized in that the control means positions the first rubbing means at a contact position where it contacts the surface of the medium immediately after the leading edge of the medium in the transport direction enters the second transport means, and starts the rubbing operation by the first rubbing means.

17. The post-processing device according to claim 15, The control means positions the second rubbing means at a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the second rubbing means, and starts the rubbing operation by the second rubbing means.

18. The post-processing device according to claim 15, The control means is characterized in that it positions the second rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium just before the trailing end of the medium in the transport direction passes through the first transport means, and stops the rubbing operation by the second rubbing means.

19. 16. The post-processing device according to claim 15, The control means positions the first rubbing means at a non-contact position away from a contact position where it contacts the surface of the medium before the leading edge of the medium in the transport direction reaches the first rubbing means, and stops the rubbing operation by the first rubbing means.

20. 2. The post-processing device according to claim 1, a determining means for determining whether the type of medium being used is a predetermined first type of medium; a selection means for selecting whether to perform a rubbing operation by the first rubbing means or the second rubbing means when the determination means determines that the medium is the first type; A post-processing device comprising:

21. 21. The post-processing device according to claim 20, 10. A post-processing device according to claim 9, wherein the first type of medium is a type of medium on whose front or back surface the wax transferred is made visible.

22. 22. The post-processing device according to claim 21, 10. A post-processing device according to claim 9, wherein the first type of media is a film media having a smooth surface.

23. 21. The post-processing device according to claim 20, The post-processing device is characterized in that the selection means selects not to perform rubbing operations by the first rubbing means and the second rubbing means when the discrimination means determines that the medium is of a type other than the first type.

24. an image forming means for holding an image on a medium using an image forming material containing wax; a fixing unit that fixes the image formed by the image forming unit onto the medium by applying heat and pressure; a post-processing device according to any one of claims 1 to 23, which performs post-processing on the medium after passing through the fixing device; An image forming system comprising:

Images