Booklet making apparatus and image forming system

Abstract

To reduce adhesion of unintended toner to a cover of a booklet.SOLUTION: The holding means holds a sheet bundle composed of one or a plurality of sheets on which a toner image by adhesive toner is formed in an adhesive area. The pressurizing unit applies pressure to the sheet bundle, and the heating unit applies heat to the toner image of the adhesive toner formed in the adhesive area of the sheet. The heating means executes heating processing every time the sheet bundle is stacked on the holding means. A storage elastic modulus of a toner image formed on a target sheet closest to the heating means in the N-1th sheet bundle is higher than a storage elastic modulus of a toner image formed on another sheet closest to the heating means in each of the first sheet bundle to the N-2th sheet bundle.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a booklet producing apparatus and an image forming system. [Background technology]

[0002] Booklet production devices create booklets by stapling multiple sheets with printed images using an electric stapler. However, metal staples hinder the recycling of booklets. Patent Document 1 proposes a post-processing device that forms an adhesive toner image on a sheet along with an image prepared by a user, and then stacks multiple sheets and applies heat and pressure to create a booklet (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-237291 Summary of the Invention [Problem to be solved by the invention]

[0004] There are cases where adhesive toner adheres to the thermocompression unit of a post-processing device. In such cases, the adhesive toner is transferred from the thermocompression unit to the cover (front cover or back cover) of a booklet, causing the cover to become soiled with the adhesive toner. Therefore, an object of the present invention is to reduce the adhesion of unintended toner to the cover of a booklet. [Means for solving the problem]

[0005] The present invention is, for example, a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on an adhesive area using adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; and a discharge means for discharging the booklet when the booklet consisting of the N sheet bundle is completed, the heating means performs a heating process every time a sheet stack is stacked on the holding means, Provided is a booklet production device in which the storage elastic modulus of a toner image made of the adhesive toner formed on the target sheet closest to the heating means in the N-1th sheet bundle, which is second closest to the heating means in the booklet, is higher than the storage elastic modulus of a toner image made of the adhesive toner formed on any sheet included in another sheet bundle in the booklet that is located farther from the heating means than the N-1th sheet bundle. [Effects of the Invention]

[0006] The present invention reduces the unintended deposition of toner on the booklet cover. [Brief explanation of the drawings]

[0007] [Figure 1] A diagram illustrating an image forming system [Figure 2] FIG. 1 is a diagram illustrating adhesive regions provided on a sheet. [Figure 3] Diagram explaining the intermediate loading section [Figure 4] Diagram explaining the thermocompression bonding unit [Figure 5] A diagram showing the stacked state of sheet bundles [Figure 6] Diagram explaining the transfer and cleaning of contaminated toner [Figure 7] FIG. 1 is a diagram illustrating a control unit of an image forming system. [Figure 8] Flowchart showing a booklet creation method according to the first embodiment [Figure 9] A diagram illustrating an image forming system [Figure 10] FIG. 1 is a diagram illustrating the relationship between heating temperature and storage modulus of toner. [Figure 11]FIG. 10 is a diagram showing a stacked state of sheet bundles in Example 2. [Figure 12] Diagram explaining how to clean dirty toner [Figure 13] Flowchart showing a booklet creation method according to a second embodiment [Figure 14] Diagram explaining cleaning paper [Figure 15] Flowchart showing cleaning control in the third embodiment [Figure 16] A diagram illustrating an image forming system DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0009] Example 1 1. Image forming system As shown in FIG. 1, the image forming system 1 has an image forming apparatus 100 and a post-processing apparatus 130. The post-processing apparatus 130 is a sheet processing apparatus connected to the image forming apparatus 100. The image forming apparatus 100 forms an image on a sheet S, which is a recording material. The intermediate conveying unit 120 conveys the sheet S on which the image has been formed to the post-processing apparatus 130. The post-processing apparatus 130 performs post-processing on the sheet S as necessary and outputs it. Note that the image forming system 1 may be understood as a booklet production apparatus, and the post-processing apparatus 130 may be understood as a booklet production apparatus. The image forming system 1 may also be called an image forming apparatus.

[0010] The image forming apparatus 100 includes a fixing device 6, a sheet cassette 8, an image forming unit 10, and a housing 19 that houses these components. The image forming unit 10 forms a toner image on a sheet S fed from the sheet cassette 8. The fixing device 6 performs a fixing process to fix the toner image on the sheet S.

[0011] The sheet cassette 8 is provided at the bottom of the image forming apparatus 100. The sheet cassette 8 is inserted into the housing 19 so as to be removable, and can store a large number of sheets S. In this embodiment, it is assumed that the maximum size of the sheet S on which an image can be formed is A4 size (297 mm length x 210 mm width). The long side of the A4 size sheet S is parallel to the conveying direction of the sheet S. A feed roller 81 feeds the sheet S from the sheet cassette 8 and passes the sheet S to a pair of conveying rollers 82. The multi-tray 20 can also feed the sheets S one by one.

[0012] The image forming unit 10 is a tandem electrophotographic unit equipped with four process cartridges 7n, 7y, 7m, and 7c, an exposure device 2, and a transfer unit 3. YMC stands for yellow, magenta, and cyan, respectively. N stands for powder adhesive. Hereinafter, as an example, the powder adhesive will be referred to as adhesive toner Tn. The letters NYMC, which indicate the toner color, may be omitted from the reference numerals. The adhesive toner may be transparent or black. When the adhesive toner is transparent, black is achieved by appropriately mixing yellow, magenta, and cyan (process black). The type (material) of the toner used as the yellow, magenta, and cyan toners and adhesive toner is, for example, thermoplastic resin. Examples of thermoplastic resins include polyester resin, vinyl resin, acrylic resin, and styrene-acrylic resin. The process cartridges 7n, 7y, 7m, and 7c allow multiple components responsible for the image formation process to be replaced as a single unit. In other words, the process cartridges 7n, 7y, 7m, and 7c are formed by integrating multiple parts. Note that the arrangement of the process cartridges 7n, 7y, 7m, and 7c in the rotation direction of the transfer belt 30 is merely an example. The process cartridge 7n may be disposed closer to the secondary transfer roller 5 than the process cartridges 7y, 7m, and 7c.

[0013] The process cartridges 7n, 7y, 7m, and 7c have corresponding developing devices Kn, Ky, Km, and Kc, photosensitive drums Dn, Dy, Dm, and Dc, and charging rollers Cn, Cy, Cm, and Cc. The process cartridges 7n, 7y, 7m, and 7c have substantially the same structure, except for the type of toner.

[0014] The developing devices Ky, Km, and Kc each have a container for storing powder (e.g., toner) and an application roller (application sleeve) for applying the powder to the photosensitive drums Dn, Dy, Dm, and Dc. More specifically, the developing devices Ky, Km, and Kc store yellow, magenta, and cyan toners for forming a visible image on the sheet S. The developing device Kn stores adhesive toner Tn. The adhesive toner Tn is used to form a user image (document image) and to thermocompress multiple sheets S together in the post-processing device 130. An image made of the adhesive toner Tn is formed on the photosensitive drum Dn by development using the adhesive toner Tn.

[0015] The image forming unit 10 may have a fifth process cartridge that uses adhesive toner or black toner. The type and number of printing toners can be changed depending on the application of the image forming apparatus 100.

[0016] The charging rollers Cn, Cy, Cm, and Cc are chargers that uniformly charge the surfaces of the corresponding photosensitive drums Dn, Dy, Dm, and Dc. The exposure device 2 is located below the process cartridges 7n, 7y, 7m, and 7c and above the sheet cassette 8. The exposure device 2 irradiates the photosensitive drums Dn, Dy, Dm, and Dc with corresponding laser beams Jn, Jy, Jm, and Jc to form electrostatic latent images. The exposure device 2 may also be called an optical scanning device.

[0017] The developing devices Kn, Ky, Km, and Kc adhere toner to the electrostatic latent images on the photosensitive drums Dn, Dy, Dm, and Dc to form toner images. The developing devices Kn, Ky, Km, and Kc may also be referred to as developing devices.

[0018] The transfer unit 3 includes a transfer belt 30 as an intermediate transfer body (secondary image carrier). The transfer belt 30 is an endless belt wound around an inner roller 31 and a tension roller 32. The outer peripheral surface (image forming surface) of the transfer belt 30 faces the photosensitive drums Dn, Dy, Dm, and Dc. Primary transfer rollers Fn, Fy, Fm, and Fc are arranged on the inner peripheral side of the transfer belt 30 so as to face the photosensitive drums Dn, Dy, Dm, and Dc.

[0019] The primary transfer rollers Fn, Fy, Fm, and Fc transfer the toner images from the corresponding photosensitive drums Dn, Dy, Dm, and Dc to the transfer belt 30. The primary transfer rollers Fn, Fy, Fm, and Fc may also be called primary transfer devices. As the transfer belt 30 rotates counterclockwise, the toner images are transported to the secondary transfer unit.

[0020] The secondary transfer roller 5 is disposed opposite the inner roller 31, and a transfer nip 52 is formed between the secondary transfer roller 5 and the transfer belt 30. The transfer nip 52 transfers a toner image from the transfer belt 30 to the sheet S. The transfer nip 52 may also be called a secondary transfer portion. The cleaning blade 71 is a cleaning member for cleaning toner remaining on the transfer belt 30. The toner scraped off by the cleaning blade 71 is accumulated in a collection container (not shown).

[0021] A fixing device 6 is disposed above the secondary transfer roller 5 (downstream in the conveying direction of the sheet S). The fixing device 6 applies heat and pressure to the sheet S passing through a fixing nip 61. This causes the toner image to be fixed onto the sheet S. The fixing device 6 has a fixing heater 62 for heating the toner image and the sheet S. The fixing heater 62 is, for example, a halogen heater or a ceramic heater.

[0022] As shown in FIG. 1, the switching guide 33 is a flap-shaped guide member provided downstream of the fixing device 6 in the conveying direction of the sheet S. When a single-sided printing mode in which an image is formed on one side of the sheet S is selected, the switching guide 33 guides the sheet S to a discharge roller 34. When a double-sided printing mode in which an image is formed on both sides of the sheet S is selected, the switching guide 33 guides the sheet S, with an image formed on one side, to a switchback roller pair 35. The switchback roller pair 35 conveys the sheet S in a first direction. When the rear end of the sheet S is in a state in which it can enter the double-sided conveying path 36, the switchback roller pair 35 starts to reverse. As a result, the sheet S is conveyed to the double-sided conveying path 36. The double-sided conveying path 36 conveys the sheet S again to the secondary transfer unit. As a result, an image is formed on the second side of the sheet S.

[0023] The discharge rollers 34 transport the sheet S to an intermediate transport unit 120. The intermediate transport unit 120 has a pair of transport rollers 121 and 122. The pair of transport rollers 121 and 122 transport the sheet S to a post-processing device 130.

[0024] 2. After-treatment device The post-processing device 130 is a floor-standing sheet processing device and includes a mechanism for buffering a plurality of sheets, a mechanism for aligning a plurality of sheets, and a mechanism for bonding (thermocompression bonding) a sheet stack.

[0025] Hereinafter, the end of the sheet S on the front side in the conveying direction is referred to as the leading edge. The end of the sheet S on the rear side in the conveying direction is referred to as the trailing edge. Of the two ends of the sheet S, the end that enters the post-processing device 130 first is referred to as the first edge. Of the two ends of the sheet S, the end that enters the post-processing device 130 last is referred to as the second edge. Note that the leading edge may be changed from the first edge to the second edge, and the trailing edge may be changed from the second edge to the first edge, due to switchback conveyance performed by the post-processing device 130.

[0026] The sheet S conveyed from the intermediate conveying unit 120 is delivered to the entrance rollers 21 of the post-processing device 130. A sheet sensor 27, also known as an entrance sensor, is arranged downstream of the entrance rollers 21. When the sheet sensor 27 detects the trailing edge of the sheet S, the pair of conveying rollers 22 accelerates the sheet S. When the trailing edge of the sheet S, whose discharge destination is set to the upper tray 25, arrives between the pair of conveying rollers 22 and the pair of conveying rollers 24, the pair of conveying rollers 22 decelerates. This causes the conveying speed of the sheet S to become a predetermined discharge speed. The pair of conveying rollers 24 discharges the sheet S onto the upper tray 25.

[0027] When the trailing edge of the sheet S, whose discharge destination is set to the lower tray 37, passes through the check valve 23, the conveying roller pair 24 stops conveying the sheet S. The conveying roller pair 24 then starts rotating in the reverse direction. This causes the sheet S to switch back and be conveyed to the conveying roller pair 26. When the sheet sensor 60 located downstream of the conveying roller pair 26 detects the leading edge of the sheet S, the two rollers constituting the conveying roller pair 24 separate. This enables the conveying roller pair 24 to accept the following sheet S. Furthermore, the conveying roller pair 26 stops with the preceding sheet S sandwiched between them. The conveying roller pair 26 starts rotating in the reverse direction in response to the arrival of the following sheet S. This causes the following sheet S to be stacked on top of the preceding sheet S. The conveying roller pair 26 repeatedly switches back the sheet S, thereby stacking multiple sheets S to form a sheet bundle. This sheet bundle formation operation may also be called a buffer operation. The unit that realizes the buffer operation is called a buffer unit 80. It is not essential to form a sheet bundle in the buffer unit 80. For example, the buffer unit 80 may switch back the sheets S arriving from the image forming apparatus 100 and transport the sheets S to the intermediate stacking unit 42. In this case, a sheet bundle is formed in the intermediate stacking unit 42.

[0028] When the sheet bundle is completed in the buffer unit 80, the conveying roller pair 26 conveys the sheet bundle toward the intermediate stacking unit 42. The sheet bundle passes through the conveying roller pair 28 and the sheet sensor 50. The sheet bundle is then conveyed to the intermediate stacking unit 42 by the kick-out roller 29. A movable vertical alignment plate 39 is disposed in a standby position at the most downstream portion of the intermediate stacking unit 42. The sheet bundle is aligned when it hits the vertical alignment plate 39.

[0029] A plurality of sheet bundles are sequentially stacked on the intermediate stacking section 42. The first sheet bundle transported to the intermediate stacking section 42 is called the first sheet bundle. The i-th sheet bundle that arrives at the intermediate stacking section 42 is called the i-th sheet bundle. The last sheet bundle that arrives at the intermediate stacking section 42 is called the N-th sheet bundle. As a result, a predetermined number of sheets S that form a booklet are stacked on the intermediate stacking section 42. Once the predetermined number of sheets S have been aligned, the thermocompression bonding unit 51 performs a binding operation (thermocompression bonding process) to form a booklet. The thermocompression bonding process may be repeated each time a sheet bundle arrives at the intermediate stacking section 42. The vertical alignment plate 39 moves from the standby position to the discharge position, pushing the booklet toward the discharge rollers 38. When the leading edge of the booklet is clamped by the discharge rollers 38, the vertical alignment plate 39 stops and returns to the standby position. The discharge rollers 38 discharge the booklet received from the vertical alignment plate 39 through the discharge opening 46 to the lower tray 37.

[0030] In the above description, the post-processing device 130 forms a sheet bundle consisting of a plurality of sheets S by using the buffer unit 80, and conveys the sheet bundle to the intermediate stacking unit 42. However, a single sheet S may be conveyed to the intermediate stacking unit 42.

[0031] 3. Printing area for adhesive toner Tn FIG. 2A shows a print area 211 of adhesive toner Tn. The print area 211 is an adhesive area secured in the binding margin of sheets S. In this example, the print area 211 extends parallel to the long sides of sheets S. The print area 211 is provided at the right or left end close to the long sides. In a right-bound booklet, the print area 211 is located at the right end of sheets S. In a left-bound booklet, the print area 213 is located at the left end of sheets S. The print area 211 may also be provided at the top or bottom end close to the short sides. The post-processing device 130 stacks multiple sheets S and applies heat and pressure to the print areas 211 of the multiple sheets S, thereby adhering the multiple sheets S to form a booklet. The booklet in this case is a long-edge bound booklet. Here, the width (length in the short-edge direction) of the adhesive toner image (print area 211) is, for example, 4.0 mm. For example, the toner amount (laying amount) per unit area of ​​the adhesive toner Tn may be 0.4 mg / cm 2. The printing area 212 is an area where a user image is printed.

[0032] As shown in FIG. 2B, a small print area 213 for adhesive toner Tn may be formed near the corner of the sheet S. This creates a corner-bound booklet. An image made of adhesive toner Tn is not formed on the sheet S that serves as the cover of the booklet. In a right-bound booklet, the print area 213 is located at the top right of the sheet S. In a left-bound booklet, the print area 213 is located at the top left of the sheet S.

[0033] As shown in FIG. 2C , the printing areas 211 and 213 of the adhesive toner Tn may be formed on both sides of the sheet S, or may be formed on only one side of the sheet S. Whether the printing areas 211 and 213 of the adhesive toner Tn are formed on only one side or both sides can be selected taking into consideration, for example, the adhesive capacity of the post-processing device 130, the adhesive capacity of the adhesive toner Tn, the type of sheet S, the intended use of the booklet, and the like. Reliable adhesiveness is required for booklets that are to be kept as archives. Reliable adhesiveness is also required when cardboard or a special sheet S is used as the cover of the booklet. Therefore, in these cases, the printing areas 211 of the adhesive toner Tn are provided on both sides of the sheet S. When a booklet for simple, single use is produced, the printing area 211 of the adhesive toner Tn may be formed on only one side of the sheet S.

[0034] When adhesive toner Tn is applied to both sides of the sheet S, adhesive toner Tn formed on the front surface of one sheet S and adhesive toner Tn formed on the back surface of the other sheet S come into contact with each other and are adhered to each other. Note that adhesive toner Tn is applied to the back surface of the front cover and the front surface of the back cover of the booklet, but adhesive toner Tn is not applied to the front surface of the front cover and the back surface of the back cover.

[0035] 4. Booklet creation operation 3(A) to 3(D) show the booklet production operation performed in the intermediate stacking unit 42. In the initial state, the intermediate stacking unit 42 is empty. As an example, a sheet stack W consisting of five sheets S is transported from the buffer unit 80 to the intermediate stacking unit 42. The intermediate stacking unit 42 first functions as a support member or holding member that supports the five sheets S.

[0036] The Y direction is a direction parallel to the stacking surface (stacking plate) of the sheets S in the intermediate stacking section 42 and parallel to the conveying direction of the sheets S conveyed from the kick-out roller 29 to the intermediate stacking section 42. The Y direction may also be called the vertical direction. The X direction is a direction parallel to the stacking surface of the sheets S in the intermediate stacking section 42 and perpendicular to the Y direction. The X direction may also be called the horizontal direction. The Z direction is a direction perpendicular to the X and Y directions (the normal direction to the stacking surface, the thickness direction of the stacked sheets S). The Z direction may also be called the height direction. The opposite directions of the X, Y, and Z directions may be called the -X direction, -Y direction, and -Z direction, respectively.

[0037] The longitudinal alignment plate 39 and the longitudinal alignment roller 40 function as a first alignment unit that aligns multiple sheets S in a first direction (Y direction). The longitudinal alignment plate 39 is disposed at the most downstream portion of the intermediate stacking section 42 in the Y direction. The longitudinal alignment plate 39 is a reference member (first reference member) that serves as a reference for the sheet position in the Y direction. The longitudinal alignment roller 40 is a conveying member that conveys the sheet S in the Y direction so that the sheet S abuts against the longitudinal alignment plate 39 for alignment. The longitudinal alignment plate 39 includes multiple contact portions 69a to 69c that are spaced apart in the X direction. The multiple contact portions 69a to 69c come into contact with the edge of the sheet S. The longitudinal alignment plate 39 and the longitudinal alignment roller 40 are integrally configured as a movable unit 59 that is movable in the Y direction. The movable unit 59 can be moved in the Y direction by a drive source such as a motor. In other words, the positions of the longitudinal alignment plate 39 and the longitudinal alignment roller 40 in the Y direction are adjustable. The lateral alignment joggers 41a to 41c function as a second alignment unit that aligns the sheet in a second direction (X direction) perpendicular to the first direction.

[0038] The lateral alignment joggers 41a to 41c are moved in the X direction by a drive source such as a motor, and press the side edges of the sheets S stacked on the intermediate stacking section 42. The lateral alignment plates 72a and 72b are reference members that serve as references for the position of the sheets S in the X direction. The lateral alignment plates 72a and 72b are arranged to face the lateral alignment joggers 41a and 41b in the X direction.

[0039] 4-1. Preparation stage As shown in FIG. 3A, sheets S1 to S5 are conveyed toward the kick-out roller 29. The sheets S1 to S5 may be conveyed to the intermediate stacker 42 with the lowermost sheet Sj protruding in the Y direction relative to the uppermost sheet Sj+1. Here, j is the index of the sheet S. Before the sheets S are stacked on the intermediate stacker 42, the vertical alignment plate 39 moves to a predetermined standby position in accordance with the size of the sheet S to be aligned. The standby position is set so that the edge position of the sheet S in the -Y direction is a predetermined position, regardless of the size of the sheet S. In other words, the standby position is a position where the distance in the Y direction from the nip position of the kick-out roller 29 to the vertical alignment plate 39 is slightly longer than the length of the sheet in the Y direction. The horizontal alignment joggers 41a to 41c wait at positions spaced apart from the sheet S being conveyed in the X direction so as not to interfere with the conveyance of the sheet S.

[0040] 4-2. Vertical alignment stage 3(B) shows that the trailing edge of the first sheet S1 has passed through the nip of the kick-out roller 29 and the leading edge of the sheet S1 has reached the longitudinal alignment roller 40. The sheet S1 abuts against the longitudinal alignment plate 39 and is aligned based on the position of the longitudinal alignment plate 39. As the longitudinal alignment roller 40 continues to rotate, the sheets S2 to S5 that arrive at the longitudinal alignment roller 40 after the sheet S1 abut against the longitudinal alignment plate 39 in order. As a result, the five sheets S1 to S5 are aligned in the Y direction (vertical direction) based on the position of the longitudinal alignment plate 39.

[0041] 4-3. Horizontal alignment stage 3(C) shows that after the alignment of sheets S1-S5 in the Y direction (longitudinal direction) is completed, alignment in the X direction (lateral direction) is started. The lateral alignment joggers 41a-41c are driven in the X direction, which is the alignment direction, and abut against the side edges of sheets S1-S5, pressing sheets S1-S5 toward the lateral alignment plates 72a and 72b. Then, the other side edges of sheets S1-S5 abut against the abutment surfaces 300 of the lateral alignment plates 72a and 72b, and sheets S1-S5 are aligned in the X direction (lateral direction) using the positions of the lateral alignment plates 72a and 72b as references.

[0042] 4-4. Adhesion stage (thermocompression stage) 3(D) shows the state where the alignment of the five sheets S1 to S5 in the X and Y directions is completed. The target position (alignment position) in the alignment operation is the position of the sheet stack W when the adhesive process (thermocompression bonding) is performed by the thermocompression bonding unit 51. As described above, the image forming apparatus 100 applies adhesive toner Tn to the sheets S1 to S5 so that the side on which the adhesive toner image is formed faces the thermocompression bonding unit 51. If the sheet S1 is the cover of a booklet, adhesive toner Tn may not be applied.

[0043] The thermocompression bonding unit 51 applies thermocompression bonding to the aligned sheets S1 to S5. Meanwhile, the lateral alignment joggers 41a to 41c retreat in the -X direction. This allows the intermediate stacking section 42 to be ready to receive the next plurality of sheets S. After that, a sheet stack W consisting of sheets S6 to S10 produced in the buffer section 80 is stacked on top of the sheets S1 to S5.

[0044] The above four steps are then repeated for the preceding sheet stack W consisting of glued sheets S1-S5 and the sheet stack W consisting of unglued sheets S6-S10, thereby gluing sheets S1-S10 together in a precisely aligned state.

[0045] As an example, the sheet bundle W is composed of five sheets S. However, the number of sheets S constituting the sheet bundle W may be two, three, etc. In other words, the number of sheets S included in the sheet bundle W may be equal to or less than the maximum number of sheets S that can be stacked in the buffer unit 80.

[0046] 5. Thermocompression unit As shown in FIG. 4A, the thermocompression bonding unit 51 has a heater 401 with a built-in heating element as a heat source, and an aluminum heating plate 402 placed on top of the heater 401. The surface of the heating plate 402 may be coated to improve the toner releasability. The coating material may be, for example, a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene (PFA). The length (thickness) of the heater 401 in the Z direction is, for example, 1.0 mm. The length (width) of the heater 401 in the X direction is, for example, 8.0 mm. The length of the heater 401 in the Y direction is, for example, 350 mm. The thickness of the heating plate 402 is, for example, 1.5 mm. The heater 401 is, for example, a ceramic heater. The temperature of the heater 401 may be measured by a temperature sensor and controlled by a control circuit so that the measured temperature becomes a target temperature. For example, a target temperature (e.g., 240°C) is set so that the surface temperature of the pressure applying portion 409 of the heating plate 402 becomes 200°C. By providing the pressure applying portion 409 on the heating plate 402, the heat and pressure of the thermocompression bonding unit 51 are concentrated at the binding position of the sheet stack W. As a result, the efficiency of heating and pressing is improved.

[0047] FIG. 4(B) shows the dimensions of the heating plate 402. d1 indicates the length (width) of the pressure applying portion 409 in the X direction. d1 is, for example, 1.0 mm. d2 indicates the thickness of the heating plate 402, and is, for example, 0.8 mm. d3 indicates the thickness from the bottom surface of the heating plate 402 to the pressure applying portion 409, and is, for example, 1.5 mm. Curved surfaces with a curvature of r1 are formed on both sides of the pressure applying portion 409. The curvature r1 is, for example, R1.5 mm. The length of the pressure applying portion 409 in the Y direction is, for example, 300 mm.

[0048] The heater 401 is supported by a resin heater support 403. The pressure lever 404 receives power from a motor M1 shown in FIG. 7 to press the thermocompression bonding unit 51 in the -Z direction (downward) and apply pressure to the sheet stack W. The pressure force of the pressure lever 404 is transmitted to the pressure section 409 via a metal stay 405, which serves as a rigid body. The pressure force of the pressure lever 404 can be controlled according to the amount of movement of the pressure lever 404 in the -Z direction (downward). For example, the average surface pressure acting on the sheet stack W is 0.2 MPa. The pressure application time (heating time) T1 is 2.0 seconds, for example.

[0049] The pressure plate 406 is a receiving member made of an elastic material (e.g., silicone rubber). The elastic material is used because the pressure plate 406 is a member that can stably receive pressure. The pressure plate 406 may also be PFA coated. The thickness of the pressure plate 406 is, for example, 2.0 mm. The thermocompression bonding unit 51 presses the sheet stack W1 consisting of sheets S1 to S5 and then separates from the sheet stack W1. In FIG. 4A, sheets S1 to S5 represent the first to fifth sheets S1 to S5 of a booklet as a finished product. Sheet S1 is the cover of the booklet. Therefore, no image is formed on the bottom surface of adhesive toner Tn on sheet S1, and an image is formed only on the top surface. Images of adhesive toner Tn are formed on the top and bottom surfaces of the second and subsequent sheets S2 to S5 of the booklet.

[0050] As shown in FIG. 4(C), sheet bundle W2 is stacked on top of sheets S1 to S5 that have been thermocompression bonded. Sheet bundle W2 is made up of sheets S6 to S10. Thermocompression bonding unit 51 applies a thermocompression bonding operation to sheet bundle W2 that has been stacked on sheet bundle W1. This creates a booklet made up of many sheets S. Note that the number of sheets that make up sheet bundle W1 may differ from the number of sheets that make up sheet bundle W2.

[0051] The sheets S6 to S10 that are stacked later are included in the same booklet as the sheets S1 to S5, and therefore, images of adhesive toner Tn are formed on the upper and lower surfaces of the sheets S6 to S10, respectively.

[0052] As an example, post-processing device 130 can create a booklet consisting of a maximum of 100 sheets S. When booklet creation begins, buffer section 80 buffers a maximum of five sheets S at a time to create a sheet bundle W, and supplies the sheet bundle W to intermediate stacker 42. Thermocompression bonding unit 51 performs a thermocompression bonding operation consisting of a lowering operation, a pressurizing operation, and a lifting operation each time a sheet bundle W arrives. By repeating the buffering operation and the thermocompression bonding operation, booklets are created efficiently without reducing the productivity of image forming apparatus 100.

[0053] When the thermocompression bonding operation on the sheet stack W including the last page of the booklet is completed in the intermediate stacking section 42, the vertical alignment plate 39 moves from the standby position to the discharge position. In other words, the vertical alignment plate 39 moves parallel to the discharge outlet 46, thereby pushing out the completed booklet. Discharge rollers 38 are provided at the discharge outlet 46. When the leading edge of the booklet slightly passes over the discharge rollers 38, the vertical alignment plate 39 stops and returns to the standby position again. The discharge rollers 38 discharge the booklet onto the lower tray 37.

[0054] 6.Cleaning control 6-1. Controlling the number of sheets that form a sheet stack To shorten the time required to create a booklet, it is necessary to increase the number of sheets S that form one sheet bundle W. For example, as shown in FIG. 4C, the number of sheets S that form sheet bundle W1 and the number of sheets that form sheet bundle W2 are each set to a maximum value max. The maximum value max is the maximum number of sheets S that can be stacked in the buffer section 80. When cleaning the thermocompression bonding unit 51, the number of sheets S that form a portion of the sheet bundle W that forms the booklet is changed from the maximum value max.

[0055] 5 shows a stack of a plurality of sheet bundles W that form a booklet. In the buffer unit 80, a plurality of sheets S are stacked in order from the bottom to the top to form the sheet bundle W.

[0056] Here, the total number of sheets S forming a booklet is defined as M. The number of sheet bundles W forming a booklet is defined as N. The maximum number of sheets S forming one sheet bundle W is defined as max. Here, the i-th sheet bundle is denoted as Wi. The smaller the value of i, the earlier the sheet bundle Wi arrives at the intermediate stacking section 42. Furthermore, the larger the value of i, the closer the sheet bundle Wi is to the heating plate 402 within the booklet. The j-th sheet in the sheet bundle Wi is denoted as Si_j. The larger the value of j, the closer the sheet Si_j in the sheet bundle Wi is to the heating plate 402. The first sheet bundle W1 is formed from max sheets S1_1 to S1_max. Each of the second sheet bundle W2 to the (N-2)th sheet bundle WN-2 is composed of max-1 sheets. The (N-1)th sheet bundle WN-1 is formed from x1 sheets S. Sheet bundle WN-1 is the second closest sheet bundle to the heating plate 402 in the booklet. The Nth sheet bundle WN is formed from x2 sheets S. Sheet bundle WN is the closest sheet bundle to the heating plate 402. Here, x1+x2 is greater than or equal to 2 and less than or equal to max. When sheet bundle WN is made up of one sheet (x2=1), x1 is greater than or equal to 1 and less than max-1. In FIG. 5, max is set to 5. Furthermore, the following equation Eq1 holds for these variables.

[0057] M=max + (N-3)×(max-1) + x1 + x2...Eq1 The booklet may be left-bound and long-edge bound, and further, sheet SN_1 may be the back cover. Since sheet SN_1 is the back cover, no toner image (adhesive layer) made of adhesive toner Tn is provided on the top surface of sheet SN_1. A toner image (adhesive layer) made of adhesive toner Tn is provided on the bottom surface of sheet SN_1.

[0058] Since the sheet S1_1 is the front cover, no toner image (adhesive layer) made of adhesive toner Tn is provided on the lower surface of the sheet S1_1, whereas a toner image (adhesive layer) made of adhesive toner Tn is provided on the upper surface of the sheet S1_1.

[0059] Toner images (adhesive layers) made of adhesive toner Tn are provided on both sides of the sheets S1_2 to SN-1_2.

[0060] In the first embodiment, since max=5, the number of sheets S forming sheet bundles W2 to WN-2 is 4. The sum of the number of sheets S forming sheet bundle WN-1 x1 and the number of sheets S forming sheet bundle WN x2 is between 2 and 5 depending on the value of M. Therefore, x1 and x2 are adjusted based on Eq1 and the total number M.

[0061] As shown in Figure 5, the number of sheets S in the last sheet bundle WN, x2, may be set to 1. The number of sheets S in the sheet bundle WN-1, x1, and the number of sheets S in the sheet bundle WN, x2, are less than max. For example, if the sum of x1 and x2 is 3, then x1 is 2.

[0062] As will be described later, in the first embodiment, the heating temperature of the heater 401 applied to the sheet bundle WN-1 is lower than the heating temperature applied to the other sheet bundles W. If the number of sheets S forming the sheet bundle WN-1 is max or max-1, the amount of heat applied to the adhesive toner Tn of the sheet bundle WN-1 is insufficient. Therefore, in the first embodiment, the number x1 of sheets S forming the sheet bundle WN-1 is reduced to less than max-1. This increases the amount of heat supplied to each adhesive toner Tn in the sheet bundle WN-1.

[0063] In FIG. 5, the number x2 of sheets S forming sheet bundle WN is 1, but this is merely an example. It is sufficient that x1 and x2 are each less than max-1. For example, the number x1 of sheets S forming sheet bundle WN-1 may be 1. In this case, x2 becomes 2.

[0064] 6-2. Cleaning details As already explained, toner may be transferred to the back cover of the booklet from the pressure applying unit 409. Therefore, in the first embodiment, cleaning of the pressure applying unit 409 of the heating plate 402 is performed during the pressure bonding process of the sheet bundle WN-1. This makes it difficult for the back cover to become soiled with toner.

[0065] FIG. 6(A) shows the thermocompression bonding process. At the start of the thermocompression bonding process, the heating plate 402 is stationary at a standby position. The heating plate 402 moves in the direction indicated by the arrow F1 (downward) and contacts the toner image formed in the adhesive area of ​​the sheet S by the adhesive toner Tn. The heating plate 402 then presses the adhesive toner Tn and the sheet SN-2_4. The heating temperature T1 of the heater 401 is, for example, 200° C. In the case of the last sheet bundle WN, the pressure applying portion 409 of the heating plate 402 directly contacts the sheet SN-2_4 and presses it.

[0066] FIG. 6(B) shows the state in which toner adheres to the heating plate 402. After a predetermined heating time has elapsed, the heating plate 402 moves away in the direction indicated by the arrow F2 (upward). At the normal heating temperature T1, the adhesive toner Tn forming the adhesive layer is sufficiently soft. When the adhesive toner Tn softens, the adhesive force between the toner particles in the adhesive layer becomes weaker than the adhesive force acting between the adhesive layer and the heating plate 402. Therefore, when the heating plate 402 moves upward, the toner on the upper side separates from the toner on the lower side that constitutes the adhesive layer, and the toner on the upper side adheres to the heating plate 402 as contaminating toner Tf.

[0067] When the heating plate 402 with adhesive toner Tn adhered thereto performs the thermocompression bonding process on the last sheet bundle WN, the stain toner Tf adheres to the back cover of the booklet. Therefore, in the first embodiment, a cleaning process is performed to make it difficult for the stain toner Tf to adhere to the back cover. This cleaning process is performed before the last sheet bundle WN arrives at the thermocompression bonding unit 51.

[0068] 6(C) shows the cleaning process of the contaminant toner Tf adhering to the heating plate 402. The pressure applying portion 409 of the heating plate 402 to which the contaminant toner Tf has adhered is in contact with the adhesive layer on the sheet SN-1_x1. Here, the sheet SN-1_x1 is the target sheet in the sheet stack WN-1 that is closest to the heating plate 402. The temperature of the heating plate 402 is, for example, a heating temperature T2 that is lower than the normal heating temperature T1. The heating temperature T2 is, for example, 120°C.

[0069] The storage modulus of adhesive toner Tn heated at heating temperature T2 is higher than the storage modulus of adhesive toner Tn heated at heating temperature T1. Therefore, the adhesive force between the adhesive toner Tn forming the adhesive layer is higher than the adhesive force acting between the heating plate 402 and the contaminating toner Tf. Furthermore, the adhesive force acting between the adhesive toner Tn and the contaminating toner Tf in the adhesive layer is also higher than the adhesive force acting between the heating plate 402 and the contaminating toner Tf.

[0070] FIG. 6(D) shows the state after the cleaning process of the contaminant toner Tf adhering to the heating plate 402 has been completed. As the heating plate 402 moves upward, separation does not occur between the adhesive toner Tn forming the adhesive layer. Separation also does not occur between the adhesive toner Tn forming the adhesive layer and the contaminant toner Tf. On the other hand, separation does occur between the heating plate 402 and the contaminant toner Tf. That is, the adhesive toner Tn contained in the adhesive layer pulls the contaminant toner Tf adhering to the heating plate 402, causing the contaminant toner Tf to separate from the heating plate 402. As a result, the contaminant toner Tf is cleaned and removed from the heating plate 402.

[0071] 7. Control Unit FIG. 7 shows the control unit of the image forming system 1. Dashed lines indicate optional functions. A CPU 701 executes control programs stored in a memory 702 to implement various functions. Some or all of these functions may be implemented by hardware circuits such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The memory 702 is a storage device that may include a read-only memory (ROM), a random-access memory (RAM), a hard disk drive (HDD), a solid-state drive (SSD), and the like. A stack counter 703 counts the number of sheet stacks W held in the intermediate stacking unit 42 or their serial numbers i. A sheet counter 704 counts the number of sheets S stacked in the buffer unit 80 or their serial numbers j.

[0072] A high-voltage power supply 707 generates a charging bias (charging voltage) supplied to the charging roller C and a developing bias (developing voltage) supplied to the developing roller of the developing device K. The CPU 701 adjusts the maximum density of the toner image by adjusting the charging bias or the developing bias.

[0073] The thermocompression bonding unit 51 includes a motor M1 that drives a pressure lever 404, and a heater 401. A motor M2 drives, for example, a feed roller 81 to rotate.

[0074] The CPU 701 performs multiple functions according to a control program. The bundle control unit 711 controls the number of sheets S included in the sheet bundle W formed in the buffer unit 80. For example, the bundle control unit 711 uses the bundle counter 703 to identify the number i of the sheet bundle W present in the buffer unit 80. Furthermore, the bundle control unit 711 uses the sheet counter 704 to identify the number j of the sheet S present in the buffer unit 80. Furthermore, the bundle control unit 711 controls the number of sheets S forming the sheet bundle W1 to max. The bundle control unit 711 controls the number of sheets S forming each of the sheet bundles W2 to WN-2 to max-1. The bundle control unit 711 controls the number of sheets S forming the sheet bundle WN-1 to x1. The bundle control unit 711 controls the number of sheets S forming the sheet bundle WN to x2. The bundle control unit 711 determines x1 and x2 using Eq1.

[0075] The temperature control unit 712 sets the heating temperature applied to the sheet bundles W1 to WN-2 to T1. The bundle control unit 711 sets the heating temperature applied to the sheet bundle WN-1 to T2. The bundle control unit 711 sets the heating temperature applied to the sheet bundle WN to T3. Here, the heating temperature T2 is lower than the heating temperature T1. The heating temperature T3 is equal to or exceeds the heating temperature T1.

[0076] The time control unit 713 controls the time during which the heating plate 402 thermocompresses (applies pressure and heat) the sheet bundle W. The heating time for each of the sheet bundles W1 to WN is, for example, 2.0 seconds.

[0077] The toner selection unit 714 selects the type of toner used to form a toner image in the adhesive area of ​​the sheet S. In the first embodiment, either a transparent toner or a black toner may be selected as the adhesive toner Tn.

[0078] The creating unit 715 is optional and is used in Example 3. The creating unit 715 controls the image forming apparatus 100 to create cleaning paper. The cleaning paper may also be called a cleaning sheet.

[0079] 8. Flowchart Fig. 8 shows a booklet production method including a cleaning process. When a booklet production job is submitted, the CPU 701 executes the following processes in accordance with a control program. Note that, for the sake of convenience, the image formation process, bundle production process, and thermocompression bonding process are executed sequentially in Fig. 8, but these may also be executed in parallel.

[0080] In S801, the CPU 701 (temperature control unit 712) sets the heating temperature of the heater 401 to T1. The heating temperature T1 is, for example, 200°C. The heating temperature T1 may be changed depending on the basis weight of the sheet S. T2 and T3 are also adjusted depending on the basis weight. However, even if the heating temperature T1 is changed, T1 is higher than T2, and T3 is equal to or higher than T1.

[0081] In S802, the CPU 701 (bundle control unit 711) controls the image forming apparatus 100 to form a user image and an adhesive image on the sheet S using toner. Adhesive images are formed on both sides of each sheet except for the front cover and back cover. The bundle control unit 711 manages the jth sheet Si_j of the i-th sheet bundle Wi using the bundle counter 703 and the sheet counter 704.

[0082] In S803, the CPU 701 (bundle control unit 711) controls the image forming apparatus 100 and the post-processing device 130 to convey the sheet S to the buffer unit 80. The buffer unit 80 creates a sheet bundle W.

[0083] In S804, the CPU 701 (bundle control unit 711) determines whether the i-th sheet bundle Wi is completed. For example, when the first sheet W1 is being created in the buffer unit 80, if the sheet S that arrived at the buffer unit 80 is the max-th sheet, the sheet bundle W1 is determined to be completed. When the N-2-th sheet bundle WN-2 is being created in the buffer unit 80, if the sheet S that arrived at the buffer unit 80 is the max-1-th sheet, the sheet bundle WN-2 is determined to be completed. When the N-1-th sheet bundle WN-1 is being created in the buffer unit 80, if the sheet S that arrived at the buffer unit 80 is the x1-th sheet, the sheet bundle WN-1 is determined to be completed. When the N-th sheet bundle WN is being created in the buffer unit 80, if the sheet S that arrived at the buffer unit 80 is the x2-th sheet, the sheet bundle WN is determined to be completed. If the sheet stack W is not complete, the CPU 701 advances the process from S804 to S802 and forms an image on the next sheet S. On the other hand, if the sheet stack W is complete, the CPU 701 advances the process from S804 to S805.

[0084] In S805, the CPU 701 (bundle control unit 711) conveys the sheet bundle W from the buffer unit 80 to the intermediate stacking unit 42. If a preceding sheet bundle Wi-1 is stacked in the intermediate stacking unit 42, the sheet bundle Wi is stacked on top of the sheet bundle Wi-1.

[0085] In S806, the CPU 701 (temperature control unit 712) determines whether the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is the N-1th sheet bundle WN-1. If the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is the N-1th sheet bundle WN-1, the CPU 701 advances the process from S806 to S807.

[0086] In S807, the CPU 701 (temperature control unit 712) sets the heating temperature of the heater 401 to T2. The heating temperature T2 is lower than the heating temperature T1, and is, for example, 120°C.

[0087] In S808, the CPU 701 (temperature control unit 712) controls the thermocompression bonding unit 51 to perform the thermocompression bonding process. The thermocompression bonding time is, for example, 2 seconds. Thereafter, the CPU 701 advances the process from S807 to S802.

[0088] If it is determined in S806 that the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is not the (N-1)th sheet bundle WN-1, the CPU 701 advances the process from S806 to S810.

[0089] In S810, the CPU 701 (temperature control unit 712) determines whether the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is the Nth sheet bundle WN. If the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is one of the first to (N-2)th sheet bundles WN, the CPU 701 proceeds from S810 to S808. Therefore, the heating temperature is maintained at T1. The thermocompression bonding time is, for example, 2 seconds. On the other hand, if the sheet bundle Wi that has arrived at the intermediate stacking unit 42 is the Nth sheet bundle WN, the CPU 701 proceeds from S810 to S811.

[0090] In S811, the CPU 701 (temperature control unit 712) sets the heating temperature of the heater 401 to T3. The heating temperature T3 is equal to or higher than the heating temperature T1.

[0091] In S812, the CPU 701 (temperature control unit 712) executes the thermocompression process by controlling the thermocompression bonding unit 51. The thermocompression bonding time is, for example, 2 seconds.

[0092] In S813, the CPU 701 (temperature control unit 712) controls the thermocompression bonding unit 51 and the discharge rollers 38 to discharge the completed booklet onto the lower tray 37.

[0093] In this way, the heating temperature applied to the sheet bundle WN-1 is lowered from the normal temperature. Therefore, the adhesive toner Tn of the sheet PN-1_x1 closest to the pressure unit 409 in the sheet bundle WN-1 becomes relatively hard. In other words, the storage modulus increases relatively. This makes it difficult for the adhesive toner Tn to separate from the sheet bundle WN-1 when the heating plate 402 separates from the sheet bundle WN-1. Furthermore, the adhesive toner Tn adhering to the sheet bundle WN-1 pulls the contaminant toner Tf adhering to the heating plate 402. As a result, the contaminant toner Tf is separated from the heating plate 402. In other words, the contaminant toner adhering to the pressure unit 409 of the heating plate 402 is removed or cleaned.

[0094] In addition, the inventors' experiments showed that when the heating temperature T2 was set equal to the heating temperature T1, the staining toner Tf sometimes adhered to the back cover of the booklet, whereas when the heating temperature T2 was set lower than the heating temperature T1, the staining toner Tf almost never adhered to the back cover of the booklet.

[0095] According to FIG. 5, M sheets S are stacked so that sheet S1_1 is the front cover and sheet SN_1 is the back cover. However, this stacking order is merely an example. Multiple sheets S may be stacked so that sheet S1_1 is the back cover and sheet SN_1 is the front cover. In this case, adhesion of stain toner Tf to the front cover of the booklet is suppressed. Unintended adhesion of toner to the cover of the booklet is reduced.

[0096] In the first embodiment, the heating temperature of the sheet bundle WN-1 is set to T2, which may result in an insufficient amount of heat for bonding the sheet bundle WN-1 and the sheet bundle WN together. However, by setting the heating temperature T3 of the sheet bundle WN equal to or higher than T1, this insufficient amount of heat can be alleviated. In other words, sufficient adhesive strength is ensured between the sheet bundle WN-1 and the sheet bundle WN.

[0097] The number x1 of sheets S forming the sheet bundle WN-1 and the number x2 of sheets S forming the sheet bundle WN are both smaller than max-1, which also helps to reduce the heat shortage.

[0098] 1 illustrates an image forming apparatus 100 capable of forming color images, but this is merely an example. The image forming apparatus 100 may also be a monochrome image forming apparatus.

[0099] According to the first embodiment, the intermediate stacking unit 42 functions as a holding unit for holding a sheet bundle W consisting of one or more sheets, each having a toner image formed with adhesive toner Tn in its adhesive area. The pressure plate 406 and the pressure unit 409 function as a pressure unit for applying pressure to the sheet bundle W held by the intermediate stacking unit 42. The heater 401 and the heating plate 402 function as a heating unit for applying heat to the adhesive toner Tn attached to the adhesive area of ​​each sheet S included in the sheet bundle W held in the intermediate stacking unit 42. The discharge roller 38 functions as a discharge unit for discharging a booklet consisting of N sheet bundles W when the booklet is completed. The heater 401 and the heating plate 402 may perform a heating process each time a sheet bundle W is stacked on the intermediate stacking unit 42. The sheet bundle W second closest to the heating plate 402 in the booklet is the (N-1)th sheet bundle WN-1. Furthermore, the target sheet in the sheet bundle WN-1 closest to the heating plate 402 is sheet SN-1_x1. Any sheet S included in another sheet bundle W that is located farther from the heating plate 402 than the sheet bundle WN-1 in the booklet may be referred to as the "other sheet." The "other sheet" may be the sheet closest to the heating plate 402 in each of the sheet bundles W1 to WN-2 in the booklet. The storage modulus of the toner image made of adhesive toner formed on the target sheet is higher than the storage modulus of the toner image made of adhesive toner formed on the other sheets. This reduces the possibility of unintended toner adhering to the cover of the booklet.

[0100] The heater 401 and the heating plate 402 heat the sheet bundles W1 to WN-2 at a first temperature (e.g., T1). The heater 401 and the heating plate 402 may heat the sheet bundle WN-1 at a second temperature (e.g., T2) lower than the first temperature. This makes the storage elastic modulus of the toner image made of adhesive toner formed on the current sheet higher than the storage elastic modulus of the toner images made of adhesive toner formed on the other sheets.

[0101] When the sheet bundle WN is placed on the sheet bundle WN-1 in the intermediate stacking section 42, the heater 401 and the heating plate 402 may perform a heating process at a third temperature (e.g., T3) that is equal to or exceeds the first temperature. This solves the problem (insufficient heat) that may arise when the second temperature is applied to the sheet bundle WN-1.

[0102] The number x2 of sheets S forming the sheet bundle WN may be smaller than the number x1 of sheets S forming the sheet bundle WN-1, thereby allowing the quantity of heat to be replenished to the sheet bundle WN-1.

[0103] At least one of the number x2 of sheets S forming the sheet bundle WN and the number x1 of sheets S forming the sheet bundle WN-1 may be 1. If x2 is 1, heat will be easily transmitted from the heating plate 402 to the sheet bundle WN-1 via the sheet bundle WN. If x1 is 1, the number of sheets S that will result in a heat shortage will be minimized. Therefore, heat will be easily replenished to the sheet bundle WN-1 via the sheet bundle WN.

[0104] At least one of the number x2 of sheets S forming the sheet bundle WN and the number x1 of sheets S forming the sheet bundle WN-1 may be smaller than the number (e.g., max-1) of sheets S forming the sheet bundle WN-2, which will make it easier for heat to be replenished to the sheet bundle WN-1 via the sheet bundle WN.

[0105] At least one of the number x2 of sheets forming the sheet bundle WN and the number x1 of sheets forming the sheet bundle WN-1 may be smaller than the maximum number (e.g., max) of sheets forming each of the sheet bundles W1 to WN-2, which will make it easier for heat to be replenished to the sheet bundle WN-1 via the sheet bundle WN.

[0106] The heating plate 402 may be disposed opposite the pressure plate 406. The heating plate 402 and the pressure plate 406 may sandwich the sheet stack held in the intermediate stacking unit 42, thereby applying pressure to the sheet stack.

[0107] In FIG. 4(A), the heating plate 402 is positioned above the pressure plate 406, but this is merely an example. It may be positioned above the pressure plate 406 and below the pressure plate 406. Furthermore, the heating plate 402 may be stationary and the pressure plate 406 may move. Alternatively, both the heating plate 402 and the pressure plate 406 may move. In any case, it is sufficient that the distance between the heating plate 402 and the pressure plate 406 can be changed by moving the heating plate 402 and the pressure plate 406 relative to each other.

[0108] <Example 2> In the second embodiment, an adhesive layer is formed using a plurality of toners having different storage moduli, thereby cleaning the heating plate 402. In the second embodiment, a description of matters common to the first embodiment will be omitted.

[0109] 1. Image forming device FIG. 9 shows an image forming apparatus 100 that can be used in Examples 1 and 2. The difference between FIG. 9 and FIG. 1 is that a process cartridge 7k for black toner is used instead of the process cartridge 7n. Furthermore, the black process cartridge 7k is disposed most downstream in the rotation direction of the transfer belt 30. The process cartridge 7k includes a developing device Kk, a photosensitive drum Dk, and a charging roller Ck. The exposure device 2 irradiates the photosensitive drum Dk with a corresponding laser beam Jk to form an electrostatic latent image. A primary transfer roller Fk is disposed opposite the photosensitive drum Dk. First, the process cartridge 7y transfers a toner image to the transfer roller 30. Second, the process cartridge 7m transfers a toner image to the transfer roller 30. Third, the process cartridge 7c transfers a toner image to the transfer roller 30. Fourth, the process cartridge 7k transfers a toner image to the transfer roller 30. As a result, a yellow toner image is formed on top of the sheet S. Second, a magenta toner image is formed. Second, a magenta toner image is formed. Third, a cyan toner image is formed. Fourth, a black toner image is formed. Thus, the yellow toner image is formed on top of the black toner image.

[0110] 2.Method for measuring storage modulus The storage modulus of a toner can be measured using a dynamic viscoelasticity measuring device (rheometer). An example of a rheometer is the ARES manufactured by Rheometrics Scientific. A serrated parallel plate with a diameter of 7.9 mm was used as the measurement jig. A cylindrical sample with a diameter of 8 mm and a height of 2 mm was molded from a 0.1 g sample using a pressure molding machine. A pressure of 15 kN was applied to the sample for 1 minute at room temperature. For example, a 100 kN press NT-100H manufactured by NPa Systems was used as the pressure molding machine. The temperature of the serrated parallel plate was set to 120°C. The sawtooth was inserted into the heated and melted cylindrical sample. A load was applied vertically so that the axial force did not exceed 30 gf (= 0.294 N). This caused the cylindrical sample to adhere to the serrated parallel plate. A steel belt was used to make the diameter of the cylindrical sample the same as that of the parallel plates. The serrated parallel plates and the cylindrical sample were slowly cooled over one hour until the temperature of the cylindrical sample decreased to the starting temperature (30.00°C).

[0111] The measurement frequency was 31.55 rad / s. The initial measurement strain was set to 0.1%. Furthermore, the measurement was performed in the automatic measurement mode. The sample extension correction was performed in the automatic measurement mode. The measurement temperature was increased from 30°C to 180°C at a rate of 2°C per minute. The measurement interval was 30 seconds. In other words, viscoelastic data was measured every 1°C.

[0112] FIG. 10 shows an example of the measurement results of the storage modulus of black toner Tk and yellow toner Ty. The horizontal axis represents temperature, and the vertical axis represents storage modulus. Comparing these storage moduli, the storage modulus of black toner Tk is relatively low, particularly in the temperature range of 120°C or higher. In other words, black toner Tk is a soft toner. The storage modulus of yellow toner Ty is relatively high. In other words, yellow toner Ty is a hard toner.

[0113] In Example 2, black toner Tk was used as adhesive toner Tn, and yellow toner Ty was used as cleaning toner.

[0114] 11 shows the stacked state of a booklet formed from N sheet bundles W. Compared to Example 1, Example 2 differs in that sheet bundle WN-1 is formed from max-1 sheets S, and sheet bundle WN is also formed from max-1 sheets S.

[0115] For the first sheet bundle W1 to the Nth sheet bundle WN, an adhesive layer is formed on both sides of each sheet S using black toner Tk as adhesive toner. However, no adhesive layer is formed on the bottom surface of sheet S1_1, which will be the front cover, or on the top surface of sheet SN_4, which will be the back cover. Furthermore, in Example 2, an adhesive layer of yellow toner Ty is laminated on top of the adhesive layer of black toner Tk formed on the top surface of sheet SN-1_4. The layer consisting of the adhesive layer of black toner Tk and the adhesive layer of yellow toner Ty may be called a cleaning layer CL. In this way, the cleaning layer CL is formed only on sheet SN-1_4 of sheet bundle WN-1.

[0116] 11, the number x2 of sheets S in the sheet bundle WN is 4, but this is just an example. The number x2 of sheets S in the sheet bundle WN is determined within the range of 1 to 4, taking into account the total number M of sheets S forming the booklet. For example, x2 is determined by the CPU 701 (bundle control unit 711) so as to satisfy Eq2.

[0117] M=max + (N-2)×(max-1) + x2...Eq2 Eq2 can be obtained by substituting max-1 for x1 in Eq1.

[0118] 3. Cleaning When black toner Tk is used as adhesive toner Tn, as shown in Fig. 6B, contaminant toner Tf may adhere to the heating plate 402. Therefore, in the second embodiment, similar to the first embodiment, cleaning of the heating plate 402 is performed for the sheet bundle WN-1.

[0119] FIG. 12A illustrates the cleaning process of contaminant toner Tf adhering to the heating plate 402. Through the thermocompression process of the first sheet bundle W1 to the second sheet bundle WN-2, the contaminant toner Tf adheres to the pressure member 409 of the heating plate 402. The pressure member 409 may also be referred to as the pressure surface or the heating surface. When the motor M1 drives the heating plate 402, the heating plate 402 moves in the direction indicated by the arrow F1, and the pressure member 409 contacts the cleaning layer CL. The cleaning layer CL is formed by laminating yellow toner Ty on black toner Tk. Therefore, the cleaning layer CL is relatively harder than an adhesive layer consisting of only black toner Tk. In other words, the storage modulus of the cleaning layer CL is relatively high. Therefore, the adhesive force acting between the toner particles in the cleaning layer CL is stronger than the adhesive force acting between the cleaning layer CL and the heating plate 402. Similarly, the adhesive force acting between the adhesive cleaning layer CL and the contaminant toner Tf is also stronger than the adhesive force acting between the cleaning layer CL and the heating plate 402.

[0120] The state shown in FIG. 12(B) is a state later in time than the state shown in FIG. 12(A). When the motor M1 drives the heating plate 402, the heating plate 402 moves in the direction indicated by the arrow F2, and the pressure member 409 moves away from the cleaning layer CL. Because the yellow toner Ty is hard, separation between the toner particles in the cleaning layer CL does not easily occur. The contaminating toner Tf does not easily separate from the cleaning layer CL. On the other hand, the contaminating toner Tf easily separates from the heating plate 402. In this way, the cleaning layer CL pulls the contaminating toner Tf adhering to the heating plate 402, causing the contaminating toner Tf to separate from the heating plate 402. As a result, the contaminating toner Tf adhering to the heating plate 402 is removed or cleaned off.

[0121] 4. Flowchart Fig. 13 shows the booklet production method of the first embodiment. Compared to Fig. 8, in Fig. 13, S802 is replaced with S1301, S1302, and S1310. Furthermore, the processing between S805 and S813 is replaced with S1303 and S1304. The CPU 701 advances the processing from S801 to S1301.

[0122] In S1301, the CPU 701 (toner selection unit 714) determines whether the sheet Si_j to be processed is the predetermined sheet SN-1_x1. If the sheet Si_j to be processed is not the predetermined sheet SN-1_x1, the CPU 701 advances the process from S1301 to S1302.

[0123] In S1302, the CPU 701 (toner selection unit 714) forms a user image and an adhesive layer on the sheet Si_j. The adhesive layer is formed using only black toner Tk. Thereafter, the CPU 701 advances the process from S1302 to S803.

[0124] If the sheet Si_j to be processed is the specified sheet SN-1_x1, the CPU 701 proceeds from S1301 to S1310. In S1310, the CPU 701 (toner selection unit 714) forms a user image and a cleaning layer CL (adhesive image) on the sheet SN-1_x1. The cleaning layer CL is formed by superimposing a layer of yellow toner Ty on a layer of black toner Tk. Thereafter, the CPU 701 proceeds from S1310 to S803. The CPU 701 executes S803 and S804 and proceeds to S805.

[0125] When the sheet bundle W is conveyed to the intermediate stacking unit 42 in S805, the CPU 701 advances the process from S805 to S1303. In S1303, the CPU 701 performs a thermocompression bonding process on the sheet bundle W. If a preceding sheet bundle W is present in the intermediate stacking unit 42, the thermocompression bonding process is performed with the succeeding sheet bundle W stacked on top of the preceding sheet bundle W. In the second embodiment, the heating temperature is T1 from the first sheet bundle W1 to the last sheet bundle WN.

[0126] The last sheet SN-1_x1 of the sheet bundle WN-1 is provided with a cleaning layer CL, which cleans the stain toner Tf during the heat and pressure bonding process of the sheet bundle WN-1.

[0127] In S1304, the CPU 701 determines whether the booklet is complete. For example, if the sheet bundle W conveyed to the intermediate stacker 42 is the last sheet bundle WN, the CPU 701 determines that the booklet is complete. If the booklet is not complete, the CPU 701 proceeds from S1304 to S1301. If the booklet is complete, the CPU 701 proceeds from S1304 to S813.

[0128] According to the second embodiment, the viscoelasticity of the toner is utilized to clean the contaminating toner Tf during the thermocompression process of the sheet bundle WN-1. According to an experiment conducted by the inventors, the contaminating toner Tf hardly adhered to the back cover. Therefore, the effect of the second embodiment was confirmed.

[0129] In the flowchart shown in FIG. 13, the heating temperature is consistently maintained at T1, but this is just one example. The second embodiment may be combined with the first embodiment. In this case, as described in the first embodiment, the number of sheets S forming the sheet bundle WN-1 is x1, and the number of sheets S forming the sheet bundle WN is x2. The method for determining x1 and x2 is the same as that described in the first embodiment. Furthermore, a cleaning layer CL is formed on the x1-th sheet SN-1_x1 in the sheet bundle WN-1. The heating temperature for the sheet bundle WN-1 is T2. The heating temperature for the sheet bundle WN is T3. In this way, the formation of the cleaning layer CL described in the second embodiment may be added to the control of the numbers x1 and x2 and the control of the heating temperature described in the first embodiment.

[0130] As suggested by the second embodiment, the process cartridge 7k is an example of a first image forming unit that forms a toner image on a sheet using a first toner. The process cartridge 7y is an example of a second image forming unit that forms a toner image on a sheet using a second toner that is harder than the first toner. A toner image is formed in the adhesive area of ​​each sheet forming the sheet bundle WN-2 using a first toner (e.g., black toner Tk) as an adhesive toner. A toner image is formed in the adhesive area of ​​the current sheet forming the sheet bundle WN-1 using the first toner as an adhesive toner, and another toner image is formed on the current toner image using a second toner (e.g., yellow toner Ty). The heater 401 and the heating plate 402 may contact other toner images when heating the sheet bundle WN-1. This makes the storage elastic modulus of the toner image formed on the current sheet using the adhesive toner higher than the storage elastic modulus of the toner images formed on the other sheets using the adhesive toner. As a result, unintended toner is less likely to adhere to the cover of the booklet.

[0131] A toner image may be formed using the first toner as an adhesive toner in each adhesive region of each sheet forming each of the first toner bundles WN-2 to WN-2, and a toner image may be formed using the first toner as an adhesive toner in each adhesive region of each sheet forming the Nth toner bundle.

[0132] In the second embodiment, the heater 401 and the heating plate 402 may also heat the sheet bundles W1 to WN-2 at a first temperature (e.g., T1). The heater 401 and the heating plate 402 may also heat the sheet bundle WN-1 at a second temperature (e.g., T2) lower than the first temperature. The heater 401 and the heating plate 402 may also heat the sheet bundle WN at a third temperature (e.g., T3).

[0133] Example 3 In the first and second embodiments, cleaning control is performed during the booklet production process. However, this is merely an example. In the third embodiment, cleaning control of the contaminated toner Tf is performed during a period when the booklet production process is not being performed. The timing of performing the cleaning control may be any timing designated or set by the user. The execution timing may be the timing when the number of sheets S conveyed to the post-processing device 130 reaches a predetermined number. The execution timing may also be periodic. In the third embodiment, the image forming apparatus 100 shown in FIG. 1 may be used, or the image forming apparatus 100 shown in FIG. 9 may be used.

[0134] 1. Background When booklets are repeatedly produced, toner mixed with paper dust and the like becomes contaminated toner Tf and may accumulate on the heating plate 402 or the pressure plate 406. When such contaminated toner Tf accumulates on the heating plate 402, the contaminated toner Tf may be transferred to the back cover of the booklet. When the contaminated toner Tf accumulates on the pressure plate 406, the contaminated toner Tf may be transferred to the front cover of the booklet. When the contaminated toner Tf is transferred to the front or back cover of the booklet, the quality of the booklet deteriorates. Therefore, in the third embodiment, the contaminated toner Tf is cleaned from the heating plate 402 and the pressure plate 406 by using cleaning paper.

[0135] 2. Cleaning paper 14 shows cleaning paper 1400. The cleaning paper 1400 has a cleaning area 1401 where a toner image for forming a cleaning layer CL is printed. When cleaning both the heating plate 402 and the pressure plate 406, the cleaning area 1401 is formed on both the first and second surfaces of the cleaning paper 1400. The cleaning area 1401 is provided at the right or left end of the cleaning paper 1400 so that it can come into contact with the object to be cleaned (e.g., the heating plate 402, the pressure plate 406).

[0136] The area of ​​the cleaning area 1401 is wider than the area of ​​the cleaning target so that the cleaning area 1401 covers the entire cleaning target. The width d5 ​​of the cleaning area 1401 is wider than the width of the cleaning target (the width of the heating plate 402 or the width of the pressure plate 406). For example, the width d5 ​​is 10 mm.

[0137] When only one of the heating plate 402 and the pressure plate 406 is to be cleaned, a single-sided printed cleaning paper 1400 is used. The location of the cleaning area 1401 is determined according to the location of the cleaning object. In other words, it is sufficient that the cleaning area 1401 can come into contact with the cleaning object in the thermocompression bonding unit 51.

[0138] 3. Flowchart 15 shows a control method for using the cleaning paper 1400. When the conditions for starting the production of the cleaning paper 1400 are met, the CPU 701 (production unit 715) executes the following process in accordance with the control program.

[0139] In S1501, the CPU 701 (creation unit 715) controls the image forming apparatus 100 to form a toner image with adhesive toner Tn in the cleaning area 1401 of the sheet S, thereby creating the cleaning paper 1400. The adhesive toner Tn may be, for example, only black toner Tk, or may be a combination of black toner Tk and yellow toner Ty.

[0140] In S1502, the CPU 701 controls the image forming apparatus 100 and the post-processing device 130 to transport the cleaning paper 1400 to the thermocompression bonding unit 51. The cleaning paper 1400 is stacked on the intermediate stacker 42 so that the cleaning area 1401 of the cleaning paper 1400 can contact the object to be cleaned (e.g., the pressure plate 406, the heating plate 402).

[0141] In S1503, the CPU 701 (temperature control unit 712) sets the heating temperature to T2. As described in the first embodiment, the heating temperature T2 is lower than the normal heating temperature T1. The heating temperature T2 is, for example, 120°C. This increases the storage modulus of the toner image (toner layer) formed in the cleaning area 1401. The temperature control unit 712 supplies power to the heater 401 so that the temperature of the heating plate 402 becomes T2.

[0142] In S1504, the CPU 701 controls the motor M1 to bring the heating plate 402 into contact with the cleaning paper 1400. As a result, the soiled toner Tf adhering to the pressure plate 406 comes into contact with the cleaning area 1401 of the cleaning paper 1400.

[0143] In S1505, the CPU 701 (time control unit 713) applies heat and pressure for a predetermined time (e.g., 3 seconds). The predetermined time is longer than the heating time (e.g., 2 seconds) required to produce a booklet. The contaminant toner Tf adhering to the pressure plate 406 adheres to the toner image formed in the cleaning area 1401 of the cleaning paper 1400.

[0144] In S1506, the CPU 701 controls the motor M1 to separate the heating plate 402 from the cleaning paper 1400. The soiling toner Tf is transferred to the cleaning paper 1400 and peeled off from the pressure plate 406. As a result, the soiling toner Tf is removed from the pressure plate 406.

[0145] In S1507, the CPU 701 turns off the heater 401. In S1508, the CPU 701 controls the thermocompression bonding unit 51 and the discharge roller 38 to discharge the cleaning paper 1400 onto the lower tray 37.

[0146] Here, a method for cleaning the dirty toner Tf accumulated on the pressure plate 406 has been mainly described, but it is also possible to clean the dirty toner Tf accumulated on the heating plate 402. In this case, a cleaning area 1401 is formed on the cleaning paper 1400 so that the cleaning area 1401 can come into contact with the heating plate 402. By providing the cleaning area 1401 on both sides of the cleaning paper 1400, it is also possible to simultaneously clean the dirty toner Tf accumulated on the heating plate 402 and the dirty toner Tf accumulated on the pressure plate 406.

[0147] According to the third embodiment, it is possible to remove or reduce the soiling toner Tf without rubbing the cleaning target with the cleaning paper 1400. Therefore, cleaning can be performed in a short time.

[0148] In the third embodiment, the cleaning paper 1400 is formed by the image forming apparatus 100 and transported to the post-processing apparatus 130, but this is merely an example. The cleaning paper 1400 formed by another image forming apparatus 100 may be manually placed on the intermediate stacker 42.

[0149] The cleaning paper 1400 may be made of paper, a resin film, or a cloth, as long as it is made of a material that can absorb the stain toner Tf.

[0150] According to the third embodiment, by using the cleaning paper 1400 to remove the soiling toner Tf from the cleaning target, the cover of the booklet is less likely to become soiled.

[0151] The image forming unit 10, the CPU 701, and the creating unit 715 function as a creating unit that creates cleaning paper 1400 for cleaning the heating plate 402. When the intermediate stacking unit 42 does not contain a sheet stack W that forms a booklet and the cleaning paper 1400 is held in the intermediate stacking unit 42, the heating plate 402 comes into contact with the cleaning paper 1400 and performs a heating process.

[0152] The heating temperature (e.g., T2) applied to the cleaning paper 1400 may be lower than the heating temperature (e.g., T1) applied to the sheet stack W forming the booklet, in order to increase the storage modulus of the cleaning toner image formed in the cleaning area 1401.

[0153] The cleaning paper 1400 may have a cleaning area 1401 corresponding to the cleaning target. That is, the cleaning area 1401 is disposed at a position corresponding to the adhesive area (print area 211) or the pressure-applied area. A toner image may be formed in the cleaning area 1401.

[0154] The area of ​​the cleaning region 1401 may be larger than the area of ​​the heating surface of the heating plate 402 (the heating and pressing surface of the pressing unit 409). This will make it easier to remove the contaminating toner Tf from the pressing unit 409.

[0155] The cleaning paper 1400 may contact both the heating plate 402 and the pressure plate 406. The area of ​​the cleaning region 1401 may be larger than the area of ​​the pressure surface of the pressure plate 406. This will make it easier to remove the contaminating toner Tf from the pressure plate 406.

[0156] In Fig. 1, the post-processing device 130 having the thermocompression bonding unit 51 is disposed beside the image forming apparatus 100, but this is merely an example. As shown in Fig. 16, the post-processing device 130 and the thermocompression bonding unit 51 may be disposed on top of the main body of the image forming apparatus 100. As explained using Fig. 9, the order of the process cartridges 7n, 7y, 7m, and 7c may be changed. Process cartridge 7k may be used in place of process cartridge 7n.

[0157] <Technical ideas derived from examples> (Item 1) a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on an adhesive area using adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; and a discharge means for discharging the booklet when the booklet consisting of the N sheet bundle is completed, the heating means performs a heating process every time a sheet stack is stacked on the holding means, a storage elastic modulus of a toner image made of the adhesive toner formed on a target sheet closest to the heating means in the N-1th sheet bundle in the booklet, which is second closest to the heating means, is higher than a storage elastic modulus of a toner image made of the adhesive toner formed on any sheet included in another sheet bundle in the booklet that is located farther from the heating means than the N-1th sheet bundle. (Item 2) Item 1. The booklet production device according to item 1, wherein the storage elastic modulus of a toner image made of the adhesive toner formed on the target sheet closest to the heating means in the N-1th sheet bundle, which is second closest to the heating means in the booklet, is higher than the storage elastic modulus of toner images made of the adhesive toner formed on other sheets closest to the heating means in the 1st sheet bundle to the N-2th sheet bundle in the booklet. (Item 3) The booklet production device described in item 1 or 2, wherein the heating means performs the heating treatment at a first temperature on the first sheet bundle to the (N-2)th sheet bundle in the booklet, and performs the heating treatment at a second temperature lower than the first temperature on the (N-1)th sheet bundle. (Item 4) Item 4. The booklet production device according to item 3, wherein the heating means performs the heating treatment at a third temperature equal to or exceeding the first temperature when the Nth sheet stack is superimposed on the N-1th sheet stack in the holding means. (Item 5) 5. The booklet producing device according to any one of items 1 to 4, wherein the number of sheets forming the Nth sheet bundle in the booklet is less than the number of sheets forming the N-1th sheet bundle. (Item 6) A booklet production device described in any one of items 1 to 4, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the N-1th sheet bundle is 1. (Item 7) A booklet creation device described in any one of items 1 to 6, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the N-1th sheet bundle in the booklet is less than the number of sheets forming the N-2th sheet bundle in the booklet. (Item 8) A booklet creation device described in any one of items 1 to 7, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the N-1th sheet bundle is less than the maximum number of sheets forming each of the sheet bundles from the 1st sheet bundle to the N-2th sheet bundle in the booklet. (Item 9) a first image forming means for forming a toner image on a sheet with a first toner; a second image forming means for forming a toner image on the sheet using a second toner harder than the first toner, the toner image is formed in each adhesive region of each sheet forming the N-2th sheet bundle in the booklet using the first toner as the adhesive toner; 9. The booklet production device according to any one of items 1 to 8, wherein the toner image is formed in the adhesive area of ​​the target sheet forming the N-1th sheet bundle using the first toner as the adhesive toner, another toner image is formed on the toner image using the second toner, and the heating means contacts the other toner image when heating the N-1th sheet bundle. (Item 10) Item 10. The booklet production device according to item 9, wherein the toner image is formed in each adhesive area of ​​each sheet forming the first sheet bundle to the N-2th sheet bundle in the booklet using the first toner as the adhesive toner. (Item 11) Item 11. The booklet producing apparatus according to item 9 or 10, wherein the toner image is formed in each adhesive region of each sheet forming an Nth sheet bundle in the booklet using the first toner as the adhesive toner. (Item 12) The booklet production device described in item 11, wherein the heating means performs the heating treatment at a first temperature on the first sheet bundle to the (N-2)th sheet bundle in the booklet, and performs the heating treatment at a second temperature lower than the first temperature on the (N-1)th sheet bundle. (Item 13) The heating device further includes a creating means for creating a cleaning sheet for cleaning the heating means, 13. The booklet production device according to any one of items 1 to 12, wherein the heating means contacts the cleaning sheet and performs the heating process when the sheet stack forming the booklet is not present in the holding means and the cleaning sheet is held by the holding means. (Item 14) a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on an adhesive area using adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; a discharge means for discharging a booklet consisting of one or more sheet bundles when the booklet is completed; a creating means for creating a cleaning sheet for cleaning the heating means, a heating means for heating the cleaning sheet when the holding means does not contain a stack of sheets forming the booklet and the cleaning sheet is held by the holding means; (Item 15) Item 15. The booklet producing apparatus according to item 13 or 14, wherein the temperature applied by the heating means to the cleaning sheet is lower than the temperature applied by the heating means to the sheet stack forming the booklet. (Item 16) 16. The booklet producing apparatus according to any one of items 13 to 15, wherein the cleaning sheet has a cleaning area corresponding to the adhesive area, and a toner image is formed in the cleaning area. (Item 17) Item 17. The booklet producing apparatus according to item 16, wherein the area of ​​the cleaning region is larger than the area of ​​the heating surface of the heating means. (Item 18) the cleaning sheet contacts both the heating means and the pressure means; Item 18. The booklet producing device according to item 16 or 17, wherein the area of ​​the cleaning region is larger than the area of ​​the pressure surface of the pressure means. (Item 19) the heating means is disposed opposite the pressure means, 19. The booklet producing apparatus according to any one of items 1 to 18, wherein the sheet bundle held by the holding means is sandwiched between the heating means and the pressing means, thereby pressing the sheet bundle. (Item 20) An image forming system including an image forming apparatus and a post-processing apparatus, the image forming apparatus, forming means for forming a toner image using adhesive toner in the adhesive area of ​​the sheet; a conveying unit for conveying the sheet to the post-processing device, The post-treatment device includes: a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on the adhesive area using the adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; and a discharge means for discharging the booklet when the booklet consisting of the N sheet bundle is completed, the heating means performs a heating process every time a sheet stack is stacked on the holding means, an image forming system, wherein the storage elastic modulus of a toner image made of the adhesive toner formed on the sheet of interest closest to the heating means in the N-1th sheet bundle in the booklet, which is second closest to the heating means, is higher than the storage elastic modulus of a toner image made of the adhesive toner formed on any sheet included in another sheet bundle in the booklet that is located farther from the heating means than the N-1th sheet bundle.

[0158] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0159] 1: image forming system, 100: image forming apparatus, 130: post-processing device, 42: intermediate stacking unit, 402: heating plate, 406: pressure plate, 38: discharge roller

Claims

1. a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on an adhesive area using adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; and a discharge means for discharging the booklet when the booklet consisting of the N sheet bundle is completed, the heating means performs a heating process every time a sheet stack is stacked on the holding means, A booklet production device, wherein the storage elastic modulus of a toner image made of the adhesive toner formed on the target sheet closest to the heating means in the N-1th sheet bundle in the booklet, which is second closest to the heating means, is higher than the storage elastic modulus of a toner image made of the adhesive toner formed on any sheet included in another sheet bundle in the booklet that is located farther from the heating means than the N-1th sheet bundle.

2. 2. The booklet production device according to claim 1, wherein a storage elastic modulus of a toner image made of the adhesive toner formed on a target sheet closest to the heating means in the N-1th sheet bundle, which is second closest to the heating means in the booklet, is higher than a storage elastic modulus of toner images made of the adhesive toner formed on other sheets closest to the heating means in the first sheet bundle to the N-2th sheet bundle in the booklet.

3. The booklet creation device according to claim 1, wherein the heating means performs the heating treatment at a first temperature on the first sheet bundle to the (N-2)th sheet bundle in the booklet, and performs the heating treatment at a second temperature lower than the first temperature on the (N-1)th sheet bundle.

4. 4. The booklet creation device according to claim 3, wherein the heating means performs the heating process at a third temperature equal to or exceeding the first temperature when the Nth sheet stack is superimposed on the N-1th sheet stack in the holding means.

5. 2. The booklet producing apparatus according to claim 1, wherein the number of sheets forming the Nth sheet bundle in the booklet is less than the number of sheets forming the N-1th sheet bundle.

6. 2. The booklet producing apparatus according to claim 1, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the (N-1)th sheet bundle is one.

7. 2. The booklet creation device according to claim 1, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the N-1th sheet bundle is less than the number of sheets forming the N-2th sheet bundle in the booklet.

8. The booklet creation device of claim 1, wherein at least one of the number of sheets forming the Nth sheet bundle in the booklet and the number of sheets forming the N-1th sheet bundle is less than the maximum number of sheets forming each sheet bundle from the 1st sheet bundle to the N-2th sheet bundle in the booklet.

9. a first image forming means for forming a toner image on a sheet with a first toner; a second image forming means for forming a toner image on the sheet using a second toner harder than the first toner, the toner image is formed in each adhesive region of each sheet forming the N-2th sheet bundle in the booklet using the first toner as the adhesive toner; 2. The booklet creation device according to claim 1, wherein the toner image is formed in the adhesive area of ​​the target sheet forming the N-1th sheet bundle using the first toner as the adhesive toner, and another toner image is formed on the toner image using the second toner, and the heating means comes into contact with the other toner image when heating the N-1th sheet bundle.

10. 10. The booklet producing apparatus according to claim 9, wherein the toner image is formed in each adhesive region of each sheet forming the first sheet bundle to the (N-2)th sheet bundle in the booklet using the first toner as the adhesive toner.

11. 10. The booklet producing apparatus according to claim 9, wherein the toner image is formed in each adhesive region of each sheet forming the Nth sheet bundle in the booklet using the first toner as the adhesive toner.

12. The booklet creation device according to claim 11, wherein the heating means performs the heating treatment at a first temperature on the first sheet bundle to the (N-2)th sheet bundle in the booklet, and performs the heating treatment at a second temperature lower than the first temperature on the (N-1)th sheet bundle.

13. The heating device further includes a creating means for creating a cleaning sheet for cleaning the heating means, 2. The booklet producing device according to claim 1, wherein the heating means contacts the cleaning sheet and performs the heating process when the sheet stack forming the booklet is not present in the holding means and the cleaning sheet is held by the holding means.

14. a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on an adhesive area using adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; a discharge means for discharging a booklet consisting of one or more sheet bundles when the booklet is completed; a creating means for creating a cleaning sheet for cleaning the heating means, a heating means for heating the cleaning sheet when the holding means does not contain a stack of sheets forming the booklet and the cleaning sheet is held by the holding means;

15. 15. The booklet producing apparatus according to claim 13, wherein the temperature applied by the heating means to the cleaning sheet is lower than the temperature applied by the heating means to a sheet stack forming the booklet.

16. 15. The booklet producing apparatus according to claim 13, wherein the cleaning sheet has a cleaning area corresponding to the adhesive area, and a toner image is formed in the cleaning area.

17. 17. The booklet producing apparatus according to claim 16, wherein the area of ​​the cleaning region is larger than the area of ​​the heating surface of the heating means.

18. the cleaning sheet contacts both the heating means and the pressure means; 17. The booklet producing apparatus according to claim 16, wherein the area of ​​the cleaning region is larger than the area of ​​the pressure surface of the pressure means.

19. the heating means is disposed opposite the pressure means, 15. The booklet producing apparatus according to claim 1, wherein the sheet bundle held by the holding means is sandwiched between the heating means and the pressing means, thereby pressing the sheet bundle.

20. An image forming system including an image forming apparatus and a post-processing apparatus, the image forming apparatus, forming means for forming a toner image using adhesive toner in the adhesive area of ​​the sheet; a conveying unit for conveying the sheet to the post-processing device, The post-treatment device includes: a holding means for holding a sheet stack consisting of one or more sheets each having a toner image formed on the adhesive area using the adhesive toner; a pressure applying means for applying pressure to the sheet stack held by the holding means; a heating unit that applies heat to the toner image formed by the adhesive toner in the adhesive region of each sheet included in the sheet bundle held by the holding unit; and a discharge means for discharging the booklet when the booklet consisting of the N sheet bundle is completed, the heating means performs a heating process every time a sheet stack is stacked on the holding means, an image forming system, wherein the storage elastic modulus of a toner image made of the adhesive toner formed on the sheet of interest closest to the heating means in the N-1th sheet bundle in the booklet, which is second closest to the heating means, is higher than the storage elastic modulus of a toner image made of the adhesive toner formed on any sheet included in another sheet bundle in the booklet that is located farther from the heating means than the N-1th sheet bundle.

Images