Sheet processing device and image forming system

Abstract

To improve productivity of a sheet processing device.SOLUTION: A sheet processing device receives the sheets one by one to form a sheet bundle consisting of a maximum of N sheets, conveys the sheet bundle to stacking means and stacks the sheets, and bonds the sheet bundle. When making of the booklets of L pieces is completed, the booklets of L pieces are discharged. Here, the sheet bundle may include an Mth sheet to be included in a kth booklet, and a first sheet to be included in a k+1th booklet. The preceding sheet and the following sheet are bonded together. The Mth sheet to be included in the kth booklet and the first sheet to be included in the k+1th booklet are not bonded together.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] According to Patent Document 1, a post-processing device is described that staples a sheet bundle conveyed to a processing tray and discharges the sheet bundle to a discharge tray. This post-processing device makes the following sheet bundle wait in a buffer section until the stapling process of the preceding sheet bundle is completed. This allows image formation to continue without reducing productivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-095291 Summary of the Invention [Problem to be solved by the invention]

[0004] A booklet is formed by piercing multiple sheets with staples. Therefore, the processing tray must only hold multiple sheets that form one booklet. If a sheet that will become part of a subsequent booklet is transported to the processing tray before the binding process of the preceding booklet is completed, the sheet for the subsequent booklet will be bound as part of the preceding booklet. In this way, the subsequent sheets must wait until the preceding booklet is discharged from the processing tray, which reduces the productivity of the sheet processing apparatus. Therefore, an object of the present invention is to improve the productivity of the sheet processing apparatus. [Means for solving the problem]

[0005] The present invention relates to, for example, a stack forming means for receiving the sheets one by one and forming a sheet stack of up to N sheets; a conveying means for conveying the sheet bundle when the formation of the sheet bundle is completed; stacking means for stacking the sheet bundle conveyed by the conveying means; a bonding means for performing a bonding process each time the sheet bundle is loaded on the loading means to create a booklet consisting of M sheets; a discharge means for discharging the L booklets from the stacking means when the stacking means has completed the production of the L booklets, the bundle forming means is configured to create a bundle of N sheets including an Mth sheet to be included in a kth booklet and a first sheet to be included in a k+1th booklet (where k is an integer between 1 and L-1, and M is not an integer multiple of N); The adhesive means provides a sheet processing device that adhesively attaches the preceding sheet and the succeeding sheet loaded on the stacking means, except for the Mth sheet to be included in the kth booklet and the first sheet to be included in the k+1th booklet. Effect of the Invention

[0006] As described above, according to the present invention, in a post-processing device that performs binding processing by thermocompression bonding, it is possible to continuously produce a plurality of booklets without reducing the productivity of booklet production. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an image forming system. [Diagram 2] Diagram explaining the adhesive printing area [Diagram 3] Diagram explaining buffer operation [Figure 4] FIG. 1 is a diagram illustrating the alignment and bonding operations; [Diagram 5] Diagram explaining the bonding operation [Figure 6] Diagram explaining the controller [Figure 7] Diagram explaining the functions of a CPU [Figure 8]Timing chart of the first embodiment [Figure 9] Diagram explaining the bonding operation [Figure 10] Flowchart showing the first embodiment [Figure 11] Timing chart of the second embodiment [Figure 12] Timing chart of the second embodiment [Figure 13] A flowchart showing a method for determining discharge from a buffer section. [Figure 14] A flowchart showing a method for determining discharge from an intermediate load section. [Figure 15] A diagram explaining the functions of the CPU and transport control unit DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0009] <Example 1> (1) Image forming system 1, the image forming system 1 includes an image forming apparatus 100 and a post-processing apparatus 300. The post-processing apparatus 300 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 200 conveys the sheet S on which the image has been formed to the post-processing apparatus 300. The post-processing apparatus 300 performs post-processing on the sheet S as necessary and outputs the sheet S.

[0010] The image forming apparatus 100 includes a sheet cassette 8, an image forming unit 10, a fixing device 6, 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 9 so as to be removable, and can store a large number of sheets S. A feed roller 81 feeds the sheet S from the sheet cassette 8, and delivers the sheet S to a conveying roller pair 82. The multi-tray 20 can also feed the sheets S one by one.

[0012] The image forming unit 10 is a tandem-type electrophotographic unit equipped with four process cartridges 7n, 7y, 7m, and 7c, a scanner unit 2, and a transfer unit 3. The "n" in the reference numerals means adhesive, and "ymc" means yellow, magenta, and cyan, respectively. The process cartridges 7n, 7y, 7m, and 7c are configured so that multiple parts that are responsible for the image forming process can be replaced as a whole. In other words, the process cartridges 7n, 7y, 7m, and 7c are formed by integrating multiple parts.

[0013] The process cartridges 7n, 7y, 7m, and 7c have corresponding toner storage units 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 toner storage units Ky, Km, and Kc store yellow, magenta, and cyan toners for forming a visible image on the sheet S. The toner storage unit Kn stores adhesive toner Tn. The adhesive toner Tn is a powder adhesive used to heat-press multiple sheets S in the post-processing device 300. An adhesive toner image is formed on the photosensitive drum Dn by development with the adhesive toner Tn. The adhesive toner image is not intended to transmit visual information. Therefore, the adhesive toner image is different from a toner image (normal toner image) formed by a printing toner for recording an image such as a figure or text on the sheet S. However, in the following description, the adhesive toner Tn is applied to the sheet S in a predetermined application pattern. Therefore, the layered image of the adhesive toner Tn developed by the electrophotographic process is also treated as one of the "toner images."

[0015] When a black image such as text is printed, yellow, magenta, and cyan toners are superimposed to produce a black image (process black). However, the image forming unit 10 may have a fifth process cartridge that uses 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 charging rollers Cn, Cy, Cm, and Cc. The scanner unit 2 is disposed below the process cartridges 7n, 7y, 7m, and 7c and above the sheet cassette 8. The scanner unit 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 scanner unit 2 may also be called an exposure device or an optical scanning device.

[0017] The toner containers Kn, Ky, Km, and Kc form toner images by attaching toner to the electrostatic latent images on the photosensitive drums Dn, Dy, Dm, and Dc. The toner containers Kn, Ky, Km, and Kc may also be called developers.

[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 disposed 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 be called primary transfer devices. The toner images are transported to the secondary transfer section by the counterclockwise rotation of the transfer belt 30.

[0020] The secondary transfer roller 5 is disposed so as to face the inner roller 31, and forms a transfer nip 52 between the secondary transfer roller 5 and the transfer belt 30. The transfer nip 52 transfers the toner image from the transfer belt 30 to the sheet S. The transfer nip 52 may be called a secondary transfer portion.

[0021] A fixing unit 6 is disposed above the secondary transfer roller 5 (downstream in the conveying direction of the sheet S). The fixing unit 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. In other words, the printing toners Ty, Tm, and Tc and the adhesive toner Tn melt and adhere to the sheet S.

[0022] FIG. 2(A) shows a printing area 211 of adhesive toner Tn. The printing area 211 extends parallel to the long side of the sheet S. The printing area 211 is provided at the end close to the long side. As a result, the post-processing device 300 stacks multiple sheets S and heats and presses the printing 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-side bound booklet. Here, the width (length in the short-side direction) of the adhesive toner image (printing area 211) is, for example, 4.0 mm.

[0023] 2B, a small print area 212 for adhesive toner Tn may be formed near the corner of the sheet S. This produces a booklet with corner fastenings. An image using adhesive toner Tn is not formed on the sheet S that will be the cover of the booklet.

[0024] As shown in FIG. 1, the switching guide 33 is a flap-shaped guide member provided downstream of the fixing unit 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 the first 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.

[0025] The discharge roller 34 conveys the sheet S to an intermediate conveying unit 200. The intermediate conveying unit 200 has a pair of conveying rollers 201 and 202. The pair of conveying rollers 201 and 202 convey the sheet S to a post-processing device 300.

[0026] (2) After-treatment device The post-processing device 300 is a floor-standing type sheet processing device and has a function of buffering a plurality of sheets, a function of aligning a plurality of sheets, and a function of gluing a sheet stack.

[0027] In the following, the end of the sheet S on the front side in the transport direction is called the leading end. The end of the sheet S on the rear side in the transport direction is called the trailing end. Of the two ends of the sheet S, the end that enters the post-processing device 300 first is called the first end. Of the two ends of the sheet S, the end that enters the post-processing device 300 later is called the second end. Note that the leading end may be changed from the first end to the second end and the trailing end may be changed from the second end to the first end due to the switchback transport performed by the post-processing device 300.

[0028] The sheet S conveyed from the intermediate conveying unit 200 is delivered to the entrance rollers 21 of the post-processing device 300. A sheet sensor called the entrance rollers 21 is disposed downstream of the entrance rollers 21. When the sheet sensor 27 detects the rear end of the sheet S, the conveying roller pair 22 accelerates the sheet S. When the rear end of the sheet S, whose discharge destination is set to the upper tray 25, arrives between the conveying roller pair 22 and the conveying roller pair 24, the conveying roller pair 22 decelerates. This causes the conveying speed of the sheet S to become a predetermined discharge speed. The conveying roller pair 22 discharges the sheet S to the upper tray 25.

[0029] When the trailing end of the sheet whose discharge destination is set to the lower tray 37 passes through the check valve 23, the conveying roller pair 22 stops conveying the sheet S. After that, the conveying roller pair 22 starts to rotate in the reverse direction. As a result, the sheet S switches back and is conveyed to the conveying roller pair 26. When the sheet sensor 60 provided downstream of the conveying roller pair 26 detects the leading end of the sheet S, the two rollers constituting the conveying roller pair 24 separate. As a result, the conveying roller pair 24 becomes able 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 to rotate in the reverse direction in response to the arrival of the following sheet S. As a result, the following sheet S is stacked on top of the preceding sheet S. By repeating the switchback of the sheet S by the conveying roller pair 26, multiple sheets S are stacked to form a sheet bundle. Such a sheet bundle forming operation may be called a buffer operation. A unit that realizes the buffer operation is called a buffer unit 80.

[0030] When the sheet stack is completed in the buffer unit 80, the conveying roller pair 26 conveys the sheet stack toward the intermediate stacking unit 42. The sheet stack passes through the conveying roller pair 28 and the sheet sensor 50. The sheet stack is further 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 stack is aligned by hitting the vertical alignment plate 39.

[0031] A plurality of sheet bundles are stacked in sequence on the intermediate stacking section 42. As a result, a predetermined number of sheets S that form a booklet are stacked on the intermediate stacking section 42. When the alignment of the predetermined number of sheets S is completed, the thermocompression bonding unit 51 performs a binding operation (adhesive processing) to form a booklet. 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 again. The discharge rollers 38 discharge the booklet received from the vertical alignment plate 39 from the discharge port 46 to the lower tray 37.

[0032] In the above description, the post-processing device 300 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.

[0033] (3) Buffer operation (overlapping operation) The buffer operation is an operation for making the succeeding sheet or sheet bundle wait in the buffer unit 80 until the post-processing of the preceding sheet bundle is completed in the intermediate stacking unit 42. The buffer operation enables the image forming system 1 to continue the image forming job including the post-processing without reducing the productivity of the image forming apparatus 100 (the number of images output per unit time).

[0034] Figures 3(A) to 3(G) illustrate the buffer operation. Here, the sheet S conveyed first is denoted as S1, and the sheet S conveyed second is denoted as S2. The sheet bundle formed by overlapping the sheet S1 and the sheet S2 is denoted as W. The conveyance speeds of the conveyance roller pairs 22, 24, and 26 are denoted as V1 and V2 (V1 < V2). The conveyance speed V1 is the conveyance speed before acceleration, and the conveyance speed V2 is the conveyance speed after acceleration. Here, acceleration (speed increase) is an acceleration process for ensuring the necessary sheet interval (hereinafter referred to as the interval between sheets) when overlapping the sheet S in the buffer unit 80 and when feeding the sheet bundle downstream. The sheet interval generally refers to the distance or conveyance time from the rear end of the preceding sheet Si to the front end of the subsequent sheet Si+1 (i is an arbitrary integer).

[0035] Figure 3(A) shows that the conveyance speeds of the conveyance roller pair 22 and the conveyance roller pair 24 are accelerated to V2 at the timing when the rear end (second end) of the sheet S1 passes through the sheet sensor 27. Figure 3(B) shows that the sheet S1 temporarily stops at the timing when the rear end of the sheet S1 has moved a predetermined distance from the sheet sensor 27 and passed through the backflow prevention valve 23. The conveyance speed of the conveyance roller pair 22 returns to V1 to receive the sheet S2. Figure 3(C) shows that the rotation direction of the conveyance roller pair 24 is switched from normal rotation to reverse rotation, and the sheet S1 is conveyed in the F1 direction at the conveyance speed V2. The sheet S2 is conveyed to the conveyance roller pair 22 at the conveyance speed V1.

[0036] FIG. 3D shows that the leading end (second end) of the sheet S1 stops at a position where it has been conveyed a predetermined distance from the pair of conveying rollers 26. In addition, at the timing when the sheet S1 is sandwiched between the pair of conveying rollers 26, the separation lever 44 separates the upper roller 24a in the direction E1. After the upper roller 24a separates from the lower roller 24b, the leading end (first end) of the sheet S2 passes through the pair of conveying rollers 24. The separation lever 44 is rotatably connected to the plunger solenoid 45 at the solenoid connection shaft. When a current flows through the plunger solenoid 45, the separation lever 44 rotates in the direction E1, and the pair of conveying rollers 24 enters a separated state. When the supply of current to the plunger solenoid 45 is stopped, the upper roller 24a moves in the direction E2 due to the pressure spring.

[0037] FIG. 3E shows that the conveying speed of the conveying roller pair 22 and the conveying roller pair 24 is accelerated to V2 after the rear end (second end) of the sheet S2 passes the sheet sensor 27. At the timing when the rear end (second end) of the sheet S2 passes the sheet sensor 27, the conveying roller pair 26 starts to rotate in the reverse direction. As a result, the sheet S1 sandwiched between the conveying roller pair 26 is conveyed in the F2 direction. At the timing when the conveying speeds of the sheets S1 and S2 become equal, the upper roller 24a moves in the E2 direction and cooperates with the lower roller 24b to sandwich the sheets S1 and S2. The conveying speed (circumferential speed) of the conveying roller pair 24 is adjusted to V2, which is the conveying speed of the sheets S1 and S2, before the conveying roller pair 24 sandwiches the sheets S1 and S2.

[0038] 3(F) shows that sheets S1 and S2 form sheet stack W after the rear end (second end) of sheet S2 passes through check valve 23. As in FIGS. 3(B) and 3(C), in FIG. 3(F) as well, when the rear end of sheet stack W passes through check valve 23, sheet stack W pauses and the rotation direction of conveying roller pair 24 switches from forward to reverse.

[0039] 3G shows that the sheet stack W is transported in the F1 direction at a transport speed V2 toward the post-processing section 71. At the timing when the sheet stack W is sandwiched between the transport roller pair 26, the separation lever 44 separates the upper roller 24a from the lower roller 24b. In other words, the upper roller 24a moves in the E1 direction.

[0040] FIG. 3H shows that the sheet S3 is newly buffered after the sheet stack W is sent to the post-processing section 71. In this case, the upper roller 24a stops once after the rear end of the sheet stack W passes through the pair of conveying rollers 24. The sheet S3 enters the pair of conveying rollers 24 while the pair of conveying rollers 24 is separated. When the rear end of the sheet S3 passes through the sheet sensor 27, the conveying speed of the pair of conveying rollers 22 is increased from V1 to V2. After that, the upper roller 24a moves in the direction of E2, and the pair of conveying rollers 24 comes into contact with each other. The rotation direction of the upper roller 24a switches from reverse to forward, and the sheet S3 is conveyed in the direction of F2 at the conveying speed V2. Before the rear end of the sheet S3 passes through the pair of conveying rollers 22, the pair of conveying rollers 24 starts conveying the sheet S3.

[0041] Here, two sheets S1 and S2 are buffered, but this is merely an example. If the third sheet S3 is also buffered, after FIG. 3(G), the leading edge of the sheet stack W stops at a position (temporary stop position) conveyed a predetermined distance from the conveying roller pair 26. Then, an overlapping operation is applied to the sheet stack W and sheet S3. The overlapping operation is the same as the overlapping operation of sheets S1 and S2 described in relation to FIG. 3(D) to FIG. 3(G).

[0042] In a print job in which multiple pages are printed consecutively, the number control unit 412 manages the number N of sheets S buffered in the buffer unit 80 based on the maximum number M of sheets S that can be buffered in the buffer unit 80 and transport information for the sheets S. The number control unit 412 determines whether to discharge the sheet stack W formed in the buffer unit 80 downstream or to overlap the succeeding sheet S on the sheet stack W. In this embodiment, the maximum number M is assumed to be five sheets.

[0043] (4) Matching operation 4(A) to 4(D) show the alignment operation of the sheets S executed in the intermediate stacking section 42. In the initial state, the intermediate stacking section 42 is empty. As an example, a sheet stack W consisting of five sheets S is conveyed from the buffer section 80 to the intermediate stacking section 42.

[0044] The Y direction is a direction parallel to the stacking surface (stack plate) of the sheets S in the intermediate stacking section 42 and parallel to the transport direction of the sheets S transported from the kick-out roller 29 to the intermediate stacking section 42. The Y direction may 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 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 be called the height direction. The opposite directions of the X, Y, and Z directions may be called the -X, -Y, and -Z directions, respectively.

[0045] The vertical alignment plate 39 and the vertical alignment roller 40 function as a first alignment unit that aligns a plurality of sheets S in a first direction (Y direction). The vertical alignment plate 39 is disposed at the most downstream portion of the intermediate stacking portion 42 in the Y direction. The vertical alignment plate 39 is a reference member (first reference member) that serves as a reference for the sheet position in the Y direction. The vertical alignment roller 40 is a conveying member that conveys the sheet S in the Y direction so that the sheet S is abutted against the vertical alignment plate 39 for alignment. The vertical alignment plate 39 includes a plurality of contact portions 39a to 39c that are spaced apart in the X direction. The plurality of contact portions 39a to 39c come into contact with the end of the sheet S. The vertical alignment plate 39 and the vertical alignment roller 40 are integrally configured as a movable unit 59 that is movable in the Y direction. The movable unit 59 is movable in the Y direction by a driving source such as a motor. That is, the positions of the vertical alignment plate 39 and the vertical 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.

[0046] The lateral alignment joggers 41a to 41c are moved in the X direction by a driving source such as a motor, and press the side edges of the sheets S stacked on the intermediate stacker 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 disposed to face the lateral alignment joggers 41a and 41b in the X direction.

[0047] (4-1) Preparation stage As shown in FIG. 4A, the 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 in a state in which the lower sheet Si protrudes in the Y direction from the upper sheet Si+1. Before the sheets S are stacked on the intermediate stacker 42, the vertical alignment plate 39 moves to a predetermined standby position in advance according to the size of the sheet S to be aligned. The standby position is set so that the end position of the sheet S in the -Y direction is constant, 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 a position away from the sheet S being conveyed in the X direction so as not to interfere with the conveyance of the sheet S.

[0048] (4-2) Vertical alignment stage 4(B) shows that the rear end of the first sheet S1 has passed through the nip of the kick-out roller 29 and the leading end of the sheet S1 has reached the vertical alignment roller 40. The sheet S1 abuts against the vertical alignment plate 39 and is aligned based on the position of the vertical alignment plate 39. As the vertical alignment roller 40 continues to rotate, the sheets S2 to S5 which arrive at the vertical alignment roller 40 after the sheet S1 abut against the vertical 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 vertical alignment plate 39.

[0049] (4-3) Lateral alignment stage 4C shows that after the alignment of the sheets S1 to S5 in the Y direction (vertical direction) is completed, the alignment in the X direction (horizontal direction) is started. The lateral alignment joggers 41a to 41c are driven in the X direction, which is the alignment direction, to come into contact with the side edges of the sheets S1 to S5 and press the sheets S1 to S5 toward the lateral alignment plates 72a and 72b. Then, the other side edges of the sheets S1 to S5 come into contact with the contact surfaces 500 of the lateral alignment plates 72a and 72b, so that the sheets S1 to S5 are aligned in the X direction (horizontal direction) based on the positions of the lateral alignment plates 72a and 72b.

[0050] (4-4) Adhesion stage (thermocompression stage) 4(D) shows a state where the alignment of the five sheets S1 to S5 in the X and Y directions has been 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 is not applied.

[0051] The thermocompression bonding unit 51 applies a thermocompression bonding operation to the sheets S1 to S5 for which alignment has been completed. During this time, the lateral alignment joggers 41a to 41c retreat in the -X direction. This allows the intermediate stacking section 42 to be in a state in which it can receive the next plurality of sheets S. After that, the sheet stack W consisting of sheets S6 to S10 generated in the buffer section 80 is stacked on top of the sheets S1 to S5.

[0052] Thereafter, the above-mentioned four steps are repeated for the sheets S1 to S10, so that the sheets S1 to S10 are bonded together in a precisely aligned state.

[0053] 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 or 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.

[0054] (5) Thermocompression unit As shown in FIG. 5A, the thermocompression bonding unit 51 has a heater 501 with a built-in heating element as a heat source, and an aluminum heating plate 502 arranged thereon. The heater 501 is, for example, a ceramic heater. The temperature of the heater 501 may be measured by a temperature sensor and controlled by a control circuit so that the measured temperature becomes a target temperature. For example, the target temperature is set so that the surface temperature of a pressure applying portion 509 of the heating plate 502 becomes 200° C. By providing the pressure applying portion 509 on the heating plate 502, 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.

[0055] The heater 501 is supported by a heater support 503 made of resin. The pressure lever 504 obtains power from a motor M8 shown in FIG. 6 in order to pressurize the sheet stack W by pushing down the thermocompression bonding unit 51 in the -Z direction (downward). The pressure force of the pressure lever 504 is transmitted to a pressure section 509 via a metal stay 505 serving as a rigid body. The pressure force of the pressure lever 504 can be controlled according to the amount by which the pressure lever 504 is moved in the -Z direction (downward). For example, the pressure force is 30 kgf.

[0056] The pressure plate 506 is made of an elastic material (e.g., silicone rubber). This is because the pressure plate 506 is a member that can stably receive pressure force. The thermocompression bonding unit 51 presses the sheet stack W1 consisting of sheets S1 to S5, and then separates from the sheet stack W1. Sheets S1 to S5 in FIG. 5(A) indicate the first to fifth sheets of a booklet as a finished product. Sheet S1 is the cover of the booklet. Therefore, no image of adhesive toner Tn is formed on sheet S1. An image of adhesive toner Tn is formed on the lower surfaces of the second and subsequent sheets S2 to S5 of the booklet.

[0057] As shown in Fig. 5(B), a sheet stack W2 is stacked on top of the sheets S1 to S5 that have been thermocompression bonded. The sheets W2 are made up of sheets S6 to S10. The thermocompression bonding unit 51 applies a thermocompression bonding operation to the sheet stack W2 stacked on the sheet stack W1. As a result, a booklet made up of many sheets S is produced.

[0058] The sheets S6 to S10 that are stacked later are included in the same booklet as the sheets S1 to S5. Therefore, an image of the adhesive toner Tn is formed on the lower surface of each of the sheets S6 to S10.

[0059] As an example, the post-processing device 300 can create a portion of a booklet consisting of a maximum of 100 sheets S. When booklet creation is started, the 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 the intermediate stacking section 42. Each time a sheet bundle W arrives, the thermocompression bonding unit 51 performs a thermocompression operation consisting of a lowering operation, a pressurizing operation, and a lifting operation. By repeating the buffering operation and the thermocompression bonding operation, the productivity of the image forming apparatus 100 is not reduced, and booklets are created efficiently.

[0060] 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 in parallel toward 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 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.

[0061] (6) Controller 6 is a diagram for explaining the controller of the image forming system 1. The printer control unit 600 is a controller that controls the image forming apparatus 100. The finisher control unit 650 is a controller that controls the post-processing device 300. The printer control unit 600 and the finisher control unit 650 are connected to each other via a communication interface, and cooperate to control the operation of the image forming system 1.

[0062] The printer control unit 600 has a central processing unit (CPU) 601 and a memory 602. The CPU 601 reads and executes a program stored in the memory 602, and controls the image forming apparatus 100 in accordance with the program. The CPU 601 executes image formation processing and sheet conveying processing in the image forming apparatus 100. The memory 602 includes a non-volatile storage medium such as a read-only memory (ROM) and a volatile storage medium such as a random access memory (RAM). The memory 602 stores programs and data, and provides a working area when the CPU 601 executes the program. The memory 602 is an example of a non-transitory storage medium that stores a program for controlling the image forming apparatus 100.

[0063] The printer control unit 600 is connected to an external device 105 such as a personal computer and a portable information device via an external interface (I / F) 104. The printer control unit 600 accepts an execution command for an image forming job for the image forming system 1 input from the external device 105. The printer control unit 600 is connected to an operation display unit 103 which is a user interface of the image forming system 1. The operation display unit 103 includes a display device (e.g., a liquid crystal panel that presents information to a user) and an input device (e.g., physical buttons and a touch sensor that accept input operations by a user). The printer control unit 600 communicates with the operation display unit 103 to control the display contents of the display device and to receive information input via the input device.

[0064] The finisher control unit 650 has a CPU 651, a memory 652, and an I / O port 653. The CPU 651 reads and executes a program stored in the memory 652, and controls the post-processing device 300 according to the program. The memory 652 includes a non-volatile storage medium (e.g., ROM, SSD, HDD) and a volatile storage medium (e.g., RAM). SSD is an abbreviation for solid state drive. HDD is an abbreviation for hard disk drive. The memory 652 stores programs and data, and provides a working space when the CPU 651 executes the program. The memory 652 is an example of a non-transient storage medium that stores a program for controlling the post-processing device 300. The CPU 651, the memory 652, and the I / O port 653 are connected to each other via a bus 654. The I / O port 653 outputs control signals to various components of the post-processing device 300 and inputs signals therefrom.

[0065] The functions of the printer control unit 600 and the finisher control unit 650 may be implemented as independent hardware such as ASIC, or may be implemented in software as a program module. ASIC is an abbreviation for application specific integrated circuit. The printer control unit 600 may be responsible for some or all of the functions of the finisher control unit 650.

[0066] The I / O port 653 is connected to the sheet sensors 27, 50, 60, and the heater 501. The I / O port 653 is connected to motors M1 to M10 serving as a drive source for conveying the sheet S and a drive source for the thermocompression bonding unit 51.

[0067] Motor M1 rotates and drives the entrance roller 21. Motor M2 rotates and drives the conveying roller pair 22. Motor M3 rotates and drives the conveying roller pair 24. Motor M4 rotates and drives the conveying roller pair 26. Motor M5 rotates and drives the kick-out roller 29. Motor M6 supplies a driving force for intermittently operating the vertical alignment roller 40 one rotation at a time. Motor M7 moves the horizontal alignment jogger 41 in the +X direction or the -X direction. Motor M8 causes the thermocompression unit 51 to perform an operation of pressing the sheet stack W. Motor M9 rotates and drives the discharge roller 38. Motor M10 drives the vertical alignment plate 39 in the +Y direction or the -Y direction.

[0068] (7) Functional configuration 7 shows functions realized by the CPU 651. The CPU 651 realizes a sensor control unit 708, a motor control unit 709, a heater control unit 710, and a transport control unit 711 according to a program. Some or all of these functions may be realized by an ASIC, a digital signal processor (DSP), a field programmable gate array (FPGA), or the like. The CPU 651 may have a communication circuit 706 that executes serial communication and the like.

[0069] The communication circuit 706 is connected to the printer control unit 600, and receives job information and information on the sheet S conveyed from the image forming apparatus 100. The communication circuit 706 instructs the printer control unit 600 to temporarily suspend an image forming job.

[0070] The sensor control unit 708 activates the sheet sensors 27, 50, and 60, and transfers signals input from the sheet sensors 27, 50, and 60 to the transport control unit 711. The transport control unit 711 instructs the motor control unit 709 to drive the motors M1 to M5 based mainly on the input from the sensor control unit 708. This realizes transport control of the sheet S, the sheet stack W, and the booklet. The post-processing control unit 714 instructs the motor control unit 709 to drive the motors M6 to M10 and instructs the heater control unit 710 to start heating the heater 501 based on the input from the sensor control unit 708. This realizes post-processing such as vertical alignment processing, horizontal alignment processing, and thermocompression bonding operation.

[0071] The conveyance control unit 711 has a buffer determination unit 712 and a discharge determination unit 713. The buffer determination unit 712 determines the separation between the preceding sheet bundle and the following sheet bundle in the buffer unit 80. The discharge determination unit 713 may determine the separation between the preceding booklet and the following booklet. For example, the buffer determination unit 712 may determine the separation between the preceding sheet bundle and the following sheet bundle by determining the number of sheets S included in the sheet bundle W created in the buffer unit 80. The discharge determination unit 713 may determine the separation between the preceding booklet and the following booklet by determining the discharge of the booklet held in the intermediate stack unit 42. The counter 715 counts the number i of sheets S stacked in the buffer unit 80. The counter 716 is used in the second embodiment and counts the number H of sheets stacked in the intermediate stack unit 42.

[0072] (8) Continuous production of multiple booklets The image forming system 1 can continuously produce multiple booklets. When the transport control unit 711 receives job information from the external device 105 via the communication circuit 706, it acquires the total number U of pages included in the job. Here, it is assumed that the total number U does not exceed the upper limit number Q (e.g. Q=100 sheets) of sheets S that can be stacked in the intermediate stacking unit 42. Furthermore, the number of sheets S included in one booklet is defined as M. The upper limit number of sheets S included in the sheet bundle W created in the buffer unit 80 is defined as N.

[0073] Fig. 8 is a transport diagram of sheet S for a job to produce two booklets L1, L2, with M=12 sheets. N is 5 sheets. The horizontal axis represents time. The vertical axis represents distance along the transport path in post-processing device 300, with inlet roller 21 as the origin. The position of the leading edge of sheet S is plotted in Fig. 8.

[0074] Sheets S are fed from the image forming apparatus 100 at a constant cycle. The buffer unit 80 forms a sheet stack W consisting of five sheets S, and feeds the sheet stack W to the intermediate stacking unit 42. The intermediate stacking unit 42 performs post-processing (alignment and crimping) every time the sheet stack W arrives.

[0075] The above operation is repeated until the booklets L1 and L2 are completed in the intermediate stacker 42. Thereafter, the discharge rollers 38 discharge the booklets L1 and L2 together onto the lower tray 37.

[0076] In addition, the conveying direction of the sheet S is changed by a switchback on the downstream side of the conveying roller pair 24. That is, the leading edge of the sheet S changes from the first edge to the second edge. Therefore, after the sheet S is temporarily stopped by the conveying roller pair 24, the leading edge of the sheet S in FIG. 8 is at the position of the second edge.

[0077] 8, sheets Sa1 to Sa5 are buffered in a buffer unit 80 to become a sheet bundle W1. The sheet bundle W1 is transported to the intermediate stacker 42, and the leading ends of sheets Sa1 to Sa5 are vertically aligned by a vertical alignment plate 39. Furthermore, sheets Sa1 to Sa5 are subjected to a lateral alignment process and a thermocompression bonding operation.

[0078] 8, the buffer operation in the buffer unit 80 is represented as a succeeding sheet S overlapping a preceding sheet S waiting at the position of the sheet sensor 60. The second sheet bundle W2 to the fifth sheet bundle W5 are also transported, aligned, and pressed in the same manner as the sheet bundle W1. The transport interval (paper interval) of the sheets S is Y1. The transport interval of the sheet bundle W is Y2.

[0079] After being thermocompression-bonded in the intermediate stacking section 42, the sheet stack W1 is held in the intermediate stacking section 42. The succeeding sheet stacks W2 to W5 are stacked in sequence on top of the sheet stack W1. When the thermocompression-bonding operation is performed on the sheet stacks W2 to W5, the sheet stack W1 is also subjected to the thermocompression-bonding operation. Similarly, the sheet stacks W2 to W4 are also subjected to the thermocompression-bonding operation multiple times. Therefore, in FIG. 8, the leading ends of the sheet stacks W1 to W4 remain at the position of the vertical alignment plate 39.

[0080] The maximum number of sheets S included in the sheet bundle W is 5. Therefore, the last sheet Sa12 of the booklet L1 and the first sheet Sb1 of the booklet L2 are included in the sheet bundle W3. As shown in Fig. 8, the sheet bundle W3 includes sheets Sa11 and Sa12 of the booklet L1 and sheets Sb1, Sb2, and Sb3 of the booklet L2.

[0081] The total number U of sheets S in the job is 24, which is not an integer multiple of N. Therefore, the last sheet W5 is made up of four sheets Sb9 to Sb12, which is less than N sheets.

[0082] 9 is a cross-sectional view of the thermocompression bonding unit 51 when the sheet bundle W3 is received by the thermocompression bonding unit 51. Adjacent sheets S included in the sheet bundles W1 and W2 have already been bonded together. No image is formed with adhesive toner Tn on sheet Sb1, which is the cover of booklet L2. Therefore, even if the thermocompression bonding operation is performed in this state, sheet Sa12 of booklet L1 and sheet Sb1 of booklet L2 will not be bonded together.

[0083] Meanwhile, the sheets Sa11 and Sa12 conveyed as the sheet bundle W3 are adhered to the sheet bundles W1 and W2 stacked underneath them. In this manner, the booklet L1 is completed, and the booklet L1 and the booklet L2 are separated from each other.

[0084] 8, when the thermocompression bonding operation of the sheet bundle W4 and the thermocompression bonding operation of the sheet bundle W5 are completed, the stacked booklets L1 and L2 are pushed toward the discharge rollers 38 by the vertical alignment plate 39. Finally, the booklets L1 and L2 are discharged together onto the lower tray 37.

[0085] (9) Flowchart 10A shows the process executed by the CPU 651 (buffer determination unit 712). When the sheet sensor 27 detects the trailing edge of the sheet S, the following steps are executed.

[0086] In S1001, the CPU 651 adds 1 to the count value i of the counter 715 that counts the number of sheets S held in the buffer unit 80. The count value i is initialized to 0 when an image forming job is started and when the sheet stack W is discharged from the buffer unit 80 to the intermediate stacking unit 42.

[0087] In S1002, the CPU 651 determines whether the count value i is equal to the upper limit number N. That is, it is determined whether the number of sheets S buffered in the buffer unit 80 (count value i) has reached the upper limit number N. In other words, it is determined whether the sheet stack W is completed. If the count value i is equal to N, the CPU 651 advances the process from S1002 to S1003.

[0088] In S1003, the CPU 651 discharges the sheet stack W from the buffer unit 80 to the intermediate stack unit 42. That is, the CPU 651 drives the conveying roller pairs 26 and 28 and the kick-out roller 29 to convey the sheet stack W to the intermediate stack unit 42. In S1004, the CPU 651 clears the count value i of the counter 715 to 0.

[0089] On the other hand, if the count value i is less than N in S1002, the CPU 651 advances the process from S1002 to S1005. In S1005, the CPU 651 determines whether the sheet S conveyed to the buffer unit 80 is a sheet corresponding to the last page of the booklet based on the information of the sheet S obtained by the communication circuit 706. If the sheet is a sheet corresponding to the last page of the booklet, the CPU 651 advances the process from S1005 to S1006. In S1006, the CPU 651 determines whether there is a subsequent booklet based on the job information. Note that the job information of the subsequent booklet is notified to the finisher control unit 650 in advance by the communication circuit 706. If there is no subsequent booklet, the sheet bundle W is completed, and the CPU 651 advances the process from S1006 to S1003. That is, the sheet bundle W is discharged from the buffer unit 80 and transported to the intermediate stack unit 42.

[0090] On the other hand, if there is a subsequent booklet, the CPU 651 advances the process from S1006 to S1007. In S1007, the CPU 651 continues to receive subsequent sheets into the buffer unit 80. That is, the buffer operation continues.

[0091] 10B shows the determination process executed by the CPU 651 (the discharge determination unit 713). When the sheet sensor 50 detects the trailing end of the sheet stack W, the following steps are executed.

[0092] In S1011, the CPU 651 determines whether the uppermost (last buffered) sheet S in the sheet stack W is the final page of the job. If the sheet S is the final page of the job, the CPU 651 advances the process from S1011 to S1012.

[0093] In S1012, since the CPU 651 completes the creation of the booklet at the stage where the post-processing of the sheet stack W is finished, the CPU 651 discharges the booklet from the intermediate stacker 42 to the lower tray 37. The CPU 651 drives the motor M10 to push the booklet out by the vertical alignment plate 39. Furthermore, the CPU 651 drives the motor M9 to rotate the discharge rollers 38 and discharge the booklet to the lower tray 37.

[0094] On the other hand, if the last sheet S of the sheet bundle W is not the last page of the job in step S1011, the CPU 651 advances the process from S1011 to S1013. In S1013, the CPU 651 continues to hold the sheet bundle W in the intermediate stacker 42 and continues stacking the subsequent sheet bundle W.

[0095] According to the first embodiment, in a job for continuously producing a plurality of booklets, it is possible to perform a thermocompression operation on the succeeding booklet L2 without discharging the preceding booklet L1 from the intermediate stacking unit 42. This makes it possible to continuously produce booklets without reducing the productivity of the image forming system 1.

[0096] <Example 2> In the first embodiment, it is assumed that the total number U (e.g., 24 sheets) of sheets S included in multiple booklets stacked on the intermediate stacker 42 does not exceed the upper limit number Q (e.g., 100 sheets) of sheets S that can be stacked on the intermediate stacker 42. Therefore, in the second embodiment, handling of a case in which the total number U (e.g., 104 sheets) exceeds the upper limit number Q (e.g., 100 sheets) will be described. In particular, a method of continuously producing booklets while observing the constraint on the upper limit number Q when the conveyance control unit 711 cannot obtain information on the total number U of sheets S in a job will be described.

[0097] Fig. 11 shows a transport diagram in the case where six or more booklets, each consisting of 12 sheets S, are produced. The explanation of Fig. 11 is basically the same as that of Fig. 8(A). However, from the viewpoint of ease of viewing Fig. 11, the reference numbers for the sheets S and the transport interval Y1 are omitted. Fig. 11 shows booklets L1 to L6, but the transport control unit 711 does not obtain information regarding the total number U of the job.

[0098] Even in this case, the conveyance control unit 711 repeats the process of forming a sheet bundle W consisting of five sheets S in the buffer unit 80, sending the sheet bundle W to the intermediate stacking unit 42 and performing the thermocompression bonding operation. Here, sheet Se12, which corresponds to the last page of the twelfth sheet bundle W12, is the last page of the fourth booklet L4. Sheet Se12 satisfies the condition of S1011 in the flowchart shown in FIG. 10(B). When booklet L5 is completed in the intermediate stacking unit 42, the five booklets L1 to L5 are discharged together onto the lower tray 37.

[0099] In FIG. 11, the production of booklet L6 continues, and sheet bundle W13 is conveyed to the emptied intermediate stacking section 42. The same operation as that for sheet bundles W1 to W12 is applied to sheet bundle W13. In this way, if the last sheet S of sheet bundle W and the last sheet S of booklet L match before the upper limit number Q of sheets S that can be stacked on intermediate stacking section 42 is reached, all booklets stacked on intermediate stacking section 42 are discharged to lower tray 37. In this way, no problem occurs if the number R of sheets S stacked on intermediate stacking section 42 (e.g., 60 sheets) becomes an integer multiple of the total number M (e.g., 12 sheets) and an integer multiple of the upper limit number N of buffer section 80 (e.g., 5 sheets) before the number R exceeds the upper limit number Q of intermediate stacking section 42.

[0100] 12 shows a case where booklets L1 and L2, each having M=52 sheets, are produced in succession. Here, sheet Sa52, which corresponds to the last page of the 11th sheet bundle W11, is the last page of booklet L1. Here, it is assumed that a sheet bundle W11 including sheets Sb1 and Sa52 of the succeeding booklet L2 is formed and sent to the intermediate stacker 42. In this case, booklet L1 cannot be discharged from the intermediate stacker 42 until booklet L2 is completed. If booklet L2 is a booklet consisting of 52 sheets S, the number R of sheets S stacked on the intermediate stacker 42 will be 104 sheets, exceeding the upper limit number Q.

[0101] Therefore, sheets Sb1 and Sa52 should not be included in the same sheet bundle W11. In other words, the sheet bundle W11 consisting of sheets Sa51 and Sa52 is transported to the intermediate stacker 42. When booklet L1 is completed, booklet L1 is discharged to the lower tray 37. Note that the interval between the last sheet bundle W11 of booklet L1 and the first sheet bundle W12 of booklet L2 must be Y2. Therefore, the transport control unit 711 notifies the image forming apparatus 100 via the communication circuit 706 that the paper interval between sheets Sa52 and Sb1 should be 4×Y1.

[0102] Fig. 13 shows a method for determining a separation of a sheet stack W executed by the CPU 651 according to a program. Compared to Fig. 10(A), steps S1301 and S1302 are added between S1006 and S1007 in Fig. 13. Therefore, steps S1301 and S1302 will be mainly described. The counter 716 counts the total number H of sheets S stacked in the intermediate stacking section 42.

[0103] S1301 is executed if the answer is Yes in S1006. In S1301, the CPU 651 obtains the sum R of the total number H of sheets S stacked on the intermediate stacker 42 and the total number M of sheets S included in the following booklet.

[0104] R = H + M (1) In S1302, the CPU 651 determines whether the subsequent booklet can be stacked on the intermediate stacker 42 based on the sum R and the upper limit number Q. If the sum R is equal to or less than the upper limit number Q, the CPU 651 determines that the subsequent booklet can be stacked, and advances the process from S1302 to S1007. On the other hand, if the sum R exceeds the upper limit number Q, the CPU 651 determines that the subsequent booklet cannot be stacked, and advances the process from S1302 to S1003.

[0105] Fig. 14 shows a process for determining ejection of a booklet from the intermediate stacker 42. Compared with Fig. 10(B), S1400 and S1401 are added in Fig. 14. S1011 to S1013 have already been described, and therefore will not be described repeatedly here.

[0106] If the final sheet of the sheet stack W that has arrived at the intermediate stacker 42 in S1011 is not the final page of the job, the CPU 651 advances the process from S1011 to S1401.

[0107] In S1401, the CPU 651 determines whether the last sheet of the sheet bundle W conveyed to the intermediate stacking unit 42 is the last page of the booklet. If the last sheet of the sheet bundle W is the last page of the booklet, the CPU 651 advances the process from S1401 to S1012. That is, all the booklets stacked on the intermediate stacking unit 42 are discharged. This case includes both the case illustrated in FIG. 11 (where H is an integer multiple of N) and the case illustrated in FIG. 12 (where H is not an integer multiple of N). On the other hand, if the last sheet of the sheet bundle is not the last page of the booklet, the booklet is not yet complete. Therefore, the CPU 651 advances the process from S1401 to S1013. As a result, stacking of the subsequent sheet bundles on the intermediate stacking unit 42 continues.

[0108] According to the second embodiment, even if the total number of sheets S in a job is unknown, booklets can be formed continuously. That is, the sheets S are stacked within the range that can be stacked in the intermediate stacker 42. It is possible to transport the sheets S constituting the preceding booklet and the sheets S constituting the following booklet together in the same sheet bundle W. As a result, it is possible to continuously create multiple booklets without reducing the productivity of the image forming system 1.

[0109] <Example 3> 15 shows in more detail the functions or modules included in the conveyance control unit 711 in the first and second embodiments. The buffer determination unit 712 determines whether to permit subsequent sheets S to be stacked in the buffer unit 80 based on the count value i of the counter 715. For example, the buffer determination unit 712 permits subsequent sheets S to be stacked in the buffer unit 80 if i is less than N. When i becomes equal to N, the buffer determination unit 712 determines that discharge of the sheet stack W from the buffer unit 80 to the intermediate stack unit 42 should be started. A discharge instruction unit 1510 instructs the motor control unit 709 to discharge the sheet stack W from the buffer unit 80 to the intermediate stack unit 42.

[0110] The final sheet determination unit 1502 analyzes job information and determines whether the ith sheet S last stacked in the buffer unit 80 is the last page (sheet) of the booklet. If the ith sheet S is the last page (sheet) of the booklet, the succeeding sheet determination unit 1503 analyzes job information and determines whether a succeeding booklet exists. If the ith sheet P is the last page (sheet) of the booklet and no succeeding booklet exists, the succeeding sheet determination unit 1503 determines that discharge of the sheet stack W from the buffer unit 80 to the intermediate stacking unit 42 should be started. As a result, the discharge instruction unit 1510 instructs the motor control unit 709 to discharge the sheet stack W from the buffer unit 80 to the intermediate stacking unit 42.

[0111] If the i-th sheet S is not the last page (sheet) of the booklet, the subsequent sheet S is received by the buffer unit 80. If the i-th sheet S is the last page (sheet) of the booklet and there is a subsequent booklet, the subsequent sheet S is received by the buffer unit 80.

[0112] In the second embodiment, when the i-th sheet S is not the last page (sheet) of the booklet, or when the i-th sheet S is the last page (sheet) of the booklet and there is a subsequent booklet, another determination is added. That is, it is determined whether the sheet stack W can be discharged to the intermediate stacking unit 42.

[0113] The sum calculation unit 1521 and the full-load determination unit 1522 are functions related to the second embodiment. The sum calculation unit 1521 adds the count value H of the counter 716 and the total number M of sheets included in the following booklet to obtain a sum R. The full-load determination unit 1522 determines whether the sum R is equal to or less than the upper limit number Q of sheets S that can be stacked in the intermediate stacking unit 42. If the i-th sheet S is the last page (sheet) of the booklet and the sum R is equal to or less than the upper limit number Q, the full-load determination unit 1522 determines that the discharge of the sheet bundle W from the buffer unit 80 to the intermediate stacking unit 42 should be started. As a result, the discharge instruction unit 1510 instructs the motor control unit 709 to discharge the sheet bundle W from the buffer unit 80 to the intermediate stacking unit 42.

[0114] The discharge determination unit 713 of the first embodiment has a job determination unit 1551 and a discharge instruction unit 1570. The job determination unit 1551 determines whether the last sheet S in the sheet stack W that has finally arrived at the intermediate stack unit 42 is the sheet S corresponding to the last page of the job, based on job information. If the last sheet S is the sheet S corresponding to the last page of the job, the job determination unit 1551 determines that all booklets stacked on the intermediate stack unit 42 should be discharged. As a result, the discharge instruction unit 1570 instructs the post-processing control unit 714 or the motor control unit 709 to discharge the booklets.

[0115] The discharge determination unit 713 of the second embodiment further includes a booklet determination unit 1561. The booklet determination unit 1561 determines whether the last sheet of the sheet stack W conveyed to the intermediate stacking unit 42 is the last page of the booklet. The case in which the last sheet of the sheet stack W is the last page of the booklet is as described with reference to FIGS. 11 and 12. When the topmost booklet in the intermediate stacking unit 42 is completed, the booklet determination unit 1561 determines that all booklets stacked in the intermediate stacking unit 42 should be discharged. As a result, the discharge instruction unit 1570 instructs the post-processing control unit 714 or the motor control unit 709 to discharge the booklets.

[0116] <Technical ideas derived from examples> (Item 1) a stack forming means for receiving the sheets one by one and forming a sheet stack of up to N sheets; a conveying means for conveying the sheet bundle when the formation of the sheet bundle is completed; stacking means for stacking the sheet bundle conveyed by the conveying means; a bonding means for performing a bonding process each time the sheet bundle is loaded on the loading means to create a booklet consisting of M sheets; a discharge means for discharging the L booklets from the stacking means when the stacking means has completed the production of the L booklets, the bundle forming means is configured to create a bundle of N sheets including an Mth sheet to be included in a kth booklet and a first sheet to be included in a k+1th booklet (where k is an integer between 1 and L-1, and M is not an integer multiple of N); The bonding means bonds the preceding sheet and the succeeding sheet loaded on the stacking means, except for the Mth sheet to be included in the kth booklet and the first sheet to be included in the k+1th booklet.

[0117] The buffer section 80 is an example of a bundle forming means. The conveying roller pairs 26 and 28 are an example of a conveying means. The intermediate stacking section 42 is an example of a stacking means. The thermocompression bonding unit 51 is an example of a bonding means. The discharge roller 38 and the vertical alignment plate 39 are an example of a discharge means. According to the first and second embodiments, the last sheet to be included in the preceding booklet and the first sheet to be included in the succeeding booklet are included in one sheet bundle and are conveyed. In addition, the multiple sheets constituting one booklet are bonded to each other, but the last sheet to be included in the preceding booklet and the first sheet to be included in the succeeding booklet are not bonded to each other. This improves the productivity of the sheet processing device. (Item 2) The method further includes a control means for controlling the bundle forming means, the conveying means, the loading means, the bonding means, and the discharging means, The control means Counting the number of sheets i stacked in the stack forming means; When the i becomes the N, the sheet bundle is transported from the bundle forming means to the stacking means by the transporting means, 2. The sheet processing apparatus according to claim 1, wherein even if the i is less than the N, if the i-th sheet that arrives at the bundle forming means is the M-th sheet in the L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means.

[0118] The finisher control unit 650 and the CPU 651 are an example of a control unit. When the sheet bundle W is completed, the sheet bundle is transported to the stacking unit. If the number of sheets included in the sheet bundle is N, the sheet bundle is completed. As described in the first embodiment, the sheet bundle is also completed when the last sheet of the job is stacked on the sheet bundle. As described in the second embodiment, there are cases where the subsequent booklet cannot be stacked on the stacking unit. In this case, if the sheet conveyed to the bundle forming unit is a sheet corresponding to the last page of the booklet, the sheet bundle is completed. In other words, if the i-th sheet that arrives at the bundle forming unit is the M-th sheet of the L-th booklet, the sheet bundle is completed. (Item 3) 3. The sheet processing apparatus according to item 2, wherein the Lth booklet is the last booklet in one job, and the Mth sheet in the Lth booklet is a sheet corresponding to the last page in the one job.

[0119] As explained in Example 1, in such a case, the sheet stack is treated as complete even though it contains less than N sheets. (Item 4) 3. The sheet processing apparatus according to item 2, wherein the Lth booklet is produced in one job for producing Y booklets (Y is an integer greater than L).

[0120] As described in the second embodiment, there are cases where it is impossible to load multiple booklets produced by one job onto the loading means. In this case, when L booklets are completed, the L booklets are discharged from the loading means. (Item 5) The control means 5. A sheet processing apparatus according to claim 4, wherein, when a total number R0 of sheets contained in the first booklet to the Lth booklet does not exceed a maximum number of sheets that can be loaded on the loading means, and a total number R1 of sheets contained in the first booklet to the L+1th booklet exceeds the maximum number Q, when the last sheet contained in the Lth booklet arrives at the bundle forming means, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means, and the discharge means discharges the first booklet to the Lth booklet.

[0121] As described in the second embodiment, there are cases where it is impossible to load multiple booklets produced by one job onto the stacking means. In other words, the first to Lth booklets can be loaded onto the stacking means, but the L+1th booklet cannot be loaded onto the stacking means. In this case, after the first to Lth booklets are discharged, the L+1th booklet is loaded onto the stacking means. (Item 6) 5. The sheet processing device according to item 4, wherein the control means delays the acceptance of the first sheet in the L+1th booklet by the bundle forming means until the bundle forming means completes discharging of a sheet bundle including the Mth sheet in the Lth booklet.

[0122] In this way, the CPU 651 delays the introduction of sheets that will form the following sheet bundle until the discharge of the preceding sheet bundle is completed, which will prevent the preceding sheet bundle and the following sheets from colliding with each other in the bundle forming means, i.e., the following sheets will not interfere with the discharge of the preceding sheet bundle. (Item 7) 7. The sheet processing apparatus according to item 6, wherein the control means delays the transport of the sheet stack that will form the L+1th booklet from the stack forming means to the stacking means until the discharge means has completed discharge of the first booklet to the Lth booklet.

[0123] This is illustrated in Fig. 12. This ensures that the sheet bundle to be included in the subsequent booklet does not interfere with the ejection of the preceding booklet, i.e., the ejection of the preceding booklet will be carried out smoothly. (Item 8) The control means When the number of sheets i reaches N, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means, (1) when the number i is less than the number N, and the i-th sheet that has arrived at the bundle forming means is the M-th sheet in the booklet, and the booklet being created at the stacking means is the L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means; (2) if the number of sheets i is less than the N sheets, and the i-th sheet that has arrived at the bundle forming means is the M-th sheet in the booklet, and the booklet being created in the stacking means is not the L-th booklet, have the bundle forming means accept the i+1-th sheet; (3) The sheet processing device according to item 2, wherein if the number i is less than the N and the i-th sheet that arrives at the stack forming means is not the M-th sheet in the booklet, the stack forming means is caused to accept the i+1-th sheet.

[0124] These are as shown in Fig. 12. (1) corresponds to the case where S1002 is No, S1005 is Yes, and S1006 is No. (2) corresponds to the case where S1002 is No, S1005 is Yes, and S1006 is Yes. Here, a case where it is not the Lth booklet means, for example, that the booklets loaded on the loading means are from 1 to L-1. Case (3) corresponds to the case where S1002 is No, and S1005 is No. (Item 9) The method further includes image forming means for forming an image on the sheet and forming an adhesive pattern by a hot melt adhesive on the remaining sheets of the booklet that do not become a cover, The sheet processing device described in item 1, wherein the adhesive means applies heat to the sheet stack loaded on the stacking means to melt an adhesive pattern formed on a subsequent sheet and adhere the preceding sheet to the subsequent sheet.

[0125] The image forming apparatus 100 is an example of an image forming means. By adopting such an adhesive means, it becomes possible to mix sheets of a preceding booklet and sheets of a succeeding booklet in one sheet bundle. As a result, the productivity of the sheet processing apparatus is improved compared to a post-processing apparatus that uses staples. (Item 10) Item 10. The sheet processing apparatus according to item 9, wherein the adhesive pattern is formed by toner.

[0126] This allows an electrophotographic image forming apparatus to be connected to a sheet processing apparatus. In general, an electrophotographic image forming apparatus forms an image using four toners, YMCK. Since K can be formed from YMC, an adhesive toner may be used instead of the K toner. In this case, an image forming apparatus designed to mount four process cartridges may be used as the image forming apparatus 100 of the first and second embodiments. (Item 11) a stacking means for stacking a plurality of sheets to form a sheet bundle and temporarily holding the sheet bundle; a conveying means for conveying the sheet stack held by the stacking means; a stacking means for stacking one or more sheet bundles conveyed by the conveying means; a bonding means for bonding one or more sheet bundles stacked on the stacking means to form a booklet; a discharge means for discharging the booklet from the loading means; a control unit for controlling the number of sheets included in each sheet bundle formed by the stacking unit and the discharge unit for discharging the booklet, The control means If the number of sheets stacked by the stacking means is less than a predetermined number, the stacking process by the stacking means is continued; when the number of sheets stacked by the stacking means reaches the predetermined number, or when the number of sheets stacked by the stacking means is less than the predetermined number but the uppermost sheet in the stacking means is a sheet corresponding to a final page of a job, the conveying means conveys the sheet bundle from the stacking means to the stacking means, A sheet processing apparatus, in which if the uppermost sheet in the sheet stack transported from the stacking means to the stacking means by the transporting means is a sheet corresponding to the final page of a job, all booklets stacked on the stacking means are discharged by the discharge means.

[0127] The buffer unit 80 is an example of a stacking unit. Basically, each of the multiple sheet bundles is composed of a predetermined number of sheets (N sheets). In other words, the sheets of a preceding booklet and the sheets of a succeeding booklet may be included in one sheet bundle. As a result, the productivity of the sheet processing apparatuses of the first and second embodiments is high, compared to a sheet processing apparatus that cannot include the sheets of a preceding booklet and the sheets of a succeeding booklet in one sheet bundle. (Item 12) The control means Item 12. The sheet processing apparatus according to item 11, wherein if the uppermost sheet in the sheet bundle transported from the stacking means to the stacking means by the transporting means corresponds to the last page of a booklet, all of the booklets stacked on the stacking means are discharged by the discharge means.

[0128] As shown in Fig. 8, the topmost sheet (last sheet) of the sheet bundle that has arrived at the stacking means may correspond to the last page of the booklet. In this case, all booklets stacked on the stacking means are discharged. This is, for example, the case where the topmost sheet (last sheet) of the sheet bundle that has arrived at the stacking means corresponds to the last page of the job. Figs. 11 and 12 also show an example where the topmost sheet (last sheet) of the sheet bundle that has arrived at the stacking means corresponds to the last page of the booklet. (Item 13) The control means 3. The sheet processing apparatus according to claim 2, wherein when the sum of the number of sheets forming the preceding booklet loaded on the loading means and the number of sheets forming the succeeding booklet exceeds a predetermined number, the sheet corresponding to the last page of the preceding booklet and the sheet corresponding to the first page of the succeeding booklet are not mixed in the overlapping means.

[0129] This is illustrated in Figure 12. This will prevent the loading means from overflowing. (Item 14) Item 12. The sheet processing apparatus according to item 11, wherein the control unit causes the bonding unit to execute the bonding process every time a sheet stack is loaded onto the loading unit.

[0130] As shown in Figures 5(A) and 5(B), the thermocompression bonding may be performed for each sheet stack, which would allow multiple sheets to be bonded reliably with a small amount of heat. (Item 15) The method further includes image forming means for forming an image on the sheet and forming an adhesive pattern by a hot melt adhesive on the remaining sheets of the booklet that do not become a cover, Item 12. The sheet processing apparatus according to item 11, wherein the adhesive means applies heat to the sheet stack loaded on the loading means to melt an adhesive pattern formed on the subsequent sheet and adhere the preceding sheet to the subsequent sheet.

[0131] In this way, an adhesive that has a low adhesive power at normal temperatures and a high adhesive power at high temperatures may be used. This would be suitable for an electrophotographic image forming apparatus 100 that employs a thermal fixing method. (Item 16) The sheet processing device described in item 11, wherein the stacking means stacks a sheet corresponding to the first page of a subsequent booklet on top of a sheet corresponding to the last page of a preceding booklet, thereby mixing one or more sheets constituting the preceding booklet and one or more sheets constituting the subsequent booklet in the sheet stack.

[0132] This makes it possible to transport the sheets of the preceding booklet and the sheets of the following booklet in the same sheet bundle. (Item 17) an image forming apparatus for forming an image on a sheet; a sheet processing apparatus connected to the image forming apparatus, The sheet processing apparatus includes: a stack forming means for receiving sheets one by one from the image forming apparatus and forming a sheet stack consisting of a maximum of N sheets; a conveying means for conveying the sheet bundle when the formation of the sheet bundle is completed; stacking means for stacking the sheet bundle conveyed by the conveying means; a bonding means for performing a bonding process each time the sheet bundle is loaded on the loading means to create a booklet consisting of M sheets; a discharge means for discharging the L booklets from the stacking means when the stacking means has completed the production of the L booklets; a control means for controlling the bundle forming means, the bundle forming means, the bundle forming means, the bonding means, and the discharge means; The control means Counting the number of sheets i stacked in the stack forming means; When the i becomes the N, the sheet bundle is transported from the bundle forming means to the stacking means by the transporting means, An image forming system in which, even if i is less than N, if the i-th sheet that arrives at the bundle forming means is the M-th sheet in the L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means.

[0133] The invention is not limited to the above-described embodiments, and various modifications and variations are possible 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]

[0134] 80: buffer section, 26: pair of conveying rollers, 42: intermediate stacking section, 51: thermocompression bonding unit, 38: discharge roller

Claims

1. a stack forming means for receiving the sheets one by one and forming a sheet stack of up to N sheets; a conveying means for conveying the sheet bundle when the formation of the sheet bundle is completed; stacking means for stacking the sheet bundle conveyed by the conveying means; a bonding means for performing a bonding process each time the sheet bundle is loaded on the loading means to create a booklet consisting of M sheets; a discharge means for discharging the L booklets from the stacking means when the stacking means has completed the production of the L booklets, the bundle forming means is configured to create a bundle of N sheets including an Mth sheet to be included in a kth booklet and a first sheet to be included in a k+1th booklet (where k is an integer from 1 to L-1, and M is not an integer multiple of N); The adhesive means adhesively attaches the preceding sheet and the succeeding sheet loaded on the stacking means, except for the Mth sheet to be included in the kth booklet and the first sheet to be included in the k+1th booklet.

2. The method further includes a control means for controlling the bundle forming means, the conveying means, the loading means, the bonding means, and the discharging means, The control means Counting the number of sheets i stacked in the stack forming means; When the i becomes equal to the N, the sheet bundle is conveyed from the bundle forming means to the stacking means by the conveying means, 2. The sheet processing apparatus according to claim 1, wherein even if i is less than N, if the i-th sheet that arrives at the bundle forming means is the M-th sheet in an L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means.

3. 3 . The sheet processing apparatus according to claim 2 , wherein the Lth booklet is a last booklet in one job, and the Mth sheet in the Lth booklet is a sheet corresponding to a last page in the one job.

4. The sheet processing apparatus according to claim 2 , wherein the Lth booklet is produced in one job for producing Y booklets (Y is an integer greater than L).

5. The control means 5. The sheet processing apparatus according to claim 4, wherein, when a total number of sheets contained in the first booklet to the Lth booklet does not exceed a maximum number of sheets that can be loaded on the stacking means and a total number of sheets contained in the first booklet to the L+1th booklet exceeds the maximum number of sheets, when the last sheet contained in the Lth booklet arrives at the stack forming means, the conveying means conveys the sheet stack from the stack forming means to the stacking means and the discharge means discharges the first booklet to the Lth booklet.

6. 5. The sheet processing apparatus according to claim 4, wherein the control means delays the acceptance of the first sheet of the L+1th booklet into the bundle forming means until the bundle forming means completes discharging of a sheet bundle including the Mth sheet of the Lth booklet.

7. 7. The sheet processing apparatus according to claim 6, wherein the control means delays transport of the sheet bundle that will form the L+1th booklet from the bundle forming means to the stacking means until the discharge means has completed discharge of the 1st booklet to the Lth booklet.

8. The control means When the number of sheets i reaches N, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means, (1) when the number i is less than the number N, the i-th sheet that has arrived at the bundle forming means is the M-th sheet in the booklet, and the booklet being created in the stacking means is the L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means; (2) if the number of sheets i is less than the number N, and the i-th sheet that has arrived at the bundle forming means is the M-th sheet in the booklet, and the booklet being created in the stacking means is not the L-th booklet, having the bundle forming means accept the i+1-th sheet; (3) The sheet processing apparatus according to claim 2, wherein when the number of sheets i is less than the number N and the i-th sheet that arrives at the stack forming means is not the M-th sheet in the booklet, the stack forming means is caused to accept the i+1-th sheet.

9. The method further includes image forming means for forming an image on the sheet and forming an adhesive pattern by a hot melt adhesive on the remaining sheets of the booklet that do not become a cover, 2 . The sheet processing apparatus according to claim 1 , wherein the bonding means applies heat to the sheet stack loaded on the loading means to melt an adhesive pattern formed on the succeeding sheet, thereby bonding the preceding sheet to the succeeding sheet.

10. The sheet processing apparatus according to claim 9 , wherein the adhesive pattern is formed by a toner.

11. a stacking means for stacking a plurality of sheets to form a sheet bundle and temporarily holding the sheet bundle; a conveying means for conveying the sheet stack held by the stacking means; a stacking means for stacking one or more sheet bundles conveyed by the conveying means; a bonding means for bonding one or more sheet bundles stacked on the stacking means to form a booklet; a discharge means for discharging the booklet from the loading means; a control unit for controlling the number of sheets included in each sheet bundle formed by the stacking unit and the discharge unit for discharging the booklet, The control means If the number of sheets stacked by the stacking means is less than a predetermined number, the stacking process by the stacking means is continued; when the number of sheets stacked by the stacking means reaches the predetermined number, or when the number of sheets stacked by the stacking means is less than the predetermined number but the uppermost sheet in the stacking means is a sheet corresponding to a final page of a job, the conveying means conveys the sheet bundle from the stacking means to the stacking means, A sheet processing apparatus, in which if the uppermost sheet in the sheet stack transported from the stacking means to the stacking means by the transporting means is the sheet corresponding to the final page of the job, all booklets loaded on the stacking means are discharged by the discharge means.

12. The control means 12. The sheet processing apparatus according to claim 11, wherein if the uppermost sheet in the sheet bundle transported from the stacking means to the stacking means by the transporting means is a sheet corresponding to a last page of a booklet, all of the booklets stacked on the stacking means are discharged by the discharging means.

13. The control means 3. The sheet processing apparatus according to claim 2, wherein when the sum of the number of sheets forming the preceding booklet loaded on the stacking means and the number of sheets forming the succeeding booklet exceeds a predetermined number, the sheet corresponding to the last page of the preceding booklet and the sheet corresponding to the first page of the succeeding booklet are not mixed in the stacking means.

14. The sheet processing apparatus according to claim 11 , wherein the control means causes the bonding means to perform the bonding process every time a sheet stack is loaded on the loading means.

15. The method further includes image forming means for forming an image on the sheet and forming an adhesive pattern by a hot melt adhesive on the remaining sheets of the booklet that do not become a cover, The sheet processing apparatus according to claim 11 , wherein the bonding means applies heat to the sheet stack stacked on the stacking means to melt an adhesive pattern formed on the succeeding sheet, thereby bonding the preceding sheet to the succeeding sheet.

16. 12. The sheet processing apparatus according to claim 11, wherein the stacking means stacks a sheet corresponding to a first page of a subsequent booklet on top of a sheet corresponding to a last page of a preceding booklet, so that one or more sheets constituting the preceding booklet and one or more sheets constituting the subsequent booklet are mixed in the sheet bundle.

17. an image forming apparatus for forming an image on a sheet; a sheet processing apparatus connected to the image forming apparatus, The sheet processing apparatus includes: a stack forming means for receiving sheets one by one from the image forming apparatus and forming a sheet stack consisting of a maximum of N sheets; a conveying means for conveying the sheet bundle when the formation of the sheet bundle is completed; stacking means for stacking the sheet bundle conveyed by the conveying means; a bonding means for performing a bonding process each time the sheet bundle is loaded on the loading means to create a booklet consisting of M sheets; a discharge means for discharging the L booklets from the stacking means when the L booklets have been produced in the stacking means; a control means for controlling the bundle forming means, the bundle forming means, the bundle forming means, the bonding means, and the discharge means; The control means Counting the number of sheets i stacked in the stack forming means; When the i becomes equal to the N, the sheet bundle is conveyed from the bundle forming means to the stacking means by the conveying means, An image forming system in which, even if i is less than N, if the i-th sheet that arrives at the bundle forming means is the M-th sheet in the L-th booklet, the conveying means conveys the sheet bundle from the bundle forming means to the stacking means.

Images