Image forming apparatus

Abstract

To provide an image forming apparatus that can create a print with high adhesive strength.SOLUTION: An image forming apparatus comprises: an image forming unit that can form an image on a sheet by using toner for image formation, and can form an adhesion layer on a sheet by using toner for adhesion; a fixing unit that applies heat and pressure to the sheet on which the image or the adhesion layer is formed to fix the toner to the sheet; and a re-conveyance path that guides a first sheet passing through the fixing unit and a second sheet subsequent to the first sheet toward the fixing unit again. During the passage of the first sheet and the second sheet through the re-conveyance path, the image forming apparatus superimposes a first adhesion surface of the first sheet on which the adhesion layer is formed on a second adhesion surface of the second sheet on which the adhesion layer is formed, and conveys the first sheet and the second sheet in the superimposed state to the fixing unit.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet. [Background technology]

[0002] Conventionally, an image forming apparatus has been proposed that glues two sheets of paper together to create a laminated sheet (see Patent Document 1). This image forming apparatus conveys the first sheet of paper to a first conveying path, and forms a pattern image on the first sheet of paper in a transfer section and a fixing section. The image forming apparatus then guides the first sheet of paper to a second conveying path without switching back, and causes the first sheet of paper to merge with the first conveying path.

[0003] At this time, the image forming device conveys the second sheet of paper so that it is superimposed on the first sheet of paper that has joined the first conveying path, and while the two sheets of paper are superimposed, the fixing unit heats the pattern image formed on the first sheet of paper, causing the toner of the pattern image to adhere the first and second sheets of paper together, creating a single interleaved sheet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-181639 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the image forming device described in Patent Document 1 adheres two sheets of paper only by a pattern image formed on the first sheet of paper, and does not form a pattern image that functions as an adhesive on the second sheet of paper. Therefore, the adhesive strength of the slip sheet formed by the two sheets of paper is weak, and there is a risk that the adhesive portion of the slip sheet will peel off.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus capable of producing printed matter with high adhesive strength. [Means for solving the problem]

[0007] The present invention is an image forming apparatus comprising an image forming section capable of forming an image on a sheet using a toner for image formation and of forming an adhesive layer on the sheet using a toner for adhesion, a fixing section which fixes the toner to the sheet by heating and pressurizing the sheet on which the image or the adhesive layer has been formed, and a re-conveying path which guides a first sheet that has passed through the fixing section and a second sheet following the first sheet back toward the fixing section, wherein while the first sheet and the second sheet pass through the re-conveying path, the first adhesive surface of the first sheet on which the adhesive layer has been formed and the second adhesive surface of the second sheet on which the adhesive layer has been formed are overlapped, and the first sheet and the second sheet are transported to the fixing section while still overlapped. Effect of the Invention

[0008] According to the present invention, a printed matter having high adhesive strength can be produced. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an image forming apparatus according to a first embodiment. [Diagram 2] 1A is a cross-sectional view showing the positions of the first and second switching members when discharging a sheet, FIG. 1B is a cross-sectional view showing the positions of the first and second switching members when reversing and transporting a sheet, and FIG. 1C is a cross-sectional view showing how the sheet is guided to a duplex transport path by the second switching member. [Diagram 3] FIG. 2 is a block diagram showing a control block of the image forming apparatus according to the first embodiment. [Figure 4] 5 is a flowchart showing adhesive print production control when the image forming apparatus produces an adhesive print. [Diagram 5]FIG. 1(a) is a diagram for explaining the movement of the first sheet and the second sheet when creating an adhesive print; FIG. 1(b) is a diagram for explaining the movement of the first sheet and the second sheet; and FIG. 1(c) is a diagram for explaining the movement of the first sheet and the second sheet. [Figure 6] 1A is a front view showing an envelope, FIG. 1B is a perspective view showing the envelope, FIG. 1C is a front view showing a document holder, and FIG. [Figure 7] 1A is a diagram showing the display part of the operations panel, FIG. 1B is a diagram showing the display part of the operations panel, FIG. 1C is a diagram showing the display part of the operations panel, and FIG. [Figure 8] 10 is a flowchart showing adhesive print production control when an image forming apparatus according to a first modified example of the first embodiment produces an adhesive print. [Figure 9] 1A is a diagram showing a shortcut transport path and a third switching member in a second modified example of the first embodiment, FIG. 1B is a diagram showing the shortcut transport path and the third switching member, and FIG. 1C is a diagram showing the shortcut transport path and the third switching member. [Figure 10] 10 is a flowchart showing adhesive print production control when an image forming apparatus according to a second embodiment produces an adhesive print. [Figure 11] (a) is a diagram for explaining the movement of the first sheet and the second sheet when producing an adhesive print, (b) is a diagram for explaining the movement of the first sheet and the second sheet, (c) is a diagram for explaining the movement of the first sheet and the second sheet, and (d) is a diagram for explaining the movement of the first sheet and the second sheet. [Figure 12] FIG. 11 is a block diagram showing a control block of an image forming apparatus according to a third embodiment. [Figure 13] 10 is a flowchart showing adhesive print production control when an image forming apparatus according to a third embodiment produces an adhesive print. [Figure 14] 10 is a flowchart showing adhesive print production control when an image forming apparatus according to a third embodiment produces an adhesive print. [Figure 15]FIG. 1(a) is a diagram for explaining the movement of the first sheet and the second sheet when creating an adhesive print; FIG. 1(b) is a diagram for explaining the movement of the first sheet and the second sheet; and FIG. 1(c) is a diagram for explaining the movement of the first sheet and the second sheet. [Figure 16] FIG. 1(a) is a diagram for explaining the movement of the first sheet and the second sheet when creating an adhesive print; FIG. 1(b) is a diagram for explaining the movement of the first sheet and the second sheet; and FIG. 1(c) is a diagram for explaining the movement of the first sheet and the second sheet. [Figure 17] 10 is a flowchart showing adhesive print production control when an image forming apparatus according to a fourth embodiment produces an adhesive print. [Figure 18] (a) is a diagram for explaining the movement of the first sheet and the second sheet when producing an adhesive print, (b) is a diagram for explaining the movement of the first sheet and the second sheet, (c) is a diagram for explaining the movement of the first sheet and the second sheet, and (d) is a diagram for explaining the movement of the first sheet and the second sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <First embodiment> First, a first embodiment of the present invention will be described. Fig. 1 is a schematic cross-sectional view showing an image forming apparatus 1 according to the first embodiment. The image forming apparatus 1 forms an image on a sheet S, which is a recording material, and outputs the image. The sheet S used in the image forming apparatus 1 includes various sheet materials of different sizes and materials, such as paper such as plain paper and cardboard, sheet materials with surface treatments such as plastic film, cloth, and coated paper, and sheet materials with special shapes such as index paper.

[0011] [General configuration of image forming device] 1, the image forming apparatus 1 includes an image forming section 1B, a sheet feeding section 1C, a fixing device 18, a discharge unit 1D, and a reverse conveying unit 1E. The image forming section 1B includes an intermediate transfer belt 8 as an intermediate transfer body, process cartridges 30s and 30k arranged along the intermediate transfer belt 8, a belt cleaner 12, and a scanner unit 4.

[0012] Each of the process cartridges 30s, 30k has a photosensitive drum 2s, 2k as an image carrier, a charging device 3s, 3k, and a developing unit 5s, 5k. Each of the process cartridges 30s, 30k is detachable from the main body 1A of the image forming apparatus 1. The developing unit 5s has a container 5s2 that contains toner as a developer, and a developing roller 5s1 that is rotatably held in the container 5s2 and serves as a developer carrier that carries the toner and rotates. Similarly, the developing unit 5k has a container 5k2 that contains toner as a developer, and a developing roller 5k1 that is rotatably held in the container 5k2 and serves as a developer carrier that carries the toner and rotates.

[0013] The process cartridge 30k is a first cartridge that forms an image using a first toner, which is a toner for image formation. The photosensitive drum 2k and the developing roller 5k1 are the first image carrier and the first developing roller, respectively, in this embodiment. The process cartridge 30s is a second cartridge that forms an image using a second toner, which is a toner for adhesion. The photosensitive drum 2s and the developing roller 5s1 are the second image carrier and the second developing roller, respectively, in this embodiment. The apparatus main body 1A includes frame members such as a metal frame that constitute the frame of the image forming apparatus 1 and members fixed to the frame, and forms an installation space in which the process cartridges 30s, 30k are installed.

[0014] The process cartridge 30k forms a toner image for recording an image on the sheet S using black toner. The process cartridge 30s forms a toner image using glue toner in order to apply a transparent toner (hereinafter referred to as glue toner) which is a powder adhesive to the sheet S. That is, the image forming apparatus 1 of the present embodiment can selectively use black toner as the first toner and glue toner as the second toner. As the glue toner, toner particles having the same components and manufacturing method as the black toner can be used except that the glue toner does not contain a coloring component, and for example, a toner having a melting point lower than that of the black toner by increasing the content of the wax component can be preferably used. That is, the black toner is a colored toner, and the glue toner is a colorless toner.

[0015] In this embodiment, the adhesive toner contained in the process cartridge 30s is a transparent toner, but for example, a white toner may be used as the powder adhesive. Also, since the toner image of the adhesive toner in this embodiment is transparent, it is different from a normal toner image for recording an image on the sheet S, but unless otherwise specified, the "toner image" in the following description includes the toner image of the adhesive toner.

[0016] A scanner unit 4 serving as an exposure unit is disposed below the process cartridges 30s, 30k. A sheet feeding unit 1C is disposed below the scanner unit 4, and the sheet feeding unit 1C has a cassette 13 serving as a stacking unit on which sheets S are stacked, a pickup roller 14 that feeds the sheets S in the cassette 13, and a separation roller pair 15. The cassette 13 is provided so as to be removable from the apparatus main body 1A.

[0017] An intermediate transfer belt 8 is disposed above the process cartridges 30s, 30k, and is an endless belt that is stretched by a drive roller 9a, a tension roller 9b, and a tension roller 10. The intermediate transfer belt 8 rotates counterclockwise in FIG. 1 as the drive roller 9a rotates.

[0018] Primary transfer rollers 7k and 7s as primary transfer members are disposed inside the intermediate transfer belt 8, and these primary transfer rollers 7k and 7s are disposed at positions facing the photosensitive drums 2k and 2s, respectively, with the intermediate transfer belt 8 in between. In addition, a secondary transfer roller 11 is provided outside the drive roller 9a with the intermediate transfer belt 8 in between. A secondary transfer nip N1 as an image forming section is formed between the intermediate transfer belt 8 and the secondary transfer roller 11.

[0019] A belt cleaner 12 is provided at a position adjacent to the tension roller 10. The belt cleaner 12 has a cleaning member 12a that comes into contact with the intermediate transfer belt 8 and removes deposits such as residual toner remaining on the intermediate transfer belt 8, and a waste toner container 6 that collects the deposits removed by the cleaning member 12a. The cleaning member 12a is composed of a blade, a brush, or the like.

[0020] The fixing device 18 has a fixing roller 18a incorporating a heater such as a ceramic heater or a halogen heater, and a pressure roller 18b forming a fixing nip N2 together with the fixing roller 18a. The sheet S that has passed through the secondary transfer nip N1 is heated and pressurized in the fixing nip N2 as a fixing section, and the toner image is fixed to the sheet S.

[0021] In the present embodiment, the toner image on the sheet S is heated by the fixing roller 18a with a built-in heater, but the present invention is not limited to this. For example, instead of the fixing roller 18a, the toner image may be heated by an endless film or belt with a built-in heater. Also, a fixing device of an electromagnetic induction heating type may be applied in which a metal heating layer is provided on the fixing sleeve and the fixing sleeve is heated by passing a high-frequency current through a coil.

[0022] A discharge unit 1D and a reversing conveying unit 1E are disposed downstream in the sheet conveying direction of the fixing device 18. The discharge unit 1D has a discharge conveying path 20, a pair of discharge rollers 25, and a discharge tray 26. The pair of discharge rollers 25 discharges the sheet S that has passed through the discharge conveying path 20 onto the discharge tray 26.

[0023] The reversing conveying unit 1E has a first switching member 19, a second switching member 23, a reversing conveying path 29, a reversing roller pair 21, a double-sided conveying path 22, a registration roller pair 24, and a conveying roller pair 28. The reversing conveying path 29 branches off from the feeding conveying path CP downstream of the fixing nip N2 in the conveying direction of the sheet conveyed through the fixing nip N2, and the first switching member 19 is disposed at a branching portion of the feeding conveying path CP and the reversing conveying path 29. The first switching member 19 can guide the sheet S to the discharge conveying path 20 or the reversing conveying path 29.

[0024] The reversing roller pair 21 as a reversing conveying section is disposed downstream of the branching portion between the discharge conveying path 20 and the reversing conveying path 29 in the sheet conveying direction and on the reversing conveying path 29. The double-sided conveying path 22 branches off from the reversing conveying path 29, and a registration roller pair 24 and a conveying roller pair 28 are provided on the double-sided conveying path 22. The double-sided conveying path 22 as a re-conveying path merges with the feeding conveying path CP as a conveying path passing through the registration roller pair 17, the secondary transfer nip N1 and the fixing nip N2, and guides the sheet again toward the fixing nip N2. The second switching member 23 as a guide member can guide the sheet S that has passed through the fixing nip N2 to the double-sided conveying path 22 without guiding it to the reversing roller pair 21 and the reversing conveying path 29. The operations of the first switching member 19 and the second switching member 23 will be described later.

[0025] In this embodiment, the device body 1A of the image forming apparatus 1 can be regarded as one housing, and the device body 1A houses the secondary transfer nip N1, the fixing nip N2, the double-sided conveying path 22, etc. In other words, the secondary transfer nip N1, the fixing nip N2, and the double-sided conveying path 22 are not provided in any housing other than the device body 1A.

[0026] [Image formation operation] Next, a description will be given of an image forming operation by the image forming apparatus 1. When an image signal is input from a personal computer (not shown) or the like to the scanner unit 4, the scanner unit 4 irradiates a laser beam corresponding to the image signal onto the photosensitive drum 2k of the process cartridge 30k.

[0027] At this time, the surface of the photosensitive drum 2k is uniformly charged to a predetermined polarity and potential by the charging device 3k, and an electrostatic latent image is formed on the surface by irradiating it with laser light from the scanner unit 4. The electrostatic latent image formed on the photosensitive drum 2k is developed using black toner by the developing roller 5k1, and a black toner image (hereinafter also referred to as a black toner image) is formed on the photosensitive drum 2k.

[0028] On the other hand, when creating an adhesive printed matter such as an envelope, the scanner unit 4 irradiates the photosensitive drum 2s with a laser beam based on information indicating the adhesive position of the sheet S. The surface of the photosensitive drum 2s is uniformly charged to a predetermined polarity and potential by the charging device 3s, and an electrostatic latent image is formed on the surface by irradiating the surface with a laser beam from the scanner unit 4. The electrostatic latent image formed on the photosensitive drum 2s is developed with glue toner by the developing roller 5s1, and a toner image of the glue toner (hereinafter also referred to as glue toner image) is formed in an area on the photosensitive drum 2s corresponding to the adhesive position. It is not necessarily required to form a toner image on both the photosensitive drums 2k and 2s, and a toner image may be formed on only one of the photosensitive drums 2k and 2s.

[0029] The toner images formed on the photosensitive drums 2k, 2s are transferred onto the intermediate transfer belt 8 by the primary transfer rollers 7k, 7s, and are transported to the secondary transfer roller 11 by the intermediate transfer belt 8 rotated by the drive roller 9a. The image forming process of each toner image is performed at a timing to be superimposed on the upstream toner image that has been primarily transferred onto the intermediate transfer belt 8.

[0030] In parallel with this image forming operation, the sheets S stored in the cassette 13 of the sheet feeding section 1C are sent out by the pickup roller 14 and separated one by one by the separation roller pair 15. One of the separation roller pair 15 is connected to a torque limiter (not shown), and when only one sheet S is fed by the pickup roller 14, the torque limiter rotates idly and rotates with the pickup roller 14. When two or more sheets are fed by the pickup roller 14, the one of the separation roller pair 15 stops rotating to prevent the second and subsequent sheets from being conveyed. Note that a drive force in the opposite direction to the sheet conveying direction may be input to one of the separation roller pair 15, and a separation pad may be provided in place of one of the separation roller pair 15.

[0031] Then, the sheet S conveyed to the feeding conveying path CP by the pickup roller 14 and the separation roller pair 15 is conveyed to the registration roller pair 17 by the conveying roller pair 16. The sheet S has its skew corrected by the registration roller pair 17, and is conveyed toward the secondary transfer nip N1 in accordance with the image conveyed by the intermediate transfer belt 8.

[0032] The toner image on the intermediate transfer belt 8 is transferred to the sheet S at the secondary transfer nip N1 by a secondary transfer bias applied to the secondary transfer roller 11. That is, the secondary transfer nip N1 of the image forming apparatus 1 can form an adhesive toner image as an adhesive layer on the sheet using an adhesive toner. The sheet S to which the toner image has been transferred is applied with a predetermined heat and pressure at the fixing nip N2 of the fixing device 18, so that the toner is melted and fixed (fixed). The sheet S that has passed through the fixing nip N2 is guided to the discharge conveying path 20 by the first switching member 19, and is discharged to the discharge tray 26 by the discharge roller pair 25 of the discharge unit 1D.

[0033] In the case of double-sided printing in which an image is formed on both sides of the sheet S, the sheet S with an image formed on the first side is guided to the reverse conveying path 29 by the first switching member 19, and is switched back by the reverse roller pair 21 after the rear end of the sheet S passes the leading edge of the first switching member 19. That is, the front end and rear end of the sheet S are switched back by the switchback. In this way, the reverse roller pair 21 can perform a reverse conveying process that reverses the sheet S. The sheet S switched back by the reverse roller pair 21 is guided to the double-sided conveying path 22, and is conveyed again toward the secondary transfer nip N1 by the registration roller pair 24 and the conveying roller pair 28. An image is formed on the second side of the sheet S in the secondary transfer nip N1, and the sheet S is discharged to the discharge tray 26 by the discharge roller pair 25.

[0034] [Operation of the first switching member and the second switching member] Next, the operations of the first switching member 19 and the second switching member 23 will be described with reference to Figs. 2(a) to (c). The first switching member 19 is configured to be movable to a discharge position shown in Fig. 2(a), a reverse position shown in Fig. 2(b), and a re-conveying position shown in Fig. 2(c). The first switching member 19 is moved to the discharge position, reverse position, and re-conveying position by a first switching motor M1 (see Fig. 3). The second switching member 23 is moved to a retracted position shown in Figs. 2(a) and (b), and a guide position shown in Fig. 2(c) by a second switching motor M2 (see Fig. 3).

[0035] 2(a), when the sheet S is transported to the discharge transport path 20 and discharged outside the image forming apparatus 1, the first switching member 19 is located at the discharge position, and the second switching member 23 is located at the retracted position. In this state, when the sheet S is transported by the fixing device 18, the sheet S is guided to the discharge transport path 20 by the first switching member 19 located at the discharge position. At this time, the second switching member 23 is retracted from the transport path so as not to obstruct the transport of the sheet S.

[0036] As shown in FIG. 2B, when the sheet S is switched back by the reversing roller pair 21 and conveyed to the double-sided conveying path 22, the first switching member 19 is located at the reversing position, and the second switching member 23 is located at the retreating position. In this state, when the sheet S is conveyed by the fixing device 18, the sheet S is guided to the reversing conveying path 29 by the first switching member 19 located at the reversing position. Then, after the rear end of the sheet S passes the leading edge of the first switching member 19, the first switching member 19 moves from the reversing position to the discharge position. The sheet S switched back by the reversing roller pair 21 is guided to the double-sided conveying path 22 by the first switching member 19 located at the discharge position. The sheet S conveyed in this manner is switched back by the reversing roller pair 21, so that the front end and the rear end of the sheet S are switched. Note that the second switching member 23 retreats from the conveying path so as not to obstruct the conveying of the sheet S until the rear end of the sheet S is conveyed to the double-sided conveying path 22.

[0037] 2(c), when the sheet S is transported to the double-sided conveying path 22 without passing through the reversing roller pair 21, the first switching member 19 is located at the re-conveying position, and the second switching member 23 is located at the guiding position. In this state, when the sheet S is transported by the fixing device 18, the sheet S is guided to the double-sided conveying path 22 by the second switching member 23 located at the guiding position, without passing through the reversing roller pair 21. The sheet S transported in this manner is not switched back by the reversing roller pair 21, so that the front end and the rear end of the sheet S are not switched. Note that the first switching member 19 located at the re-conveying position may guide the sheet S to the double-sided conveying path 22 together with the second switching member 23, and may not abut against the sheet S.

[0038] In the present embodiment, when the sheet S is transported to the double-sided transport path 22 without passing through the reversing roller pair 21, the first switching member 19 is located at the re-transport position, but this is not limiting. For example, when the sheet S is guided to the double-sided transport path 22 by the second switching member 23, the first switching member 19 may be located at the discharge position as long as the transport of the sheet S is not impeded. This eliminates the need to move the first switching member 19 to the re-transport position, and the first switching member 19 may be configured to be movable between the discharge position and the reversing position.

[0039] [Control Block] Fig. 3 is a block diagram showing a control block of the image forming apparatus 1. As shown in Fig. 3, the image forming apparatus 1 has a control unit 100. The control unit 100 has a central processing unit (CPU) 111, a read only memory (ROM) 112, and a random access memory (RAM) 113. The CPU 111 reads and executes various programs stored in the ROM 102. The RAM 103 is used as a working area for the CPU 111.

[0040] 3, various sensors provided in the image forming apparatus 1 are not shown, but the image forming apparatus 1 may have sensors. For example, the image forming apparatus 1 may be provided with one or more sheet detection sensors for detecting the position of the sheet S on the feeding conveying path CP, the discharge conveying path 20, the reversing conveying path 29, and the double-sided conveying path 22. The control unit 100 may recognize the position of the conveyed sheet S based on the detection result of the sheet detection sensor, and control the movement timing of the first switching member 19 and the second switching member 23 described above, the temperature rise timing of the fixing device 18, the drive timing of the various rollers, and the like.

[0041] The output side of the control unit 100 is connected to a first switching motor M1 that drives the first switching member 19, a second switching motor M2 that drives the second switching member 23, an alignment motor M3 that drives the alignment unit 31, and the like. As shown in FIG. 1, the alignment unit 31 is disposed between the registration roller pair 24 and the conveying roller pair 28 in the sheet conveying direction, and has a pair of alignment members. The pair of alignment members moves in the width direction perpendicular to the sheet conveying direction by being driven by the alignment motor M3. The pair of alignment members aligns the sheet S in the width direction by abutting against both ends of the sheet S in the width direction.

[0042] In addition, an operation panel 110 serving as an operation unit is connected to the control unit 100. The operation panel 110 has a display unit 35 that can be viewed and touched by a user. The display unit 35 is composed of, for example, a liquid crystal panel or an LED panel. The display unit 35 can display the operating status of the image forming apparatus 1 and the status of consumables such as toner, and also has a navigation function that guides the user to specific operations.

[0043] [Creating adhesive prints] Next, the operation of the image forming apparatus 1 when two sheets are superimposed and adhered to create an adhesive printed matter such as an envelope will be described with reference to Figs. 4 to 5(c). Fig. 4 is a flowchart showing adhesive printed matter creation control when the image forming apparatus 1 creates an adhesive printed matter. Figs. 5(a) to (c) are diagrams for explaining the movements of the first sheet S1 and the second sheet S2 when creating an adhesive printed matter. In Figs. 5(a) to (c), the first sheet S1 is indicated by a solid line, and the second sheet S2 following the first sheet S1 is indicated by a dashed line.

[0044] It should be noted that the first sheet S1 does not necessarily have to be the first sheet of the job, and the second sheet S2 does not necessarily have to be a sheet fed immediately after the first sheet S1. In other words, another sheet may be fed by the sheet feeding section 1C between the first sheet S1 and the second sheet S2.

[0045] As shown in FIG. 4, the control unit 100 first judges whether an adhesive print production job has been input to the control unit 100 from the operation panel 110 or an external PC (step S11). When it is judged that an adhesive print production job has been input to the control unit 100 (step S11: Yes), the control unit 100 forms an adhesive toner image on the first adhesive surface S1s of the first sheet S1 (step S12). The step S12 can also be called a first adhesive layer forming process for forming an adhesive toner image as an adhesive layer on the first adhesive surface S1s. Specifically, the control unit 100 forms an adhesive toner image on the photosensitive drum 2s using adhesive toner, and feeds the first sheet S1 by the sheet feeding unit 1C. Then, the control unit 100 transfers the adhesive toner image on the photosensitive drum 2s to the first sheet S1 at the secondary transfer nip N1, and fixes the adhesive toner image to the first sheet S1 at the fixing nip N2.

[0046] Next, as shown in FIG. 5A, the control unit 100 reverses and conveys the first sheet S1 by the pair of reversing rollers 21, that is, switches back and conveys the first sheet S1 (step S13). The step S13 can also be called a reverse conveying process or a first reverse conveying process. Specifically, the control unit 100 positions the first switching member 19 and the second switching member 23 at a reverse position and a retreat position, respectively, before the first sheet S1 reaches the first switching member 19 and the second switching member 23. Then, the first sheet S1 is guided to the reverse conveying path 29 by the first switching member 19 positioned at the reverse position. The control unit 100 performs a reverse conveying process in which the first sheet S1 is conveyed by the pair of reversing rollers 21 a predetermined distance in a first direction toward the outside of the machine, and then conveys the first sheet S1 in a second direction opposite to the first direction. At this time, the control unit 100 moves the first switching member 19 from the inversion position to the discharge position, and the first sheet S1 is guided to the double-sided conveying path 22 by the first switching member 19 located at the discharge position.

[0047] After being guided to the double-sided conveying path 22, the leading edge of the first sheet S1 hits the nip of the registration roller pair 24, which is in a stopped state. The control unit 100 stops the reversing roller pair 21 at the timing when the leading edge of the first sheet S1 hits the nip of the registration roller pair 24, or at the timing when the first sheet S1 is further conveyed a little and forms a small loop in the space in the double-sided conveying path 22. In FIG. 5(a), the first adhesive surface S1s of the first sheet S1, on which a glue toner image is formed as an adhesive layer, is formed on the lower surface side of the first sheet S1.

[0048] Next, the control unit 100 forms a glue toner image on the second adhesive surface S2s of the second sheet S2 following the first sheet S1 (step S14), as shown in Fig. 4. This step S14 can also be called a second adhesive layer forming process for forming a glue toner image as an adhesive layer on the second adhesive surface S2s. Note that the process for forming the glue toner image on the second sheet S2 is the same as step S12, so a description thereof will be omitted.

[0049] 5B, the control unit 100 guides the second sheet S2 to the double-sided conveying path 22 by the second switching member 23 (step S15). Step S15 can also be considered as a guide process in which the second sheet S2 is guided to the double-sided conveying path 22 by the second switching member 23 without undergoing a reverse conveying process. Specifically, the control unit 100 positions the first switching member 19 and the second switching member 23 at the re-conveying position and the guiding position, respectively, before the second sheet S2 reaches the first switching member 19 and the second switching member 23. Then, the second sheet S2 is guided directly to the double-sided conveying path 22 by the second switching member 23 positioned at the guiding position without being guided to the reverse conveying path 29.

[0050] The second sheet S2 is guided to the double-sided conveying path 22 and further conveyed by the fixing device 18, so that the second sheet S2 is superimposed on the first sheet S1 in the double-sided conveying path 22 (step S16). The step S16 can be said to be a superimposing process in which the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are superimposed. In FIG. 5B, the second adhesive surface S2s of the second sheet S2 on which the glue toner image is formed is formed on the upper surface side of the second sheet S2. By conveying the first sheet S1 and the second sheet S2 in this manner, the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 can be superimposed. In other words, the first adhesive surface S1s and the second adhesive surface S2s are superimposed while the first sheet S1 and the second sheet S2 pass through the double-sided conveying path 22.

[0051] When the second sheet S2 is conveyed to the double-sided conveying path 22, the registration roller pair 24 remains in a stopped state. The control unit 100 drives the registration roller pair 24 when the leading edge of the second sheet S2 hits the nip of the registration roller pair 24, or when the second sheet S2 is conveyed a little further and forms a loop in the space in the double-sided conveying path 22. This makes it possible to convey the first sheet S1 and the second sheet S2 in an overlapping state while aligning the leading edge of the first sheet S1 and the leading edge of the second sheet S2. FIG. 5(c) shows the state in which the first sheet S1 and the second sheet S2 in an overlapping state are conveyed through the double-sided conveying path 22 toward the registration roller pair 17.

[0052] 4, the control unit 100 heats and presses the overlapping first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18 to bond the first sheet S1 and the second sheet S2 together (step S17). That is, the adhesive toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, thereby firmly bonding the first sheet S1 and the second sheet S2 together.

[0053] Then, the control unit 100 positions the first switching member 19 and the second switching member 23 at the discharge position and the retracted position, respectively, before the bonded first sheet S1 and the second sheet S2 reach the first switching member 19 and the second switching member 23. In this state, the control unit 100 conveys the first sheet S1 and the second sheet S2 by the fixing device 18, and the first sheet S1 and the second sheet S2 are guided to the discharge conveyance path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and the second sheet S2 to the discharge tray 26 by the discharge roller pair 25 (step S18), and ends the control for producing one bonded printed matter. The control unit 100 may continuously produce bonded printed matters according to the contents of the bonded printed matter production job.

[0054] In the above example, when the overlapping first sheet S1 and second sheet S2 pass through the secondary transfer nip N1 before the fixing device 18, the toner image is not transferred to the first sheet S1 and the second sheet S2, but this is not limited to the above. For example, in the secondary transfer nip N1, a black toner image may be transferred to the surface of the first sheet S1 opposite to the first adhesive surface S1s. This allows the cover of the adhesive print to be printed.

[0055] Furthermore, the control unit 100 may execute an alignment process in which the overlapped first sheet S1 and second sheet S2 are aligned by the alignment unit 31 between the above-mentioned steps S16 and S17. For example, in the alignment process, the control unit 100 causes the overlapped first sheet S1 and second sheet S2 to abut against the nip of the conveying roller pair 28 in a stopped state, and then separates the rollers of the registration roller pair 24. Thereafter, the control unit 100 drives the alignment motor M3 so that a pair of alignment members of the alignment unit 31 move from both sides of the sheet conveying area toward the center. Then, both ends in the width direction of the overlapped first sheet S1 and second sheet S2 are pressed by the pair of alignment members, thereby aligning them. By such an alignment process, the adhesive print can be aligned not only in the sheet conveying direction but also in the width direction, and a high-quality adhesive print can be created.

[0056] [Adhesive printed matter] Next, examples of adhesive printed matter will be described with reference to Figs. 6(a) to (d). Figs. 6(a) and (b) are diagrams showing an envelope as an example of an adhesive printed matter. Figs. 6(c) and (d) are diagrams showing a document holder as an example of an adhesive printed matter.

[0057] As shown in Figures 6(a) and 6(b), the envelope SB1 has a glued portion 27a in which a glue toner image is formed linearly along three sides of the first sheet S1 and the second sheet S2. Therefore, one side of the envelope SB1 where the glued portion 27a is not formed (the upper side in Figure 6(b)) is open, and a document or the like can be inserted through the opening. When sealing the envelope SB1, a user may insert a document or the like into the envelope SB1 and then glue the opening to close it. In the example of Figures 6(a) and 6(b), the two long sides and one short side of the first sheet S1 and the second sheet S2 are glued, but for example, the two short sides and one long side may be glued.

[0058] As shown in Figures 6(c) and 6(d), the document holder SB2 has a glued section 27b in which a glue toner image is formed linearly along two adjacent sides of the first sheet S1 and the second sheet S2. Therefore, the two sides of the document holder SB2 where the glued section 27b is not formed (the upper and right sides in Figure 6(d)) are open, and documents, etc. can be inserted through the openings.

[0059] 4 to 5(c), in the glued portions 27a and 27b, glue toner images are formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2, respectively. Then, the glue toner images on the first adhesive surface S1s and the second adhesive surface S2s in the overlapping state are softened by heat in the fixing device 18 and then fixed to each other, so that the glued portions 27a and 27b of the first sheet S1 and the second sheet S2 are firmly attached to each other.

[0060] [Display operation] Next, operations on the display unit 35 of the operation panel 110 when creating an adhesive print will be described with reference to Figs. 7(a) to (d). In Figs. 7(a) to (d), different displays (screens) are displayed on the display unit 35. As shown in Fig. 7(a), the display unit 35 displays a text information display section 101 and operation menu display sections 102, 103, and 104 for selecting operation contents. For example, a character string saying "Please select an operation menu" is displayed on the text information display section 101.

[0061] The operation menu display sections 102, 103, and 104 each display a different operation content, and the user can select one to change the settings of the image forming device 1 or check the remaining toner amount. For example, the character string "Create adhesive print" is displayed on the operation menu display section 103, and when the user selects the operation menu display section 103, the display section 35 switches to the display shown in FIG. 7(b).

[0062] Next, as shown in FIG. 7(b), the display unit 35 displays the text information display section 101, the adhesive print selection area 108, and the "Back" display area 105. In FIG. 7(b), the text information display section 101 displays, for example, "Please select the type of adhesive print." The adhesive print selection area 108 includes three selection areas in which the adhesive prints R1 to R3 can be independently selected. In FIG. 7(b), the adhesive print R1 is an envelope with a short side opening, the adhesive print R2 is an envelope with a long side opening, and the adhesive print R3 is a document holder. When any of the adhesive prints R1 to R3 is selected, the display unit 35 switches to the display shown in FIG. 7(c). Also, when the user touches the "Back" display area 105, the display unit 35 switches from the display in FIG. 7(b) to the display in FIG. 7(a).

[0063] As shown in FIG. 7(c), the display unit 35 displays a text information display section 101, a sheet size selection area 109, and a "Back" display section 105. In FIG. 7(c), the text information display section 101 displays, for example, "Please select a sheet size." The sheet size selection area 109 includes four selection areas in which the sheet sizes A4, LTR, B5, and A5 can be independently selected. When the user selects any of the sheet sizes displayed in the sheet size selection area 109, the display unit 35 switches to the display shown in FIG. 7(d). Also, when the user touches the "Back" display section 105, the display unit 35 switches from the display in FIG. 7(c) to the display in FIG. 7(b).

[0064] As shown in Fig. 7(d), the display unit 35 displays a text information display section 101, a print instruction area 106, and a "Back" display section 105. In Fig. 7(d), for example, "To start printing, press 'Start Printing' below" is displayed in the text information display section 101. The print instruction area 106 displays "Start Printing", and when the user touches the display of "Start Printing", the adhesive print production job described in Figs. 4 to 5(c) is input to the control unit 100. Also, when the user touches the "Back" display section 105, the display unit 35 switches from the display in Fig. 7(d) to the display in Fig. 7(c).

[0065] In the above, an example has been described in which the adhesive print production job is output to the control unit 100 using the display unit 35 of the operation panel 110, but the present invention is not limited to this. For example, the adhesive print production job may be instructed to the control unit 100 via an external device (e.g., a PC) connected to the image forming apparatus 1 and a display connected to the external device.

[0066] As described above, in this embodiment, the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are overlapped while the first sheet S1 and the second sheet S2 pass through the double-sided conveying path 22. Then, the first sheet S1 and the second sheet S2 are conveyed to the fixing device 18 while overlapped, and the first adhesive surface S1s and the second adhesive surface S2s facing each other are heated and pressed at the fixing nip N2 of the fixing device 18. As a result, the glue toner images formed on the first adhesive surface S1s and the second adhesive surface S2s, respectively, are softened by heat and then fixed to each other, so that the first sheet S1 and the second sheet S2 can be firmly adhered to each other. Therefore, it is possible to provide an image forming apparatus 1 capable of producing a printed matter with high adhesive strength.

[0067] Furthermore, the first sheet S1 and the second sheet S2 are overlapped with each other with the surfaces on which the adhesive toner images are formed by passing through the double-sided conveying path 22 only once, thereby improving productivity. Furthermore, since the adhesive printed matter can be produced by the image forming apparatus 1 alone without connecting other devices to the image forming apparatus 1, the adhesive printed matter can be produced inexpensively.

[0068] Furthermore, the image forming apparatus 1 of the present embodiment has both black toner and adhesive toner, and can form a black toner image and an adhesive toner image on the sheet S. By using black toner specialized for printing and adhesive toner specialized for bonding sheets together, it is possible to achieve both high image quality and strong adhesive strength between sheets.

[0069] In this embodiment, the image forming apparatus 1 uses adhesive toner dedicated to bonding sheets together, but is not limited to this. For example, the image forming apparatus 1 may not store adhesive toner, and may use black toner as adhesive toner. In other words, the black toner used as the toner for image formation may also serve as the toner for bonding. In this case, the process cartridge 30s, the intermediate transfer belt 8, the belt cleaner 12, and the primary transfer rollers 7s and 7k may be omitted, and the toner image may be transferred directly from the photosensitive drum 2k of the process cartridge 30k to the sheet S. This allows the image forming apparatus 1 to be manufactured at a reduced cost.

[0070] In a full-color electrophotographic printer having four color toners, Y (yellow), M (magenta), C (cyan), and K (black), any one of these toners may be used as adhesive toner. Also, in addition to the four color toners, Y (yellow), M (magenta), C (cyan), and K (black), an adhesive toner dedicated to adhesion may be used. This makes it possible to create an adhesive print with a color image formed on the front cover or back cover.

[0071] [First Modification of the First Embodiment] Next, a first modified example of the first embodiment will be described. In this modified example, a black toner image can be printed on both the front cover and the back cover of the adhesive printed product. FIG. 8 is a flowchart showing adhesive printed product production control when the image forming apparatus 1 according to the first modified example of the first embodiment produces an adhesive printed product. Note that steps S11, and S16 to S18 are similar to the control of the first embodiment described in FIG. 4.

[0072] As shown in FIG. 8, the control unit 100 first judges whether an adhesive print production job has been input to the control unit 100 from the operation panel 110 or an external PC (step S11). When it is judged that an adhesive print production job has been input to the control unit 100 (step S11: Yes), the control unit 100 forms a black toner image on the first sheet S1 (step S20). Specifically, the control unit 100 forms an adhesive toner image on the photosensitive drum 2k using black toner, and feeds the first sheet S1 by the sheet feeding unit 1C. Then, the control unit 100 transfers the black toner image on the photosensitive drum 2k to the first sheet S1 at the secondary transfer nip N1, and fixes the black toner image to the first sheet S1 at the fixing nip N2.

[0073] Next, the control unit 100 causes the first sheet S1 to be reversed and conveyed, that is, switched back, by the pair of reversing rollers 21 (step S21). A specific operation of the switchback conveyance will be omitted since it has been described in step S13 of FIG.

[0074] Next, the control unit 100 forms a glue toner image on the second sheet S2 (step S22). Then, the control unit 100 inverts and conveys the second sheet S2 by the reversing roller pair 21, and stops the second sheet S2 by abutting its leading edge against the nip of the registration roller pair 24, which is in a stopped state (step S23). At this time, the second adhesive surface S2s of the second sheet S2 on which the glue toner image has been formed is formed on the lower surface side of the second sheet S2.

[0075] Then, the control unit 100 forms an adhesive toner image on the first sheet S1 conveyed to the feed conveying path CP via the double-sided conveying path 22 (step S24). Furthermore, the control unit 100 guides the first sheet S1 to the double-sided conveying path 22 by the second switching member 23 (step S25). The specific operation of conveying the sheet to the double-sided conveying path 22 by the second switching member 23 has been described in step S15 of FIG. 4 and will not be described here.

[0076] The first sheet S1 is guided to the double-sided conveying path 22 and is further conveyed by the fixing device 18, so that the first sheet S1 is superimposed on the first sheet S1 in the double-sided conveying path 22 (step S16). At this time, the first sheet S1 enters below the second sheet S2 in the double-sided conveying path 22, and the first adhesive surface S1s of the first sheet S1 on which the glue toner image is formed is formed on the upper surface side of the first sheet S1. By conveying the first sheet S1 and the second sheet S2 in this manner, the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 can be superimposed. In other words, the first adhesive surface S1s and the second adhesive surface S2s are superimposed while the first sheet S1 and the second sheet S2 pass through the double-sided conveying path 22.

[0077] The registration roller pair 24 remains in a stopped state when the first sheet S1 is conveyed to the double-sided conveying path 22. The control unit 100 drives the registration roller pair 24 when the leading edge of the first sheet S1 hits the nip of the registration roller pair 24, or when the first sheet S1 is conveyed a little further and forms a loop in the space within the double-sided conveying path 22. This makes it possible to convey the first sheet S1 and the second sheet S2 in an overlapping state while aligning the leading edge of the first sheet S1 and the leading edge of the second sheet S2.

[0078] Next, the control unit 100 conveys the overlapped first sheet S1 and second sheet S2 to the secondary transfer nip N1, and forms a black toner image on the surface opposite to the second adhesive surface S2s of the second sheet S2 in the secondary transfer nip N1 (step S26). Furthermore, the control unit 100 heats and presses the overlapped first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18, and bonds the first sheet S1 and the second sheet S2 (step S17). That is, the glue toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, so that the first sheet S1 and the second sheet S2 are firmly bonded to each other. At this time, the black toner image formed on the second sheet S2 is also fixed to the second sheet S2.

[0079] Then, the control unit 100 positions the first switching member 19 and the second switching member 23 at the discharge position and the retracted position, respectively, before the bonded first sheet S1 and second sheet S2 reach the first switching member 19 and the second switching member 23. In this state, the control unit 100 conveys the first sheet S1 and the second sheet S2 by the fixing device 18, and the first sheet S1 and the second sheet S2 are guided to the discharge conveying path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and second sheet S2 onto the discharge tray 26 by the discharge roller pair 25 (step S18), and ends the control for creating one copy of the bonded printed matter.

[0080] By conveying the first sheet S1 and the second sheet S2 in this manner, black toner images can be printed on both the front cover and the back cover of the adhesive printed product, and various types of adhesive printed products can be handled. In this modified example, black toner images are printed on both the front cover and the back cover of the adhesive printed product, but it goes without saying that toner images of other colors may be printed instead of black toner images.

[0081] [Second Modification of the First Embodiment] Next, a second modified example of the first embodiment will be described. Figs. 9(a) to (c) are diagrams showing a shortcut path 32 and a third switching member 33 according to the second modified example of the first embodiment. In this modified example, as shown in Fig. 9(a), the reversing conveying unit 1E has a shortcut path 32 and a third switching member 33. The third switching member 33 is movable by an actuator (not shown) such as a motor, and guides the sheet S conveyed by the registration roller pair 24 to the shortcut path 32 or the double-sided conveying path 22. The shortcut path 32 branches off from the double-sided conveying path 22 and merges with the feeding conveying path CP between the secondary transfer nip N1 and the fixing nip N2 in the sheet conveying direction.

[0082] In this modification, the conveyance control of the first sheet S1 and the second sheet S2 when creating an adhesive print is almost the same as that of the first embodiment described with reference to Figs. 4 to 5(c), but differs in the following respects. That is, as shown in Fig. 9(a), the first sheet S1 and the second sheet S2 are conveyed to the state shown in Fig. 5(b) in the same manner as in the first embodiment. Then, before the first sheet S1 and the second sheet S2 reach the third switching member 33, the third switching member 33 moves to a position where the sheets are guided to the shortcut conveyance path 32. The second sheet S2 is guided to the double-sided conveyance path 22 and further conveyed by the fixing device 18, so that the second sheet S2 is superimposed on the first sheet S1 in the double-sided conveyance path 22 (step S16 in Fig. 4). In other words, the first adhesive surface S1s and the second adhesive surface S2s are superimposed on each other while the first sheet S1 and the second sheet S2 pass through the double-sided conveyance path 22.

[0083] The leading edge of the first sheet S1 and the leading edge of the second sheet S2 are aligned by the registration roller pair 24 in a stopped state, and the first sheet S1 and the second sheet S2 are conveyed in an overlapping state by driving the registration roller pair 24. As shown in Fig. 9(b) , the overlapping first sheet S1 and second sheet S2 are guided to the shortcut conveying path 32 by the third switching member 33, and merge with the feeding conveying path CP at a position between the secondary transfer nip N1 and the fixing nip N2 in the sheet conveying direction.

[0084] Next, as shown in Fig. 9(c), the control unit 100 heats and presses the overlapping first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18 to bond the first sheet S1 and the second sheet S2 together (step S17 in Fig. 4). That is, the adhesive toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, thereby firmly bonding the first sheet S1 and the second sheet S2 together.

[0085] Then, the control unit 100 positions the first switching member 19 and the second switching member 23 at the discharge position and the retracted position, respectively, before the bonded first sheet S1 and second sheet S2 reach the first switching member 19 and the second switching member 23. In this state, the control unit 100 conveys the first sheet S1 and the second sheet S2 by the fixing device 18, and the first sheet S1 and the second sheet S2 are guided to the discharge conveyance path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and second sheet S2 onto the discharge tray 26 by the discharge roller pair 25 (step S18 in FIG. 4), and ends the control for creating one copy of the bonded printed matter.

[0086] By transporting the first sheet S1 and the second sheet S2 in this manner, it is possible to improve productivity when producing an adhesive print in which a black toner image is not printed on the second sheet S2.

[0087] <Second embodiment> Next, a second embodiment of the present invention will be described, in which the second embodiment omits the second switching member 23 from the reversing conveying unit 1E of the first embodiment, and adds a fourth switching member 40 and a connecting conveying path 41. For this reason, the same configurations as those of the first embodiment will be described with the same reference numerals or omitted from the illustrations.

[0088] Fig. 10 is a flowchart showing adhesive print production control when the image forming apparatus 1 according to the second embodiment produces an adhesive print. Figs. 11(a) to (d) are diagrams for explaining the movements of the first sheet S1 and the second sheet S2 when producing an adhesive print. In Figs. 11(a) to (d), the first sheet S1 is indicated by a solid line, and the second sheet S2 following the first sheet S1 is indicated by a dashed line.

[0089] The reversing conveying unit 2E according to the second embodiment has a fourth switching member 40 and a connecting conveying path 41. Note that the reversing conveying path 29 as the first reversing conveying path branches off from the feeding conveying path CP at a first branching portion BR1 (see FIG. 11(a)) downstream of the fixing nip N2 in the conveying direction of the sheet conveyed through the fixing nip N2, and connects to the double-sided conveying path 22. The discharge conveying path 20 as the second reversing conveying path branches off from the feeding conveying path CP at a second branching portion BR2 between the fixing nip N2 and the first branching portion BR1.

[0090] The connection conveying path 41 connects the discharge conveying path 20 and the double-sided conveying path 22, and the fourth switching member 40 is configured to be movable by an actuator such as a motor between a retracted position shown in FIG. 11(a) and a reverse guide position shown in FIG. 11(c). The fourth switching member 40 is configured to retract from each conveying path at the retracted position so as not to impede the conveying of the sheet S. Also, at the reverse guide position, the fourth switching member 40 guides a sheet that has been reversed and conveyed from the discharge conveying path 20 toward the connection conveying path 41. In this embodiment, the discharge roller pair 25 as the second reverse conveying section is configured to reverse and convey the sheet, that is, to switch back, like the reverse roller pair 21.

[0091] Next, the adhesive print production control when the image forming apparatus 1 according to the second embodiment produces an adhesive print will be described with reference to Fig. 10 to Fig. 11(d). Note that steps S11 to S14 and S16 to S18 are similar to the control in the first embodiment described with reference to Fig. 4, and therefore the description will be omitted as appropriate.

[0092] As shown in FIG. 10, when a bonded object production job is input, the control unit 100 forms a glue toner image on the first adhesive surface S1s of the first sheet S1, and reverses and conveys the first sheet S1 in the reverse conveying path 29 (steps S11 to S13). Step S13 can be said to be a first reverse conveying process in which the first sheet S1 is reversed and conveyed by the reverse roller pair 21 and guided to the double-sided conveying path 22. Then, the control unit 100 forms a glue toner image on the second adhesive surface S2s of the second sheet S2 in the secondary transfer nip N1 (step S14). The first sheet S1, which has been reversed and conveyed and guided to the double-sided conveying path 22, is conveyed through the double-sided conveying path 22 without stopping at the registration roller pair 24. The fourth switching member 40 is located at the retreat position until the state shown in FIG. 11(c).

[0093] Next, as shown in FIG. 10 and FIG. 11(a), the control unit 100 conveys the second sheet S2 to the inversion conveying path 29, and inverts and conveys it by the inversion roller pair 21 (step S30). The step S30 can be said to be a second inversion conveying process in which the second sheet S2 is inverted and conveyed by the inversion roller pair 21 and guided to the double-sided conveying path 22. As shown in FIG. 11(b), the second sheet S2 is guided to the double-sided conveying path 22, and then the leading edge of the second sheet S2 hits the nip of the registration roller pair 24, which is in a stopped state. The control unit 100 stops the inversion roller pair 21 at the timing when the leading edge of the second sheet S2 hits the nip of the registration roller pair 24, or at the timing when the second sheet S1 is conveyed slightly further and forms a slight loop in the space in the double-sided conveying path 22. In FIG. 11(b), the second adhesive surface S2s of the second sheet S2 on which the glue toner image is formed is formed on the lower surface side of the second sheet S2.

[0094] Next, as shown in FIG. 11C, the control unit 100 guides the first sheet S1, which has merged with the feeding conveyance path CP from the double-sided conveyance path 22, to the discharge conveyance path 20, and reverses and conveys the first sheet S1 by the discharge roller pair 25 (step S31). The step S31 can also be called a third reverse conveyance process in which the first sheet S1 is reversed and conveyed by the discharge roller pair 25 and guided to the double-sided conveyance path 22. Specifically, the control unit 100 positions the first switching member 19 and the fourth switching member 40 at the discharge position and the retreat position, respectively, before the first sheet S1 reaches the first switching member 19 and the fourth switching member 40. Then, the first sheet S1 is guided to the discharge conveyance path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 conveys the first sheet S1 by the discharge roller pair 25 for a predetermined distance in the first direction toward the outside of the machine, and then conveys the first sheet S1 in a second direction opposite to the first direction. At this time, the control unit 100 moves the fourth switching member 40 from the retracted position to the reverse guide position, and the first sheet S1 is guided to the double-sided conveying path 22 via the connecting conveying path 41 by the fourth switching member 40 positioned at the reverse guide position.

[0095] The first sheet S1 passes under the second sheet S2 in the double-sided conveying path 22 and is further conveyed by the discharge roller pair 25, so that the first sheet S1 is superimposed on the second sheet S2 in the double-sided conveying path 22 (step S16). In FIG. 11(c), the first adhesive surface S1s of the first sheet S1 on which the glue toner image is formed is formed on the upper surface side of the first sheet S1. By conveying the first sheet S1 and the second sheet S2 in this manner, the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 can be superimposed. In other words, the first adhesive surface S1s and the second adhesive surface S2s are superimposed while the first sheet S1 and the second sheet S2 pass through the double-sided conveying path 22.

[0096] When the first sheet S1 is conveyed to the double-sided conveying path 22, the pair of registration rollers 24 remains in a stopped state. The control unit 100 drives the pair of registration rollers 24 when the leading edge of the first sheet S1 hits the nip of the pair of registration rollers 24, or when the first sheet S1 is conveyed a little further and forms a loop in the space in the double-sided conveying path 22. This allows the first sheet S1 and the second sheet S2 to be conveyed in an overlapping state while aligning the leading edge of the first sheet S1 and the leading edge of the second sheet S2. That is, the leading edge of the first sheet S1 and the leading edge of the second sheet S2 are aligned midway through the double-sided conveying path 22. FIG. 11(d) shows the state in which the first sheet S1 and the second sheet S2 in an overlapping state are conveyed through the double-sided conveying path 22 toward the fixing device 18.

[0097] 10 and 11(d), the control unit 100 heats and presses the overlapping first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18 to bond the first sheet S1 and the second sheet S2 together (step S17). That is, the adhesive toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, thereby firmly bonding the first sheet S1 and the second sheet S2 together.

[0098] Then, the control unit 100 positions the first switching member 19 and the fourth switching member 40 at the discharge position and the retracted position, respectively, before the bonded first sheet S1 and second sheet S2 reach the first switching member 19 and the fourth switching member 40. In this state, the control unit 100 conveys the first sheet S1 and the second sheet S2 by the fixing device 18, and the first sheet S1 and the second sheet S2 are guided to the discharge conveying path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and second sheet S2 onto the discharge tray 26 by the discharge roller pair 25 (step S18), and ends the control for creating one copy of the bonded printed matter.

[0099] Note that, before the first sheet S1 is reversed and conveyed on the discharge conveying path 20, a black toner image may be transferred in the secondary transfer nip N1 to the side opposite the first adhesive surface S1s of the first sheet S1. Also, when the overlapped first sheet S1 and second sheet S2 pass through the secondary transfer nip N1, a black toner image may be transferred to the side opposite the second adhesive surface S2s of the second sheet S2. This allows printing on the front cover and back cover of the adhesive printed product. Also, printing may be done on only one of the front cover and back cover of the adhesive printed product.

[0100] As a result, it is possible to achieve the same effects as in the first embodiment. In the present embodiment, the first sheet S1 is reversed and conveyed not only in the reverse conveying path 29 but also in the discharge conveying path 20. This makes it possible to reduce the curvature of the conveying path compared to guiding the sheet using the second switching member 23 in the first embodiment, and makes it possible to create an adhesive print using a stiff sheet such as cardboard.

[0101] <Third embodiment> Next, a third embodiment of the present invention will be described. In the third embodiment, the second switching member 23 is omitted from the first embodiment, and a conveying roller pair 128 and a registration roller pair 124 are provided in the positions of the registration roller pair 24 and the conveying roller pair 28, respectively. Therefore, the same configurations as those in the first embodiment will be described by omitting illustrations or by assigning the same reference numerals in the drawings.

[0102] [Control Block] FIG. 12 is a block diagram showing a control block of the image forming apparatus 1 according to the third embodiment. As shown in FIG. 12, the image forming apparatus 1 has a control unit 100. Although various sensors provided in the image forming apparatus 1 are not shown in FIG. 12, the image forming apparatus 1 may have sensors. For example, the image forming apparatus 1 may have one or more sheet detection sensors for detecting the position of the sheet S on the feeding conveying path CP, the discharge conveying path 20, the reversing conveying path 29, and the double-sided conveying path 22. The control unit 100 may recognize the position of the conveyed sheet S based on the detection result of the sheet detection sensor, and control the movement timing of the first switching member 19, the temperature rise timing of the fixing device 18, and the drive timing, contact and separation operation, etc. of various rollers.

[0103] A first switching motor M1 that drives the first switching member 19, a first separating solenoid SO1, a second separating solenoid SO2, a first torque limiter TQ1, a second torque limiter TQ2, and an alignment motor M3 are connected to the output side of the control unit 100. Although an alignment unit 31 is not shown in Fig. 15(a) to Fig. 16(c) described later, an alignment unit 31 driven by an alignment motor M3 may be provided as in the first embodiment.

[0104] The first separation solenoid SO1 can bring a pair of rollers of the reversing roller pair 21 into contact with and away from each other. As shown in FIG. 16(a), the conveying roller pair 128 has a first roller 128a and a second roller 128b. As shown in FIG. 12, the first roller 128a and the second roller 128b can bring them into contact with and away from each other by the second separation solenoid SO2. In other words, the conveying roller pair 128 can transition between a contact state in which the first roller 128a and the second roller 128b are in contact with each other, and a separation state in which the first roller 128a and the second roller 128b are separated from each other.

[0105] The first roller 128a and the second roller 128b are configured to be independently drivable. A first torque limiter TQ1 is provided on a drive transmission path between the first roller 128a and a motor (not shown) as a drive source that transmits a drive force to the first roller 128a. When the load torque acting on the first roller 128a exceeds the limit value of the first torque limiter TQ1, the first torque limiter TQ1 cuts off the transmission of the drive force to the first roller 128a. Similarly, a second torque limiter TQ2 is provided on a drive transmission path between the second roller 128b and a motor (not shown) as a drive source that transmits a drive force to the second roller 128b. When the load torque acting on the second roller 128b exceeds the limit value of the second torque limiter TQ2, the second torque limiter TQ2 cuts off the transmission of the drive force to the second roller 128b.

[0106] Next, the adhesive print production control when the image forming apparatus 1 according to the third embodiment produces an adhesive print will be described with reference to Figs. 13 to 16(c). Steps S11 to S14 and S17 to S18 are similar to the control of the first embodiment described in Fig. 4, and therefore will not be described as appropriate. Figs. 13 and 14 are flowcharts showing the adhesive print production control when the image forming apparatus 1 according to the third embodiment produces an adhesive print. Figs. 15(a) to 16(c) are diagrams for explaining the movements of the first sheet S1 and the second sheet S2 when producing an adhesive print. In Figs. 15(a) to 16(c), the first sheet S1 is indicated by a solid line, and the second sheet S2 following the first sheet S1 is indicated by a dashed line.

[0107] As shown in FIG. 13, when a bonded object production job is input, the control unit 100 forms a glue toner image on the first adhesive surface S1s of the first sheet S1, and reverses and conveys the first sheet S1 in the reverse conveying path 29 (steps S11 to S13). In step S12, the glue toner image is formed on the first adhesive surface S1s of the first sheet S1 before the reverse conveying process is first performed on the first sheet S1 by the reverse roller pair 21. Step S13 can also be called a first reverse conveying process in which the first sheet S1 is reversed and conveyed by the reverse roller pair 21 and guided to the double-sided conveying path 22. Then, as shown in FIG. 13 and FIG. 15(a), the control unit 100 forms a glue toner image on the second adhesive surface S2s of the second sheet S2 in the secondary transfer nip N1 (step S14). The first sheet S1 reversed and conveyed and guided to the double-sided conveying path 22 is conveyed directly through the double-sided conveying path 22 without stopping at the conveying roller pair 128 or the registration roller pair 124.

[0108] Next, as shown in FIG. 13 and FIG. 15(b), the control unit 100 conveys the second sheet S2 to the reversing conveying path 29, and the reversing roller pair 21 reverses and conveys the second sheet S2 (step S40). The step S40 can also be called a second reversing conveying process in which the second sheet S2 is reversed and conveyed by the reversing roller pair 21 and guided to the double-sided conveying path 22. At this time, the first sheet S1 joins the feeding conveying path CP from the double-sided conveying path 22 and is conveyed toward the reversing roller pair 21. Then, as shown in FIG. 13 and FIG. 15(c), the control unit 100 separates the reversing roller pair 21 from each other by the first separation solenoid SO1 before the first sheet S1 reaches the reversing roller pair 21 (step S41). That is, the control unit 100 executes a separation process in which the reversing roller pair 21 transitions to a separated state. As a result, while the first sheet S1 is conveyed to the reversal conveying path 29 by the fixing device 18, the second sheet S2 can be conveyed toward the registration roller pair 124 by the conveying roller pair 128. At this time, the registration roller pair 124 is in a stopped state.

[0109] Next, as shown in FIG. 13, FIG. 14, and FIG. 16(a), the control unit 100 judges whether the trailing end of the second sheet S2 has passed through the reversing roller pair 21 (step S42). When it is judged that the trailing end of the second sheet S2 has passed through the reversing roller pair 21 (step S42: Yes), the control unit 100 causes the reversing roller pair 21 to contact each other, and reverses and conveys the first sheet S1 toward the double-sided conveying path 22 (step S43). The step S43 can be called a fourth reverse conveying process in which the first sheet S1 is reversed and conveyed by the reversing roller pair 21 and guided to the double-sided conveying path 22. The control unit 100 also separates the conveying roller pair 128 from each other (step S44). Note that, regarding the steps S43 and S44, the step S44 may be executed first, or steps S43 and S44 may be executed in parallel.

[0110] 14 and 16(b), the control unit 100 determines whether or not the trailing edge of the first sheet S1 has passed through the pair of reversing rollers 21 (step S45). If it is determined that the trailing edge of the first sheet S1 has passed through the pair of reversing rollers 21 (step S45: Yes), the control unit 100 causes the pair of conveying rollers 128 to contact each other, and conveys the first sheet S1 and the second sheet S2 by the pair of conveying rollers 128 (step S46).

[0111] The conveying roller pair 128 continues to be driven for a predetermined time even after the leading ends of the first sheet S1 and the second sheet S2 hit the nip of the registration roller pair 124 that is in a stopped state. At this time, for example, when the second sheet S2 conveyed by the first roller 128a of the conveying roller pair 128 hits the nip of the registration roller pair 124, the first torque limiter TQ1 acts to cut off the drive transmission to the first roller 128a. Also, when the first sheet S1 conveyed by the second roller 128b of the conveying roller pair 128 hits the nip of the registration roller pair 124, the second torque limiter TQ2 acts to cut off the drive transmission to the second roller 128b. As a result, the leading ends of the first sheet S1 and the second sheet S2 are aligned, and the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are superimposed (step S47).

[0112] Then, as shown in Fig. 14 and Fig. 16(c), the control unit 100 drives the registration roller pair 124 to convey the overlapped first sheet S1 and second sheet S2 toward the fixing device 18 (step S48). Next, the control unit 100 heats and presses the overlapped first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18 to bond the first sheet S1 and the second sheet S2 together (step S17). That is, the adhesive toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, so that the first sheet S1 and the second sheet S2 are firmly bonded together.

[0113] Then, the control unit 100 positions the first switching member 19 at the discharge position before the bonded first sheet S1 and second sheet S2 reach the first switching member 19. In this state, the control unit 100 conveys the first sheet S1 and second sheet S2 by the fixing device 18, and the first sheet S1 and second sheet S2 are guided to the discharge conveyance path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and second sheet S2 onto the discharge tray 26 by the discharge roller pair 25 (step S18), and ends the control for creating one copy of the bonded printed matter.

[0114] As shown in FIG. 15(b), before the first sheet S1 is reversed and conveyed in the reverse conveying path 29 in step S43, a black toner image may be transferred to the surface of the first sheet S1 opposite to the first adhesive surface S1s in the secondary transfer nip N1. Also, when the overlapped first sheet S1 and second sheet S2 pass through the secondary transfer nip N1, a black toner image may be transferred to the surface of the second sheet S2 opposite to the second adhesive surface S2s. This allows printing on the front cover and back cover of the adhesive printed product. Also, printing may be done on only one of the front cover and back cover of the adhesive printed product.

[0115] As a result, the same effects as those of the first embodiment can be achieved. As with the second embodiment, the curvature of the conveying path can be made smaller than when the sheet is guided using the second switching member 23 of the first embodiment, and adhesive prints can be created using stiff sheets such as cardboard. Furthermore, in this embodiment, there are no points where the conveying paths intersect (for example, the points where the feeding conveying path CP, the discharge conveying path 20, and the connection conveying path 41 intersect) as in the second embodiment, so that the sheet can be conveyed stably and conveying failures such as jams can be reduced.

[0116] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the second switching member 23 is omitted and a loop unit 53 is added to the reverse transport unit 1E of the first embodiment. Therefore, the same configuration as in the first embodiment will be omitted from the illustration or will be described by using the same reference numerals in the drawings. The loop unit 53 is a part of the device body 1A as the housing of the image forming device 1. In other words, the loop unit 53 is housed in the device body 1A.

[0117] Fig. 17 is a flowchart showing adhesive print production control when the image forming apparatus 1 according to the fourth embodiment produces an adhesive print. Figs. 18(a) to (d) are diagrams for explaining the movements of the first sheet S1 and the second sheet S2 when producing an adhesive print. In Figs. 18(a) to (d), the first sheet S1 is indicated by a solid line, and the second sheet S2 following the first sheet S1 is indicated by a dashed line.

[0118] The reversing conveying unit 4E of the present embodiment has a loop unit 53, as shown in FIG. 18(a). The loop unit 53 has a fifth switching member 50, a loop conveying path 51, and conveying roller pairs 52a, 52b, and 52c as a loop conveying section arranged along the loop conveying path 51. The inlet and outlet of the loop conveying path 51 are connected to the reversing conveying path 29, and the sheet conveyed to the reversing conveying path 29 is conveyed along the loop conveying path 51 in the counterclockwise direction in FIG. 18(a) and returns to the reversing conveying path 29 after making one revolution. In other words, the loop conveying path 51 is connected to the reversing conveying path 29 and guides the sheet conveyed from the reversing conveying path 29 back to the reversing conveying path 29.

[0119] The fifth switching member 50 is configured to be movable by an actuator (not shown) between an entrance position where the fifth switching member 50 guides the sheet conveyed from the reversing conveying path 29 to the entrance side of the loop conveying path 51, and an exit position where the fifth switching member 50 guides the sheet conveyed from the exit of the loop conveying path 52 to the reversing conveying path 29. Similarly to the third embodiment, the reversing roller pair 21 is configured so that the pair of rollers can be brought into contact with or separated from each other by the first separation solenoid SO1 (see FIG. 12). In other words, the reversing roller pair 21 includes a roller pair, and can transition between an abutting state where the roller pair abuts against each other, and a separating state where the roller pair is separated from each other.

[0120] Next, the adhesive print production control when the image forming apparatus 1 according to the fourth embodiment produces an adhesive print will be described with reference to Fig. 17 to Fig. 18(d). Note that steps S11 to S14 and S16 to S18 are similar to the control in the first embodiment described with reference to Fig. 4, and therefore will not be described as appropriate.

[0121] As shown in FIG. 17, when an adhesive object production job is input, the control unit 100 forms a glue toner image on the first adhesive surface S1s of the first sheet S1, and reverses and conveys the first sheet S1 in the reverse conveying path 29 (steps S11 to S13). Step S13 can also be called a first reverse conveying process in which the first sheet S1 is reversed and conveyed by the reverse roller pair 21 and guided to the double-sided conveying path 22. At this time, the fifth switching member 50 is located at the entrance position as shown in FIG. 18(a), and a part of the first sheet S1 is guided to the loop conveying path 51 by the fifth switching member 50 during the process of being reversed and conveyed. In addition, the sheet conveying speed of the reverse roller pair 21 and the conveying roller pairs 52a to 52c are set to the same speed.

[0122] The reversing roller pair 21 and the conveying roller pairs 52a to 52c convey the first sheet S1 a predetermined distance in a first direction (counterclockwise direction of the loop conveying path 51), and then convey the first sheet S1 in a second direction opposite to the first direction, thereby conveying the first sheet S1 in a reversed manner. The first sheet S1 conveyed in a reversed manner is guided to the double-sided conveying path 22, and then the leading edge of the first sheet S1 hits the nip of the registration roller pair 24, which is in a stopped state. The control unit 100 stops the reversing roller pair 21 and the conveying roller pairs 52a to 52c at the timing when the leading edge of the first sheet S1 hits the nip of the registration roller pair 24, or at the timing when the second sheet S1 is further conveyed slightly and forms a loop in the space in the double-sided conveying path 22. In FIG. 18(a), the first adhesive surface S1s of the first sheet S1 on which the glue toner image is formed is formed on the lower surface side of the first sheet S1. Further, the length of the first sheet S1 and the length of the conveying path from the registration roller pair 24 to the conveying roller pair 52a are set so that the rear end S1t of the first sheet S1 is not pinched by the conveying roller pair 52a.

[0123] Then, the control unit 100 forms a glue toner image on the second adhesive surface S2s of the second sheet S2 in the secondary transfer nip N1 (step S14). Furthermore, as shown in FIG. 17 and FIG. 18(b), the control unit 100 separates the pair of reversing rollers 21 from each other by the first separation solenoid SO1 before the leading edge of the second sheet S2 reaches the pair of reversing rollers 21 (step S50). That is, the control unit 100 executes a reversing separation process that transitions the pair of reversing rollers 21 to a separated state. This allows the fixing device 18 to convey the second sheet S2 toward the loop conveying path 51 while stopping the first sheet S1 in the double-sided conveying path 22. Note that steps S14 and S50 may be executed before the leading edge of the first sheet S1 hits the nip of the pair of registration rollers 24.

[0124] Next, the control unit 100 drives the fixing device 18 so that the second sheet S2 is conveyed through the loop conveying path 51, and the second sheet S2 is guided to the loop conveying path 51 via the reverse conveying path 29 (step S51). This step S51 can also be called a first loop conveying process for conveying the second sheet S2 to the loop conveying path 51 via the reverse conveying path 29. Then, the second sheet S2 is conveyed counterclockwise through the loop conveying path 51 by the conveying roller pairs 52a to 52c. That is, the control unit 100 executes a second loop conveying process for guiding the second sheet S2 to the double-sided conveying path 22 via the reverse conveying path 29 by the conveying roller pairs 52a to 52c. Note that the conveying path from the fixing device 18 to the conveying roller pair 52a is set shorter than the length of the second sheet S2 so that the leading edge S2u of the second sheet S2 is conveyed to the conveying roller pair 52a by the fixing device 18.

[0125] Next, the control unit 100 positions the fifth switching member 50 at the exit position (the position shown in FIG. 18(c)) before the leading edge S2u of the second sheet S2 reaches the fifth switching member 50, and guides the second sheet S2 to the reversing conveying path 29 by the fifth switching member 50 (step S52). The second sheet S2 is conveyed toward the registration roller pair 24 via the reversing conveying path 29 and the double-sided conveying path 22.

[0126] Then, the control unit 100 judges whether the leading edge S2u of the second sheet S2 has reached the nip of the registration roller pair 24 (step S53). If it is judged that the leading edge S2u of the second sheet S2 has reached the nip of the registration roller pair 24 (step S53: Yes), the control unit 100 causes the pair of reversing rollers 21 to contact each other and drive them (step S54). As a result, the leading edge positions of the first sheet S1 and the second sheet S2 are aligned, and the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are overlapped (step S16). In other words, the first adhesive surface S1s and the second adhesive surface S2s are overlapped while the first sheet S1 and the second sheet S2 pass through the double-sided conveying path 22.

[0127] As shown in Fig. 17 and Fig. 18(d), the control unit 100 drives the registration roller pair 24 to convey the overlapped first sheet S1 and second sheet S2 toward the fixing device 18. Next, the control unit 100 heats and presses the overlapped first sheet S1 and second sheet S2 in the fixing nip N2 of the fixing device 18 to bond the first sheet S1 and the second sheet S2 together (step S17). That is, the adhesive toner images formed on the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2 are softened by heat and then fixed to each other, so that the first sheet S1 and the second sheet S2 are firmly bonded together.

[0128] Then, the control unit 100 positions the first switching member 19 at the discharge position before the bonded first sheet S1 and second sheet S2 reach the first switching member 19. In this state, the control unit 100 conveys the first sheet S1 and second sheet S2 by the fixing device 18, and the first sheet S1 and second sheet S2 are guided to the discharge conveyance path 20 by the first switching member 19 positioned at the discharge position. The control unit 100 discharges the bonded first sheet S1 and second sheet S2 onto the discharge tray 26 by the discharge roller pair 25 (step S18), and ends the control for creating one copy of the bonded printed matter.

[0129] When the overlapping first sheet S1 and second sheet S2 pass through the secondary transfer nip N1, a black toner image may be transferred to the surface of the first sheet S1 opposite to the first adhesive surface S1s, thereby allowing printing to be done on the cover of the adhesive print.

[0130] As a result, the same effects as those of the first embodiment can be achieved. Also, as in the second embodiment, the curvature of the conveying path can be made smaller than when the sheet is guided using the second switching member 23 of the first embodiment, and adhesive prints can be created using stiff sheets such as cardboard. Furthermore, as in the third embodiment, there is no point where the conveying paths intersect (for example, the point where the feeding conveying path CP, the discharge conveying path 20, and the connection conveying path 41 in FIG. 11(a) intersect), so the sheet can be conveyed stably and conveying failures such as jams can be reduced.

[0131] In the present embodiment, the loop unit 53 has been described as a part of the main body 1A of the image forming apparatus 1, but is not limited thereto. For example, the loop unit 53 as the second unit may be configured as a separate unit that is detachably attached to the main body 1A as the first unit. This makes it possible to provide an inexpensive image forming apparatus 1 without the loop unit 53 for users who do not create adhesive printed matter such as envelopes.

[0132] <Other embodiments> In any of the above-described embodiments, the control unit 100 is provided in the image forming apparatus 1, but is not limited to this. For example, the control unit 100 may be provided not in the image forming apparatus 1 but in another unit connected to the image forming apparatus 1 or an external PC.

[0133] In addition, the shortcut transport path 32 described in FIG. 9 may be provided in the second to fourth embodiments, and the overlapped first sheet S1 and second sheet S2 may be transported to the fixing device 18 through the shortcut transport path 32. In any of the above-described embodiments, one or both of the roller pairs provided in the image forming apparatus 1 may be formed of other rotating bodies such as a belt.

[0134] In addition, in each of the above-mentioned embodiments, the adhesive toner image is formed on each of the first adhesive surface S1s of the first sheet S1 and the second adhesive surface S2s of the second sheet S2, but the present invention is not limited to this. For example, when strong adhesive strength is not required for the adhesive printed matter, it is sufficient to form an adhesive toner image on only one of the two sheets, and it is possible to selectively create an adhesive printed matter in which the opposing sheets are glued on both sides or an adhesive printed matter in which the sheets are glued on only one side depending on the purpose. When an adhesive printed matter is created with glue on only one side, the amount of toner consumed can be reduced compared to when the sheets are glued on both sides, and therefore the cost of creating the adhesive printed matter can be saved.

[0135] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0136] The disclosure of the present embodiment also includes the following configuration examples and method examples. (Configuration 1) an image forming unit capable of forming an image on a sheet using a toner for image formation and also capable of forming an adhesive layer on the sheet using a toner for adhesive; a fixing section that fixes the toner to the sheet by applying heat and pressure to the sheet on which the image or the adhesive layer is formed; a re-conveying path that guides the first sheet that has passed through the fixing unit and the second sheet that follows the first sheet toward the fixing unit again, a first adhesive surface of the first sheet on which the adhesive layer is formed and a second adhesive surface of the second sheet on which the adhesive layer is formed are overlapped while the first sheet and the second sheet pass through the re-conveying path, and the first sheet and the second sheet are transported to the fixing unit while being overlapped. 1. An image forming apparatus comprising: (Configuration 2) The fixing unit applies heat and pressure to the first sheet and the second sheet in a state in which the first adhesive surface and the second adhesive surface are superimposed on each other. 2. The image forming apparatus according to claim 1, (Configuration 3) the leading edge of the first sheet and the leading edge of the second sheet are aligned midway through passing through the re-conveyance path; 3. The image forming apparatus according to claim 1, wherein the first and second components are arranged in a same plane. (Configuration 4) a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit that is disposed on the reversing conveying path and is capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a guide member disposed downstream of the fixing unit in the conveying direction and configured to guide the sheet to the re-conveying path without conveying the sheet to the reversing conveying path, performing the reversing and conveying process on the first sheet by the reversing and conveying unit, guiding the first sheet to the re-conveying path, and then guiding the second sheet to the re-conveying path by the guide member without performing the reversing and conveying process, and overlapping the first adhesive surface of the first sheet and the second adhesive surface of the second sheet on the re-conveying path; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 5) the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the second sheet is guided to the re-conveyance path by the guide member; 5. The image forming apparatus according to claim 4, (Configuration 6) a conveying path that passes through the fixing unit and joins with the re-conveying path; a first reversing conveying path that branches off from the conveying path at a first branching portion downstream of the fixing portion in a conveying direction of the sheet conveyed through the fixing portion and is connected to the re-conveying path; a first reversing conveying section that is disposed on the first reversing conveying path and is capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a second reversing conveying path branching off from the conveying path at a second branching portion between the fixing portion and the first branching portion in the conveying direction; a second reversing conveying section disposed on the second reversing conveying path and capable of performing the reversing conveying process; a connecting conveying path that connects the second branching portion and the re-conveying path, after performing the reversing conveying process on the first sheet by the first reversing conveying unit to guide the first sheet to the re-conveying path, performing the reversing conveying process on the second sheet by the first reversing conveying unit to guide the second sheet to the re-conveying path, further performing the reversing conveying process on the first sheet that has merged with the conveying path from the re-conveying path by the second reversing conveying unit to guide the first sheet to the re-conveying path, and overlapping the first adhesive surface of the first sheet and the second adhesive surface of the second sheet on the re-conveying path; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 7) the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the first reversing and conveying unit performs the reversing and conveying process; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the first reversing and conveying unit performs the reversing and conveying process; 7. The image forming apparatus according to configuration 6, (Configuration 8) a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit that is disposed on the reversing conveying path and is capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a conveying roller pair disposed on the re-conveyance path, the conveying roller pair including a first roller and a second roller, the conveying roller pair being capable of transitioning between a contact state in which the first roller and the second roller are in contact with each other and a separation state in which the first roller and the second roller are separated from each other; the reversing conveying section performs the reversing conveying process on the first sheet to guide the first sheet to the re-conveying path, and then the reversing conveying section performs the reversing conveying process on the second sheet to guide the second sheet to the re-conveying path, and further performs the reversing conveying process on the first sheet that has joined the conveying path from the re-conveying path while the conveying roller pair is in the separated state, to guide the first sheet to the re-conveying path, and overlaps the first adhesive surface of the first sheet and the second adhesive surface of the second sheet in the re-conveying path. 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 9) the conveying roller pair transitions from the contact state to the separated state after the rear end of the second sheet passes through the reverse conveying section. 9. The image forming apparatus according to configuration 8, (Configuration 10) the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the first reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; 10. The image forming apparatus according to claim 8 or 9, (Configuration 11) a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit that is disposed on the reversing conveying path and is capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a loop conveying path connected to the reversing conveying path and configured to guide the sheet conveyed from the reversing conveying path back to the reversing conveying path; a loop conveying section that is disposed on the loop conveying path and conveys the sheet conveyed from the reversing conveying path to the reversing conveying path via the loop conveying path, the reverse conveying section includes a roller pair and is capable of transitioning between a contact state in which the roller pair contacts each other and a separation state in which the roller pair is separated from each other; after performing the reversing conveying process on the first sheet by the reversing conveying unit and guiding the first sheet to the re-conveying path, transitioning the reversing conveying unit from the abutting state to the separated state, conveying the second sheet to the loop conveying path via the reversing conveying path, guiding the second sheet to the re-conveying path via the reversing conveying path by the loop conveying unit, and overlapping the first adhesive surface of the first sheet and the second adhesive surface of the second sheet on the re-conveying path; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 12) the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the second sheet is guided to the loop transport path; 12. The image forming apparatus according to claim 11, (Configuration 13) a housing that houses the image forming unit, the fixing unit, the re-conveying path, the conveying path, the reverse conveying path, and the reverse conveying unit, The loop transport path and the loop transport unit are housed in the housing. 13. The image forming apparatus according to claim 11 or 12. (Configuration 14) a first unit that houses the image forming unit, the fixing unit, the re-conveying path, the conveying path, the reverse conveying path, and the reverse conveying unit; a second unit that houses the loop transport path and the loop transport section and is detachably attached to the first unit; 13. The image forming apparatus according to claim 11 or 12. (Configuration 15) The image forming unit, the fixing unit, and the re-conveying path are accommodated in one housing. 11. The image forming apparatus according to any one of configurations 1 to 10. (Configuration 16) the image forming unit is capable of forming an image on a surface of the first sheet opposite to the first adhesive surface by using the toner for image formation; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 17) the image forming unit is capable of forming an image on a surface of the second sheet opposite to the second adhesive surface by using the toner for image formation; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 18) an alignment unit disposed on the re-conveyance path and configured to align the first sheet and the second sheet in a width direction perpendicular to a sheet conveyance direction; 18. The image forming apparatus according to any one of configurations 1 to 17. (Configuration 19) a conveying path that passes through the fixing unit and joins with the re-conveying path; a shortcut conveying path that branches off from the re-conveying path and joins the conveying path between the image forming unit and the fixing unit in a sheet conveying direction, the first sheet and the second sheet, in which the first adhesive surface and the second adhesive surface are superimposed on each other in the re-conveying path, are conveyed to the fixing unit via the shortcut conveying path; 19. The image forming apparatus according to any one of configurations 1 to 18. (Configuration 20) the toner for forming an image is a color toner, The adhesive toner is a colorless toner. 20. The image forming apparatus according to any one of configurations 1 to 19. (Configuration 21) The toner for image formation also serves as the toner for adhesion. 20. The image forming apparatus according to any one of configurations 1 to 19. [Explanation of symbols]

[0137] 1: image forming apparatus / 1A: housing, first unit (apparatus body) / 20: second reverse conveying path (discharge conveying path) / 21: reverse conveying section (reverse roller pair) / 22: re-conveying path (double-sided conveying path) / 23: guide member (second switching member) / 25: second reverse conveying section (discharge roller pair) / 29: reverse conveying path, first reverse conveying path / 31: alignment unit / 32: shortcut conveying path / 41: connection conveying path / 51: loop conveying path / 52a, 52b, 52c: loop conveying section (pair of conveying rollers) / 53: second unit (loop unit) / 128: pair of conveying rollers / 128a: first roller / 128b: second roller / BR1: first branching section / BR2: second branching section / CP: conveying path (feed conveying path) / N1: image forming section (secondary transfer nip) / N2: fixing section (fixing nip) / S1: first sheet / S1s: first adhesive surface / S2: second sheet / S2s: second adhesive surface

Claims

1. an image forming unit capable of forming an image on a sheet using a toner for image formation and also capable of forming an adhesive layer on the sheet using a toner for adhesive; a fixing section that fixes the toner to the sheet by applying heat and pressure to the sheet on which the image or the adhesive layer is formed; a re-conveying path for guiding the first sheet that has passed through the fixing unit and the second sheet that follows the first sheet toward the fixing unit again, a first adhesive surface of the first sheet on which the adhesive layer is formed and a second adhesive surface of the second sheet on which the adhesive layer is formed are overlapped while the first sheet and the second sheet pass through the re-conveying path, and the first sheet and the second sheet are transported to the fixing section while being overlapped.

1. An image forming apparatus comprising:

2. the fixing unit applies heat and pressure to the first sheet and the second sheet in a state in which the first adhesive surface and the second adhesive surface are superimposed on each other; 2. The image forming apparatus according to claim 1,

3. the leading edge of the first sheet and the leading edge of the second sheet are aligned midway through passing through the re-conveying path; 2. The image forming apparatus according to claim 1,

4. a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit disposed on the reversing conveying path and capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a guide member disposed downstream of the fixing unit in the conveying direction and configured to guide the sheet to the re-conveying path without conveying the sheet to the reversing conveying path, performing the reversing and conveying process on the first sheet by the reversing and conveying unit, guiding the first sheet to the re-conveying path, and then guiding the second sheet to the re-conveying path by the guide member without performing the reversing and conveying process, and overlapping the first adhesive surface of the first sheet and the second adhesive surface of the second sheet on the re-conveying path; 2. The image forming apparatus according to claim 1,

5. the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the second sheet is guided to the re-conveying path by the guide member; 5. The image forming apparatus according to claim 4.

6. a conveying path that passes through the fixing unit and joins with the re-conveying path; a first reversing conveying path that branches off from the conveying path at a first branching portion downstream of the fixing portion in a conveying direction of the sheet conveyed through the fixing portion and is connected to the re-conveying path; a first reversal conveying unit that is disposed on the first reversal conveying path and is capable of performing a reversal conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a second reversing conveying path branching off from the conveying path at a second branching portion between the fixing portion and the first branching portion in the conveying direction; a second reversing conveying unit disposed on the second reversing conveying path and capable of performing the reversing conveying process; a connecting conveying path that connects the second branching portion and the re-conveying path, the first reversing conveying unit performs the reversing conveying process on the first sheet to guide the first sheet to the re-conveying path, the first reversing conveying unit performs the reversing conveying process on the second sheet to guide the second sheet to the re-conveying path, and the second reversing conveying unit performs the reversing conveying process on the first sheet that has merged with the conveying path from the re-conveying path to guide the first sheet to the re-conveying path, and the first adhesive surface of the first sheet and the second adhesive surface of the second sheet are superimposed on each other in the re-conveying path.

2. The image forming apparatus according to claim 1,

7. the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the first reversing and conveying unit performs the reversing and conveying process; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the second sheet is subjected to the reversal and conveying process by the first reversal and conveying unit; 7. The image forming apparatus according to claim 6,

8. a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit disposed on the reversing conveying path and capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a conveying roller pair disposed on the re-conveyance path, the conveying roller pair including a first roller and a second roller, the conveying roller pair being capable of transitioning between a contact state in which the first roller and the second roller are in contact with each other and a separation state in which the first roller and the second roller are separated from each other; the reversing conveying unit performs the reversing conveying process on the first sheet to guide the first sheet to the re-conveying path, and then the reversing conveying unit performs the reversing conveying process on the second sheet to guide the second sheet to the re-conveying path, and further, with the conveying roller pair in the separated state, the reversing conveying unit performs the reversing conveying process on the first sheet that has joined the conveying path from the re-conveying path to guide the first sheet to the re-conveying path, and the first adhesive surface of the first sheet and the second adhesive surface of the second sheet are superimposed on each other in the re-conveying path.

2. The image forming apparatus according to claim 1,

9. the conveying roller pair transitions from the contact state to the separated state after the rear end of the second sheet passes through the reverse conveying portion.

9. The image forming apparatus according to claim 8,

10. the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the first reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; 9. The image forming apparatus according to claim 8,

11. a conveying path that passes through the fixing unit and joins with the re-conveying path; a reversing conveying path that branches off from the conveying path downstream of the fixing unit in a conveying direction of the sheet conveyed through the fixing unit and is connected to the re-conveying path; a reversing conveying unit disposed on the reversing conveying path and capable of performing a reversing conveying process of conveying a sheet in a first direction and then conveying the sheet in a second direction opposite to the first direction; a loop conveying path connected to the reversing conveying path and configured to guide the sheet conveyed from the reversing conveying path back to the reversing conveying path; a loop conveying section that is disposed on the loop conveying path and conveys the sheet conveyed from the reversing conveying path to the reversing conveying path via the loop conveying path, the reverse conveying section includes a roller pair and is capable of transitioning between a contact state in which the roller pair contacts each other and a separation state in which the roller pair is separated from each other; after performing the reversing conveying process on the first sheet by the reversing conveying unit and guiding the first sheet to the re-conveying path, transitioning the reversing conveying unit from the abutting state to the separated state, conveying the second sheet to the loop conveying path via the reversing conveying path, guiding the second sheet to the re-conveying path via the reversing conveying path by the loop conveying unit, and overlapping the first adhesive surface of the first sheet and the second adhesive surface of the second sheet on the re-conveying path; 2. The image forming apparatus according to claim 1,

12. the adhesive layer is formed on the first adhesive surface of the first sheet by the image forming unit before the reverse conveying process is performed by the reverse conveying unit; the adhesive layer is formed on the second adhesive surface of the second sheet by the image forming unit before the second sheet is guided to the loop transport path; 12. The image forming apparatus according to claim 11.

13. a housing that houses the image forming unit, the fixing unit, the re-conveying path, the conveying path, the reverse conveying path, and the reverse conveying unit, The loop transport path and the loop transport unit are housed in the housing.

12. The image forming apparatus according to claim 11.

14. a first unit that houses the image forming unit, the fixing unit, the re-conveying path, the conveying path, the reverse conveying path, and the reverse conveying unit; a second unit that houses the loop transport path and the loop transport section and is detachably attached to the first unit; 12. The image forming apparatus according to claim 11.

15. the image forming unit, the fixing unit, and the re-conveying path are accommodated in one housing; 2. The image forming apparatus according to claim 1,

16. the image forming unit is capable of forming an image on a surface of the first sheet opposite to the first adhesive surface by using the toner for image formation; 2. The image forming apparatus according to claim 1,

17. the image forming unit is capable of forming an image on a surface of the second sheet opposite to the second adhesive surface by using the toner for image formation; 2. The image forming apparatus according to claim 1,

18. an alignment unit disposed on the re-conveyance path and configured to align the first sheet and the second sheet in a width direction perpendicular to a sheet conveyance direction; 2. The image forming apparatus according to claim 1,

19. a conveying path that passes through the fixing unit and joins with the re-conveying path; a shortcut conveying path that branches off from the re-conveying path and joins the conveying path between the image forming unit and the fixing unit in a sheet conveying direction, the first sheet and the second sheet, in which the first adhesive surface and the second adhesive surface are superimposed on each other in the re-conveying path, are conveyed to the fixing unit via the shortcut conveying path; 19. The image forming apparatus according to claim 1,

20. the toner for forming an image is a color toner, The adhesive toner is a colorless toner.

19. The image forming apparatus according to claim 1,

21. The toner for image formation also serves as the toner for adhesion.

19. The image forming apparatus according to claim 1,

Images