Image formation apparatus

Abstract

To reduce unintended sheet detachment.SOLUTION: An adhesion pattern includes a first side part, a second side part, a third side part, a first corner part connecting the first side part and the second side part, a second corner part connecting the second side part and the third side part, and a third corner part connecting the third side part and the first side part. The first corner part is positioned at an end of the adhesion pattern near the corner in a diagonal direction of a sheet that passes through the corner where the first side and the second side of the sheet intersect each other. The second corner part is positioned at an end of the adhesion pattern farther from the second side in a direction of the first side of the sheet. The third corner part is positioned at an end of the adhesion pattern farther from the first side in a direction of the second side of the sheet. The second corner part and the third corner part are curved so that a minimum value of a curvature radius of the second corner part and a minimum value of a curvature radius of the third corner part are larger than a minimum value of a curvature radius of the first corner part.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Patent document 1 describes an image forming device that forms a pattern image of adhesive toner on the corners of paper and then heats a stack of paper to adhere them together, and that makes it possible to set the adhesive strength by changing the area ratio of the pattern image, etc.

[0003] Patent document 2 describes an image forming apparatus that forms a pattern of adhesive toner along the long side of a sheet and then heats and adheres the sheet stack, increasing the amount of toner at the end of the long side compared to the central portion, thereby increasing the adhesive strength in the end region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-043751 A [Patent Document 2] JP 2005-162352 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above documents, the adhesive toner layer is formed in a right-angled triangular pattern or a rectangular pattern, so that when a user turns over a stack of sheets, stress is concentrated at the corners of the pattern, which may cause the sheet to unintentionally peel off from the corners.

[0006] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS The present invention has an object to provide an image forming apparatus capable of reducing unintentional peeling of a sheet. [Means for solving the problem]

[0007] One aspect of the present invention is an image forming apparatus including an image forming means for forming, on a sheet, a visible image and an adhesive pattern formed with a powder adhesive for adhering sheets to each other, and an adhesive means for adhering the multiple sheets by heating the adhesive pattern in a state in which the multiple sheets are stacked together, wherein the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion, and the first corner portion is located at a point where a first edge and a second edge of the sheet intersect. the second corner portion is located at an end of the adhesive pattern close to the corner in a diagonal direction of the sheet passing through the corner, the second corner portion is located at an end of the adhesive pattern far from the second side in the direction of the first side of the sheet, and the third corner portion is located at an end of the adhesive pattern far from the first side in the direction of the second side of the sheet, and the second corner portion and the third corner portion are curved such that a minimum value of the radius of curvature of the second corner portion and a minimum value of the radius of curvature of the third corner portion are greater than a minimum value of the radius of curvature of the first corner.

[0008] Another aspect of the present invention is an image forming apparatus including an image forming means for forming, on a sheet, a visible image and an adhesive pattern formed with a powder adhesive for adhering sheets to each other, and an adhesive means for adhering the multiple sheets by heating the adhesive pattern in a state where the multiple sheets are stacked, wherein the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion, and the first corner portion passes through a corner where a first side and a second side of the sheet intersect. an adhesive pattern including a first region including the first corner and a second region including the second corner and the third corner, the second corner being located at an end of the adhesive pattern close to the corner in the diagonal direction of the sheet, the second corner being located at an end of the adhesive pattern farther from the second side in the direction of the first side of the sheet, and the third corner being located at an end of the adhesive pattern farther from the first side in the direction of the second side of the sheet, and the adhesive pattern having a first region including the first corner and a second region including the second corner and the third corner, in which the amount of powder adhesive applied is greater than the amount of powder adhesive applied in the first region.

[0009] Another aspect of the present invention is an image forming apparatus including an image forming means for forming, on a sheet, a visible image and an adhesive pattern formed with a powder adhesive for adhering sheets to each other, and an adhesive means for adhering the multiple sheets by heating the adhesive pattern in a state in which the multiple sheets are stacked together, wherein the adhesive pattern includes a first side portion, a second side portion, a third side portion, a fourth side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the first side portion and the fourth side portion, a third corner portion connecting the third side portion and the second side portion, and a fourth corner portion connecting the third side portion and the fourth side portion, and the adhesive pattern is The image forming device has an elongated shape extending along a first edge of the sheet, the first side portion extending along the first edge of the sheet, and the third side portion is located closer to the center of the sheet than the first side portion in the direction of a second edge of the sheet that intersects with the first edge, and the third corner portion and the fourth corner portion are curved so that the minimum value of the radius of curvature of the third corner portion is greater than the minimum value of the radius of curvature of the first corner portion and the minimum value of the radius of curvature of the second corner portion, and the minimum value of the radius of curvature of the fourth corner portion is greater than the minimum value of the radius of curvature of the first corner portion and the minimum value of the radius of curvature of the second corner portion. Effect of the Invention

[0010] According to the present invention, unintentional peeling of the sheet can be reduced. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a thermal fixing unit according to the first embodiment. [Diagram 3] FIG. 13 is a diagram showing an example of a deliverable in the first embodiment. [Figure 4] 3A to 3E are diagrams showing examples of adhesive patterns according to Example 1. [Diagram 5] FIG. 11 is a schematic diagram of an image forming apparatus according to a second embodiment. [Figure 6] FIG. 13 is a diagram showing an example of a product in the second embodiment. [Figure 7] 6A to 6E are diagrams showing examples of adhesive patterns according to Example 2. [Figure 8] 11A to 11D are diagrams (a to i) showing examples of adhesive patterns according to Example 3. [Figure 9] FIG. 11 is a schematic diagram of an image forming apparatus according to a fourth embodiment. [Figure 10] FIG. 13 is a diagram showing an example of a product in Example 4. [Figure 11] FIG. 11 is an explanatory diagram of an adhesive pattern according to Example 4. [Figure 12] 13 is a graph showing the relationship between the corner shape of the adhesive pattern and adhesive strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0013] In this disclosure, the term "image forming apparatus" refers to a general apparatus having a function of forming an image on a sheet, which is a recording material (recording medium). The image forming apparatus may be a single-function printer, a copier, or a multifunction machine. The image forming apparatus may be an apparatus that mainly forms color images, or an apparatus that mainly forms monochrome images. The image forming apparatus may also be a system (image forming system) in which an accessory device used integrally with the image forming apparatus main body is connected to the image forming apparatus main body that forms an image on a recording material. Examples of the accessory device include a sheet processing apparatus (finisher) that processes the sheet on which an image has been formed, a conveying device that conveys the sheet from the image forming apparatus main body to another device, and a feeding device (optional feeder) that feeds the sheet toward the image forming apparatus main body.

[0014] Example 1 The overall configuration of an image forming apparatus 1 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the cross-sectional configuration of the image forming apparatus 1.

[0015] 1, the image forming apparatus 1 has an image forming apparatus main body (hereinafter referred to as the apparatus main body 10) and a post-processing apparatus 300. The image forming apparatus 1 can form images on sheets P one by one in succession, and then create a product (adhesive print) in which a plurality of sheets P are adhered together.

[0016] The device main body 10 includes a sheet cassette 8 as a sheet storage section for storing sheets P as recording materials, an image forming unit 1e as an image forming means, a fixing device 6 as a fixing means, and a housing 19 for accommodating these. The image forming unit 1e is an example of an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for bonding sheets together on a sheet. The device main body 10 has a function (image forming device) of forming a toner image on a sheet P fed from the sheet cassette 8 by the image forming unit 1e, and producing a printed matter by performing a fixing process by the fixing device 6. The post-processing device 300 is a sheet processing device that performs an adhesive process (binding process, thermocompression process) on the sheet P on which an image has been formed by the device main body 10.

[0017] The sheet cassette 8 is inserted into the housing 19 at the bottom of the device main body 10 so as to be removable, and stores a large number of sheets P. The sheets P stored in the sheet cassette 8 are fed from the sheet cassette 8 by a feed roller 8a serving as a feed section, and are transported by a transport roller pair 8b. As the sheets P, various sheet materials of different sizes and materials can be used, including paper such as plain paper and thick paper, surface-treated sheet materials such as coated paper, sheet materials of special shapes such as envelopes and index paper, plastic films, cloth, etc.

[0018] The image forming unit 1e of this embodiment is a tandem-type electrophotographic unit including four process units 7n, 7y, 7m, and 7c, a scanner unit 2, and a transfer unit 3. The process units 7n, 7y, 7m, and 7c may be configured as a unit (process cartridge) in which a plurality of parts responsible for the image forming process can be replaced as a whole.

[0019] The process units 7n, 7y, 7m, and 7c have a substantially common configuration, except for the type of powder (toner) contained in the four powder containers Gn, Gy, Gm, and Gc. That is, each of the process units 7n, 7y, 7m, and 7c includes a photosensitive drum Dn, Dy, Dm, or Dc that is an image carrier, a charging roller Cn, Cy, Cm, or Cc that is a charger, and a powder container Gn, Gy, Gm, or Gc that contains powder and supplies it to the photosensitive drum.

[0020] Of the four powder containers, the three powder containers Gy, Gm, and Gc on the right side of the drawing contain toners of three colors, yellow, magenta, and cyan, respectively, as printing toners for mainly forming visible images on sheet P. In contrast, the powder container Gn on the leftmost side of the drawing contains powder adhesive Tn, which is a powder (adhesive toner) for adhering sheets together after printing.

[0021] In this embodiment, the "toner image" created by the image forming unit 1e includes both a visible image formed by printing toner and a pattern image (called an adhesive pattern) formed in a predetermined area on the sheet by powder adhesive (adhesive toner).

[0022] In this embodiment, when printing a black image such as text, the image is expressed by process black, which is a combination of yellow (Ty), magenta (Tm), and cyan (Tc) toners. However, for example, a fifth process unit using black printing toner may be added to the image forming unit 1e, so that black images can be expressed by black printing toner. However, the present invention is not limited to this, and the type and number of printing toners can be changed depending on the application of the image forming device 1.

[0023] The scanner unit 2 is disposed below the process units 7n, 7y, 7m, and 7c and above the sheet cassette 8. The scanner unit 2 is an example of an exposure unit that writes an electrostatic latent image by irradiating the photosensitive drums Dn, Dy, Dm, and Dc of each of the process units 7n, 7y, 7m, and 7c with laser light.

[0024] The transfer unit 3 includes a transfer belt 3a as an intermediate transfer body (secondary image carrier). The transfer belt 3a is a belt member wound around a secondary transfer inner roller 3b and a tension roller 3c, and its outer circumferential surface faces the photosensitive drums Dn, Dy, Dm, and Dc of each process unit 7n, 7y, 7m, and 7c. On the inner circumferential side of the transfer belt 3a, primary transfer rollers Fn, Fy, Fm, and Fc are disposed at positions corresponding to the photosensitive drums Dn, Dy, Dm, and Dc. In addition, a secondary transfer roller 5 as a transfer means is disposed at a position facing the secondary transfer inner roller 3b. A transfer nip 5n between the secondary transfer roller 5 and the transfer belt 3a is a transfer portion (secondary transfer portion) where a toner image is transferred from the transfer belt 3a to a sheet P.

[0025] The fixing device 6 is a fixing device of a thermal fixing type that heats the toner image on the sheet P to fix it to the sheet P. The fixing device 6 is disposed above the secondary transfer roller 5. The fixing device 6 has, for example, a ceramic heater 6a as a heat source, a heating film 6b as a fixing member, and a pressure roller 6c as a pressure member. The fixing member is not limited to the flexible heating film 6b, and may be, for example, a cylindrical roller having rigidity. The heat source may be, for example, a halogen lamp or a heat generating mechanism of an induction heating type.

[0026] The pressure roller 6c is rotated by a driving means (not shown). The ceramic heater 6a is held by a holding member (not shown), and is pressed against the pressure roller 6c with the heating film 6b sandwiched therebetween by a biasing member such as a spring. This pressing force forms a nip portion (fixing nip 6n) between the heating film 6b and the pressure roller 6c. A temperature detection element such as a thermistor is attached to the ceramic heater 6a. The control unit of the image forming apparatus 1 controls the power supply to the ceramic heater 6a based on a detection signal from the temperature detection element, thereby maintaining the surface temperature of the heating film 6b at a predetermined target temperature suitable for fixing an image.

[0027] (Printing toner) In this embodiment, a conventionally known printing toner can be used. Among them, a printing toner using a thermoplastic resin as a binder resin is preferred. The resin that can be used as the thermoplastic resin is not particularly limited. As the thermoplastic resin, a resin used in a conventional printing toner, such as a polyester resin, a vinyl resin, an acrylic resin, or a styrene-acrylic resin, can be used. A plurality of these resins may be contained. Among them, a printing toner using a styrene-acrylic resin is more preferred. The printing toner may contain a colorant, a magnetic material, a charge control agent, a wax, and an external additive.

[0028] (powder adhesive) In this embodiment, a powder adhesive containing a thermoplastic resin can be used. The resin that can be used as the thermoplastic resin is not particularly limited, and examples thereof include known thermoplastic resins such as polyester resin, vinyl resin, acrylic resin, styrene-acrylic resin, polyethylene, polypropylene, polyolefin, ethylene-vinyl acetate copolymer resin, and ethylene-acrylic acid copolymer resin. A plurality of these resins may be included.

[0029] The powder adhesive preferably further contains a wax, and as the wax, known waxes such as ester waxes which are esters of alcohol and acid, and hydrocarbon waxes such as paraffin wax can be used.

[0030] The powder adhesive may contain a colorant. Known colorants such as black colorants, yellow colorants, magenta colorants, and cyan colorants can be used as the colorant. The content of the colorant in the powder adhesive is preferably 1.0% by mass or less, and more preferably 0.1% by mass or less. The powder adhesive may contain a magnetic material, a charge control agent, a wax, and an external additive.

[0031] In order to form an adhesive pattern on a recording material by electrophotography, the weight average particle size of the powder adhesive is preferably 5.0 μm or more and 30 μm or less, and more preferably 6.0 μm or more and 20 μm or less.

[0032] In addition, printing toner may be used as the powder adhesive as long as it satisfies the adhesive property. For example, in this embodiment, the process unit 7n may use black printing toner to form a black toner image, and in that case, the adhesive pattern may be formed with one or more types of printing toner among yellow, magenta, cyan, and black.

[0033] (Example of powder adhesive manufacturing) The powder adhesive is, for example, produced as follows. Styrene 75.0 parts n-Butyl acrylate 25.0 parts Polyester resin 4.0 parts (Polyester resin with weight average molecular weight (Mw) of 20,000, glass transition temperature (Tg) of 75°C, and acid value of 8.2 mgKOH / g) Ethylene glycol distearate 14.0 parts (Ester wax made by esterifying ethylene glycol and stearic acid) Hydrocarbon wax (HNP-9, Nippon Seiro) 2.0 parts Divinylbenzene 0.5 parts

[0034] The mixture of the above materials was kept at 60° C. and stirred at 500 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to dissolve uniformly, thereby preparing a polymerizable monomer composition.

[0035] Meanwhile, 0.10 mol / L-Na was added to a vessel equipped with a high-speed stirring device Clearmix (M Technique Co., Ltd.). 3 PO 4 850.0 parts of the aqueous solution and 8.0 parts of 10% hydrochloric acid were added, the rotation speed was adjusted to 15,000 rpm, and the mixture was heated to 70°C. 2127.5 parts of the aqueous solution was added to prepare an aqueous medium containing a calcium phosphate compound.

[0036] After the polymerizable monomer composition was added to the aqueous medium, 7.0 parts of t-butyl peroxypivalate, a polymerization initiator, was added, and the mixture was granulated for 10 minutes while maintaining a rotation speed of 15,000 rpm. After that, the high-speed agitator was replaced with a propeller agitator, and the mixture was reacted at 70°C for 5 hours under reflux, and then the liquid temperature was increased to 85°C and the mixture was reacted for another 2 hours.

[0037] After the polymerization reaction was completed, the resulting slurry was cooled, and then hydrochloric acid was added to the slurry to adjust the pH to 1.4 and stirred for 1 hour to dissolve the calcium phosphate salt. The slurry was then washed with three times the amount of water, filtered, dried, and classified to obtain powder adhesive particles.

[0038] Then, silica fine particles (number-average particle size of primary particles: 10 nm, BET specific surface area: 170 m) that had been hydrophobized using dimethyl silicone oil (20% by mass) were added as an external additive to 100.0 parts of the powder adhesive particles. 2 The mixture was mixed for 15 minutes at 3000 rpm using a Mitsui Henschel mixer (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) to obtain a powder adhesive.

[0039] The powder adhesive obtained by the above manufacturing method had a weight average particle size of 6.8 μm.

[0040] (Example of printing toner production) The printing toner is produced, for example, in the following manner. Styrene 60.0 parts Colorant 6.5 parts (CI Pigment Blue 15:3, Dainichi Seika Chemicals Co., Ltd.)

[0041] The above materials were placed in an attritor (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.), and further dispersed using zirconia particles having a diameter of 1.7 mm at 220 rpm for 5 hours to obtain a pigment dispersion liquid. Styrene 15.0 parts n-Butyl acrylate 25.0 parts Polyester resin 4.0 parts (Polyester resin with weight average molecular weight (Mw) of 20,000, glass transition temperature (Tg) of 75°C, and acid value of 8.2 mgKOH / g) Behenyl behenate 12.0 parts (Ester wax made by esterifying behenic acid and behenyl alcohol) Divinylbenzene 0.5 parts

[0042] The above materials were mixed and added to the pigment dispersion liquid. The resulting mixture was kept at 60° C. and stirred at 500 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to dissolve and disperse uniformly, thereby preparing a polymerizable monomer composition.

[0043] Meanwhile, 0.10 mol / L-Na was added to a vessel equipped with a high-speed stirring device Clearmix (M Technique Co., Ltd.). 3 PO 4 850.0 parts of the aqueous solution and 8.0 parts of 10% hydrochloric acid were added, the rotation speed was adjusted to 15,000 rpm, and the mixture was heated to 70° C. 127.5 parts of a 1.0 mol / L-CaCl2 aqueous solution was added thereto to prepare an aqueous medium containing a calcium phosphate compound.

[0044] After the polymerizable monomer composition was added to the aqueous medium, 7.0 parts of t-butyl peroxypivalate, a polymerization initiator, was added, and the mixture was granulated for 10 minutes while maintaining a rotation speed of 15,000 rpm. After that, the high-speed agitator was replaced with a propeller agitator, and the mixture was reacted at 70°C for 5 hours under reflux, and then the liquid temperature was increased to 85°C and the mixture was reacted for another 2 hours.

[0045] After the polymerization reaction was completed, the resulting slurry was cooled, and then hydrochloric acid was added to the slurry to adjust the pH to 1.4 and the slurry was stirred for 1 hour to dissolve the calcium phosphate salt.The slurry was then washed with three times the amount of water, filtered, dried, and classified to obtain toner particles.

[0046] Thereafter, silica fine particles (number average particle diameter of primary particles: 10 nm, BET specific surface area: 170 m) that had been hydrophobized using dimethyl silicone oil (20% by mass) were added to 100.0 parts of the toner particles as an external additive. 2 The mixture was mixed at 3000 rpm for 15 minutes using a Mitsui Henschel mixer (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) to obtain a toner. The weight average particle diameter of the obtained toner was 6.5 μm.

[0047] (Method of measuring weight average particle size) The weight average particle size of the printing toner and powder adhesive is calculated as follows.

[0048] The measurement device used is a precision particle size distribution measurement device using the pore electrical resistance method, "Coulter Counter Multisizer 3" (registered trademark product name, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.). The measurement is performed with an effective measurement channel count of 25,000.

[0049] The electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter).

[0050] Before performing measurements and analysis, the dedicated software is set up as follows. In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count number in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter). Press the "Threshold / Noise Level Measurement Button" to automatically set the threshold and noise level. In addition, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

[0051] In the "Pulse to particle size conversion setting" screen of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

[0052] The specific measurement method is as follows. (1) Pour 200 mL of electrolyte solution into a 250 mL round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Aperture tube flush" function of the dedicated software to remove dirt and air bubbles from inside the aperture tube.

[0053] (2) 30 mL of the electrolyte solution is placed in a 100 mL flat-bottom glass beaker. 0.3 mL of a solution of "Contaminon N" (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments made from a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times by mass with ion-exchanged water is added as a dispersant.

[0054] (3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System TetoRa150" (manufactured by Nikkaki Bios Co., Ltd.) that has two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees, and has an electrical output of 120 W. Place 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank, and add 2 mL of Contaminon N to this tank.

[0055] (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolyte solution in the beaker is maximized.

[0056] (5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, add the toner or powder adhesive to the electrolyte solution in small amounts of 10 mg at a time and disperse it. Then, continue ultrasonic dispersion for another 60 seconds. During ultrasonic dispersion, adjust the water temperature in the water tank appropriately so that it is between 10°C and 40°C.

[0057] (6) Using a pipette, drip the electrolytic solution (5) in which the toner or powder adhesive has been dispersed into the round-bottom beaker (1) placed in the sample stand to adjust the measurement concentration to 5%. Then, measurements are continued until the number of particles measured reaches 50,000.

[0058] (7) The measurement data is analyzed using dedicated software provided with the device to calculate the weight average particle diameter.

[0059] (Image formation operation) The image forming operation by the apparatus main body 10 will be described. When visible image data and an image formation command are input to the image forming apparatus 1, a control unit (not shown) of the image forming apparatus 1 starts executing an image forming job. The image forming job is a series of tasks including an image forming operation for forming a visible image (and an adhesive pattern, if necessary) while transporting the sheets P one by one, and an adhesive operation for bonding the sheets together in the post-processing device 300. When transmitting an image formation command to the image forming apparatus 1, the user inputs setting information in advance, such as whether or not bonding is required by the post-processing device 300.

[0060] In the image forming operation, first, the sheets P are fed one by one from the sheet cassette 8 and conveyed toward the transfer nip 5n via the conveying roller pair 8b. In parallel with the feeding of the sheets P, the process units 7n, 7y, 7m, and 7c are sequentially driven, and the photosensitive drums Dn, Dy, Dm, and Dc are rotated and driven. The charging rollers Cn, Cy, Cm, and Cc uniformly charge the surfaces of the photosensitive drums Dn, Dy, Dm, and Dc to a predetermined polarity and potential. The scanner unit 2 irradiates the photosensitive drums Dn, Dy, Dm, and Dc with laser light modulated based on the visible image data, and forms an electrostatic latent image on the surfaces of the photosensitive drums Dn, Dy, Dm, and Dc. The developing rollers Hn, Hy, Hm, and Hc carry the powder (printing toner or powder adhesive) in the powder storage sections Gn, Gy, Gm, and Gc and supply it to the photosensitive drums Dn, Dy, Dm, and Dc, developing the electrostatic latent images into powder images (toner images).

[0061] The powder adhesive layer formed on the photosensitive drum Dn by development with the powder adhesive Tn differs from a toner image (visible image) of printing toner for recording images such as figures and text on the sheet P in that it is not intended to transmit visual information. However, in the following description, a pattern image (hereinafter referred to as an adhesive pattern) formed with the powder adhesive Tn is also treated as one of the "toner images." The adhesive pattern is a layer of the powder adhesive Tn formed in a predetermined area (adhesive area) of the sheet P that is the target of the adhesive process.

[0062] The transfer belt 3a rotates in a counterclockwise direction (arrow v) in the figure. The toner images formed in each process unit 7n, 7y, 7m, 7c are primarily transferred from the photosensitive drums Dn, Dy, Dm, Dc to the transfer belt 3a by an electric field formed between the photosensitive drums Dn, Dy, Dm, Dc and the primary transfer rollers Fn, Fy, Fm, Fc. The toner images carried on the transfer belt 3a and reaching the transfer nip 5n are secondarily transferred to the conveyed sheet P by an electric field formed between the secondary transfer roller 5 and the inner secondary transfer roller 3b. As a result, the visible image and adhesive pattern are transferred to the sheet P.

[0063] Thereafter, the sheet P is conveyed to the fixing device 6 and undergoes a fixing process. That is, when the sheet P passes through the fixing nip 6n, the toner image on the sheet P is heated and pressurized, so that the printing toners Ty, Tm, and Tc and the powder adhesive Tn melt and then solidify, thereby obtaining a toner image fixed on the sheet P.

[0064] When the adhesive process of the sheet P is not performed, no adhesive pattern of the powder adhesive Tn is formed on the sheet P. In this case, the switching guide 33 guides the sheet P to the discharge roller pair 34. The discharge roller pair 34 discharges the sheet P onto the discharge tray 40, and the image forming apparatus 1 ends the operation for one sheet P.

[0065] On the other hand, when performing the bonding process on the sheet P, a bonding pattern of the powder adhesive Tn is formed on the sheet P. The switching guide 33 guides the sheet P to a pair of conveying rollers 38 of the post-processing device 300. The post-processing device 300 stacks and aligns a plurality of sheets P, and then performs a thermocompression bonding process (bonding process) using the thermocompression bonding unit 51. This creates a sheet bundle in which the sheets are bonded together via the bonding pattern of the powder adhesive Tn. The post-processing device 300 discharges the bonded sheet bundle as a finished product onto the discharge tray 37.

[0066] (After-treatment device) The post-processing device 300 will be described. The post-processing device 300 is a sheet bonding device capable of bonding sheets together by thermocompression bonding of a sheet P on which an adhesive pattern has been formed in advance. The post-processing device 300 of this embodiment is disposed on the upper part of the device main body 10. The post-processing device 300 may be housed in a common housing with the device main body 10, or may have a housing separate from the housing of the device main body 10 and be connected to the upper surface of the housing of the device main body 10.

[0067] 1, the post-processing device 300 has pairs of conveying rollers 38 and 39, a width direction alignment section 41, a conveying direction alignment section 42, an intermediate stacking section 43, a thermocompression bonding unit 51, and a discharge tray 37. In the following description, the sheet conveying direction may be referred to as the "vertical direction", and the width direction perpendicular to the sheet conveying direction may be referred to as the "lateral direction".

[0068] The intermediate stacking section 43 is a place (processing tray) where a plurality of sheets P to be subjected to the bonding process are stacked. The conveying direction alignment section 42 and the width direction alignment section 41 are examples of alignment means for aligning the sheets P stacked on the intermediate stacking section 43 to a position when the thermocompression bonding operation is performed by the thermocompression bonding unit 51. The conveying direction alignment section 42 is, for example, a roller that conveys the sheets P toward a reference plate provided at the upstream end of the intermediate stacking section 43 in the sheet conveying direction. The width direction alignment section 41 is, for example, a pair of alignment plates facing each other in the width direction perpendicular to the sheet conveying direction. Each alignment plate is formed in a U-shape that is open toward the inside in the width direction, and the sheet P is aligned in the width direction by moving one alignment plate as a reference. The conveying roller pair 39 can be switched between a nip state in which a nip portion for holding the sheet P is formed and an open state (separated state) in which the nip portion is opened. The thermocompression bonding unit 51 will be described in detail later.

[0069] The sheet P guided to the post-processing device 300 by the switching guide 33 is transported by the transport roller pair 38 toward the intermediate stacking section 43, and is stacked in the intermediate stacking section 43. When the sheet P is stacked in the intermediate stacking section 43, the transport roller pair 39 is in an open state and stands by. The sheet P stacked in the intermediate stacking section 43 is aligned in the width direction by the width direction alignment section 41, and then aligned in the sheet transport direction by the transport direction alignment section 42. That is, each sheet P is aligned in the vertical and horizontal directions in the intermediate stacking section 43.

[0070] When a predetermined number of sheets P (the number of sheets P that will be one part of the finished product) are stacked and aligned, a thermocompression bonding process is performed by a thermocompression bonding unit 51, which heats and presses the predetermined number of sheets P. The thermocompression bonding unit 51 is an example of a bonding means that heats an adhesive pattern in a state where multiple sheets are stacked together to bond the multiple sheets. This heats the adhesive pattern again, and a sheet bundle is created in which the facing sheet surfaces of the predetermined number of sheets P are bonded together via a layer of powder adhesive Tn (adhesive layer). After the thermocompression bonding process is completed, the conveying roller pair 39 is switched to a nip state and driven to rotate, clamping the sheet bundle and discharging it from the intermediate stacking unit 43 to the discharge tray 37.

[0071] (Thermocompression unit) Further description will be given of the thermocompression unit 51. Fig. 2 is a cross-sectional view of the thermocompression unit 51. In Fig. 2, the width direction is indicated by an arrow X, and the height direction (thickness direction of the sheet P) perpendicular to both the sheet conveying direction and the width direction is indicated by an arrow Z.

[0072] The thermocompression bonding unit 51 includes a heater 501 , a heating plate 502 , a support 503 , a pressure lever 504 , a metal stay 505 , and a receiving plate 506 .

[0073] The heating plate 502 (first pressure member) is a member (heating member) that, together with the receiving plate 506 (second pressure member), clamps and heats and presses the stack of sheets P to be processed (sheet stack Ps). The heating plate 502 has a contact portion that contacts the upper surface of the sheet stack Ps, and the surface opposite the contact portion in the height direction contacts the heater 501. The heating plate 502 in this embodiment is an aluminum plate having a thickness of 1.5 mm.

[0074] The heater 501 is a heat source for heating the heating plate 502. The heater 501 in this embodiment is a ceramic heater in which a pattern of a resistance heating element is formed on a ceramic substrate having a thickness of 1.0 mm.

[0075] The support 503 supports the heater 501. In this embodiment, the support 503 is made of a heat-resistant resin. The support 503 is provided with a temperature detection element (such as a thermistor) as a temperature detection means for detecting the temperature of the heater 501, and an electric circuit for energizing the heater 501. The control unit of the image forming apparatus 1 controls the energization of the heater 501 based on a detection signal from the temperature detection element, thereby maintaining the heating plate 502 at a temperature suitable for thermocompression bonding of the sheet stack Ps. For example, the control unit maintains the heater 501 at a target temperature of 240°C so that the surface temperature of the heating plate 502 becomes 200°C.

[0076] The metal stay 505 supports the support body 503. The metal stay 505 moves by receiving a force from a pressure lever 504 that moves in the height direction by the driving force of a driving source. The heating plate 502, heater 501, support body 503 and metal stay 505 form a unit (heating unit) that moves integrally in the height direction. The metal stay 505 has high rigidity to uniformly transmit the driving force of the pressure lever 504 to the heating unit.

[0077] The receiving plate 506 is, for example, a 2.0 mm thick silicone rubber plate. The receiving plate 506 is fixed to the frame of the thermocompression bonding unit 51 and receives the force of the heating plate 502 pressing the sheet stack Ps downward in the figure.

[0078] The heating plate 502 is pressed downward in the drawing by the pressure lever 504 via the metal stay 505, the support 503, and the heater 501, and is pressed against the upper surface of the sheet stack Ps. In this embodiment, the pressure force received by the sheet stack Ps is set to 0.2 MPa as the average pressure (average surface pressure) in the pressure range of the heating plate 502 (contact area between the heating plate 502 and the upper surface of the sheet stack Ps). In the thermocompression bonding operation, the thermocompression bonding unit 51 is driven so that the heating plate 502 presses the sheet stack Ps for two seconds and then moves away from the sheet stack Ps.

[0079] In this embodiment, the pressure application range of the heating plate 502 is a triangle shape of 13 mm in the X direction (width direction, horizontal direction) and 25 mm in the Y direction (sheet conveying direction, vertical direction). The pressure application range may be a right-angled triangle shape with a side of 13 mm in the horizontal direction and a side of 25 mm in the Y direction intersecting at right angles.

[0080] (Adhesive Pattern) FIG. 3 is a schematic diagram showing the visible images I1, I2 and adhesive pattern S when creating a product G1, which is an adhesive print product in which two sheets P1 and P2 are corner-bound. The first sheet P1 has a front side P1-1 that serves as the cover of the product G1, and a back side P1-2. The second sheet P2 has a front side P2-1 that faces the back side P1-2 of the first sheet, and a back side P2-2 that serves as the back cover of the product G1. In this example, visible images J1 and J2 are formed on the front sides P1-1 and P2-2 of the first and second sheets, respectively, and the back sides P1-2 and P2-2 are left blank. The visible images I1 and I2 are formed using at least one of printing toners Ty, Tm, and Tc.

[0081] The adhesive pattern S shown by the dotted area in the figure is formed in a predetermined area on the surface P2-1 of the second sheet P2 using a powder adhesive Tn. In this embodiment, the adhesive pattern S is formed near one corner (the upper left corner in the figure) of the sheet P2. The shape of the adhesive pattern S is stored in advance in a memory unit provided in the control unit of the image forming apparatus 1. It is also possible to allow the user to select or newly set the shape of the adhesive pattern S. The detailed shape of the adhesive pattern S will be described later.

[0082] The post-processing device 300 performs a thermocompression process on the two sheets P1 and P2 in a superimposed state using the thermocompression bonding unit 51, thereby creating a corner-bound product G1 in which the sheets P1 and P2 are bound at their corners.

[0083] (Details of adhesive pattern) Next, the pattern S will be described in detail. The powder adhesive Tn is applied in any one of the adhesive patterns S-1, S-2, S-3, S-4, and S-5 having the shapes shown in FIGS. 4(a) to 4(e). Hereinafter, the adhesive patterns S-1, S-2, S-3, S-4, and S-5 illustrated in FIGS. 4(a) to 4(e) are collectively referred to as each adhesive pattern S.

[0084] First, the shape common to each adhesive pattern S will be described. The outer shape of the adhesive pattern S is a substantially triangular shape including three side portions (sides) and three corner portions. The adhesive pattern S includes a first side portion Se1, a second side portion Se2, and a third side portion Se3. Further, the adhesive pattern S includes a first corner portion Sc1 connecting the first side portion Se1 and the second side portion Se2, a second corner portion Sc2 connecting the first side portion Se1 and the third side portion Se3, and a third corner portion Sc3 connecting the second side portion Se2 and the third side portion Se3.

[0085] The first corner portion Sc1 is located at an end portion of the adhesive pattern S close to the corner C1 in the diagonal direction D3 of the sheet P (sheet P2 in FIG. 3) passing through the corner C1 where the first side E1 and the second side E2 of the sheet P on which the adhesive pattern S is formed intersect. The second corner portion Sc2 is located at an end portion of the adhesive pattern S on the side far from the second side E2 in the direction D1 of the first side E1 of the sheet P. The third corner portion Sc3 is located at an end portion of the adhesive pattern S on the side far from the first side E1 in the direction of the second side E2 of the sheet P.

[0086] In each adhesive pattern S, the second corner portion Sc2 and the third corner portion Sc3 are curved so that the minimum value of the radius of curvature of the second corner portion Sc2 and the minimum value of the radius of curvature of the third corner portion Sc3 are larger than the minimum value of the radius of curvature of the first corner portion Sc1. Let the minimum value of the radius of curvature of the first corner portion Sc1 be R1 (mm), the minimum value of the radius of curvature of the second corner portion Sc2 be R2 (mm), and the minimum value of the radius of curvature of the third corner portion Sc3 be R3 (mm). Then, R1 < R2 and R2 < R3. In other words, each adhesive pattern S is rounded so that the second corner portion Sc2 and the third corner portion Sc3 close to the central region of the sheet P where the visible image is mainly formed are in a gently curved (rounded) curve shape compared to the first corner portion Sc1 close to the corner of the sheet P.

[0087] When a deliverable G1 is created with corner C1 bound as shown in Fig. 3, it can be assumed that the user will turn over sheet P1 from the lower right to the upper left (or from right to left, or from bottom to top). In this case, stress (tensile force in the thickness direction of the sheet) in a direction that causes sheets P1 and P2 to peel off is generated at second corner Sc2 and third corner Sc3 of adhesive pattern S. If second corner Sc2 and third corner Sc3 were sharp corners (corners where adjacent sides intersect at a single point), stress would be concentrated at the corners, which would likely cause adhesive pattern S to peel off.

[0088] In this embodiment, the second corner Sc2 and the third corner Sc3 are rounded to avoid stress concentration. This reduces the possibility that the sheets P1 and P2 will peel off when the user turns over the sheets of the deliverable G1 in the normal manner. In other words, this embodiment reduces the possibility of unintentional peeling of the sheets.

[0089] On the other hand, the first corner Sc1 has a smaller minimum radius of curvature than the second corner Sc2 and the third corner Sc3, and therefore stress is likely to concentrate thereon, which is likely to trigger peeling of the adhesive pattern S. This has the advantage that when a user wants to peel off the sheets P1 and P2, the sheets P1 and P2 can be easily peeled off by flipping the sheet P1 over from the corner C1 of the result G1.

[0090] The first side portion Se1, the second side portion Se2, and the third side portion Se3 may be straight or curved. The second corner portion Sc2 and the third corner portion Sc3 may be arc-shaped curves or other curved curves. The first corner portion Sc1 may be a corner where the straight first side portion Se1 and the straight second side portion Se2 intersect at a right angle at one point, or may be a curve with a rounded corner.

[0091] In addition, when the first side portion Se1, the second side portion Se2, and the third side portion Se3 are linear as in the adhesive patterns S-1 to S-3 in Figures 4(a) to 4(c), the curved or bent curved portion that connects adjacent sides is defined as the corner of the adhesive pattern S. On the other hand, when at least one of the first side portion Se1, the second side portion Se2, and the third side portion Se3 is curved as in Figures 4(d) and 4(e), it may be difficult to distinguish between the side portion and the corner by simply considering the curved portion as the corner. In this case, the corner of the adhesive pattern S refers to the portion of the periphery of the adhesive pattern S where the radius of curvature is the minimum value or the bent portion.

[0092] Specifically, in the example of Fig. 4(d), the third side portion Se3 is curved. In this case, the second corner portion Sc2 of the adhesive pattern S-4 is a location where the radius of curvature of the periphery of the adhesive pattern S-4 is a minimum value at the end portion of the adhesive pattern S-4 far from the second side E2 in the direction D1 of the first side E1 of the sheet P. The third corner portion Sc3 of the adhesive pattern S-4 is a location where the radius of curvature of the periphery of the adhesive pattern S-4 is a minimum value at the end portion of the adhesive pattern S-4 far from the first side E1 in the direction D2 of the second side E2 of the sheet P.

[0093] In the example of FIG. 4(e), the first side portion Se1, the second side portion Se2, and the third side portion Se3 are all curved. In this case, the first corner portion Sc1 of the adhesive pattern S-5 is a portion where the radius of curvature of the periphery of the adhesive pattern S-5 is a minimum value at the end of the adhesive pattern S that is closer to the corner C1 of the sheet P in the diagonal direction D3 of the sheet P. The second corner portion Sc2 of the adhesive pattern S-5 is a portion where the radius of curvature of the periphery of the adhesive pattern S-5 is a minimum value at the end of the adhesive pattern S that is farther from the second side E2 in the direction D1 of the first side E1 of the sheet P. The third corner portion Sc3 of the adhesive pattern S-5 is a portion where the radius of curvature of the periphery of the adhesive pattern S is a minimum value at the end of the adhesive pattern S-5 that is farther from the first side E1 in the direction D2 of the second side E2 of the sheet P.

[0094] The specific shapes of the adhesive patterns S in Fig. 4(a) to Fig. 4(e) will be described. The adhesive pattern S-1 in Fig. 4(a) is a substantially right-angled triangle with the third side portion Se3 as the hypotenuse. That is, the first side portion Se1, the second side portion Se2, and the third side portion Se3 are each linear, the first side portion Se1 and the second side portion Se2 are perpendicular to each other at the first corner portion Sc2, and a right-angled triangle with the extension line of the third side portion Se3 as the hypotenuse is formed. The second corner portion Sc2 and the third corner portion Sc3 are curved shapes in which the acute angles of the right-angled triangle are rounded into an arc shape. This shape can reduce unintentional peeling of the sheet. In addition, it can make it easier to peel the sheet from the side of the corner C1 of the product G1.

[0095] The adhesive pattern S-2 in FIG. 4(b) has a right-angled triangular outer diameter similar to that of the adhesive pattern S-1 in FIG. 4(a). However, in the adhesive pattern S-2, the application area of ​​the powder adhesive Tn is divided into an area NB (first area) including the first corner Sc1 and an area NA (second area) including the second corner Sc2 and the third corner Sc3. A gap may be set between the area NA and the area NB, or the two may be in contact with each other. As will be described in Example 3 later, the application amount of the powder adhesive Tn in the area NA (weight of the powder adhesive Tn per unit area, so-called toner application amount) may be greater than the application amount of the powder adhesive Tn in the area NB. In this case, the effect of reducing unintentional peeling of the sheet can be enhanced while the effect of making it easier to peel the sheet from the side of the corner C1 of the deliverable G1 can be enhanced.

[0096] The adhesive pattern S-3 in Fig. 4(c) has a right-angled triangular outer diameter similar to the adhesive pattern S-1 in Fig. 4(a). However, in the adhesive pattern S-3, the application area of ​​the powder adhesive Tn is divided into an area including the first corner Sc1 and the third corner Sc3, and an area including the second corner Sc2. Even with this pattern, it is possible to reduce unintentional peeling of the sheet.

[0097] In the adhesive pattern S-4 of FIG. 4(d), the third side portion Se3 is formed in a curved shape. The first side portion Se1 and the second side portion Se2 are linear and intersect at the first corner portion Sc1. The third side portion Se3 is preferably formed in a curved shape that is convexly curved toward the center side (face center side) of the sheet P in the diagonal direction D3. The third side portion Se3 may be in the shape of a circular arc or part of an ellipse. This pattern can also reduce unintended peeling of the sheet.

[0098] In the adhesive pattern S-4 of Fig. 4(e), the first side portion Se1, the second side portion Se2, and the third side portion Se3 are each curved, and the overall shape is approximately triangular. Each side portion may be curved convexly toward the outside of the approximately triangular shape. This pattern can also reduce unintentional peeling of the sheet.

[0099] The above adhesive patterns S-1 to S-5 are merely examples, and the adhesive pattern S may have shapes different from those shown in FIGS. 4(a) to (e).

[0100] (Adhesive strength measured using a Tensilon tester) In order to confirm that the adhesive pattern S of this embodiment can reduce unintended peeling of the sheet, the adhesive strength was measured by the following method. First, an adhesive pattern was formed on one of two test sheets using a powder adhesive Tn, and the sheets were thermocompressed together. The thermocompressed sheet was cut to an overall length of 100 mm and an overall width of 20 mm to obtain a sample piece. The adhesive region of the sample piece was made to include the corner of the adhesive pattern S, such as the second corner Sc2 of the adhesive pattern S in FIG. 4(a). In addition, a plurality of sample pieces with different curvature radii R of the corners were prepared. The adhesive strength of the sample piece was measured using a Tensilon tester (manufactured by A&D Co., Ltd., RTG-1225). The gradient of the initial rise part was confirmed in the tension-strain curve obtained at room temperature (23°C) and a test speed of 50 mm / min. That is, the adhesive strength between sheets in this embodiment is the magnitude of the slope of the tangent to the curve just before the end of the adhesive pattern S starts to peel off in the above tension-strain curve that represents the magnitude of the load when the sheets are pulled to peel off. The initial rise portion can be determined, for example, based on the amount of strain (the distance the sample piece is pulled) when the end of the adhesive pattern S starts to peel off by visual inspection. For example, in the measurement results shown in Figure 12, the range from 0 mm to 5 mm can be determined as the initial rise portion.

[0101] The graph in Figure 12 shows the results of measuring the adhesive strength of sample pieces with the corner curvature radius R (mm) set to three levels: R=0 (not rounded), R=1, and R=2. The graphs for R=1 and R=0 show that the adhesive strength of the sheet pieces is increased by rounding the corners of the adhesive pattern S. Additionally, the graphs for R=2 and R=1 show that the adhesive strength of the sheet pieces is higher when the corner curvature radius is 2 mm than when it is 1 mm.

[0102] That is, when a substantially triangular adhesive pattern S is formed at the corner of the sheet P for corner binding, the minimum value R2 (mm) of the curvature radius of the second corner Sc2 and the minimum value R3 (mm) of the curvature radius of the third corner Sc3 of the adhesive pattern S are preferably 1 mm or more. This makes it possible to more reliably reduce unintended peeling of the sheet. It is more preferable that the minimum value R2 (mm) of the curvature radius of the second corner Sc2 and the minimum value R3 (mm) of the curvature radius of the third corner Sc3 are 2 mm or more. This makes it possible to more reliably reduce unintended peeling of the sheet.

[0103] On the other hand, in the graph of Fig. 12, the adhesive strength is weakest when R = 0. This shows that by making the first corner Sc1 a sharp corner as in Fig. 4(a) to (d), it is possible to easily peel the sheets from each other by turning them over from the corner C1 side.

[0104] Example 2 Example 2 will be described with reference to Figures 5 to 7. In the following, unless otherwise specified, elements having the same reference symbols as Example 1 will have substantially the same configurations and functions as those described in Example 1, and differences from Example 1 will be mainly described.

[0105] As shown in Figure 5, the image forming apparatus 1 of this embodiment includes an apparatus main body 10, a post-processing device 301 arranged to the side of the apparatus main body 10, and a relay conveying unit 200 connected to the apparatus main body 10 and the post-processing device 301.

[0106] The post-processing device 301 has an inlet roller pair 21, a conveying roller pair 22, a reversing roller pair 24, an inner discharge roller pair 26, a conveying roller pair 28, a kick-out roller pair 29, an intermediate stacking section 52 (processing tray), and a thermocompression bonding unit 51. The post-processing device 301 also has a bundle discharge guide 59, a bundle discharge roller pair 58, an upper discharge tray 25, and a lower discharge tray 57.

[0107] The image forming apparatus 1 of this embodiment, like the first embodiment, can form images on sheets P one by one in succession, and then create a product (adhesive print) by adhering a plurality of sheets P together. The sheet P on which the toner image has been formed in the apparatus main body 10 is received by an inlet roller pair 21 of the post-processing device 301 via a conveying roller pair 201, 202 of the relay conveying unit 200. The conveying roller pair 22 conveys the sheet P received from the inlet roller pair 21 to a reversing roller pair 24. The conveying roller pair 22 accelerates the conveying speed of the sheet P based on the timing when the inlet sensor 27 detects the rear end of the sheet P.

[0108] When an adhesive print is not to be produced, no adhesive pattern is formed on the sheet P in the device body 10. In this case, when the rear end of the sheet P reaches a predetermined position between the pair of conveying rollers 22 and the pair of reversing rollers 24, the conveying speed of the sheet P is decelerated, and the pair of reversing rollers 24 discharges the sheet P onto the upper discharge tray 25.

[0109] When creating an adhesive print, a visible image and an adhesive pattern are formed on the sheet P in the device body 10. In this case, when the rear end of the sheet P passes through the backflow prevention guide 23 between the conveying roller pair 22 and the reversing roller pair 24, the rotation of the reversing roller pair 24 is temporarily stopped, and the reversing roller pair 24 is driven to rotate in the reverse direction. This causes the sheet P to switch back and be conveyed by the inner discharge roller pair 26, the conveying roller pair 28, and the kick-out roller pair 29. The kick-out roller pair 29 then stacks the sheet P on the intermediate stacking section 43. The sheet P stacked on the intermediate stacking section 43 is aligned in the width direction (horizontal direction) and the conveying direction (vertical direction) by the width direction alignment section and the conveying direction alignment section.

[0110] When a predetermined number of sheets P are stacked and aligned on the intermediate stacker 43, a thermocompression bonding operation is performed by the thermocompression bonding unit 51. The thermocompression bonding unit 51 heats and presses the adhesive pattern of the sheets P, thereby creating a sheet bundle in which the sheets are bonded together via a layer of powder adhesive Tn (adhesive layer).

[0111] After the thermocompression bonding process by the thermocompression bonding unit 51 is completed, the bundle discharge guide 59 moves from the standby position toward the discharge port 45 and pushes the sheet bundle out of the intermediate stacking section 43. The bundle discharge roller pair 58 arranged at the discharge port 45 holds the sheet bundle and discharges it outside the post-processing device 301, and stacks it on the lower discharge tray 57.

[0112] The structure of the thermocompression bonding unit 51 can be the same as that of the first embodiment (FIG. 2). However, in this embodiment, long-side binding or short-side binding can be performed to bind the sheet stack along one side of the sheets P. In particular, in this embodiment, A4-sized sheets P can be transported in a long-side feed (the long side is parallel to the sheet transport direction) and long-side binding can be performed to bind the sheet stack along the long side of each sheet P. In accordance with this, the pressure range of the heating plate 502 is set to, for example, 4.0 mm in the X direction (horizontal direction) and 300 mm in the Y direction (vertical direction).

[0113] (Adhesive Pattern) FIG. 6 is a schematic diagram showing the visible images J1, J2, and adhesive pattern U when creating a product G2, which is an adhesive print product formed by binding two sheets P1 and P2 on their long edges. The first sheet P1 has a front side P1-1 that serves as the cover of the product G2, and a back side P1-2. The second sheet P2 has a front side P2-1 that faces the back side P1-2 of the first sheet, and a back side P2-2 that serves as the back cover of the product G2. In this example, the visible images J1 and J2 are formed on the front sides P1-1 and P2-2 of the first and second sheets, respectively, and the back sides P1-2 and P2-2 are left blank. The visible images J1 and J2 are formed using at least one of printing toners Ty, Tm, and Tc.

[0114] The adhesive pattern U shown by the dotted area in the figure is formed in a predetermined area on the surface P2-1 of the second sheet P2 using a powder adhesive Tn. In this embodiment, the adhesive pattern U is formed along one long side (first side E1) of the sheet P2. The shape of the adhesive pattern U is stored in advance in a memory unit provided in the control unit of the image forming apparatus 1. It may be possible to allow the user to select or newly set the shape of the adhesive pattern U.

[0115] (Details of adhesive pattern) The adhesive pattern U will be described in detail. The powder adhesive Tn is applied in one of the adhesive patterns U-1, U-2, U-3, U-4, and U-5 having shapes as shown in Figures 7(a) to (e). Hereinafter, the adhesive patterns U-1, U-2, U-3, U-4, and U-5 illustrated in Figures 7(a) to (e) will be collectively referred to as each adhesive pattern U.

[0116] First, a description will be given of a shape common to each adhesive pattern U. The adhesive pattern U has an outer shape of a substantially rectangular shape including four sides (edges) and four corners. Although Fig. 6 shows an example in which one adhesive pattern U is formed along substantially the entire length of the first edge E1 of the sheet P, a plurality of adhesive patterns U may be formed side by side along the first edge E1.

[0117] The adhesive pattern U includes a first side portion Ue1, a second side portion Ue2, a third side portion Ue3, and a fourth side portion Ue4. The adhesive pattern U also includes a first corner portion Uc1 connecting the first side portion Ue1 and the second side portion Ue2, and a second corner portion Uc2 connecting the first side portion Ue1 and the fourth side portion Ue4. The adhesive pattern U also includes a third corner portion Uc3 connecting the third side portion Ue3 and the second side portion Ue2, and a fourth corner portion Uc4 connecting the third side portion Ue3 and the fourth side portion Ue4.

[0118] The adhesive pattern U has an elongated shape extending along the first side E1 of the sheet P. The first side portion Ue1 extends along the first side E1 (FIG. 6) of the sheet P. The third side portion Ue3 is located closer to the center of the sheet P than the first side portion Ue1 in the direction D2 of the second side E2.

[0119] In each bonding pattern U, the third corner Uc3 is curved such that the minimum value of the radius of curvature of the third corner Uc3 is greater than the minimum value of the radius of curvature of the first corner Uc1 and the minimum value of the radius of curvature of the second corner Uc2. Also, the fourth corner Uc4 is curved such that the minimum value of the radius of curvature of the fourth corner Uc4 is greater than the minimum value of the radius of curvature of the first corner Uc1 and the minimum value of the radius of curvature of the second corner Uc2. Let the minimum value of the radius of curvature of the first corner Uc1 be r1 (mm), the minimum value of the radius of curvature of the second corner Uc2 be r2 (mm), the minimum value of the radius of curvature of the third corner Uc3 be r3 (mm), and the minimum value of the radius of curvature of the fourth corner Uc4 be r4 (mm). In this case, r1 < r3, r2 < r3, r1 < r4, and r2 < r4. In other words, in each bonding pattern U, the third corner Uc3 and the fourth corner Uc4, which are closer to the central region of the sheet P where the visible image is mainly formed, are in a gently curved (rounded) shape compared to the first corner Uc1 and the second corner Uc2 closer to the side edges of the sheet P.

[0120] When the product G2 bound along the first side E1 is created as shown in FIG. 6, it can be assumed that the user turns the sheet P1 from the lower right to the upper left (or from the upper right to the lower left). In this case, in the third corner Uc3 and the fourth corner Uc4 of the bonding pattern U, a stress (tensile force in the thickness direction of the sheet) in the direction in which the sheets P1 and P2 are peeled off is generated. If the third corner Uc3 and the fourth corner Uc4 were sharp corners, stress would tend to concentrate at the corners, providing a trigger for the bonding pattern U to peel off.

[0121] In this embodiment, by rounding the third corner Uc3 and the fourth corner Uc4, stress concentration can be avoided. Therefore, the possibility of the sheets P1 and P2 peeling off when the user turns the sheet of the product G2 in the normal usage method can be reduced. That is, according to this embodiment, unintended peeling of the sheet can be reduced.

[0122] On the other hand, the first corner Uc1 and the second corner Uc2 have a smaller minimum radius of curvature than the third corner Uc3 and the fourth corner Uc4, and therefore stress is likely to concentrate thereon, which is likely to trigger peeling of the adhesive pattern U. This has the advantage that when a user wants to peel off the sheets P1 and P2, the sheets P1 and P2 can be easily peeled off by flipping the sheet P1 from any of the corners on the first side E1 side of the deliverable G2.

[0123] Similarly to Example 1, the minimum value of the curvature radius of the third corner Uc3 (r3) and the minimum value of the curvature radius of the fourth corner Uc4 (r4) are preferably 1 mm or more, more preferably 2 mm or more, which can more reliably reduce unintended peeling of the sheet.

[0124] On the other hand, the first corner Uc1 and the second corner Uc2 may be corners where adjacent sides of the adhesive pattern U intersect at one point. This makes it easier to peel the sheet from either corner on the first side E1 side of the result G1.

[0125] As shown in FIG. 7(a), the adhesive pattern U-1 may be rectangular in shape with the third corner Uc3 and the fourth corner Uc4 rounded in an arc shape and the first corner Uc1 and the second corner Uc2 at a right angle. As shown in FIG. 7(b)(c), the adhesive patterns U-2 and U-3 may be rectangular in shape similar to FIG. 7(a), and the application area of ​​the powder adhesive Tn may be divided into two or more areas. The application amount of the powder adhesive Tn may be different between these areas as described in Example 3 below. In that case, it is preferable that the application amount of the powder adhesive Tn in the second area including the third corner Uc3 and the fourth corner Uc4 is greater than the application amount of the powder adhesive Tn in the first area including the first corner Uc1 and the second corner Uc2. As shown in FIG. 7(d), the adhesive pattern U-1 may be curved so that the third side Ue3 protrudes toward the center in the direction D2 of the second side E2. As shown in FIG. 7(e), the adhesive pattern U-1 may be curved with four curved sides.

[0126] Each adhesive pattern U in this embodiment may be formed on each of the sheet surfaces that face each other when superimposed, as will be described in Example 4 below.

[0127] Example 3 Example 3 will be described with reference to Figures 8(a) to 8(i). In the following, unless otherwise specified, elements having the same reference symbols as Example 1 will have substantially the same configurations and functions as those described in Example 1, and differences from Example 1 will be mainly described.

[0128] 8(a) to 8(i), in this embodiment, a part of the adhesive pattern formed on the sheet P is provided with an area where the amount of powder adhesive Tn applied is larger than other areas. The shape of each adhesive pattern S and the amount of powder adhesive Tn applied for each area are stored in advance in a memory unit provided in the control unit of the image forming apparatus 1. It is also possible to allow the user to select or newly set the shape of the adhesive pattern S and the amount of powder adhesive Tn applied for each area.

[0129] 8(a)-(i) show examples of adhesive patterns S for performing corner binding similarly to Example 1. Adhesive patterns S-11, S-12, S-13, S-14, S-17, S-18, and S-19 shown in Fig. 8(a)-(i) have a substantially triangular shape having a first corner Sc1, a second corner Sc2, and a third corner Sc3. More precisely, adhesive patterns S-15 and S-16 shown in Fig. 8(e) and (f) are formed in a trapezoid shape having a fourth corner Sc4 in addition to the first corner Sc1, the second corner Sc2, and the third corner Sc3.

[0130] In these examples, the amount of powder adhesive Tn applied in a region NA (second region) including the second corner Sc2 and the third corner Sc3 of each adhesive pattern S is greater than the amount of powder adhesive Tn applied in a region NB (first region) including the first corner Sc1. In other words, each adhesive pattern S has a first region (NB) including the first corner Sc1, and a second region (NA) including the second corner Sc2 and the third corner Sc3, in which the amount of powder adhesive applied is greater than the amount of powder adhesive applied in the first region.

[0131] This increases the adhesive strength of the second corner Sc2 and the third corner Sc3, where stress is likely to concentrate when a user turns the pages of a corner-bound deliverable, and reduces the possibility of the sheet unintentionally peeling off from the second corner Sc2 or the third corner Sc3.

[0132] Furthermore, since the amount of powder adhesive Tn applied in the first region (NB) is less than the amount of powder adhesive Tn applied in the second region (NA), the amount of powder adhesive Tn consumed can be reduced while reducing the possibility of the sheet being unintentionally peeled off.

[0133] In addition, since the amount of powder adhesive Tn applied to the first corner Sc1 (and the fourth corner Sc4) is small, when the user wants to peel off sheets P1 and P2, there is an advantage that the sheets P1 and P2 can be easily peeled off by flipping sheet P1 from corner C1 of the resultant product G1.

[0134] As shown in Fig. 8(a), the adhesive pattern S-11 may have a right-angled triangular shape. As shown in Fig. 8(b) and (c), the adhesive patterns S-12 and S13 may have a right-angled triangular shape similar to that of Fig. 8(a), and the application area of ​​the powder adhesive Tn may be divided into two or more areas.

[0135] 8(d) and (h), the adhesive patterns S-14 and S-18 may be substantially triangular in shape with rounded second corners Sc2 and / or third corners Sc3. In this case, the synergistic effect of rounding the corners as in Example 1 and increasing the amount of powder adhesive Tn applied can further reduce the possibility of the sheet being unintentionally peeled off starting from the second corner Sc2 or the third corner Sc3.

[0136] As shown in FIGS. 8(a) to (i), the shape of the area (NA) where the amount of powder adhesive Tn applied is large is not particularly limited, and may be, for example, a triangular, circular, elliptical, rectangular, or trapezoidal shape.

[0137] 8(i), the region (NA) where the amount of powder adhesive Tn in the adhesive pattern S-19 is large may be one continuous region along the third side portion Se3 from the second corner portion Sc2 to the third corner portion Sc3. In this case, the adhesive strength of the third side portion Se3 as a whole is increased, which further reduces the possibility of sheets being peeled off unintentionally when a user turns over the corner-bound deliverable.

[0138] Example 4 A fourth embodiment will be described below. In the following, unless otherwise specified, elements having the same reference symbols as those in the first embodiment have substantially the same configurations and functions as those in the first embodiment, and the following mainly describes the parts that are different from the first embodiment.

[0139] 9 is a schematic diagram of the image forming apparatus 1 according to this embodiment. In this embodiment, when the image forming apparatus 1 creates an adhesive print, it can form a visible image and an adhesive pattern on both sides of the sheet P. Note that, although the following description will be given taking a corner-bound product as an example, it is also possible to create a product bound along one side of the sheet as in the second embodiment.

[0140] As shown in Fig. 9, the image forming apparatus 1 includes a switching guide 33', a pair of reversing rollers 35, and a double-sided conveying path 36. The sheet P that has passed through the fixing device 6 is guided to one of two conveying paths by the switching guide 33', which is a flap-shaped guide member. The first conveying path is a path (discharge path) toward the pair of discharge rollers 34 or the post-processing device 300. The second conveying path is a path (reversing path) toward the pair of reversing rollers 35.

[0141] A user can select, as setting information for an image forming job, a single-sided printing mode in which an image is formed on one side of a sheet P, or a double-sided printing mode in which an image is formed on both sides of a sheet P. When the single-sided printing mode is specified, the sheet P that has passed through the fixing device 6 is guided to a discharge path by a switching guide 33'. When the double-sided printing mode is specified, the sheet P that has passed through the fixing device 6 with a toner image formed on the first side is guided to a reversing path by a switching guide 33'. Thereafter, the sheet P is switched back by a pair of reversing rollers 35, and is conveyed again to the image forming unit 1e via a double-sided conveying path 36. Then, the sheet P that has a toner image formed on the second side opposite to the first side by passing through the transfer nip 5n and the fixing nip 6n is guided to a discharge path by a switching guide 33'. The conveying operation of the sheet P after being guided to the discharge path is the same as that of the first embodiment.

[0142] 10 is a schematic diagram showing visible images K1-K4 and adhesive patterns V1 and V2 when creating a product G3, which is an adhesive print product in which two sheets P1 and P2 are corner-bound. The first sheet P1 has a front side P1-1 that serves as the cover of the product G3, and a back side P1-2. The second sheet P2 has a front side P2-1 that faces the back side P1-2 of the first sheet, and a back side P2-2 that serves as the back cover of the product G3. In this example, visible images K1 and K2 are formed on the front side P1-1 and back side P1-2 of the first sheet, respectively, and visible images K3 and K4 are formed on the front side P2-1 and back side P2-2 of the second sheet, respectively.

[0143] The adhesive patterns V1 and V2 are formed on the back surface P1-2 (first sheet surface) of the first sheet and the front surface P2-1 (second sheet surface) of the second sheet, which are the sheet surfaces that face each other when the sheets P1 and P2 are superimposed. The adhesive patterns V1 and V2 are formed at positions that face each other when the sheets P1 and P2 are superimposed. The visible images K1 to K4 are formed using at least one of the printing toners Ty, Tm, and Tc. The shapes of the adhesive patterns V1 and V2 may be the same as those described in the first embodiment. The shapes of the adhesive patterns V1 and V2 are stored in advance in a storage unit provided in the control unit of the image forming apparatus 1. The shapes of the adhesive patterns V1 and V2 may be selected or newly set by the user.

[0144] Generally, when creating adhesive printed matter, forming an adhesive pattern on each of the opposing sheet surfaces when the sheets are superimposed on top of each other can increase the adhesive strength compared to forming an adhesive pattern on only one of the sheet surfaces.

[0145] However, if one adhesive pattern is misaligned with the other adhesive pattern when the sheets are overlapped, the sheets may become more likely to peel off starting from the misaligned location. To explain in more detail, as shown on the left side of Fig. 11, the third corners Sc3 of the adhesive patterns V1 and V2 may be misaligned (misaligned location Q1), or the second corners Sc2 of the adhesive patterns V1 and V2 may be misaligned (misaligned location Q2). The misaligned location Q1 occurs, for example, due to a misalignment of the adhesive patterns V1 and V2 in the sheet conveying direction (vertical direction). The misaligned location Q2 occurs, for example, due to a misalignment of the margin amount in the width direction (horizontal direction).

[0146] In this embodiment, as shown on the right side of Fig. 11, each of the adhesive patterns V1 and V2 has a rounded second corner Sc2 and a rounded third corner Sc3, similar to the embodiment 1. The second corner Sc2 and the third corner Sc3 are gently curved. This reduces the possibility that the sheet will peel off from the misaligned point, even if the second corners or the third corners Sc3 of the adhesive patterns V1 and V2 are misaligned.

[0147] That is, in the example shown in the upper left of Fig. 11, (a) the third corner Sc3 of the adhesive pattern V1, (b) the third corner Sc3 of the adhesive pattern V2, and (c) the area where the third corners Sc3 of the adhesive patterns V1 and V2 overlap at the misaligned portion Q1 are all sharp corners. Therefore, for example, when a user turns over the sheet P1 of the product G3 in Fig. 10 from right to left, stress may be concentrated in the order of (a) to (c) at the corners, causing the sheet to peel off.

[0148] In contrast, in the example shown in the upper right of FIG. 11, (a) the third corner Sc3 of the adhesive pattern V1 and (b) the third corner Sc3 of the adhesive pattern V2 are both gently curved. Furthermore, in the example shown in the upper right of FIG. 11, (c) the area Q3 where the third corners Sc3 of the adhesive patterns V1 and V2 overlap is not sharp, but has a certain width in the vertical direction in the figure. Therefore, for example, when a user turns over the sheet P1 of the product G3 in FIG. 10 from the right side to the left side, not only the adhesive strength of the corners (a) and (b) is high, but also the adhesive strength of the area Q3 (c) is high, so the sheet is unlikely to peel off. Therefore, it is possible to more reliably reduce unintended peeling of the sheet.

[0149] Similarly to Example 1, the minimum value of the radius of curvature (R2) of the second corner Sc2 and the minimum value of the radius of curvature (R3) of the third corner Sc3 are preferably 1 mm or more, more preferably 2 mm or more, which can more reliably reduce unintended peeling of the sheet.

[0150] (Other embodiments) In the above embodiments, the case where a product consisting of two sheets P1 and P2 is created has been exemplified, but the present technology can also be applied to the case where a product (adhesive printed product) including three or more sheets P is created. In that case, the adhesive pattern S may be formed on at least one of the sheet surfaces that face each other when overlapped in the intermediate stacking section 43. The post-processing device 300 may perform the thermocompression bonding operation of the thermocompression bonding unit 51 after all the sheets P included in one part of the product are stacked on the intermediate stacking section 43 and aligned. The post-processing device 300 may also repeat the thermocompression bonding operation of the thermocompression bonding unit 51 once every time a preset number of sheets P are stacked on the intermediate stacking section 43 and aligned.

[0151] Summary of the Disclosure The present disclosure includes at least the following configurations.

[0152] (Configuration 1) an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where the plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion; the first corner portion is located at an end portion of the adhesive pattern that is close to the corner in a diagonal direction of the sheet that passes through a corner where a first side and a second side of the sheet intersect, the second corner portion is located at an end portion of the adhesive pattern farther from the second side in a direction of the first side of the sheet, the third corner portion is located at an end portion of the adhesive pattern that is farther from the first side in a direction of the second side of the sheet, The second corner portion and the third corner portion are curved such that a minimum value of a radius of curvature of the second corner portion and a minimum value of a radius of curvature of the third corner portion are greater than a minimum value of a radius of curvature of the first corner portion. 1. An image forming apparatus comprising:

[0153] (Configuration 2) The minimum value of the radius of curvature of the second corner portion and the minimum value of the radius of curvature of the third corner portion are both 1 mm or more. 2. The image forming apparatus according to claim 1,

[0154] (Configuration 3) The minimum value of the radius of curvature of the second corner portion and the minimum value of the radius of curvature of the third corner portion are both 2 mm or more. 2. The image forming apparatus according to claim 1,

[0155] (Configuration 4) The adhesive pattern is formed on each of a first sheet surface and a second sheet surface that face each other when the multiple sheets are stacked. 4. The image forming apparatus according to any one of configurations 1 to 3.

[0156] (Configuration 5) the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 5. The image forming apparatus according to any one of configurations 1 to 4.

[0157] (Configuration 6) An image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where a plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion; the first corner portion is located at an end portion of the adhesive pattern that is close to the corner in a diagonal direction of the sheet that passes through a corner where a first side and a second side of the sheet intersect, the second corner portion is located at an end portion of the adhesive pattern farther from the second side in a direction of the first side of the sheet, the third corner portion is located at an end portion of the adhesive pattern that is farther from the first side in a direction of the second side of the sheet, the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 1. An image forming apparatus comprising:

[0158] (Configuration 7) The second region is continuous along the third side portion from the second corner portion to the third corner portion. 7. The image forming apparatus according to configuration 5 or 6.

[0159] (Configuration 8) the first side portion, the second side portion, and the third side portion are each linear, and are arranged so that the first side portion and the second side portion intersect at right angles at the first corner portion and form a right-angled triangle with an extension line of the third side portion as a hypotenuse; The second corner and the third corner are curves in which the acute angles of the right triangle are rounded into an arc shape. 8. The image forming apparatus according to any one of configurations 1 to 7.

[0160] (Configuration 9) an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where a plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a fourth side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the first side portion and the fourth side portion, a third corner portion connecting the third side portion and the second side portion, and a fourth corner portion connecting the third side portion and the fourth side portion; the adhesive pattern has an elongated shape extending along a first side of the sheet, the first side portion extends along the first edge of the sheet; the third side portion is located closer to the center of the sheet than the first side portion in a direction of a second side of the sheet that intersects with the first side, The third corner portion and the fourth corner portion are curved such that the minimum value of the radius of curvature of the third corner portion is greater than the minimum value of the radius of curvature of the first corner portion and the minimum value of the radius of curvature of the second corner portion, and the minimum value of the radius of curvature of the fourth corner portion is greater than the minimum value of the radius of curvature of the first corner portion and the minimum value of the radius of curvature of the second corner portion. 1. An image forming apparatus comprising:

[0161] (Configuration 10) The minimum value of the radius of curvature of the third corner portion and the minimum value of the radius of curvature of the fourth corner portion are both 1 mm or more. 10. The image forming apparatus according to claim 9,

[0162] (Configuration 11) The minimum value of the radius of curvature of the third corner portion and the minimum value of the radius of curvature of the fourth corner portion are both 2 mm or more. 10. The image forming apparatus according to claim 9,

[0163] (Configuration 12) The adhesive pattern is formed on each of a first sheet surface and a second sheet surface that face each other when the multiple sheets are stacked. 12. The image forming apparatus according to any one of configurations 9 to 11.

[0164] (Configuration 13) the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 13. The image forming apparatus according to any one of configurations 9 to 12.

[0165] (Configuration 14) The first side portion, the second side portion, the third side portion, and the fourth side portion are each linear, the first side portion and the second side portion are perpendicular to each other at the first corner portion, the first side portion and the fourth side portion are perpendicular to each other at the second corner portion; The third corner portion and the fourth corner portion are arc-shaped curves. 14. The image forming apparatus according to any one of configurations 9 to 13. [Explanation of symbols]

[0166] 1e...image forming means (image forming unit) / 51...adhesive means (thermocompression unit) / S, U, V...adhesive pattern / Sc1, Uc1...first corner / Sc2, Uc2...second corner / Sc3, Uc3...third corner / Uc4...fourth corner / Se1, Ue1...first side / Se2, Ue2...second side / Se3, Ue3...third side / Ue4...fourth side

Claims

1. an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where the plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion; the first corner portion is located at an end portion of the adhesive pattern that is close to the corner in a diagonal direction of the sheet that passes through a corner where a first side and a second side of the sheet intersect, the second corner portion is located at an end portion of the adhesive pattern that is farther from the second side in a direction of the first side of the sheet, the third corner portion is located at an end portion of the adhesive pattern that is farther from the first side in a direction of the second side of the sheet, The second corner portion and the third corner portion are curved such that a minimum value of a radius of curvature of the second corner portion and a minimum value of a radius of curvature of the third corner portion are greater than a minimum value of a radius of curvature of the first corner portion.

1. An image forming apparatus comprising:

2. The minimum value of the radius of curvature of the second corner portion and the minimum value of the radius of curvature of the third corner portion are both 1 mm or more.

2. The image forming apparatus according to claim 1,

3. The minimum value of the radius of curvature of the second corner portion and the minimum value of the radius of curvature of the third corner portion are both 2 mm or more.

2. The image forming apparatus according to claim 1,

4. The adhesive pattern is formed on each of a first sheet surface and a second sheet surface that face each other when the multiple sheets are stacked.

2. The image forming apparatus according to claim 1,

5. the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 2. The image forming apparatus according to claim 1,

6. an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where the plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the second side portion and the third side portion, and a third corner portion connecting the third side portion and the first side portion; the first corner portion is located at an end portion of the adhesive pattern that is close to the corner in a diagonal direction of the sheet that passes through a corner where a first side and a second side of the sheet intersect, the second corner portion is located at an end portion of the adhesive pattern that is farther from the second side in a direction of the first side of the sheet, the third corner portion is located at an end portion of the adhesive pattern that is farther from the first side in a direction of the second side of the sheet, the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 1. An image forming apparatus comprising:

7. The second region is continuous along the third side portion from the second corner portion to the third corner portion.

7. The image forming apparatus according to claim 5, wherein the image forming apparatus is a multi-color image forming apparatus.

8. the first side portion, the second side portion, and the third side portion are each linear, and are arranged so that the first side portion and the second side portion intersect at right angles at the first corner portion and form a right-angled triangle with an extension line of the third side portion as a hypotenuse; The second corner and the third corner are curves in which acute angles of the right triangle are rounded into an arc shape.

7. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-color image forming apparatus.

9. an image forming means for forming a visible image and an adhesive pattern formed with a powder adhesive for adhering the sheets to each other on the sheet; an adhesive means for heating the adhesive pattern in a state where the plurality of sheets are stacked together to adhere the plurality of sheets; An image forming apparatus comprising: the adhesive pattern includes a first side portion, a second side portion, a third side portion, a fourth side portion, a first corner portion connecting the first side portion and the second side portion, a second corner portion connecting the first side portion and the fourth side portion, a third corner portion connecting the third side portion and the second side portion, and a fourth corner portion connecting the third side portion and the fourth side portion; The adhesive pattern has an elongated shape extending along a first side of the sheet, the first side portion extends along the first edge of the sheet; the third side portion is located closer to a center of the sheet than the first side portion in a direction of a second side of the sheet that intersects with the first side, the third corner portion and the fourth corner portion are curved such that a minimum value of a radius of curvature of the third corner portion is greater than a minimum value of a radius of curvature of the first corner portion and a minimum value of a radius of curvature of the second corner portion, and a minimum value of a radius of curvature of the fourth corner portion is greater than a minimum value of a radius of curvature of the first corner portion and a minimum value of a radius of curvature of the second corner portion.

1. An image forming apparatus comprising:

10. The minimum value of the radius of curvature of the third corner portion and the minimum value of the radius of curvature of the fourth corner portion are both 1 mm or more.

10. The image forming apparatus according to claim 9,

11. The minimum value of the radius of curvature of the third corner portion and the minimum value of the radius of curvature of the fourth corner portion are both 2 mm or more.

10. The image forming apparatus according to claim 9,

12. The adhesive pattern is formed on each of a first sheet surface and a second sheet surface that face each other when the multiple sheets are stacked.

10. The image forming apparatus according to claim 9,

13. the adhesive pattern has a first region including the first corner portion, and a second region including the second corner portion and the third corner portion, the second region having a larger amount of powder adhesive applied thereto than the amount of powder adhesive applied in the first region; 10. The image forming apparatus according to claim 9,

14. The first side portion, the second side portion, the third side portion, and the fourth side portion are each linear, the first side portion and the second side portion are perpendicular to each other at the first corner portion; the first side portion and the fourth side portion are perpendicular to each other at the second corner portion; The third corner portion and the fourth corner portion are arc-shaped curves.

10. The image forming apparatus according to claim 9,

Images