Image forming device

Abstract

To provide an image forming apparatus that can improve laminate processing.SOLUTION: An image forming apparatus comprises a fixing device 80 that fixes an image onto a sheet through application of heat and pressure, and includes an image forming mode and a laminate mode, and the sheet conveyance speed of the fixing device 80 in the laminate mode is slower than the sheet conveyance speed in the image forming mode. The degree of the slow speed is preferably 50% or less. The degree is more preferably 30% or less. It is preferable to provide cooling pressure rollers 91, 92 on the downstream side in a sheet conveyance direction of the fixing device.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Conventionally, there is known an image forming apparatus equipped with a fixing device that fixes an image on a sheet by applying heat and pressure. For example, Patent Document 1 discloses such an image forming apparatus that has a print mode (image forming mode) and a lamination mode, and in the lamination mode, a lamination process is performed by applying heat and pressure to the fixing device. Summary of the Invention [Problem to be solved by the invention]

[0003] However, there is still room for improvement in the lamination process of conventional image forming apparatuses. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, the present invention provides an image forming apparatus having a fixing device that fixes an image on a sheet by applying heat and pressure, the image forming apparatus having an image forming mode and a lamination mode, The above The sheet transport speed in the fixing device is slower than the sheet transport speed in the image forming mode. In addition, the conveying speed is slower than the conveying speed of the sheet conveying member during at least a part of the period until the leading edge of the sheet reaches the fixing device and the period after the trailing edge of the sheet has passed through the fixing device in the lamination mode, and for at least a part of the sheet conveying members on the upstream side and downstream side of the fixing device in the sheet conveying direction, a drive transmission on / off switching means is provided in a drive transmission system from a drive source other than the drive source of the fixing device, and for the sheet conveying member at a position facing the sheet being conveyed by the fixing device, the drive transmission is interrupted by the drive transmission on / off switching means during the period when the sheet being conveyed by the fixing device faces the sheet. It is characterized by the above. Effect of the Invention

[0005] The present invention allows for improved lamination processes. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating the configuration of a printer as an example of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] Schematic diagram of the drive transmission system for paper transport [Figure 4] This shows an example of a similar device with an internal paper discharge system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] An embodiment in which the present invention is applied to an electrophotographic image forming apparatus will be described. Fig. 1 is a schematic diagram of a printer as an example of an image forming apparatus according to this embodiment. This printer 100 includes a paper feeder 60, a pair of registration rollers 4, a photoconductor drum 20 as an image carrier, a primary transfer device 12, a secondary transfer device including a secondary transfer roller 5, and a fixing device 80. This is a four-color tandem type image forming apparatus that forms toner images of the respective colors of yellow, cyan, magenta, and black on the photoconductor drum 20.

[0008] The paper feed device 60 includes a paper feed tray in which sheets S as recording materials are stored in a stacked state, and a paper feed roller 3 that separates and sends out the sheets S stored in the paper feed tray one by one, starting from the top one. The paper S sent out by the paper feed roller 3 is temporarily stopped by a pair of registration rollers 4, and after any misalignment is corrected, it is sent by the pair of registration rollers 4 to a secondary transfer nip consisting of the intermediate transfer belt 10 and secondary transfer roller 5 at a timing synchronized with the rotation of the photosensitive drum 20 and intermediate transfer belt 10, that is, at a timing when the leading edge of the toner image formed on the photosensitive drum 20 and intermediate transfer belt 10 coincides with a predetermined position of the leading edge of the paper S in the transport direction. A support roller 11 is arranged on the back surface of the intermediate transfer belt 10 with which the secondary transfer roller 5 comes into contact.

[0009] Around the photoconductor drum 20 of each color, in the order of the rotation direction indicated by the arrow, there are arranged a charging roller 30 as a charging device, an exposure device 8, a developing device 40 equipped with a developing roller, a primary transfer device 12, a cleaning device 50 equipped with a cleaning blade, etc. Between the charging roller 30 and the developing device 40, exposure light Lb is irradiated onto an exposure portion on the photoconductor drum 20 via a mirror, so that the exposure light is scanned.

[0010] Above the intermediate transfer belt 10, toner bottles 9 (Y, C, M, K) containing toner of each color are disposed so as to be detachable from the main body of the copier 100. The toner contained in the toner bottle 9 of each color is supplied to a developing device 40 of each color.

[0011] When the photoconductor drum 20 starts to rotate, the surface of the photoconductor drum 20 is uniformly charged by the charging roller 30, and the exposure light Lb is irradiated and scanned onto the exposure portion based on image information to form an electrostatic latent image corresponding to the image to be created. This electrostatic latent image is moved to the developing device 40 by the rotation of the photoconductor drum 20, where toner is supplied to make it visible and a toner image is formed. The toner image formed on the photoconductor drum 20 is transferred to the intermediate transfer belt 10 by the application of a transfer bias by the primary transfer device 12, and is then transferred to the paper S that has entered the secondary transfer nip at a predetermined timing by the application of a transfer bias by the secondary transfer roller 5.

[0012] The paper S carrying the toner image is transported toward the fixing device 80, where the toner image is fixed, and then discharged by the pair of discharge rollers 7 onto a paper discharge tray and stacked. Residual toner that is not transferred at the transfer site and remains on the photosensitive drum 20 and intermediate transfer belt 10 reaches the cleaning devices 50, 70 as the paper rotates, and is scraped off and cleaned by the cleaning blades as it passes through the cleaning devices 50, 70. Thereafter, the residual potential on the photosensitive drum 20 is removed by a static eliminator, and the paper is prepared for the next image forming process.

[0013] Fig. 2 is a schematic diagram of fixing device 80. Fixing device 80 has fixing sleeve 81 and pressure roller 82, and fixing sleeve 81 is directly heated from the inner circumferential side by radiant heat from heat source 83 (a halogen heater in the example of Fig. 2). Inside fixing sleeve 81 in Fig. 2, there is provided nip forming member 84 that forms a nip with pressure roller 82 that faces fixing sleeve 81 across it. This nip forming member 84 slides directly against the inner surface of fixing sleeve 81, or indirectly through a sliding sheet.

[0014] In Figure 2, the shape of the nip is flat, but it may be concave or have other shapes. A concave nip shape is advantageous in that the leading edge of the recording paper is discharged closer to the pressure roller, improving separation and preventing jams.

[0015] The fixing sleeve 81 is an endless sleeve (or film) made of a metal sleeve such as nickel or SUS, or a resin material such as polyimide. The surface layer of the sleeve has a release layer such as a PFA or PTFE layer, which provides release properties to prevent toner from adhering to it. An elastic layer made of a silicone rubber layer or the like may be provided between the base material of the sleeve and the PFA or PTFE layer. If there is no silicone rubber layer, the heat capacity is reduced and energy saving is improved, but when an unfixed image is crushed and fixed, minute irregularities on the sleeve surface are transferred to the image, resulting in a problem in which orange peel-like uneven gloss (orange peel image) remains in the solid part of the image. To improve this, it is necessary to provide a silicone rubber layer of 100 μm or more. The deformation of the silicone rubber layer absorbs the minute irregularities, improving the orange peel image.

[0016] Fixing device 80 includes support members 85 (stays) for supporting the nip portion inside fixing sleeve 81. Support members 85 prevent bending of nip forming member 84 that receives pressure from pressure roller 82, and ensure that a uniform nip width can be obtained in the axial direction. By supporting the pressure with support members 85, it is possible to obtain the surface pressure at the fixing nip that is necessary for melting and fixing the toner.

[0017] The support member 85 is formed by bending iron or stainless steel, and has a large heat capacity because it is made of an iron plate or SUS plate with a thickness of about 2 to 4 mm. In addition, the support member 85 is held and fixed to holding members at both ends and positioned. Therefore, the fixing device 80 is provided with a reflecting member 86 between the heat source 83 and the support member 85. The reflecting member 86 suppresses unnecessary energy consumption caused by the support member 85 being heated by radiant heat from the heat source 83. Here, the same effect can be obtained by insulating or mirror-finishing the surface of the support member 85 instead of providing the reflecting member 86.

[0018] The pressure roller 82 has an elastic rubber layer on a core metal, and a release layer (PFA or PTFE layer) is provided on the surface to obtain releasability. The pressure roller 82 rotates by a driving force transmitted through a gear from a driving source such as a motor provided in the image forming apparatus, as described later. The pressure roller 82 is pressed against the fixing sleeve 81 by a spring or the like, and the elastic rubber layer is crushed and deformed to have a predetermined nip width. The pressure roller 82 may be a hollow roller, and the pressure roller 82 may have a heating source such as a halogen heater. The elastic rubber layer may be solid rubber, but if there is no heater inside the pressure roller 82, sponge rubber may be used. Sponge rubber is more preferable because it has higher insulation properties and is less likely to lose heat from the fixing sleeve.

[0019] The fixing sleeve 81 rotates together with the pressure roller 82. Specifically, the pressure roller 82 is rotated by a drive source, and a drive force is transmitted to the sleeve by frictional force of the nip portion N, causing the fixing sleeve 81 to rotate together. The fixing sleeve 81 rotates while being sandwiched in the nip portion N, and runs while being guided by holding members (flanges) at both ends other than the nip portion. With the above-mentioned configuration, it is possible to realize a fixing device that is inexpensive and has a fast warm-up time.

[0020] [Curl of Paper S] Paper that is left in a high-temperature, high-humidity environment for a long time absorbs moisture and becomes highly moisture-rich, and recycled paper is particularly prone to high moisture content. When such paper passes through the fixing device 80 with a high temperature difference between the fixing sleeve 81 and the pressure roller 82, a temperature difference occurs between the front and back of the paper, and moisture moves from the higher temperature side (the fixing sleeve side) to the lower temperature side (the pressure roller side). The moisture evaporates from the pressure roller side, causing the paper to shrink and curl in the opposite direction to the printed side (back curl).

[0021] In order to correct the back curl, the paper should be bent in the opposite direction before it becomes a back curl. The curl correction device 90 is located downstream in the transport direction from the fixing device 80, and rotates by a driving force transmitted from the same driving source as the pressure roller 82. The image side roller 91 rotates by the frictional force from the non-image side roller 92. The paper passes through the nip portion between the image side roller 91 and the non-image side roller 92, and is bent by the guide plate 93 to correct the curl.

[0022] In this embodiment, the curl correction device 90 is used as cooling and pressure rollers 91 and 92. After fixing, rollers such as a conveying roller and a decurler, which is a curl correction device, are replaced with cooling and pressure rollers. The cooling and pressure rollers are rollers with an elastic layer that is uniform in the axial direction. The film is pulled at a line speed that is slightly faster than that of fixing to reduce waviness.

[0023] In the case of a curl correction device, one of the pair of rollers may be a hard roller, but in this embodiment, both rollers are elastic rollers equipped with an elastic layer. The distance between the axes is fixed, and when printing on plain paper in the normal printing mode, which is an image formation mode, the surface pressure is small, and when a recording medium that is sandwiched between laminating films on both sides and thickened as a whole is passed through, as in the laminating mode, the surface pressure is high and the nip width is widened. A large pressure is applied only when a thick film passes through, and the laminating film can be sufficiently pressed. In addition, the elastic layer of the roller is compressed in the radial direction at the nip and stretched in the circumferential direction compared to when printing on plain paper, so the linear speed at the nip is faster than when printing on plain paper.

[0024] [Lamination process] The paper feed device 60 is equipped with a paper feed cassette as a storage unit for recording media. When printing on paper, a large number of cut-paper-like recording media are stored in the paper feed cassette of the paper feed device 60. On the other hand, when performing lamination processing, the paper feed cassette stores printed paper sandwiched between a pouch-type lamination film by the user.

[0025] Pouch-type laminating film refers to a structure in which one of the four sides of two films is glued together, or one film is folded into two and the printed material is sandwiched between the two films. The film is placed in the paper feed cassette so that the glued side or the folded side is on the downstream side in the paper feed direction.

[0026] In addition to the paper feed cassette, the image forming apparatus is also equipped with a manual feed tray 61 (see FIG. 1). On the other hand, when performing a lamination process, a laminate film may be set on the manual feed tray 61.

[0027] [Drive transmission system for paper transport] In this embodiment, the image forming mode and the lamination mode are provided, and the sheet conveying speed in the fixing device in the lamination mode is lower than the sheet conveying speed in the image forming mode. As a method of low linear conveyance during lamination, if the drive motor is driven at a rotation speed lower than the rated range, the rotation speed may fluctuate. Therefore, a reducer is generally used to drive at a low linear speed. On the other hand, when a reducer is used, an expensive motor capable of high speed rotation must be used to drive at the rotation speed in normal printing, leading to increased costs. In particular, since the conveying motor for conveyance other than fixing and transfer is accelerated above the process linear speed of fixing and transfer in order to shorten the printing time, if a reducer is used to reduce the linear speed in the lamination mode, an expensive motor must be used. On the other hand, since the maximum speed of the fixing roller and the transfer roller (maximum speed in the image forming mode) is not so high, it is possible to use a reducer to handle from low speed to normal speed without using a very expensive motor.

[0028] 3 is a schematic diagram of a drive transmission system for paper transport in this embodiment. The paper feed roller 3 is driven by a drive motor 3b via a clutch 3a, which is a drive transmission on / off switching means. When a transport force is applied to the paper S, the clutch 3a is connected and the drive motor 3b rotates to transport the paper S. When the clutch 3a is disengaged [disconnected], the drive force is not transmitted to the paper S, and the paper S is transported by a transport force from another drive source. The pair of registration rollers 4 and the pair of paper discharge rollers 7 are also configured in a similar manner.

[0029] The secondary transfer roller 5 is driven by a drive motor 5b via a reducer 5a. The fixing device 80 is driven by a drive motor 80b via a reducer 80a. By installing a reducer, it is possible to handle low linear speeds during lamination. The following motors are used as these drive motors. When a normal motor is rotated at a speed slower than a predetermined range, problems arise in terms of rotation unevenness and stopping accuracy. In this embodiment, a powerful motor that is capable of high-speed printing and does not have problems in rotation unevenness and stopping accuracy even with a large reduction ratio that can be up to 10 mm / sec is used. The linear speed is changed by changing the rotation speed of the drive motor 80b. The clutch and motor are controlled by a control unit 300, and an operation panel 310 for selecting and instructing a lamination mode is connected to the control unit 300.

[0030] In this embodiment, in the lamination mode, the laminate film is transported at a normal linear speed until it reaches the transfer roller, and while it is sandwiched between the transfer roller, the fixing roller, and the cooling and pressure roller, the driving force of the transport roller is turned off by a clutch, and the laminate film is transported by the driving force of the transfer roller, the fixing roller, and the cooling and pressure roller. After it passes through the cooling and pressure roller, the driving force of the transport roller is turned on again by a clutch, and the laminate film is transported at a normal linear speed. If the transfer roller can be separated, the transfer rollers may be separated during lamination.

[0031] A specific example is as follows. When a laminate film [a recording medium sandwiched between laminate films on both sides] is passed through, the paper feed roller 3 and the pair of registration rollers 4 rotate at a low-speed printing linear speed of 75 mm / sec to transport the laminate film. When the leading edge of the laminate film reaches the secondary transfer roller 5, the clutches 3a and 4a separate, and the transport force to the laminate film is no longer transmitted. The secondary transfer roller 5, the fixing device 80, and the cooling and pressure rollers 91 and 92 rotate at a linear speed of 30 mm / sec or 20 mm / sec to bond the laminate film while transporting it. When the trailing edge of the laminate film passes the cooling and pressure rollers 91 and 92, the clutch 7a of the pair of discharge rollers 7 is connected, and the pair of discharge rollers 7 rotates at a low-speed printing linear speed of 75 mm / sec to discharge the laminate film.

[0032] To shorten the time from when the paper is fed to when it is discharged, the paper feed roller 3, the pair of registration rollers 4, and the pair of discharge rollers 7 are made to have a linear speed faster than that of the secondary transfer roller 5 and fixing device 80, which are the imaging units. During lamination, the linear speed should be 50% or less, and preferably 30%, of the low-speed printing linear speed. There is a difference of 10 times or more between the conveying linear speed other than fixing and transfer during normal printing and the lamination linear speed. The rated speed of the drive motor can only handle a linear speed of about 8 times. At higher linear speeds than this, the torque is insufficient, and at lower linear speeds the motor rotation speed is unstable.

[0033] Therefore, since there is no need to slow down only the fixing device 80, which affects the lamination quality, or to increase the speed of the secondary transfer roller 5, it is possible to accommodate a low linear speed synchronized with the fixing device 80, and by slowing down the linear speeds of the fixing device 80 and the transfer device, it is possible to improve the lamination quality.

[0034] [Verification experiment] We modified the Ricoh Co., Ltd. MPC5504 (product name) multifunction printer and performed a lamination quality evaluation. This multifunction printer is a so-called internal paper discharge type, with two paper discharge outlets, one above and one below, inside the printer, and an internal intermediate tray [inner 1 bin tray] that receives paper discharged from the upper paper discharge outlet. Figure 4 shows an example of a device with this type of internal paper discharge type.

[0035] This configuration example differs from the printer in Fig. 1 in that a scanner 200 is provided on top of the printer body. A space 210 for paper discharge is formed between the bottom surface of the scanner 200 and the top surface of the printer body. A horizontal internal intermediate tray 220 is provided to divide this space 210 into upper and lower sections. A paper discharge outlet from the paper discharge roller pair 7 is formed below the internal intermediate tray 220, and a paper discharge outlet from the paper discharge roller pair 17 is formed above it. A switching claw 230 is provided to switch which of the paper discharge roller pairs the paper is conveyed to from the fixing device 80. A curl correction device 90 consisting of cooling and pressurizing rollers 91, 92 is provided midway toward the upper paper discharge roller pair 17, and a guide plate 93 is also provided.

[0036] In the illustrated example, cassettes 60a, 60b are provided in two tiers, one above the other. Also shown is a manual feed tray 61 in an open state, and a paper feed roller 62 for paper set in the manual feed tray 61. The rest of the configuration is a tandem structure for four colors, yellow, magenta, cyan, and black, similar to the printer in Figure 1, and corresponding members are given the same reference numerals.

[0037] The laminate film used was a 100μm laminate film manufactured by Iris Ohyama, and the inner paper was Ricoh's My Paper (product name) paper with a solid image printed on the entire surface. The following three items were evaluated.

[0038] ·Adhesiveness ◎: Adhesion is strong enough, and there is no uneven melting of the glue. 〇: Adhesion is strong enough, but the adhesive melts unevenly △: Adheres, but not strong enough ×: Only partially adhered and easily peeled off

[0039] Wavy ◎: No waviness at all 〇: There are some small wavy areas △: Small wavy areas overall ×: There is a large amount of waviness overall

[0040] ·curl ◎: Curl amount less than 5mm 〇: Curl amount 5mm or more, less than 10mm △: Curl amount 10mm or more, less than 20mm ×: Curl amount 20mm or more The amount of curl was determined by placing the curled paper on a horizontal surface and measuring the height of the highest point of the curled paper.

[0041] The conditions for carrying out Examples 1 to 4 and Comparative Examples 1 to 3 are as shown in Table 1. [Table 1]

[0042] [Example 1] The lamination process was performed under the conditions described in the implementation conditions for Example 1 in Table 1. The lamination line speed was set to 30 mm / sec, which is 50% of the low-speed printing line speed of 75 mm / sec, to improve the adhesion of the laminate film. By applying pressure and tension using a cooling pressure roller, it was possible to reduce waviness due to thermal contraction after passing through the fixing device 80, and by cooling the laminate film, it was possible to suppress deformation. In addition, by discharging the laminate film onto the internal intermediate tray 220 (inner 1 bin tray) instead of the usual internal tray (the tray below the internal intermediate tray 220), the transport path was made gentler, and curling was also suppressed.

[0043] [Example 2] The lamination process was carried out under the conditions described in the working conditions for Example 2 in Table 1. The lamination line speed was set to 20 mm / sec, which is 30% or less, to further improve the adhesion of the laminate film. In addition, by further reducing the line speed, the cooling time was extended, and waviness and curl quality were also improved.

[0044] [Example 3] Lamination was performed under the conditions described in the implementation conditions for Example 3 in Table 1. Since the center distance of the cooling and pressing rollers was variable, the nip width during lamination was 0.5 mm, which worsened waviness.

[0045] [Example 4] Lamination processing was carried out under the conditions described under the working conditions for Example 4 in Table 1. Since the sheet was discharged onto a normal internal tray, curling was aggravated.

[0046] [Comparative Example 1] The lamination process was carried out under the conditions described under the implementation conditions for Comparative Example 1 in Table 1. Since the lamination line speed was also 75 mm / sec, while the low-speed printing line speed was 75 mm / sec, the adhesion, waviness, and curl were all rated x.

[0047] [Comparative Example 2] Lamination was performed under the conditions described under the implementation conditions for Comparative Example 2 in Table 1. The lamination line speed was 40 mm / sec, which was 50% of the low-speed printing line speed of 75 mm / sec, so adhesion, waviness, and curl were all rated fair.

[0048] [Comparative Example 3] The lamination process was carried out under the conditions described under the implementation conditions for Example 3 in Table 1. Since the cooling and pressurizing rollers 91 and 92 were not provided, waviness was rated as x.

[0049] As described above, the image forming apparatus of the present embodiment has a fixing device that fixes a toner image formed on a recording medium, and the fixing device has a fixing rotor and a pressure rotor that contacts the fixing rotor to form a nip, and the linear speed at which the laminate film passes is set to 50% or less of the lowest speed printing mode among a plurality of normal printing modes, and a cooling pressure roller that applies pressure to the entire axial surface downstream of the fixing device in the conveying direction is provided. Therefore, by laminating in a low-speed mode different from normal printing, it is possible to sufficiently heat and melt the glue. By setting the linear speed during lamination to 50% or less of normal printing, it is possible to improve the adhesiveness of the laminate film. Conventionally, the linear speed of normal printing is high, so if lamination processing is performed at this linear speed, heat is not sufficiently transferred to the laminate film and fixation is not possible.

[0050] In addition, the cooling and pressurizing roller can reduce waviness after passing through the fixing process. Conventionally, there is no cooling and pressurizing roller after fixing, so waviness is likely to occur due to shrinkage after heating. A short cooling time also makes waviness more likely to occur. Furthermore, a short cooling time makes the film more likely to be scratched or curled.

[0051] In contrast, when a cooling and pressure roller is used, the film shrinks in a pressurized state, which means that the film shrinks in a restrained state, making it difficult for waviness to occur. If the film shrinks after heating in an unrestrained state, the film shrinks in a free state, making it more likely to become waviness. This allows for sufficient cooling time after heating.

[0052] As described above, according to the image forming apparatus of the present embodiment, the following unique effects are obtained for each aspect. (Aspect 1) In an image forming apparatus equipped with a fixing device that fixes an image on a sheet by applying heat and pressure, the image forming mode and the lamination mode are provided, and the sheet conveying speed in the fixing device in the lamination mode is slower than the sheet conveying speed in the image forming mode. In an image forming apparatus that can switch between a plurality of sheet conveying speeds in the image forming mode according to the type of paper, such as the thickness of the paper, the sheet conveying speed in the fixing device in the lamination mode is set to be slower than the slowest sheet conveying speed in the image forming mode. By slowing down the fixing speed in the lamination mode in this way, the laminate film can be pressed and heated better than when the sheet conveying speed in the fixing device in the image forming mode is used. This improves the adhesiveness of the laminate film and improves the lamination process. If the sheet conveying speed was the same as that in the image forming mode, the conveying speed would be too fast and heat would not be sufficiently transferred to the laminate film, resulting in insufficient adhesive strength.

[0053] (Aspect 2) In the image forming apparatus according to the first aspect, the degree of the low speed is preferably 50% or less. (Aspect 3) In the image forming apparatus according to aspect 2, the degree of the low speed is more preferably 30% or less. The lower the speed, the more the adhesiveness of the laminate film can be improved.

[0054] (Aspect 4) In the image forming apparatus according to any one of aspects 1 to 3, the conveying speed of the fixing device in the laminating mode is slower than the conveying speed of the sheet conveying member in the laminating mode during the period until the leading edge of the sheet reaches the fixing device and during at least a part of the period after the trailing edge of the sheet leaves the fixing device. In other words, when passing a laminate film, the linear speed of the fixing device (if the transfer device is also in a paper clamping state, the fixing device and the transfer device) is slower than the linear speed of the other conveying members such as the conveying roller. (Aspect 5) In the image forming apparatus according to aspect 4, the degree of the slow speed is 50% or less. According to the fourth and fifth aspects, in the lamination mode, the conveying speed of the fixing device is faster than that of the lamination mode during at least a portion of the period until the leading edge of the sheet reaches the fixing device and after the trailing edge of the sheet leaves the fixing device, thereby enabling the processing speed to be increased accordingly.

[0055] (Aspect 6) In the image forming apparatus according to any one of aspects 1 to 5, a drive transmission on / off switching means is provided in a drive transmission system from a drive source for at least some of the sheet transport members located upstream and downstream of the fixing device in the sheet transport direction. (Aspect 7) In the image forming apparatus described in aspect 6, the drive transmission is interrupted by the drive transmission on / off switching means for the sheet transporting member at a location facing the sheet transported by the fixing device during the period in which the sheet transported by the fixing device faces the sheet. According to the sixth and seventh aspects, the drive transmission switching means can cut off the drive transmission to the sheet transport member at the location facing the sheet transported by the fixing device during the period when the sheet transported by the fixing device faces the sheet, allowing the sheet to be transported by the fixing device. For example, while the laminate film is sandwiched between the transfer roller, the fixing roller, and the cooling and pressure roller, the laminate film can be transported without any problems by being transported only by the drive force of the transfer roller, the fixing roller, and the cooling and pressure roller. Therefore, an inexpensive motor can be used as the motor of the sheet transport member provided with the drive transmission switching means.

[0056] (Aspect 8) In the image forming apparatus according to any one of the first to seventh aspects, a cooling and pressurizing roller is provided downstream of the fixing device in the sheet conveying direction. (Aspect 9) In the image forming apparatus according to embodiment 8, the cooling and pressure rollers are a pair of rollers both having an elastic layer, and the center distance is the same in the image forming mode and the laminating mode. (Aspect 10) In the image forming apparatus according to aspect 8 or 9, The cooling and pressure rollers are a pair of rollers, at least one of which has an elastic layer, and the nip width when clamping plain paper is 1 mm or less, and the nip width when clamping a sheet with laminate films on both sides is in the range of 1 mm or more and 3 mm or less. (Aspect 11) In the image forming apparatus according to any one of aspects 8 to 10, the cooling and pressing roller has a release layer as a surface layer. According to these aspects 8 to 11, the occurrence of waviness, scratches on the film, and curling can be suppressed. This is for the following reasons. The distance between the axes of the rollers is constant regardless of the printing mode and the type of recording medium, and the pressure changes depending on the thickness of the recording medium. When printing on plain paper at a normal linear speed, the surface pressure is small and the torque of the drive motor does not increase. On the other hand, during lamination, the surface pressure is large, which can reduce waviness of the laminate film. In addition, by pulling the film by slightly increasing the linear speed of the cooling and pressure roller compared to that of fixing, waviness of the film can be further reduced. The elastic layer deforms and the linear speed increases only when a thick film passes. In particular, according to aspect 11, toner adhesion to the image surface can be reduced.

[0057] (Aspect 12) In the image forming apparatus according to any one of the first to eleventh aspects, at least two paper discharge locations are provided for discharging the sheet that has passed through the fixing device, and in the lamination mode, the sheet is discharged to the paper discharge location that has a relatively longer transport path from the fixing device. This can reduce curling of the laminate film. [Explanation of symbols]

[0058] 3: Paper feed roller 3a: Clutch 3b: Drive motor 4: Registration roller pair 4a: Clutch 5: Secondary transfer roller 5a: Reducer 5b: Drive motor 7: Paper ejection roller pair 7a: Clutch 8: Exposure equipment 9: Toner bottle 10: Intermediate transfer belt 11: Support roller 12: Primary transfer device 17: Paper ejection roller pair 20: Photoconductor drum 30: Charging roller 40: Developing device 50: Cleaning device 60: Paper feeder 60a: Cassette 60b: Cassette 61: Manual feed tray 62: Paper feed roller 70: Cleaning device 80: Fixing device 80a: Reducer 80b: Drive motor 81: Fixing sleeve 82: Pressure roller 83:Heat source 84: Nip forming member 85: Support member 86: Reflective material 90: Curl straightener 91: Image side roller 92: Non-image side roller 93: Guide plate 100: Printer 200: Scanner 210: Space 220: Internal middle tray 230: Switching claw 300: Control section 310: Operation panel Lb: Exposure light N: Nip part S: Paper [Prior art documents] [Patent documents]

[0059] [Patent Document 1] JP 2016-161744 A

Claims

1. In an image forming apparatus having a fixing device that fixes an image on a sheet by applying heat and pressure, The printer has an image forming mode and a lamination mode, The sheet conveying speed in the fixing device in the lamination mode is The sheet conveying speed is slower than the sheet conveying speed in the image forming mode, the conveying speed is slower than the conveying speed of the sheet conveying member during at least a part of a period until the leading edge of the sheet reaches the fixing device and a period after the trailing edge of the sheet leaves the fixing device in a lamination mode; a drive transmission on / off switching means for switching a drive transmission system from a drive source different from a drive source of the fixing device to at least a part of the sheet conveying members on the upstream side and downstream side of the fixing device in the sheet conveying direction; An image forming apparatus characterized in that, for the sheet transport member at a location facing the sheet transported by the fixing device, the drive transmission is cut off by the drive transmission on / off switching means during the period when the sheet transported by the fixing device is facing the sheet.

2. 2. The image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the sheet conveying speed in the image forming mode is 50% or less slower than the sheet conveying speed in the image forming mode.

3. 3. The image forming apparatus according to claim 2, The image forming apparatus according to claim 1, wherein the degree of the low speed is 30% or less.

4. In the image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the speed of said sheet conveying member is 50% or less slower than the conveying speed of said sheet conveying member.

5. In the image forming apparatus according to any one of claims 1 to 4, The image forming apparatus further comprises a cooling and pressing roller disposed downstream of the fixing device in a sheet conveying direction.

6. 6. The image forming apparatus according to claim 5, The image forming apparatus according to claim 1, wherein the cooling and pressure rollers are a pair of rollers each having an elastic layer, and the center distance between the rollers is the same in the image forming mode and in the laminating mode.

7. 7. The image forming apparatus according to claim 5, The cooling and pressure rollers are a pair of rollers, at least one of which has an elastic layer, and the nip width when clamping plain paper is 1 mm or less, and the nip width when clamping a sheet with laminate films on both sides is in the range of 1 mm or more and 3 mm or less.

8. An image forming apparatus having a fixing device that fixes an image on a sheet by applying heat and pressure, The printer has an image forming mode and a lamination mode, a sheet conveying speed in the fixing device in a lamination mode is slower than a sheet conveying speed in an image forming mode; a cooling and pressing roller is provided downstream of the fixing device in a sheet conveying direction; The cooling and pressure rollers are a pair of rollers, at least one of which has an elastic layer, and the nip width when clamping plain paper is 1 mm or less, and the nip width when clamping a sheet with laminate films on both sides is in the range of 1 mm or more and 3 mm or less.

9. In the image forming apparatus according to claim 8, The image forming apparatus according to claim 1, wherein the cooling and pressure rollers are a pair of rollers each having an elastic layer, and the center distance between the rollers is the same in the image forming mode and in the laminating mode.

10. 10. The image forming apparatus according to claim 5, The image forming apparatus is characterized in that the cooling and pressure roller has a release layer as a surface layer.

11. 11. The image forming apparatus according to claim 1, An image forming apparatus characterized in that at least two paper discharge locations are set for discharging sheets that have passed through the fixing device, and in the lamination mode, the sheet is discharged to the paper discharge location that has a relatively longer transport path from the fixing device.

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