Inkjet recording apparatus

Abstract

To provide an inkjet recording device that has high durability.SOLUTION: An inkjet recording device includes: a surface modification part for modifying a surface of a sheet that is transported from one direction toward the other direction; a registration part for positioning a width direction orthogonal to the transportation direction thereof; and a recording head part for discharging ink to the surface modified by a surface modification mechanism to form an image thereon, which are arranged so that the sheet passes through the surface modification part, the registration part and the recording head in this order.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus.

[0002] Before printing by applying ink onto a sheet by an inkjet method, there is known an inkjet recording apparatus that performs surface modification of the sheet by corona discharge to enhance printability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The structure of an inkjet head is extremely delicate and vulnerable to external stimuli. In particular, corona discharge for surface modification of a sheet has an adverse effect on the durability of the inkjet head.

[0005] The present invention has been made in such circumstances, and an exemplary object of one aspect thereof is to provide an inkjet recording apparatus with high durability.

Means for Solving the Problems

[0006] In order to solve the above problems, in an inkjet recording apparatus according to an aspect of the present invention, a sheet conveyed from one direction to the other direction passes through a surface modification unit that modifies the surface thereof, a registration unit that performs positioning in the width direction orthogonal to the conveyance direction, and a recording head unit that discharges ink onto the surface modified by the surface modification unit to form an image, in this order, and the surface modification unit, the registration unit, and the recording head unit are arranged. At the same time, the resist section has a skew feed mechanism for skew-feeding the sheet toward a reference guide having a guide surface extending in the sheet conveyance direction and arranged on one side in the width direction. The skew feed mechanism has a skew feed belt that is angled with respect to the conveyance direction and is driven in a circular motion so as to approach the reference guide toward the downstream side, and an air suction mechanism for sucking the lower surface of the sheet to the skew feed belt.

Effects of the Invention

[0007] According to the present invention, the durability of an inkjet recording apparatus can be enhanced.

Brief Description of the Drawings

[0008] [FIG. 1] It is a diagram schematically showing the printing system of the embodiment. [FIG. 2] It is a diagram schematically showing the printing system of the embodiment. [FIG. 3] It is a top view showing details of the resist portion 24. [FIG. 4] It is a sectional view taken along line A-A in FIG. 3. [FIG. 5] FIGS. 5(a) to (d) are diagrams showing the state of foil pressing by the foil pressing apparatus according to the comparative example. [FIG. 6] It is a side view of the foil pressing apparatus of FIG. 1. [FIG. 7] It is a side view of the foil pressing apparatus of FIG. 1. [FIG. 8] It is a diagram showing an enlarged view of the periphery of the foil pressing section. [FIG. 9] It is a diagram showing an enlarged view of the periphery of the sheet conveying guide 82 shown in FIG. 8. [FIG. 10] It is a diagram showing an enlarged view of the periphery of the foil pressing section. [FIG. 11] It is a diagram showing an enlarged view of the periphery of the sheet conveying guide 82 shown in FIG. 10. [FIG. 12] It is a diagram showing an enlarged view of the periphery of the foil pressing section. [FIG. 13] It is a diagram showing an enlarged view of the periphery of the foil pressing section when the nip rollers 62 and 64 are in the raised position. [FIG. 14] FIGS. 14(a) to (f) are diagrams for explaining the feeding-back by the foil pressing apparatus of FIG. 1. [FIG. 15] FIGS. 15(a) and (b) are diagrams showing the state of foil pressing.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and repeated explanations are appropriately omitted.

[0010] FIGS. 1 and 2 are diagrams schematically showing a printing system 10 in which a foil pressing device (transfer device) 16 according to an embodiment is used. FIG. 1 is a side view, and FIG. 2 is a plan view. The printing system 10 is a device that performs predetermined printing on a sheet while conveying the sheet. The materials of the sheet are various, such as paper, cloth, resin, and metal. Hereinafter, the direction in which the sheet is conveyed (the direction from right to left in FIGS. 1 and 2) is referred to as the conveyance direction Y, and the direction orthogonal to the conveyance direction Y (the direction orthogonal to the paper surface in FIG. 1 and the vertical direction in FIG. 2) is referred to as the width direction X.

[0011] The printing system 10 includes a sheet feeding device 12 that feeds sheets one by one, an adhesive coating device 14 that applies an adhesive to the sheets fed one by one, a foil pressing device 16 that performs foil pressing by transferring a foil onto the adhesive on the sheet using the tackiness of the adhesive, a stacker 18 that accumulates the sheets, and a control device 20 that integrally controls the printing system 10. The sheet feeding device 12, the adhesive coating device 14, the foil pressing device 16, and the stacker 18 are arranged in a row in this order from the upstream side (the right side in FIGS. 1 and 2) in the conveyance direction Y. The control device 20 is connected to the sheet feeding device 12, the adhesive coating device 14, the foil pressing device 16, and the stacker 18 via a network 2.

[0012] The sheet feeding device 12 includes a feeder 22, a corona treatment unit 26, and a resist unit 24. The feeder 22 includes a table 28 and a suction head 30. Sheets are stacked on the table 28. The table 28 is configured to be able to move up and down. The suction head 30 feeds out the sheets stacked on the table 28 one by one in order from above.

[0013] The corona treatment unit 26 (surface modification unit) includes an electrode 36 (applied electrode) disposed above the conveyance path 34 and a dielectric roller 38 (opposing electrode) disposed below the conveyance path 34 so as to face the electrode 36 vertically. The corona treatment unit 26 performs surface modification of the sheet fed out by the feeder 22 by means of corona discharge between the electrode 36 and the dielectric roller 38. Specifically, hydrophilic groups are generated on the surface of the sheet to improve wettability. When the sheet is conveyed in a state of being adsorbed to the conveyance path 34 by the air suction unit 40, the distance between the electrode 36 and the sheet becomes constant, and the corona discharge becomes stable. The air suction unit 40 generates negative pressure by disposing one of the suction ports of an exhaust blower (not shown), but it may be configured to generate negative pressure by disposing a suction fan.

[0014] The resist unit 24 aligns the position of the sheet in the width direction X fed out by the feeder 22 by abutting against the resist reference guide 32.

[0015] The varnish coating device 14 includes a sheet sensor 42, a pair of CCD sensors 44, at least one varnish discharge unit 46, a semi-curing ultraviolet lamp 48, and a full-curing ultraviolet lamp 50. The pair of CCD sensors 44, the varnish discharge unit 46, the semi-curing ultraviolet lamp 48, and the full-curing ultraviolet lamp 50 are arranged in this order from the upstream side. In the illustrated example, the varnish coating device 14 includes three varnish discharge units 46, but it is not limited thereto. The varnish coating device 14 may include one varnish discharge unit 46 extending over the entire width direction X, or may include two or four or more varnish discharge units 46. LEDs for irradiating ultraviolet rays are used for the semi-curing ultraviolet lamp 48 and the full-curing ultraviolet lamp 50, but other light sources such as electric bulbs and fluorescent lamps may be used as long as they irradiate ultraviolet rays. It is desirable that the light source be adjustable in output.

[0016] The sheet sensor 42 detects the sheet fed from the sheet feeding device 12.

[0017] The varnish ejection unit 46 is a line-type inkjet head, although it is not particularly limited. The varnish ejection unit 46 ejects an ultraviolet curable varnish according to the varnish ejection data triggered by the detection of the leading edge of the sheet by the sheet sensor 42, and applies the ultraviolet curable varnish to the sheet. The varnish ejection data is data indicating where on the sheet the varnish is to be applied.

[0018] On the sheet fed by the sheet feeding device 12, a base image and a plurality of registration marks serving as a reference for specifying the position of the base image may be printed in advance. The varnish coating device 14 applies the varnish so as to have a predetermined relationship with the base image according to the varnish ejection data that defines the varnish coating portion on the sheet. For example, the varnish may be applied so as to overlap the base image.

[0019] Here, the base image of the sheet may be displaced or distorted. Therefore, when applying the varnish so as to have a predetermined relationship with the base image, it is necessary to correct the varnish ejection data in consideration of the displacement and distortion. For example, the CCD sensor 44 images the sheet triggered by the detection of the sheet by the sheet sensor 42, and the control device 20 analyzes the imaging data by the CCD sensor 44, and corrects the varnish ejection data of the area surrounded by the registration marks based on the difference from the theoretical positions of the plurality of registration marks. Note that the method described in Japanese Patent Application Laid-Open No. 2016-083898 previously filed by the applicant can be applied to the correction.

[0020] The ultraviolet lamp 48 for semi-curing irradiates the varnish on the sheet with ultraviolet rays having a relatively weak output, semi-curing the varnish. Semi-curing means lightly curing to such an extent that it reduces the fluidity of the varnish but does not completely cure it (for example, to a state where it can be further cured). By semi-curing at least the surface of the varnish, it is possible to maintain the tackiness of the varnish while preventing the varnish from flowing on the sheet and stabilizing the position of the varnish on the sheet. The semi-cured varnish is fully cured in the foil pressing device 16. When not transferring the foil to the sheet (not performing foil pressing), usually, the ultraviolet lamp 48 for semi-curing is turned off. Note that the ultraviolet lamp 48 for semi-curing may be used even when not performing foil pressing. For example, when the varnish applied on the sheet is likely to bleed, the ultraviolet lamp 48 for semi-curing is turned on to semi-cure at least the surface of the varnish. Thereby, bleeding of the varnish can be suppressed.

[0021] The ultraviolet lamp 50 for full curing irradiates the varnish applied to the sheet with ultraviolet rays, fully curing the varnish. When transferring the foil to the sheet (performing foil pressing), the ultraviolet lamp 50 for full curing is turned off.

[0022] That is, when performing foil pressing on the sheet, the varnish is semi-cured by the ultraviolet lamp 48 for semi-curing, and the semi-cured varnish is fully cured by the ultraviolet lamp 66 for foil pressing in the foil pressing device 16. In this case, the ultraviolet lamp 50 for full curing is turned off. When not performing foil pressing on the sheet, that is, when only applying the varnish to the sheet, the varnish is fully cured by the ultraviolet lamp 50 for full curing. In this case, the ultraviolet lamp 48 for semi-curing and the ultraviolet lamp 66 for foil pressing in the foil pressing device 16 are turned off. Note that, as described above, the ultraviolet lamp 48 for semi-curing may be turned on even when not performing foil pressing. Also, an LED that irradiates ultraviolet rays is used as the light source of the ultraviolet lamp 66 for foil pressing, but other light sources may be used as long as they irradiate ultraviolet rays.

[0023] Note that in FIG. 1, although the sheet is depicted as being conveyed on a single loop belt in the portion facing the varnish discharge unit 46, the ultraviolet lamp 48 for main curing, and the ultraviolet lamp 50 for semi-curing, the portion facing the varnish discharge unit 46, the portion facing the ultraviolet lamp 48 for main curing, and the portion facing the ultraviolet lamp 50 for semi-curing may each be configured to be conveyed by all or part of individual loop belts.

[0024] The foil pressing device 16 conveys the web (transfer web) 52 in a roll-to-roll manner. The web 52 of the present embodiment is a foil holding film in which a foil such as a metal foil is held (laminated) on a long film (substrate sheet). In the foil pressing device 16, the web 52 and the sheet are brought into contact while being conveyed. Due to the tackiness of the semi-cured varnish on the sheet, the foil held by the web 52 adheres. In this state, that is, in the state where the foil is held by the web 52 and adheres to the semi-cured varnish, the ultraviolet lamp 66 for foil pressing irradiates the varnish with ultraviolet rays to fully cure the varnish. When the varnish is fully cured, the force with which the fully cured varnish adheres to the foil becomes stronger than the force with which the web 52 holds the foil. In this state, when the sheet is conveyed and the sheet and the web 52 are separated, the foil held by the web 52 is transferred to the portion of the sheet where the varnish is applied.

[0025] The stacker 18 accumulates the sheets carried out from the foil pressing device 16.

[0026] The control device 20 is an information processing terminal such as a PC. The control device 20 receives an input regarding the definition of a print job. The control device 20 may display a predetermined job management screen and receive an input regarding the definition of the job via the job management screen. The definition of the job includes, for example, the number of sheets to be printed (number of printing units), the sheet size of the sheet to be printed, varnish discharge data, the presence or absence of corona treatment, the presence or absence of foil pressing, and the adjustment of the strength of pinning (degree of curing of semi-curing), etc. The control device 20 controls the paper feeding device 12, the varnish coating device 14, and the foil pressing device 16 based on the definition of the job.

[0027] The above is the basic configuration of the printing system 10.

[0028] As a modification, instead of the sheet feeding device 12, the printing system 10 may include a printer that prints a base image and registration marks on a sheet, and may feed the sheets one by one from the printer.

[0029] Further, the printing system 10 may include a post-processing device that cuts or binds the sheets between the foil pressing device 16 and the stacker 18.

[0030] FIG. 3 is a top view showing details of the resist portion 24, and FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3. The resist portion 24 includes a resist reference guide 32, a skew feed mechanism 102, an inlet guide 104, a conveyance guide 106, and an outlet guide 108. Sa and Sb indicate the sheets conveyed through the resist portion 24.

[0031] The resist reference guide 32 is provided on the upper side in FIG. 3 (right side toward the conveyance direction Y, left side in FIG. 4, hereinafter referred to as the "reference side") in the width direction X. The resist reference guide 32 extends in the conveyance direction Y.

[0032] The resist reference guide 32 has a horizontally provided support surface 32a, a reference surface 32b that rises vertically upward from the support surface 32a at a right angle, and a ceiling surface 32c that is parallel to the support surface 32a and faces in the height direction (see FIG. 4). The reference surface 32b is provided parallel to the conveyance direction Y and extends in the conveyance direction Y over substantially the entire area of the resist portion 24.

[0033] The skew feed mechanism 102 is provided on the resist reference guide 32 side in the width direction X. The skew feed mechanism 102 is composed of a skew feed belt 110 and a suction chamber 112. The skew feed belt is driven to circulate at an angle with respect to the conveyance direction Y so as to approach the resist reference guide 32 toward the downstream side. In the present embodiment, four skew feed belts 110 are provided at intervals in the width direction X. Note that the number of skew feed belts 110 is not limited to four.

[0034] The suction chamber 112 is provided inside the circulating inclined conveyor belt 110 (see FIG. 4). In the suction chamber 112, at a portion corresponding to the gaps between a plurality of inclined conveyor belts 110 arranged at intervals in the width direction, in other words, at a portion avoiding the inclined conveyor belt 110 in plan view, and further in other words, at a portion exposed without being blocked by the inclined conveyor belt 110 in plan view, a plurality of openings 110a are provided. The openings 112a are arranged at predetermined intervals along the outside of the end portion of the inclined conveyor belt 110 in the width direction X. When a suction fan (not shown) is turned on, a negative pressure is formed in the suction chamber 112, and air is sucked from the openings 112a.

[0035] The inlet guide 104 extends in the width direction X adjacent to the upstream end portion of the resist portion 24 in the conveyance direction Y, that is, adjacent to the corona treatment portion 26. The outlet guide 108 extends in the width direction X adjacent to the downstream end portion of the resist portion 24 in the conveyance direction Y, that is, adjacent to the varnish coating device 14.

[0036] The conveyance guide 106 is a plate member provided at a portion closer to the side opposite to the reference side (hereinafter referred to as the "anti-reference side") in the width direction than the reference side where the inclined conveyance mechanism 102 is provided. The inlet guide 104, the conveyance guide 106, and the outlet guide 108 receive the lower surface of the conveyed sheet. The inlet guide 104, the conveyance guide 106, and the outlet guide 108 are, for example, flat stainless steel plates, and are preferably composed of a runner stainless steel plate or the like with good slidability.

[0037] The sheet that has passed through the corona treatment unit 26 enters the resist unit 24 with its lower surface guided by the entrance guide 104. The upper surface of the inclined conveyor belt 110 rotates in the direction from right to left in FIG. 3. Due to the air suction from the opening 112a, the lower surface of the sheet is adsorbed to the inclined conveyor belt 110 and conveyed by the inclined conveyor belt 110. While the sheet is being conveyed along the circumferential direction of the inclined conveyor belt 110, the position of the sheet in the width direction X changes from a position away from the reference plane 32b (sheet Sa) to a position where the reference side edge of the sheet abuts against the reference plane 32b (sheet Sb). Thereafter, it is conveyed along the reference plane 32b with the reference side edge remaining in contact with the reference plane 32b, and its lower surface is guided by the exit guide 108 and sent into the varnish coating device 14. Therefore, the position of the reference side edge of the sheet in the width direction X is registered at a fixed position defined by the reference plane 32b and sent to the varnish coating device 14.

[0038] The resist reference guide 32 has its position in the width direction X fixed closer to the reference side of the device. Therefore, the sheet is always registered such that the position of the reference side edge of the sheet in the width direction X is at the fixed position where the reference plane 32b is located. That is, the sheet is sent to the varnish coating device 14 with the reference side edge as a reference. On the other hand, the position of the resist reference guide 32 in the width direction X may be adjusted according to the size of the sheet in the width direction X so that the central position of the sheet in the width direction X is always at a predetermined position in the width direction X of the device. In that case, it becomes possible to apply it to a device with the central position of the sheet in the width direction X as a reference. Also in this case, it is desirable that the inclined conveyor belt 110 is also movable together with the resist reference guide 32.

[0039] The upper surface of the inclined conveyor belt 110 is substantially at the same height as the support surface 32a of the resist reference guide 32. Therefore Skew The sheet with its lower surface adsorbed to the conveyor belt 110 moves on the support surface 32a without bending downward and abuts against the reference plane 32b. Also, since the ceiling surface 32c is formed in the vicinity of the reference plane 32b in the width direction X, upward bending of the sheet is also suppressed. Therefore, problems such as buckling when the reference side edge of the sheet abuts against the reference plane 32b can be prevented.

[0040] The upper surface of the conveyance guide 106 is lower than the upper surface of the inclined conveyance belt 110. Therefore, the sheet adsorbed and conveyed by the inclined conveyance belt 110 is less affected by friction with the conveyance guide 106, enabling stable conveyance and resist application. Additionally, it is possible to prevent the sheet from being scratched due to friction with the conveyance guide 106. The upper surface of the conveyance guide 106 is formed, for example, 2 to 3 mm lower than the upper surface of the inclined conveyance belt 110.

[0041] Corona treatment section 2 6 (surface modification section) generates hydrophilic groups on the sheet surface using corona discharge to enhance wettability, thus effectively preventing ink repellency. However, when the corona treatment section 2 6 is disposed near the ink application section 14, there is concern about the influence of corona discharge on the ink application section 14. Particularly when an inkjet head is employed in the ink application section 14, the durability significantly decreases due to the influence of corona discharge. On the other hand, since the resist section 24 abuts against the reference surface 32b while being conveyed by the inclined conveyance belt 110 for resist application, the processing efficiency is good because the sheet is not stopped, but a certain conveyance length is required. In the present embodiment, since this resist section 24 is disposed between the corona treatment section 2 6 and the ink application section 14, to that extent, the ink application section 14 can be separated from the corona treatment section 2 6, and a decrease in the durability of the ink application section 14 due to the influence of corona discharge can be suppressed. Therefore, it is possible to obtain an apparatus with good processing efficiency of the sheet at the resist section and excellent durability.

[0042] Next, using a comparative example, the problems to be solved by the foil pressing apparatus 16 according to the present embodiment will be described. Hereinafter, in the web conveyance path of the web 52, the section for transferring the foil to the sheet is referred to as the "foil pressing section".

[0043] Figs. 5(a) to 5(d) are diagrams showing the state of foil pressing by the foil pressing device according to the comparative example. In Figs. 5(a) to 5(d), the foil pressing scenes are shown in time series. In Figs. 5(a) to 5(d), the web 52 shown by the solid line indicates an unused web (i.e., a web on which foil is held). The web 52 shown by the dotted line indicates a used web (i.e., a web from which at least a part of the foil has been peeled off by the transfer of the foil to the sheet S1, or a web facing the varnish application region R on the sheet S1 in the foil pressing section P and on which the transfer of the foil to the sheet S1 has started).

[0044] In Fig. 5(a), the sheet S1 is passing through the foil pressing device section P, and the foil is being transferred from the web 52 to the varnish application region R on the sheet S1. As shown in Fig. 5(b), at the timing when the rear end of the sheet S1 reaches the downstream end of the foil pressing section P, that is, at the timing when the sheet S1 has passed through the foil pressing section P, the feeding of the web 52 is stopped. As shown in Fig. 5(c), when the next sheet S2 reaches the foil pressing section P, the feeding of the web 52 is restarted. In Fig. 5(d), the sheet S2 is passing through the foil pressing section P, and the foil is being transferred from the web 52 to the varnish application region R on the sheet S2. In particular, the foil is transferred from the web 52 located upstream of the foil pressing section P in Fig. 5(c). In the example of Fig. 5, the timing at which the feeding of the web 52 stops is the timing when the rear end of the sheet S1 reaches the downstream end of the foil pressing section P (Fig. 5(b)), but it may also be the timing when the rear end of the varnish application region R on the sheet reaches the downstream end of the foil pressing section P. Similarly, the timing at which the feeding of the web 52 is restarted may also be the timing when the varnish application region R on the sheet reaches the foil pressing section P.

[0045] Here, the web 52 is fed out only while the sheet is passing through the foil pressing section P, or only while the varnish coating area R on the sheet is passing through the foil pressing section P. This can reduce the amount of the web 52 that is wound onto the unused take-up roll 76. However, even in this case, when the sheet S1 has passed through the foil pressing transfer section P, that is, at the time of FIG. 5(c), the web 52 present in the foil pressing section P will not be used for the transfer to the next sheet S2 either, and thus will be wound onto the take-up roll 76 unused. That is, it results in wasteful consumption of the foil holding film.

[0046] Before the next sheet S2 reaches the foil pressing section P, if the web 52 present in the foil pressing section P at the time of FIG. 5(c) is returned to the upstream side of the foil pressing section P, it will be used for the transfer to the next sheet S2, and thus wasteful consumption can be reduced. To achieve this, it is conceivable to reverse-rotate the unwind roll to wind back the web 52, but wrinkles may occur in the foil wound back onto the unwind roll. Also, as will be described later, the foil pressing device 16 according to the present embodiment uses friction shafts for the unwind shaft and the take-up shaft, fixes the axial center portion of the friction shaft of the unwind shaft to the housing of the device, and does not include a drive motor for reverse rotation. Therefore, the unwind roll cannot be reverse-rotated in the first place. Thus, the foil pressing device 16 according to the present embodiment realizes a "feeding-back" that returns at least a part of the web 52 that has passed the upstream end of the foil pressing section P, that is, at least a part of the web 52 present in the foil pressing section P, to the upstream side of the foil pressing section P without winding back the web 52 onto the unwind roll.

[0047] Next, the configuration of the foil pressing device 16 will be described in detail. FIGS. 6 and 7 are diagrams showing the foil pressing device 16. FIGS. 6 and 7 are side views. FIG. 6 shows the state when the nip roller or the like is in the lowered position, and FIG. 7 shows the state when the nip roller or the like is in the raised position.

[0048] The foil pressing device 16 includes a plurality of conveying rollers 54, an unwinding shaft 56, a winding shaft 58, a plurality of guide rollers 60, a first nip roller 62, a second nip roller 64, an ultraviolet lamp 66 for foil pressing, and a sheet detection sensor 77.

[0049] The plurality of conveying rollers 54 convey the sheet toward the downstream side in the conveying direction (the left side in FIGS. 6 and 7) while sandwiching the sheet between the paper pressing roller 72, the nip rollers 62 and 64, or the paper pressing roller 73.

[0050] The paper pressing roller 72 is spherical, and a pair of paper pressing rollers 72 spaced apart in the width direction X with respect to one conveying roller 54 are arranged. At least one of the pair of paper pressing rollers 72 is configured to be movable in the width direction X according to the width of the conveyed sheet. With this configuration, only both end portions in the width direction X of the conveyed sheet are sandwiched between the paper pressing roller 72 and the conveying roller 54 and conveyed. When only one of the pair of paper pressing rollers 72 is movable in the width direction X, a roller-shaped paper pressing member may be used instead of the other paper pressing roller 72 that does not move in the width direction X. On the upstream side in the conveying direction Y (the right side in FIG. 6) from the foil pressing section P, the semi-cured varnish on the sheet is exposed. If the conveying member contacts the exposed varnish, problems such as the application state of the varnish being disturbed or the conveying member being soiled may occur. In contrast, by the paper pressing roller 72 pressing only both end portions in the width direction X of the sheet, the occurrence of this problem can be suppressed.

[0051] The paper pressing roller 73 is a member in which a plurality of roller portions 73a are intermittently arranged with respect to a single rotating shaft 73b extending in the width direction X. The plurality of roller portions 73a are configured not to move in the width direction (axial direction) X. On the downstream side in the conveying direction Y from the foil pressing section P, since the varnish on the sheet is fully cured, the sheet can be conveyed without the above-mentioned problems occurring even when the roller portion 73a of the paper pressing roller 73 contacts.

[0052] The unwind shaft 56 supports a roll of unused web (hereinafter referred to as the unwind roll 74). The unwind shaft 56 and the windup shaft 58 are constituted by friction shafts. This friction shaft includes an outer peripheral ring that holds a paper tube serving as the core of the unwind roll 74 or the windup roll 76, and a shaft core portion that rotatably holds the outer peripheral ring, and is configured such that the holding torque that serves as resistance when rotating the outer peripheral ring with respect to the shaft core portion is adjustable. When an external force that attempts to rotate the outer peripheral ring with respect to the shaft core portion acts, if the rotational torque due to this external force is greater than the holding torque, the outer peripheral ring rotates with respect to the shaft core portion, and if the rotational torque is smaller than the holding torque, the outer peripheral ring maintains a stopped state with respect to the shaft core portion. The shaft core portion of the unwind shaft 56 is fixed to the housing of the apparatus, and the shaft core portion of the windup shaft 58 is rotationally driven by a drive source (not shown). The unwind shaft 56 is set with the holding torque such that when a force that causes the web 52 to be carried along with the sheet or the conveying roller 54 acts in the foil pressing section P and a force that pulls out the web 52 from the unwind roll 74 acts, the outer peripheral ring rotates with respect to the fixed shaft core portion.

[0053] A plurality of guide rollers 60, a first nip roller 62, and a second nip roller 64 define a substantially U-shaped web conveyance path from the unwind roll 74 to the windup roll 76. The second nip roller 64 is adjacent to the first nip roller 62 on the downstream side of the web conveyance path. The first nip roller 62 and the second nip roller 64 define a horizontally extending section of the web conveyance path. In the present embodiment, this section corresponds to the foil pressing section P.

[0054] One of the plurality of guide rollers 60 that define the web conveyance path upstream of the foil pressing section P (hereinafter also referred to as guide roller 60a), and one of the plurality of guide rollers 60 that define the web conveyance path downstream of the foil pressing section P (hereinafter also referred to as guide roller 60b) are configured to be movable in the conveyance direction Y. Guide roller 60a is provided upstream of the other guide rollers 60 in the conveyance direction Y in a section of the web conveyance path upstream of the foil pressing section P, in a section of the web conveyance path where the web 52 travels generally vertically downward. Guide roller 60b is provided downstream of the other guide rollers 60 in the conveyance direction Y in a section of the web conveyance path downstream of the foil pressing section P, in a section of the web conveyance path where the web 52 travels generally vertically upward.

[0055] Both guide roller 60a and guide roller 60b are connected to bracket 80. Accordingly, guide roller 60a and guide roller 60b are interlocked. When the bracket 80 is moved upstream in the conveyance direction Y (the right side in FIGS. 6 and 7) by a driving device (not shown), guide rollers 60a and 60b also move upstream in the conveyance direction Y, and when the bracket 80 is moved downstream in the conveyance direction Y (the right side in FIGS. 6 and 7), guide rollers 60a and 60b also move downstream in the conveyance direction Y.

[0056] When the guide rollers 60a and 60b are moved to the upstream side in the conveyance direction Y, the conveyance path on the upstream side of the foil pressing section P in the web conveyance path becomes longer and the conveyance path on the downstream side becomes shorter. Also, when the guide rollers 60a and 60b are moved to the downstream side in the conveyance direction Y, the conveyance path on the upstream side of the foil pressing section P in the web conveyance path becomes shorter and the conveyance path on the downstream side becomes longer. Preferably, when the guide rollers 60a and 60b are moved in the conveyance direction Y, the conveyance path on the upstream side and the conveyance path on the downstream side of the foil pressing section P in the web conveyance path increase and decrease complementarily. When moving the guide rollers 60a and 60b to the upstream side in the conveyance direction Y, control is performed to increase the holding torque of the friction shaft of the pay-out shaft 56 so that the outer peripheral ring does not rotate with respect to the shaft core portion and the pay-out from the pay-out roll 74 is stopped. Thereby, at least a part of the web 52 that has passed the upstream end of the foil pressing section P, that is, at least a part of the web 52 present in the foil pressing section P, is returned to the upstream side of the foil pressing section P. That is, the return of the web 52 that has reached the foil pressing section P is realized without winding back the web 52 wound from the pay-out roll 74 to the pay-out roll 74. When the resistance when moving the web 52 by the return is smaller than the holding torque of the pay-out shaft 56, the return can be performed with the pay-out from the pay-out roll 74 stopped without performing control to increase the holding torque.

[0057] Between the first nip roller 62 and the second nip roller 64, the web 52 and the sheet come into contact. At this time, the foil is transferred from the web 52 to the semi-cured varnish on the sheet. During the transfer, since the varnish on the sheet and the web 52 temporarily adhere to each other, the web 52 is fed at the same speed as the sheet. Alternatively, the second nip roller 64 may be rotationally driven to feed the web 52 at the same speed as the sheet. Here, if a drive source for rotationally driving the nip rollers 62 and 64 is provided and a speed difference in the surface movement speed occurs between the nip rollers 62 and 64 and the opposing conveyance roller 54, a speed difference occurs between the web 52 that holds the foil and contacts the nip rollers 62 and 64 and the sheet to which the foil is transferred and contacts the conveyance roller 54, which causes wrinkles in the foil. In contrast, in the present embodiment, a drive source for rotationally driving the nip rollers 62 and 64 is not provided, and the nip rollers 62 and 64 are configured to rotate passively with respect to the movement of the web 52, thereby suppressing the occurrence of wrinkles in the foil.

[0058] The take-up shaft 58 winds up the web 52 unwound from the unwind roll 74 in a roll shape. Hereinafter, the roll-shaped web 52 wound up by the take-up shaft 58 is referred to as a take-up roll 76. The take-up shaft 58 is constituted by a friction shaft. The holding torque of the take-up shaft 58 is set to be smaller than the holding torque of the unwind shaft 56, and the axial center portion of the take-up shaft 58 is driven to rotate by a drive source (not shown). Further, the friction shaft has a plurality of outer peripheral rings in the axial direction and has a structure that allows the rotational speed to differ depending on the position in the axial direction (i.e., the width direction X). Specifically, only a part of the plurality of outer peripheral rings may rotate and the other outer peripheral rings may stop, and further, the rotational speeds of the rotating outer peripheral rings may differ from each other.

[0059] At least one of the guide rollers 60 is attached with an encoder (not shown) for detecting its rotation speed. The guide roller 60 to which the encoder is attached preferably reduces slippage with the web 52, such as by using a material with a high coefficient of friction on its surface. In the foil pressing section P, the web 52 moves downstream in the sheet conveying direction Y by the peripheral foil on its outer peripheral surface contacting the surface of the sheet or the conveying roller 54 and rotating together with these surfaces. The control device 20 calculates the moving speed of the web 52 based on the detection result by the encoder, and controls the rotation speed of the unwinding shaft 56 so that the feeding speed of the web 52 from the unwinding roll 74 becomes slower than the calculated moving speed of the web 52. At this time, although the moving speed of the web 52 is faster than the feeding by the rotation of the unwinding shaft 56, the peripheral surface of the unwinding shaft 56 made of a friction shaft rotates with respect to the driving input shaft, and by rotating faster than the driving input shaft, the web 52 can be fed out while keeping the web 52 in a tensioned state and at the same speed as the moving speed of the sheet in the foil pressing section P.

[0060] Also, the control device 20 controls the rotation speed of the driving rotation of the core part of the winding shaft 58 so that the winding speed of the web 52 by the winding roll 76 becomes faster than the moving speed of the web 52. At this time, although the moving speed of the web 52 is slower than the winding by the rotation of the unwinding shaft 56, the outer peripheral ring forming the peripheral surface of the winding shaft 58 made of a friction shaft rotates with respect to the core part which is the driving input shaft, and the driving input shaft idles with respect to the peripheral surface. Thereby, the web 52 can be wound up while keeping the web 52 in a tensioned state and at the same speed as the moving speed of the sheet in the foil pressing section P.

[0061] The ultraviolet lamp 66 for foil pressing is provided above the web conveying path between the first nip roller 62 and the second nip roller 64.

[0062] The first nip roller 62, the second nip roller 64, the ultraviolet lamp 66 for foil pressing, and some of the guide rollers 60 are each configured to be vertically movable between the lowered position shown in FIG. 6 and the raised position shown in FIG. 7. The raised position is a position where the web 52 cannot contact the sheet being conveyed. The lowered position is a position where the web 52 can contact the sheet being conveyed and adjacent and parallel to the web 52. The control device 20 positions the nip roller or the like at the raised position, for example, when not performing foil pressing on the sheet (i.e., when only applying varnish to the sheet), and positions the nip roller or the like at the lowered position when performing foil pressing on the sheet.

[0063] Among the plurality of guide rollers 60 that define the web conveyance path upstream of the foil pressing section P, the guide roller (hereinafter also referred to as guide roller 60c) located immediately upstream of the first nip roller 62 is disposed close to the first nip roller 62 and moves vertically together with the first nip roller 62 between the lowered position shown in FIG. 6 and the raised position shown in FIG. 7. Also, among the plurality of guide rollers 60 that define the web conveyance path downstream of the foil pressing section P, the guide roller (hereinafter also referred to as guide roller 60d) located immediately downstream of the second nip roller 64 is disposed close to the second nip roller 64 and moves vertically together with the second nip roller 64 between the lowered position shown in FIG. 6 and the raised position shown in FIG. 7. By providing guide rollers 60 such as guide roller 60c and guide roller 60d that are disposed close to the nip rollers 62, 64 and move vertically together with the nip rollers 62, 64, it is possible to suppress the occurrence of wrinkles in the web 52 compared to a configuration without such guide rollers 60.

[0064] The sheet detection sensor 77 is a sensor that detects the transfer timing in the foil pressing section P. The sheet detection sensor 77 detects the presence or absence of a sheet at the detection position, and based on the detection result, can detect the passing timing of the leading edge and the trailing edge of the sheet. When the nip roller or the like is in the raised position, after detecting that the leading edge of the sheet for foil pressing has passed through the detection position of the sheet detection sensor 77, the nip roller or the like is moved toward the lowered position at a predetermined timing. Also, after detecting that the trailing edge of the sheet for foil pressing has passed through the detection position of the sheet detection sensor 77, the nip roller or the like is moved from the lowered position toward the raised position at a predetermined timing as necessary.

[0065] Figure 8 is a diagram showing an enlarged view of the periphery of the foil pressing section P. Although not shown in Figures 6 and 7, the foil pressing device 16 includes a sheet conveyance guide that supports the sheet and guides the conveyance of the sheet. The sheet conveyance guide 82 corresponding to the foil pressing section P (that is, provided below the foil pressing section P) has at least a part thereof protruding above the nip line L passing through the first nip point N1 at the upstream end and the second nip point N2 at the downstream end of the foil pressing section P. The first nip point N1 is a point between the first nip roller 62 in the lowered position and the conveyance roller 54 facing it vertically, and exists on the line segment connecting the rotation axis of the first nip roller 62 when in the lowered position and the rotation axis of the conveyance roller 54 facing it vertically. The second nip point N2 is a point between the second nip roller 64 in the lowered position and the conveyance roller 54 facing it vertically, and exists on the line segment connecting the rotation axis of the second nip roller 64 when in the lowered position and the rotation axis of the conveyance roller 54 facing it vertically.

[0066] As described above, since the semi-cured varnish has tackiness, the foil held by the web 52 adheres to the varnish while being sandwiched between the first nip roller 62 and the conveying roller 54. However, for example, if the sheet separates from the web 52 during conveyance in the foil pressing section P due to the stiffness of the sheet, the varnish may cure with the unbonded foil peeled off from the varnish, resulting in a risk of transfer failure. On the other hand, since at least a part of the sheet conveying guide 82 protrudes above the nip line L, the sheet is pressed against the web 52 in the foil pressing section P, the degree of adhesion between the sheet and the web 52 increases, and the foil is prevented from peeling off from the varnish.

[0067] The material of the sheet conveying guide 82 is not particularly limited. However, since the ultraviolet rays from the ultraviolet lamp 66 for foil pressing are irradiated, a material with high heat dissipation and heat resistance such as metal is preferable. Among the light sources that can irradiate ultraviolet rays that can be used for the ultraviolet lamp 66 for foil pressing, depending on the type of wavelength of the irradiated ultraviolet rays, some generate ozone during irradiation. When a light source that generates ozone during irradiation is used as the ultraviolet lamp 66 for foil pressing, the material of the sheet conveying guide 82 preferably has ozone resistance.

[0068] The sheet conveying guide 82 is not particularly limited as long as it is a guide that supports the sheet, and it may be a plate, a block, or a roller. In the illustrated example, the sheet conveying guide 82 is a plate that is convex upward. The sheet conveying guide 82 preferably has at least a part protruding above the nip line L within the irradiation range of the ultraviolet lamp 66 for foil pressing.

[0069] FIG. 9 is a diagram showing an enlarged view of the periphery of the sheet conveyance guide 82 shown in FIG. 8 (the ultraviolet lamp 66 for foil pressing is omitted in FIG. 9). When the web 52 is stretched without the sheet conveyance guide 82, the path of the web 52, that is, the stretching line between the first nip point N1 at the upstream end and the downstream end in the foil pressing section P (transfer section), coincides with the nip line L. That is, at least a part of the sheet conveyance guide 82 protrudes above this stretching line. Therefore, since the web 52 is pushed up by the sheet conveyance guide 82, the actual path is the thick line shown in FIG. 9.

[0070] The sheet conveyance guide 82 has an upper surface 82x formed as a convex curved surface facing upward. In the range C1 where the web 52 is in contact with this upper surface 82x, it becomes a convex curved surface facing upward like the upper surface 82x. The sheet passes between the web 52 and the upper surface 82x in this range C1. Then, the leading end of the sheet always faces the tangential direction in the sheet conveyance direction Y of the curved surface forming the upper surface 82x in this range C1. This tangential direction is the direction toward the outside of the curved surface forming the upper surface 82x, that is, the direction intersecting the path of the web 52. For example, when the leading end of the sheet reaches a predetermined position D1 in the range C1, the leading end of the sheet faces the tangential direction D2. Therefore, over the entire range C1, a leading end side directing portion is formed so that the leading end side of the sheet faces the direction intersecting the path of the transfer web in the foil pressing section P.

[0071] Also, the trailing end of the sheet always faces the tangential direction in the sheet conveyance direction Y of the curved surface forming the upper surface 82x in this range C1. This tangential direction is the direction toward the outside of the curved surface forming the upper surface 82x, that is, the direction intersecting the path of the web 52. For example, when the trailing end of the sheet reaches a predetermined position D3 in the range C1, the trailing end of the sheet faces the tangential direction D4. Therefore, over the entire range C1, a trailing end side directing portion is formed so that the trailing end side of the sheet faces the direction intersecting the path of the transfer web in the foil pressing section P.

[0072] When the first nip roller 62 and the second nip roller 64 are in the raised position, as shown in FIG. 13(a), the web 52 is separated from the sheet conveyance guide 82. When it moves to the lowered position, as shown in FIG. 9, the web 52 abuts against the sheet conveyance guide 82. The leading - end - side directing portion and the trailing - end - side directing portion are formed when in this lowered position.

[0073] This movement to the lowered position may be performed after a part of the sheet near the leading end enters the foil pressing section P. For example, it is the case when it is moved to the lowered position in accordance with the timing when the varnish - coating region R formed only near the trailing end of the sheet enters the foil pressing section P. In such a case, with a part of the sheet already in the foil pressing section P, the first nip roller 62 and the second nip roller 64 move to the lowered position, and the leading - end - side directing portion is formed. At the position D1 at that time, the leading - end side of the passing sheet faces the tangential direction D2. Therefore, at the leading - end - side directing portion, the leading - end side of the passing sheet faces in a direction intersecting the path of the web 52.

[0074] Also, the movement to the raised position may be performed before a part of the sheet near the trailing end exits the foil pressing section P. For example, it is the case when it is moved to the raised position in accordance with the timing when the varnish - coating region R formed only near the leading end of the sheet exits the foil pressing section P. In such a case, with a part of the sheet still remaining in the foil pressing section P, the first nip roller 62 and the second nip roller 64 move to the raised position, and the trailing - end - side directing portion is eliminated. Until immediately before the elimination, at the position D3, the trailing - end side of the passing sheet faces the tangential direction D4. Therefore, at the trailing - end - side directing portion, the trailing - end side of the passing sheet faces in a direction intersecting the path of the web 52.

[0075] FIG. 10 is a diagram showing an enlargement of the periphery of the foil pressing section P and shows another example of the sheet conveyance guide 82. In this example, the sheet conveyance guide 82 is a block and has a flat upper surface (horizontal surface) 82a that protrudes above the nip line L in the irradiation range of the ultraviolet lamp 66 for foil pressing.

[0076] FIG. 11 is a view showing an enlarged periphery of the sheet conveyance guide 82 shown in FIG. 10 (the ultraviolet lamp 66 for foil pressing is omitted in FIG. 11). When the web 52 is stretched without the sheet conveyance guide 82, the path of the web 52, that is, the stretching line between the first nip point N1 at the upstream end and the second nip point N2 at the downstream end in the foil pressing section P (transfer section), coincides with the nip line L. Therefore, the upper surface (horizontal plane) 82a of the sheet conveyance guide 82 protrudes above the stretching line.

[0077] The sheet conveyance guide 82 further has an upward slope 82b that continuously forms an upward gradient toward the conveyance direction Y at the upstream end of the upper surface 82a in the conveyance direction Y. Also, the sheet conveyance guide 82 has a downward slope 82c that continuously forms a downward gradient toward the conveyance direction Y at the downstream end of the upper surface 82a in the conveyance direction Y.

[0078] The web 52 is pushed up by the sheet conveyance guide 82 and follows the path shown by the thick line in FIG. 11. That is, the web 52 forms an upward gradient 52a from the first nip point N1 toward the second nip point N2 and reaches the upstream end of the upper surface 82a in the conveyance direction Y. Subsequently, it forms a horizontal path while remaining in contact with the upper surface 82a until it reaches the downstream end of the upper surface 82a in the conveyance direction Y. Subsequently, it forms a downward gradient 52b and reaches the second nip point N2.

[0079] In the case of a relatively limp sheet with a semi-cured varnish applied on the sheet near the tip of the sheet, due to the tackiness of the varnish, the sheet adheres to the web 52, so the tip of the sheet advances along the upward gradient 52a of the web 52. When the tip of the sheet reaches a predetermined position D5 at that time, the tip of the sheet is facing in the same direction D6 as the upward gradient 52a. Since the web 52 is horizontal on the downstream side in its conveyance direction Y, the direction D6 intersects the path of the web 52. Therefore, at this upward gradient 52a, a tip-side directing portion is formed so that the tip side in the conveyance direction of the conveyed sheet faces in a direction intersecting the path of the web 52.

[0080] Whether the sheet is relatively stiff or relatively weak, if there is no semi-cured varnish applied on the sheet near the tip of the sheet, the tip of the sheet advances along the nip line L and contacts the upward slope 82b. Thereafter, the tip of the sheet ascends along the upward slope 82b. When the sheet reaches a predetermined position D7 at that time, the tip of the sheet faces in the direction D8 which is the extension of the line connecting the first nip point N1 and the position D7. Extending the direction D8 intersects the path of the web 52. Therefore, on this upward slope 82b, a tip-side directing portion is formed so that the tip side in the conveyance direction of the conveyed sheet faces in a direction intersecting the path of the web 52.

[0081] When the sheet is relatively weak and there is semi-cured varnish applied on the sheet near the rear end of the sheet, due to the tackiness of the varnish, the sheet is adhered to the web 52, so the rear end of the sheet advances along the downward slope 52b of the web 52. When the sheet reaches a predetermined position D9 at that time, the rear end of the sheet faces in the same direction D10 as the downward slope 52b. Since the web 52 is horizontal on the upstream side in its conveyance direction Y, the direction D10 intersects the path of the web 52. Therefore, on this downward slope 52b, a rear-end-side directing portion is formed so that the rear-end side in the conveyance direction of the conveyed sheet faces in a direction intersecting the path of the web 52.

[0082] Whether the sheet is relatively stiff or relatively weak, if there is no semi-cured varnish applied on the sheet near the rear end of the sheet, after the rear end of the sheet passes through the downstream end in the conveyance direction Y of the upper surface 82a, it separates from the web 52 and descends along the downward slope 82c. When the sheet reaches a predetermined position D11 at that time, the rear end of the sheet faces in the direction D12 which is the extension of the line connecting the position D11 and the second nip point N2. Extending the direction D12 intersects the path of the web 52. Therefore, on this downward slope 82c, a rear-end-side directing portion is formed so that the rear-end side in the conveyance direction of the conveyed sheet faces in a direction intersecting the path of the web 52.

[0083] When the first nip roller 62 and the second nip roller 64 are in the raised position, as shown in FIG. 13(b), the web 52 is separated from the sheet conveyance guide 82. When it moves to the lowered position, as shown in FIG. 11, the web 52 abuts against the sheet conveyance guide 82. The leading - side - directed portion and the trailing - side - directed portion are formed when in this lowered position.

[0084] Even if this movement to the lowered position is performed after a part of the sheet near the leading end enters the foil pressing section P, if the leading end of the sheet has reached the upper surface 82a at the time of lowering, at position D5, the leading - end side of the passing sheet faces the direction D6. Therefore, in the leading - side - directed portion, the leading - end side of the passing sheet faces in a direction intersecting the path of the web 52. If the leading end of the sheet has not reached the upper surface 82a at the time of lowering, the leading end of the sheet abuts against the inclined surface 82b and climbs the inclined surface 82b, and faces the direction D8 when reaching position D7. Therefore, in the leading - side - directed portion, the leading - end side of the sheet faces in a direction intersecting the path of the web 52.

[0085] Also, even if the movement to the raised position is performed before a part of the sheet near the trailing end exits from the foil pressing section P, if the trailing end of the sheet remains on the upper surface 82a at that time, until immediately before that, at position D9, the trailing - end side of the passing sheet faces the direction D10. Therefore, in the trailing - side - directed portion, the trailing - end side of the passing sheet faces in a direction intersecting the path of the web 52. If the leading end of the sheet has not reached the upper surface 82a at the time of rising, the trailing end of the sheet abuts against the inclined surface 82c and descends the inclined surface 82c, and faces the direction D12 when reaching position D11. Therefore, in the trailing - side - directed portion, the trailing - end side of the sheet faces in a direction intersecting the path of the web 52.

[0086] In the examples of FIGS. 9 and 11, instead of the sheet conveyance guide 82, it may be constituted by a roller member. That is, at least a part of it is arranged so as to protrude above the nip line L passing through the first nip point N1 at the upstream end and the second nip point N2 at the downstream end of the foil pressing section P. As a result, the web 52 is pushed up by its outer peripheral surface.

[0087] For example, the roller members may be rollers of the same diameter and at the same height, spaced apart in the conveyance direction Y. In this case, a tip-side directing portion is formed on the outer peripheral surface of the roller member disposed on the upstream side in the conveyance direction Y at the portion where the web 52 is being pushed up, and a rear-end-side directing portion is formed on the outer peripheral surface of the roller member disposed on the downstream side in the conveyance direction Y at the portion where the web 52 is being pushed up.

[0088] Alternatively, one relatively large-diameter roller may be disposed between the first nip point N1 and the second nip point N2 as the roller member. In this case, as in the example of FIG. 9, a tip-side directing portion and a rear-end-side directing portion are formed over the entire portion of the curved surface of the outer peripheral surface of the roller member that contacts and pushes up the web 52.

[0089] FIG. 12 is a diagram showing an enlarged view of the periphery of the foil pressing section P of yet another example (the ultraviolet lamp 66 for foil pressing is omitted in FIG. 12). In this example, a sheet support guide 83 is provided. The sheet support guide 83 has a flat upper surface 83a. This upper surface 83a is a horizontal plane and coincides with the conveyance lower surface line L2 connecting the uppermost positions of the outer peripheral surfaces of the conveyance rollers 54 facing the nip rollers 62 and 64, respectively. In the example of FIG. 12, the conveyance roller 54 facing below the nip roller 62 is also referred to as the conveyance roller 54a, and the conveyance roller 54 facing below the nip roller 64 is also referred to as the conveyance roller 54b.

[0090] The sheet support guide 83 further has an upward slope 83b that forms an upward gradient toward the conveyance direction Y, continuously connected to the upstream end portion of the upper surface 83a in the conveyance direction Y. Further, the sheet conveyance guide 83 has a bent-back portion 83c that is bent downward and in the direction opposite to the conveyance direction Y, continuously connected to the downstream end portion of the upper surface 83a in the conveyance direction Y.

[0091] The web 52 follows the path indicated by the thick line in FIG. 12. That is, the web 52 is horizontally stretched between the nip rollers 62 and 64. The nip rollers 62 and 64 are set at a height such that the web 52 is stretched with a gap D13 from the upper surface 83a of the sheet support guide 83. This gap D13 is a value slightly smaller than the thickness of the sheet which is the object to be transferred. The heights of the nip rollers 62 and 64 may be adjustable according to the thickness of the applied sheet.

[0092] The axis of the conveying roller 54a is offset by a distance D14 to the downstream side in the conveying direction Y from the axis of the nip roller 62. The height difference D15 between the axis of the conveying roller 54a and the axis of the nip roller 62 is a value obtained by adding the distance D13 to the sum of the radius of the conveying roller 54a and the radius of the nip roller 62.

[0093] When the leading end of the sheet is press-clamped between the conveying roller 54a and the nip roller 62, due to the offset in the conveying direction Y between the conveying roller 54a and the nip roller 62, the leading end of the sheet faces a direction D17 that is substantially orthogonal to the line D16 connecting the axes of the conveying roller 54a and the nip roller 62. The direction D17 intersects the path of the web 52. Therefore, in the region sandwiched between the conveying roller 54a and the nip roller 62, a leading end side directing portion is formed such that the leading end side in the conveying direction of the conveyed sheet faces the direction intersecting the path of the web 52.

[0094] The axis of the conveying roller 54b is offset by a distance D18 to the upstream side in the conveying direction Y from the axis of the nip roller 64. In the example of FIG. 12, the distance D18 is the same as the distance D14, but it is not limited to being the same. The height difference D19 between the axis of the conveying roller 54b and the axis of the nip roller 64 is a value obtained by adding the distance D13 to the sum of the radius of the conveying roller 54b and the radius of the nip roller 64.

[0095] Just before the rear end of the sheet exits from the pressure clamping between the conveying roller 54b and the nip roller 64, due to the offset in the conveying direction Y between the conveying roller 54b and the nip roller 64, the rear end of the sheet faces the direction D21 that is substantially orthogonal to the line D20 connecting the axial centers of the conveying roller 54b and the nip roller 64. The direction D21 intersects the path of the web 52. Therefore, in the region sandwiched between the conveying roller 54b and the nip roller 64, a rear-end side directing portion is formed such that the rear-end side in the conveying direction of the conveyed sheet faces the direction intersecting the path of the web 52.

[0096] The distance D13 is smaller than the thickness of the sheet, and when the sheet enters between the conveying rollers 54a, 54b and the nip rollers 62, 64, it is set to such an extent that it can advance in the conveying direction Y between them while being pressure-clamped between the web 52 along the outside of the conveying rollers 54a, 54b and the nip rollers 62, 64. Also, in the portion between the nip roller 62 and the nip roller 64, since the sheet is supported from below by the sheet support guide 83, the sheet is prevented from escaping downward. Therefore, throughout the entire foil pressing section P, the contact between the sheet and the web 52 can be promoted.

[0097] When the first nip roller 62 and the second nip roller 64 are in the raised position, as shown in FIG. 13(c), the web 52 is largely separated from the sheet support guide 83. When it moves to the lowered position, as shown in FIG. 12, the web 52 and the upper surface 83a of the sheet support guide 83 are at a position separated by the distance D13. The front-end side directing portion and the rear-end side directing portion are formed when in this lowered position.

[0098] Even if this movement to the lowered position is performed after a part near the front end of the sheet enters the foil pressing section P, at the position D16, the front-end side of the passing sheet faces the direction D17. Therefore, in the front-end side directing portion, the front-end side of the passing sheet faces the direction intersecting the path of the web 52.

[0099] Also, even if the movement to the raised position is performed before a part on the rear end side of the sheet exits from the foil pressing section P, the rear end side of the passing sheet faces the direction D21 at the position D20 until immediately before that. Therefore, in the rear end side directing portion, the rear end side of the passing sheet is directed in a direction intersecting the path of the web 52.

[0100] As a modification of the example of FIG. 12, the conveying roller 54a may be disposed slightly above the example of FIG. 12. That is, the height difference D15 between the axis of the conveying roller 54a and the axis of the nip roller 62 may be slightly smaller than the sum of the radius of the conveying roller 54a and the radius of the nip roller 62 plus the distance D13. By arranging in this way, the leading end of the sheet that has entered between the conveying roller 54a and the nip roller 62 faces further upward than the direction D17. Therefore, the directivity of the leading end side directing portion can be enhanced.

[0101] Similarly, the conveying roller 54b may be disposed slightly above the example of FIG. 12. That is, the height difference D19 between the axis of the conveying roller 54b and the axis of the nip roller 64 may be slightly smaller than the sum of the radius of the conveying roller 54b and the radius of the nip roller 64 plus the distance D13. By arranging in this way, the rear end of the sheet that has entered between the conveying roller 54b and the nip roller 64 faces further upward than the direction D21. Therefore, the directivity of the rear end side directing portion can be enhanced.

[0102] When the stretching line of the web 52 is completely parallel to the upper surface of the sheet onto which the foil is to be transferred, even if it is designed such that the web 52 contacts the upper surface of the sheet, due to component errors or the like, there are problems such as it being slightly separated or, even if in contact, the contact pressure being insufficient, resulting in poor transfer. However, in each of the examples of FIGS. 9, 11, and 12, since the leading end side of the sheet faces in a direction intersecting the path of the foil at the leading end side directing portion, pressure contact between the sheet and the foil is promoted at the leading end side of the sheet. Also, since the trailing end side of the sheet faces in a direction intersecting the path of the foil at the trailing end side directing portion, pressure contact between the sheet and the foil is promoted at the trailing end side of the sheet. Therefore, the sheet and the foil can be surely pressure contacted and the foil can be surely transferred onto the sheet.

[0103] Note that the leading end side directing portion and the trailing end side directing portion may both be provided, or only one of them may be provided. Also, in the case of a thin sheet, the gap D13 may be zero, that is, the sheet may wait in a state where the web 52 contacts the upper surface 83a of the sheet support guide 83. Further, if the gap D13 is smaller than the thickness of the sheet, the upper surface 83a may be lower than the conveyance lower surface line L2.

[0104] The above is the detailed configuration of the foil pressing device 16. Next, the operation of the foil pressing device 16 will be described.

[0105] FIGS. 14(a) to (f) are diagrams for explaining the forward and backward feeding by the foil pressing device 16. In FIGS. 14(a) to (f), the forward and backward feeding scenes are shown in time series. In FIGS. 14(a) to (d), the web 52 shown by a solid line indicates an unused web, and the web 52 shown by a dotted line indicates a used web.

[0106] In FIG. 14(a), the sheet S1 is passing through the foil pressing section P, and the foil is being transferred from the web 52 to the varnish application area R on the sheet S1. As shown in FIG. 14(b), the feeding of the web 52 is stopped at the timing when the rear end (the upstream end in the conveying direction Y) of the varnish application area R on the sheet S1 reaches the downstream end of the foil pressing section P. The control device 20 only needs to specify the timing when the rear end of the varnish application area R on the sheet S1 reaches the downstream end of the foil pressing section P based on the varnish discharge data.

[0107] As shown in FIG. 14(c), a nip roller or the like is moved to the raised position to separate the web 52 from the sheet S1 and a conveying roller 54 (not shown). In FIG. 14(d), the guide rollers 60a and 60b are moved to the upstream side in the conveying direction Y. As shown in FIG. 14(e), the nip roller or the like is moved to the lowered position at the timing when the front end of the varnish application area R of the next sheet S2 reaches the upstream end of the foil pressing section P. By the operations of FIGS. 14(c) to 14(e), at least a part of the web 52 existing in the foil pressing section P is returned to the upstream side of the foil pressing section P. That is, the feeding-back is realized. Preferably, the feeding-back is realized such that all of the unused web 52 existing in the foil pressing section P is returned to the upstream side of the foil pressing section P. Specifically, the web 52 located at the downstream end of the foil pressing section P is positioned at the upstream end of the foil pressing section P.

[0108] In FIG. 14(f), the sheet S2 is passing through the foil pressing section P, and the foil is being transferred from the web 52 to the varnish application area R on the sheet S1. At this time, first, the guide rollers 60a and 60b are moved to the downstream side in the conveying direction Y, so as to send the web 52 existing upstream of the foil pressing section P and which was in the foil pressing section P in FIGS. 14(b) and 14(c) to the foil pressing section P. After the guide rollers 60a and 60b are moved to a predetermined position (for example, the limit of the movable range on the downstream side in the conveying direction Y), the web 52 is fed to the foil pressing section by unwinding the web 52 from an unwinding roll 74 (not shown in FIG. 14).

[0109] Note that when the nip roller or the like is raised in Fig. 14(c), the web conveyance path becomes shorter. Therefore, the web 52 may be wound up by the take-up roll 76 while raising the nip roller or the like so that the web 52 does not slacken. In this case, when the nip roller or the like is lowered in Fig. 14(e), that is, when the conveyance path becomes longer, the web 52 may be unwound from the pay-out roll 74. Note that since the unused web 52 is slightly fed out into the foil pressing section P by this unwinding, the guide rollers 60a and 60b may be moved in Fig. 14(d) in consideration of this amount as well.

[0110] As described above, the present invention has been described based on the embodiments. These embodiments are illustrative, and it is understood by those skilled in the art that various modifications are possible for each of the constituent elements and combinations of each processing process, and such modifications are also within the scope of the present invention. Hereinafter, such modifications will be described.

[0111] (Modification 1) Figs. 15(a) and (b) are diagrams showing the state of foil pressing. In this example, a plurality of varnish coating regions R-i (i = 1,..., N) exist on the sheet. In this case, as shown in Figs. 15(a) and (b), the web 52 that was in contact with the region Rb-k (k = 1,..., N-1) between the varnish coating region R-k (k = 1,..., N-1) and the varnish coating region R-k+1 becomes unused.

[0112] In Fig. 15(a), the length of the region Rb-1 in the conveyance direction Y is equal to or less than the length of the foil pressing section P. In this case, when the rear end of the varnish coating region R-1 reaches the downstream end of the foil pressing section P, the varnish coating region R-2 has already reached the foil pressing section P. In this case, since it cannot be fed back, the web 52 that was in contact with the region Rb-k is wound up by the take-up roll 76 as unused.

[0113] In Fig. 15(b), the length of the region Rb-1 in the conveyance direction Y exceeds the length of the foil pressing section P. In this case, when the rear end of the varnish application region R-1 reaches the downstream end of the foil pressing section P, the varnish application region R-2 has not yet reached the foil pressing section P. In this case, the web 52 that was in contact with the region Rb-k can be used by feeding it back.

[0114] Specifically, the control device 20 identifies the existence of two varnish application regions R-1 and R-2 based on the varnish discharge data at a predetermined timing of the start of the job. Next, it is confirmed whether the length of the region Rb-1 between the two varnish application regions R-1 and R-2 exceeds the length of the foil pressing section P. If the length of the region Rb-1 is less than or equal to the length of the foil pressing section, no feeding back is performed for the region Rb-1. If the length of the region Rb-1 exceeds the length of the foil pressing section, the feeding of the web 52 is stopped at the timing when the rear end of the varnish application region R-1 reaches the downstream end of the foil pressing section P, and the web 52 corresponding to the region Rb-1 is fed back.

[0115] According to this modification example, more wasteful consumption of the foil can be reduced.

[0116] (Modification Example 2) In the embodiment, the case where the guide roller 60a and the guide roller 60b are connected via the bracket 80 and driven by a single driving device has been described, but it is not limited thereto. The guide roller 60a and the guide roller 60b may not be connected to each other and may be driven by separate driving devices. In this case, the guide roller 60a may be moved so that the conveyance path on the upstream side of the foil pressing section P becomes longer, and the guide roller 60b may be moved so that the conveyance path on the downstream side becomes shorter, and the guide roller 60a and the guide roller 60b may be interlocked.

[0117] (Modification Example 3) In the embodiment, the feeding-back is realized by moving the guide roller 60a on the upstream side and the guide roller 60b on the downstream side with respect to the foil pressing section P. However, the feeding-back may be realized by moving only the guide roller 60a on the upstream side, that is, by increasing or decreasing only the conveyance path on the upstream side. More specifically, the feeding-back may be realized by moving the guide roller 60a so that the conveyance path on the upstream side becomes longer and unwinding the used web 52 from the take-up roll 76. In this case, the outer peripheral ring of the friction shaft of the take-up shaft 58 rotates in the direction opposite to that during winding.

[0118] (Modification Example 4) Instead of the guide rollers 60a and 60b, simple non-rotating guides may be provided. In this case, the guide surface is preferably formed with low friction.

[0119] (Modification Example 5) The technical idea of the embodiment is not limited to the case of transferring the foil to the sheet. That is, the object to be transferred to which the foil pressing device 16 transfers the foil may be other than the sheet.

[0120] (Modification Example 6) The transfer material held by the web 52 and transferred in the transfer section such as the foil pressing section P is not limited to a thinly stretched metal called "foil", and may be a thin layer other than metal. Further, it may be a web as a substrate with a transfer material such as ink applied thereto, like an ink ribbon. Further, the long base sheet that supports the transfer material is not limited to a film, and may be any material such as a belt-like woven fabric that can hold the transfer material and transfer it to the object to be transferred in the transfer section.

[0121] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiments resulting from the combination have the effects of the respective embodiments and modifications being combined. Also, it is understood by those skilled in the art that the functions to be fulfilled by each constituent element described in the claims are realized by a single one of the constituent elements shown in the embodiments and modifications or by the association thereof. For example, the conveying system described in the claims is realized by a combination of the unwinding shaft 56, the winding shaft 58, the plurality of guide rollers 60, the nip rollers 62, 64, and the sheet detection sensor 77. Further, the transfer means described in the claims is realized by a combination of the nip rollers 62, 64, the conveying roller 54 facing the nip rollers 62, 64, and the ultraviolet lamp 66 for pressing the foil. Also, the web conveying path changing mechanism described in the claims is realized by a combination of the guide rollers 60a, 60b, the bracket 80, and a driving device (not shown) for moving the bracket 80. The aspects described in the claims of the present application at the time of initial filing are described below. [Aspect 1] A sheet conveyed from one direction to another direction passes through a surface modification section for modifying its surface, a resist section for positioning in the width direction orthogonal to its conveyance direction, a recording head section for discharging ink onto the surface modified by the surface modification mechanism to form an image, in this order, An inkjet recording apparatus, characterized in that the surface modification section, the resist section, and the recording head section are arranged. [Aspect 2] The surface modification section has an applied electrode and a counter electrode that are arranged to face each other across a conveyance path through which the conveyed sheet passes, and performs surface modification of the sheet by discharge between the applied electrode and the counter electrode. The inkjet recording apparatus according to Aspect 1. [Aspect 3] The resist mechanism positions the sheet in the width direction while conveying the sheet. The inkjet recording apparatus according to Aspect 1 or 2. [Aspect 4] The positioning in the width direction is performed by bringing the guide surface of a reference guide having a guide surface extending in the sheet conveyance direction and arranged on at least one side in the width direction into contact with the sheet. The inkjet recording apparatus according to Aspect 3. [Aspect 5] The resist mechanism has a skew feed mechanism for skew-feeding the sheet toward a reference guide having a guide surface extending in the sheet conveyance direction and arranged on one side in the width direction. The inkjet recording apparatus according to Aspect 3.

Explanation of Symbols

[0122] 10 Printing system 16 Foil stamping device 52 Web 74 Unwinding roll 82 Sheet conveying guide 83 Sheet support guide

Claims

1. A sheet conveyed from one direction to the other direction passes through a surface modification unit that modifies its surface, a resist unit that positions the sheet in the width direction orthogonal to the conveyance direction, a recording head unit that discharges ink onto the surface modified by the surface modification unit to form an image, in this order, the surface modification unit, the resist unit, and the recording head unit are arranged, and the resist unit has a skew feed mechanism that skews the sheet toward a reference guide having a guide surface extending in the sheet conveyance direction and arranged on one side in the width direction, the skew feed mechanism has a skew feed belt that is driven to rotate at an angle with respect to the conveyance direction so as to approach the reference guide toward the downstream side, and an air suction mechanism that sucks the lower surface of the sheet to the skew feed belt, and is characterized in that it is an inkjet recording apparatus.

2. A plurality of the skew feed belts are provided side by side with a gap in the width direction, and the air suction mechanism is provided with a plurality of openings for air suction at a portion corresponding to the gap between the plurality of skew feed belts. The inkjet recording apparatus according to claim 1.

3. A conveyance guide for receiving the lower surface of the conveyed sheet is provided on the side opposite to the reference guide in the width direction with respect to the skew feed mechanism, and the upper surface of the conveyance guide is lower than the upper surface of the skew feed belt. The inkjet recording apparatus according to claim 1 or 2.

4. The reference guide is provided horizontally along the guide surface and includes a support surface on which the sheet moves, and the upper surface of the support surface is substantially at the same height as the upper surface of the skew feed belt. The inkjet recording apparatus according to any one of claims 1 to 3.

Images