Printing device

Abstract

To prevent breakage of a splice part without lowering productivity of a printed matter.SOLUTION: While a splice part SP of a continuous form paper being conveyed as detected by a detector is positioned in a dry part 21, a control unit reduces a tension applied to the splice part SP without changing the conveyance speed of the continuous form paper WP by operating drive rollers M3 and M4. Though the splice part is susceptible to heat and has low strength, breakage of the splice part SP can thus be prevented without lowering productivity of a printed matter obtained by printing images on a continuous form paper.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a printing device that prints on continuous form (also called continuous paper) printing media, and in particular to a technique for printing on printing media that has a splice portion, which is a joint between the printing media. [Background technology]

[0002] Conventionally, there is a device of this type that prints on continuous paper, a type of continuous print medium (see, for example, Patent Document 1). The continuous paper is attached to a paper feed section in the form of a roll. When the continuous paper on the previous roll runs out, a splicer device joins the rear end of the continuous paper on the previous roll to the leading end of the continuous paper on the next roll. Hereinafter, this joint is referred to as the splice section. The continuous paper on the next roll is then sent to the printing section following the continuous paper on the previous roll, and the previous roll and the following roll are printed on consecutively.

[0003] The splice section is where the continuous paper is joined together using adhesive tape or similar, making it weaker than other sections. Therefore, tension and heat can cause the splice section to tear or peel. If the continuous paper is damaged, it must be reloaded into the paper transport path, which requires time for reprinting. Therefore, in conventional printers, the transport speed of the continuous paper is slowed down while the splice section is located between the paper feed section and the paper discharge section. This prevents damage to the splice section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6415364 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional example having such a configuration has the following problems. In other words, conventional printers perform printing while slowing down the transport speed while the splice section is positioned between the paper feed section and the paper discharge section. This results in a problem of reduced productivity of printed materials. Furthermore, because printing is performed while the transport speed is kept slow, it is inevitable that print quality will decline due to differences in the drying state and ink ejection timing.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a printing device that can prevent damage to the splice portion without reducing the productivity of printed matter. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following configuration. That is, the invention described in claim 1 is a printing device that prints on continuous printing media, comprising a conveying section that conveys the printing media, a detecting section that detects a splice portion, which is a joint, of the printing media being conveyed by the conveying section, a printing section that prints on the printing media being conveyed by the conveying section, and a drying section that performs a drying process at a drying temperature on the printing media that has been printed by the printing section and is being conveyed by the conveying section, and at least while the splice portion is located in the drying section, Without changing the transport speed of the print medium, and a control unit that operates the transport unit so as to reduce the tension applied to the splice portion.

[0008] [Operation and Effect] According to the invention described in claim 1, when a splice portion detected by the detection unit is in the drying unit among print media being transported by the transport unit, the control unit operates the transport unit to reduce the tension applied to the splice portion without changing the print media transport speed. Although the splice portion is heat-sensitive and has low strength, this can prevent damage to the splice portion without reducing the productivity of printed materials.

[0009] In the present invention, it is preferable that the control unit operates the transport unit so as to reduce tension applied to the splice unit when the splice unit passes through the printing unit (claim 2).

[0010] The control unit reduces the tension applied to the splice when the splice passes through the printing unit. This reduces the tension applied to the splice before the splice reaches the drying unit. Therefore, when the splice reaches the drying unit, the tension applied to the splice can be reliably reduced, thereby reliably preventing damage to the splice.

[0011] In order to achieve the above object, the present invention has the following configuration. That is, the invention described in claim 3 is a printing device that prints on a continuous sheet of printing media, comprising a conveying unit that conveys the printing medium, a detection unit that detects a splice portion, which is a seam, of the printing medium being conveyed by the conveying unit, a printing unit that prints on the printing medium being conveyed by the conveying unit, a drying unit that performs a drying process at a drying temperature on the printing medium printed by the printing unit and being conveyed by the conveying unit, and a control unit that operates the conveying unit to reduce the tension applied to the splice portion at least while the splice portion is located in the drying unit, and further comprises a cooling unit that is arranged downstream of the drying unit and cools the printing medium dried in the drying unit, and the control unit operates the conveying unit to reduce the tension applied to the splice portion while the splice portion is located in the cooling unit.

[0012] The cooling section is structurally designed to apply high tension to the print medium. Therefore, the control unit reduces the tension applied to the splice while the splice is positioned in the cooling section. This prevents damage to the splice in the cooling section.

[0013] In the present invention, it is preferable that the control section lowers the drying temperature while the splice section is positioned in the drying section (claim 4).

[0014] The splice portion is weak against heat and has low strength, but since the drying temperature is low while the splice portion is located in the drying section, damage caused by heat in the drying section can be prevented.

[0015] In the present invention, it is preferable that the control section restores the tension in the drying section to its original state after the splice section has passed through the drying section (claim 5).

[0016] This allows the print medium located upstream of the splice portion to be transported to the drying portion in a state suitable for drying, thereby enabling efficient drying in the drying portion.

[0017] In the present invention, it is preferable that the control section restores the tension in the cooling section after the splice section has passed through the cooling section (claim 6).

[0018] This allows the print medium located upstream of the splice portion to be transported to the cooling portion in a state suitable for cooling, thereby enabling efficient cooling in the cooling portion.

[0019] The invention described in claim 7 is a printing device that prints on continuous printing media, comprising a conveying section that conveys the printing media, a detecting section that detects a splice section, which is a joint, of the printing media being conveyed by the conveying section, a printing section that prints on the printing media being conveyed by the conveying section, and a drying section that performs a drying process at a drying temperature on the printing media that has been printed by the printing section and is being conveyed by the conveying section, and at least while the splice section is located in the drying section, Without changing the transport speed of the print medium, and a control unit that operates the drying unit so as to lower the drying temperature. The invention described in claim 10 is a printing device that prints on a continuous sheet of printing media, comprising a transport unit that transports the printing medium, a detection unit that detects a splice portion, which is a seam, of the printing medium being transported by the transport unit, a printing unit that prints on the printing medium being transported by the transport unit, a drying unit that performs a drying process at a drying temperature on the printing medium printed by the printing unit and transported by the transport unit, and a control unit that operates the drying unit to lower the drying temperature at least while the splice portion is located in the drying unit, wherein the control unit reduces the tension applied to the splice portion at least while the splice portion is located in the drying unit, and further comprises a cooling unit that is located downstream of the drying unit and cools the printing medium dried in the drying unit, and the control unit operates the transport unit to reduce the tension applied to the splice portion while the splice portion is located in the cooling unit.

[0020] [Operation and Effect] According to the invention described in claim 7, when the splice portion detected by the detection unit is located in the drying unit among the print media being transported by the transport unit, the control unit operates the drying unit to lower the drying temperature without changing the print media transport speed. Although the splice portion is heat-sensitive and has low strength, this prevents damage to the splice portion without reducing the productivity of printed materials.

[0021] In the present invention, it is preferable that the detection unit is configured as an auto splicer that generates the splice portion at the joint between the old continuous paper and the new continuous paper and outputs a splice signal to the control unit (claim 14). Furthermore, in the present invention, it is preferable that the transport section comprises a first drive roller arranged upstream of the drying section in the transport direction and a second drive roller arranged downstream of the drying section in the transport direction, the first drive roller and the second drive roller are configured to transport the printing medium, and are arranged downstream of the first drive roller in the transport direction and upstream of the second drive roller in the transport direction, and further comprise a tension sensor that detects the tension of the printing medium, the detection section being arranged upstream of the first drive roller in the transport direction, and the control section drives the first drive roller to transport the printing medium at a constant transport speed, drives the second drive roller so that a first target tension value and a tension detection value of the tension sensor match, and drives the second drive roller so that the tension applied to the splice section matches a second target tension value that is lower than the first target tension value by a predetermined value, at least while the splice section is located in the drying section (claim 15).

[0022] Since the detection unit is configured as an auto splicer, there is no need to provide a separate detection unit, which simplifies the configuration and reduces costs. [Effects of the Invention]

[0023] In the printing device according to the present invention, when a splice portion detected by the detection unit is in the drying unit while the print medium is being transported by the transport unit, the control unit operates the transport unit to reduce the tension applied to the splice portion without changing the transport speed of the print medium. Although the splice portion is heat-sensitive and has low strength, this can prevent damage to the splice portion without reducing productivity of printed materials. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram illustrating the overall configuration of a printing device according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a tension control system. [Figure 3] 10 is a flowchart showing an example of control when printing continuous paper including a splice portion. [Figure 4] FIG. 10 is a diagram illustrating an example of a transition of tension. [Figure 5] 10 is a flowchart showing another example of control when printing continuous paper including a splice portion. [Figure 6] FIG. 10 is a diagram illustrating an example of a transition of tension. [Figure 7] 10 is a flowchart illustrating an example of control in a printing device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] An embodiment of the present invention will be described below. [Example]

[0026] A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a diagram illustrating the overall configuration of a printing apparatus according to Example 1. Fig. 2 is a schematic diagram illustrating a tension control system.

[0027] The printing device 1 according to this embodiment is, for example, an inkjet printing device that prints by ejecting ink droplets. The printing device 1 includes a paper feed unit 3, an auto splicer 5, an inkjet printing device 7, a paper discharge unit 9, and a control unit 11.

[0028] The paper feed unit 3 holds, for example, a roll of continuous paper WP so that it can rotate around a horizontal axis. The paper feed unit 3 unwinds and supplies the continuous paper WP in the transport direction to the inkjet printing device 7. An auto-splitter 5 is disposed between the paper feed unit 3 and the inkjet printing device 7. The auto-splitter 5 joins the end of the continuous paper WP in the paper feed unit 3 to the beginning of a new continuous paper WP (not shown) before it runs out. The joining is performed, for example, using adhesive tape. This joint is called a splice. This splice is weaker than other parts and is also sensitive to heat.

[0029] The inkjet printing device 7 prints an image by ejecting ink droplets onto the web paper WP unwound from the paper feed unit 3 via the auto splicer 5. The inkjet printing device 7 performs a drying process on the printed web paper WP, and then performs a cooling process on the web paper WP. The inkjet printing device 7 performs an inspection process on the cooled web paper WP. The paper discharge unit 9 winds up the printed web paper WP around a horizontal axis. The control unit 11 provides overall control of the inkjet printing device 7 described above.

[0030] The above-mentioned continuous paper WP corresponds to the "printing medium" in the present invention, and the above-mentioned inkjet printing device 7 corresponds to the "printing device" in the present invention.

[0031] The inkjet printing device 7 has a first drive roller M1 on the upstream side for taking in the web paper WP from the paper feeder 3 and the auto splicer 5. The web paper WP unwound by the first drive roller M1 is transported downstream toward the paper discharge unit 9 along rotatable transport rollers 13 and the like. A detection unit SD is provided upstream of the first drive roller M1 for detecting splice portions SP formed in the web paper WP. The detection unit SD detects the splice portions SP by detecting the thickness of the web paper WP and identifying the color of the web paper WP.

[0032] An edge position control unit 15 is disposed downstream of the first drive roller M1. The edge position control unit 15 automatically adjusts the paper web WP when it meanders in a direction perpendicular to the conveying direction, and controls the paper web WP to be conveyed to the correct position in the width direction perpendicular to the conveying direction.

[0033] A second drive roller M2 is disposed downstream of the edge position control unit 15. The web paper WP sent downstream by the second drive roller M2 has its transport direction changed to a substantially horizontal position by transport rollers 13 disposed downstream of the second drive roller M2 in a printing area PA along the transport path where printing is performed. A rotary encoder (not shown) is attached to this transport roller 13. A signal from the rotary encoder is output to the control unit 11. The control unit 11 can determine the transport speed and position of the web paper WP based on the signal from the rotary encoder. In the printing area PA, multiple transport rollers 13 are disposed along the transport path of the web paper WP.

[0034] The printing unit 19 is disposed above the printing area PA. The printing unit 19 is composed of, for example, four inkjet heads 19a to 19d. For example, the most upstream inkjet head 19a ejects black (K) ink droplets, the next inkjet head 19b ejects cyan (C) ink droplets, the next inkjet head 19c ejects magenta (M) ink droplets, and the next inkjet head 19d ejects yellow (Y) ink droplets. The inkjet heads 19a to 19d are disposed at predetermined intervals in the transport direction of the web paper WP.

[0035] The transport direction of the web paper WP printed in the printing area PA is changed by the downstream transport rollers 13. The drying unit 21 is located at this position. The drying unit 21 includes transport rollers 13 that are arranged so that the web paper WP is transported in a spiral. The drying unit 21 includes, for example, four heating units H1 to H4. The four heating units H1 to H4 heat the web paper WP guided by the transport rollers 13. The four heating units H1 to H4 are arranged along the transport path of the web paper WP in the order of heating unit H4, heating unit H1, heating unit H2, and heating unit H3. Each of the heating units H1 to H4 heats the web paper WP in a non-contact manner. Each of the heating units H1 to H4 includes, for example, multiple carbon heaters that irradiate infrared rays. The drying temperature of the drying unit 21 is controlled by the control unit 11.

[0036] A drive roller M3 is disposed downstream of the drying unit 21. A cooling unit 23 is disposed downstream of the drive roller M3. The cooling unit 23 is composed of, for example, a plurality of cooling rollers 25. Specifically, a refrigerant (e.g., cooling water) flows through the cooling rollers 25. To allow the refrigerant to flow through the interior, a refrigerant inlet / outlet is formed on the rotation shaft (not shown). The cooling rollers 25 have a characteristic of having a larger inertia than the other driven roller, the transport roller 13. Therefore, the cooling unit 23 is more likely to apply a load to the web paper WP during transport. The cooling unit 23 cools the web paper WP heated in the drying unit 21 by bringing the web paper WP into contact with the outer peripheral surface of the cooling roller 25.

[0037] Downstream of the cooling unit 23, the web paper WP is changed to a substantially horizontal position by a plurality of transport rollers 13. An inspection unit 27 is disposed in this area. The inspection unit 27 inspects the image printed by the printing unit 19.

[0038] A drive roller M4 is disposed downstream of the inspection unit 27. The web paper WP transported by the drive roller M4 is changed in direction by the transport roller 13 and wound up onto the paper discharge unit 9.

[0039] The drive rollers M1 to M4 are rotated by a motor (not shown). The drive rollers M1 to M4 are composed of pinch rollers. The pinch rollers are composed of, for example, a large-diameter roller and a small-diameter roller, and clamp the web paper WP by pressing the small-diameter roller against the large-diameter roller. A tension sensor TP1 is provided on the transport roller 13, which is located between the drive rollers M1 and M2 and near the downstream side of the drive roller M1. A tension sensor TP2 is provided on the transport roller 13, which is located between the drive rollers M2 and M3 and near the downstream side of the drive roller M2. A tension sensor TP3 is provided on the transport roller 13, which is located between the drive rollers M3 and M4 and near the upstream side of the drive roller M4.

[0040] The above-mentioned conveying roller 13 and driving rollers M1 to M4 correspond to the "conveying section" in the present invention.

[0041] The control unit 11 is made up of a CPU, memory, etc. (not shown). The control unit 11 performs overall control of the inkjet printing device 7. The control unit 11 receives print data from a computer (not shown). Based on the received print data, the control unit 11 operates each unit according to specified printing conditions (for example, resolution, conveying speed, tension, drying temperature, etc.) to perform printing processing. The control unit 11 operates the drive rollers M to M4 to control the conveyance of the continuous paper WP at a predetermined conveying speed and tension according to the printing conditions. The control unit 11 operates the drying unit 21 to perform drying processing at a predetermined drying temperature according to the printing conditions.

[0042] The control unit 11 operates each of the drive rollers M1 to M4 according to the printing conditions. At that time, feedback control is performed as shown in FIG. 2. The drive roller M2 is called the base shaft. In other words, the drive roller M2 is operated so as to maintain a constant transport speed according to the printing conditions. The drive rollers M1, M3, and M4 other than the base shaft drive roller M2 are feedback controlled according to the tension sensors TP1 to TP3. In other words, the printing conditions specify the tension to be applied to the web paper WP. The control unit 11 operates the drive force of each of the drive rollers M1, M3, and M4 so as to achieve the specified target tension value.

[0043] Specifically, the control unit 11 operates the drive roller M1 so that the target tension value TT1 of the printing conditions matches the tension detected by the tension sensor TP1. The control unit 11 operates the drive roller M3 so that the target tension value TT2 of the printing conditions matches the tension detected by the tension sensor TP2. The control unit 11 operates the drive roller M4 so that the target tension value TT3 of the printing conditions matches the tension detected by the tension sensor TP3. Therefore, the tension is controlled at the target tension value TT1 in the region between the drive roller M1 and the drive roller M2. The tension is controlled at the target tension value TT2 in the region between the drive roller M2 and the drive roller M3 where the printing unit 19 and the drying unit 21 are located. The tension is controlled at the target tension value TT3 in the region between the drive roller M3 and the drive roller M4 where the cooling unit 23 is located.

[0044] Even if the transport speed of the web paper WP is specified as V1 under the specified printing conditions, the transport speed V1 remains constant regardless of the tension in the three regions. For example, if the rotation speed of drive roller M1, which is between drive roller M1 and drive roller M2, is increased, the tension detection value of tension sensor TP1 decreases, but because the rotation speed of drive roller M2, which is the base shaft, remains constant, the transport speed of the web paper WP remains constant at V1. Conversely, if the rotation speed of drive roller M1 is decreased, the tension detection value of tension sensor TP1 increases, but the transport speed of the web paper WP remains constant at V1. This relationship also holds true in the region between drive roller M2 and drive roller M3 and the region between drive roller M3 and drive roller M4.

[0045] When the detection unit SD detects a splice SP in the web paper WP, it outputs a detection signal to the control unit 11. The control unit 11 can determine the position of the splice SP in the inkjet printing device 7 from the time when the detection signal is received and the transport speed under specified printing conditions. In other words, the control unit 11 can determine whether the splice SP formed in the web paper WP is in the printing area PA directly below the printing unit 19, in the drying unit 21, or in the cooling unit 23, etc.

[0046] A feature of the control unit 11 in this embodiment is that it controls the tension depending on the position of the splice portion SP. A specific description will now be given with reference to FIG. 3. FIG. 3 is a flowchart showing an example of control when printing a continuous paper including a splice portion. It is assumed that predetermined printing conditions have been set in advance, and that the continuous paper WP is transported at a transport speed (= V1) and target tension values ​​TT1 to TT3 = 20 kg. It is also assumed that the splice portion SP has been formed in the continuous paper WP by the auto splicer 5.

[0047] Step S1 The control unit 11 determines whether the splice portion SP is located in the drying unit 21 based on the timing at which the splice portion SP is detected by the detection unit SD and the printing conditions. If the control unit 11 determines that the splice portion SP is located in the drying unit 21, the control unit 11 proceeds to the next step S2.

[0048] Step S2 The control unit 11 reduces the target tension value TT2 by a predetermined value α. For example, the predetermined value α is reduced by 2 kg (10% of the default value). As a result, the control unit 11 reduces only the target tension value TT2 from 20 kg to 18 kg. Specifically, the control unit 11 reduces the rotation speed of the drive rollers M3 and M4.

[0049] Step S3 The control unit 11 branches the process depending on whether or not the splice portion SP has passed through the drying unit 21. While the splice portion SP is in the drying unit 21, the determination in step S3 is repeated, and if the splice portion SP has passed through the drying unit 21, the process proceeds to the next step S4.

[0050] Step S4 The control unit 11 returns the target tension value TT2 to the default value. That is, the control unit 11 returns the target tension value TT2 from 18 kg to the original 20 kg. This allows the web paper WP located upstream of the splice portion SP to be transported to the drying unit 23 in a state suitable for drying. Therefore, the drying process of the web paper WP in the drying unit 23 can be performed efficiently.

[0051] Now, let us refer to Figure 4. Figure 4 is a diagram showing an example of the transition of tension. Note that in Figure 4, the target tension values ​​TT1 to TT3 are all the same value, but are drawn shifted vertically to make them easier to distinguish.

[0052] Due to the tension control by the control unit 11 described above, the target tension values ​​TT1 and TT3 remain unchanged regardless of the position of the splice portion SP. In other words, they remain the values ​​set in the printing conditions. On the other hand, the target tension value TT2 is reduced by a predetermined value α while the splice portion SP is located in the drying unit 21. Then, once the splice portion SP has passed the drying unit 21, the target tension value TT2 is returned to the default value. In other words, the predetermined value α is added to the target tension value TT2.

[0053] In this embodiment, while the splice portion SP of the transported web paper WP detected by the detection unit SD is located in the drying unit 21, the control unit 11 operates the drive roller M3 to reduce the tension applied to the splice portion SP without changing the transport speed of the web paper WP. The splice portion SP is heat-sensitive and has low strength, but this prevents damage to the splice portion SP without reducing the productivity of printed materials obtained by printing images on the web paper WP. In addition, the transport speed remains constant. Therefore, there is no difference in the drying state or ink ejection timing, and therefore a reduction in print quality is prevented.

[0054] In the above-described embodiment, the tension is controlled to be reduced only when the splice portion SP is located in the drying section 21. However, the present invention is not limited to such an embodiment, and the following modifications are possible.

[0055] (1) In the above-described embodiment, the target tension value TT2 is reduced while the splice portion SP is positioned in the drying portion 21. However, in the present invention, the target tension value TT2 may be reduced when the splice portion SP passes through the printing portion 19.

[0056] Depending on the transport speed of the web paper WP, as described above, there may be a delay in the tension actually applied, even if the target tension value TT2 is reduced when the splice portion SP reaches the drying portion 21. Therefore, the target tension value TT2 is reduced when the web paper passes through the printing portion 19. This reduces the target tension value earlier, thereby eliminating such inconvenience.

[0057] (2) As described above, the cooling section 23 is structurally subject to a load on the web paper WP. Therefore, the target tension value TT3 may be reduced by a predetermined value α while the splice portion SP is positioned in the cooling section 23. This prevents damage to the splice portion SP in the cooling section 23. Also, as in the example of the drying section 21 described above, it is preferable to return the target tension value TT3 to the default value after the splice portion SP has passed through the cooling section 23. This allows the web paper WP located upstream of the splice portion SP to be transported to the cooling section 23 in a state suitable for cooling. Therefore, the cooling process in the cooling section 23 can be performed efficiently.

[0058] (3) In the above-described embodiment, the tension is reduced only in the region of the drying section 21 and / or the cooling section 23. However, in the present invention, the tension may be reduced in each region sequentially according to the position of the splice portion SP. Specifically, for example, this may be implemented as shown in FIG. 5. FIG. 5 is a flowchart showing another example of control when printing continuous paper including a splice portion. Note that, according to the tension sensors TP1 to TP3, the area between drive roller M1 and drive roller M2 is referred to as the TP1 area, the area between drive roller M2 and drive roller M3 is referred to as the TP2 area, and the area between drive roller M3 and drive roller M4 is referred to as the TP3 area.

[0059] Step S11 The control unit 11 repeatedly executes step S11 until the detection unit SD detects the splice part SP. When the splice part SP is detected, the process proceeds to step S12.

[0060] Step S12 The control unit 11 branches the process depending on whether the splice part SP is in the TP1 area or not.

[0061] Step S13 When the control unit 11 determines that the splice portion SP is in the TP1 area, it reduces the target tension value TT1 by a predetermined value α.

[0062] Step S14 The control unit 11 branches the process depending on whether the splice part SP is in the TP2 area or not.

[0063] Step S15 When the control unit 11 determines that the splice portion SP is in the TP2 area, it reduces the target tension value TT2 by a predetermined value α. Furthermore, the control unit 11 returns the target tension value TT1 to the default value.

[0064] Step S16 The control unit 11 branches the process depending on whether the splice part SP is in the TP3 area or not.

[0065] Step S17 When the control unit 11 determines that the splice portion SP is in the TP3 area, it reduces the target tension value TT3 by a predetermined value α. Furthermore, the control unit 11 returns the target tension value TT2 to the default value.

[0066] Step S18 The control unit 11 branches the process depending on whether the splice portion SP has reached the outside of the inkjet printing device 7 or not.

[0067] Step S19 When the control unit 11 determines that the splice portion SP is outside the inkjet printing device 7, it returns the target tension value TT3 to the default value.

[0068] When tension adjustment is performed in this manner, the tension changes as shown in Figure 6. Figure 6 is a diagram showing an example of tension transition. Note that in Figure 6, the target tension values ​​TT1 to TT3 are all the same value, but are drawn shifted vertically to make them easier to distinguish. This prevents damage to the splice portion SP in each of the TP1 to TP3 areas. Furthermore, since the tension is returned to the default value at the location where the splice portion SP has passed, processing can be carried out appropriately at each location upstream of the splice portion SP.

[0069] (4) In the above-described embodiment, attention is focused only on the tension. However, attention may also be focused on the drying temperature in the drying section 21.

[0070] Specifically, when the splice portion SP is located in the drying section 21, the control section 11 reduces the target tension value TT2 and lowers the drying temperature of the drying section 21. The splice portion SP is weak to heat and has low strength. However, since the drying temperature is lowered while the splice portion SP is located in the drying section 21, damage caused by heat in the drying section 21 can be prevented. Needless to say, after the splice portion SP has passed through the drying section 21, it is preferable to return the drying temperature of the drying section 21 to the default value. [Example]

[0071] Next, a second embodiment of the present invention will be described with reference to the drawings. Note that the configuration of the printing device 1 itself is the same as that of the first embodiment described above, so a detailed description of the configuration will be omitted.

[0072] Now, reference is made to Fig. 7. Fig. 7 is a flowchart showing an example of control in the printing apparatus according to the second embodiment. The control unit 11 operates each unit under predetermined printing conditions that have been set in advance. The drying unit 23 is operated at a target temperature TM so as to reach a drying temperature specified in the printing conditions.

[0073] Step S21 The control unit 11 determines whether the splice portion SP has reached the drying unit 21 or not.

[0074] Step S22 When the control unit 11 determines that the splice portion SP has reached the drying unit 21, it lowers the target temperature TM in the drying unit 21 by a predetermined value β. Note that, taking into consideration the delay until the temperature actually drops from the target temperature TM, the target temperature TM may be lowered by the predetermined value β at the time the splice portion SP passes through the printing unit 19.

[0075] Step S23 The control section 11 determines whether the splice section SP has passed through the drying section 21 or not.

[0076] Step S24 When the control unit 11 determines that the splice portion SP has passed through the drying unit 21, it returns the target temperature TM in the drying unit 21 to the default value.

[0077] According to this embodiment, while the splice portion SP of the web paper WP being transported by the drive rollers M1 to M4 and transport roller 13 and detected by the detection unit SD is located in the drying unit 21, the control unit 11 operates the drying unit 21 to lower the drying temperature without changing the transport speed of the web paper WP. The splice portion SP is sensitive to heat and has low strength, but this makes it possible to prevent damage to the splice portion SP without reducing the productivity of printed matter.

[0078] In this embodiment, only the drying temperature in the drying section 21 is reduced. However, as in the above-described first embodiment, the tension at each location may also be reduced depending on the location of the splice portion SP.

[0079] The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0080] (1) In the first and second embodiments described above, the printing medium is the web paper WP, but the present invention is not limited to this printing medium. For example, a plastic film may be used as the printing medium.

[0081] (2) In the above-described first and second embodiments, the drying section 21 is made up of heating units H1 to H4. However, instead of this configuration, a heat roller may be used that dries the web paper WP by wrapping it around its outer periphery.

[0082] (3) In each of the first and second embodiments described above, the auto-splicer 5 is provided as an example, but the auto-splicer 5 is not an essential requirement of the present invention.

[0083] (4) In the above-described first and second embodiments, printing is performed by the inkjet printing device 7, but the present invention does not require inkjet printing. In other words, any configuration of printing device that prints on a print medium having a splice portion SP formed thereon can be applied.

[0084] (5) In the above-described first and second embodiments, a detection unit SD for detecting the splice portion SP is provided, but this is not essential to the present invention. A configuration that does not include a detection unit SD is, for example, as follows. In the following configuration, the auto splicer 5 corresponds to the "detection unit" in the present invention.

[0085] That is, the control unit 11 is connected to the auto splicer 5 and is configured to receive signals from the auto splicer 5. The auto splicer 5 joins the end of the old roll of web paper WP to the leading edge of the new roll of web paper to create a splice portion SP. The auto splicer 5 outputs a splice signal to the control unit 11 at this timing. The control unit 11 detects the occurrence of a splice portion SP in the web paper WP based on this splice signal. The control unit 11 controls the tension in the transport path based on the length of the transport path from the auto splicer 5 to the drying unit 21 and the transport speed of the web paper WP from the auto splicer 5 so that the tension decreases while the splice portion SP is located in the drying unit 21.

[0086] According to this configuration, the detection unit SD is configured as the auto splicer 5, so there is no need to provide a separate detection unit SD. Therefore, the configuration can be simplified and costs can be reduced. [Industrial Applicability]

[0087] As described above, the present invention is suitable for a printing device that prints on a print medium having a splice portion. [Explanation of symbols]

[0088] 1 … Printing device 3 … Paper feed section 5...Auto splicer 7... Inkjet printing device 9... Paper ejection section 11 ... Control section M1: First drive roller M2: Second drive roller M3: Third drive roller M4: Fourth drive roller SD: Detector PA … Print area 15...Transport roller 19 … Printing Department 21 … Drying section 23 … Cooling section TP1~TP3 ... tension sensors TT1~TT3 ... Target tension value

Claims

1. In a printing device that prints on continuous printing media, a conveying unit that conveys the print medium; a detection unit that detects a splice portion, which is a joint, of the print medium being transported by the transport unit; a printing unit that prints on the print medium being transported by the transport unit; a drying unit that performs a drying process at a drying temperature on the print medium that has been printed by the printing unit and is being transported by the transport unit; a cooling section disposed downstream of the drying section and configured to cool the print medium dried in the drying section; a control unit that operates the conveying unit to reduce tension applied to the splice portion at least while the splice portion is located in the drying unit; Equipped with The printing device, wherein the control unit operates the transport unit to reduce tension applied to the splice portion while the splice portion is positioned in the cooling unit.

2. In the printing device according to claim 1, The printing apparatus is characterized in that the control unit lowers the drying temperature while the splice unit is located in the drying unit.

3. In the printing device according to claim 1 or claim 2, The printing apparatus is characterized in that the control unit returns the tension in the drying unit to its original state after the splice unit has passed through the drying unit.

4. In the printing device according to claim 1, The printing apparatus is characterized in that the control unit returns the tension in the cooling section to its original state after the splice section has passed through the cooling section.

5. In a printing device that prints on continuous printing media, a conveying unit that conveys the print medium; a detection unit that detects a splice portion, which is a joint, of the print medium being transported by the transport unit; a printing unit that prints on the print medium being transported by the transport unit; a drying unit that performs a drying process at a drying temperature on the print medium that has been printed by the printing unit and is being transported by the transport unit; a cooling section disposed downstream of the drying section and configured to cool the print medium dried in the drying section; a control unit that operates the drying unit to lower the drying temperature at least while the splice portion is located in the drying unit; Equipped with The control unit reducing tension applied to the splice portion at least while the splice portion is positioned in the drying section; A printing apparatus, characterized in that the conveying unit is operated so as to reduce tension applied to the splice portion while the splice portion is positioned in the cooling unit.

6. In the printing device according to claim 5, The printing apparatus is characterized in that the control unit returns the drying temperature to the original value after the splice portion has passed through the drying unit.

7. In the printing device according to claim 5, The printing apparatus is characterized in that the control unit returns the tension in the drying unit to its original state after the splice unit has passed through the drying unit.

8. In the printing device according to claim 5, The printing apparatus is characterized in that the control unit returns the tension in the cooling section to its original state after the splice section has passed through the cooling section.

9. A printing device according to any one of claims 1 to 8, A printing device characterized in that the detection unit is composed of an auto splicer that generates the splice portion at the joint between old and new continuous paper and outputs a splice signal to the control unit.

10. A printing device that prints on continuous printing media, a conveying unit that conveys the print medium; a detection unit that detects a splice portion, which is a joint, of the print medium being transported by the transport unit; a printing unit that prints on the print medium being transported by the transport unit; a drying unit that performs a drying process at a drying temperature on the print medium that has been printed by the printing unit and is being transported by the transport unit; a control unit that operates the transport unit to reduce tension applied to the splice portion without changing the transport speed of the print medium at least while the splice portion is located in the drying unit; Equipped with the transport unit includes a first drive roller disposed upstream of the drying unit in the transport direction, and a second drive roller disposed downstream of the drying unit in the transport direction, the first drive roller and the second drive roller are configured to transport the print medium; a tension sensor disposed downstream of the first drive roller in the transport direction and upstream of the second drive roller in the transport direction, the tension sensor detecting the tension of the print medium; the detection unit is disposed upstream of the first drive roller in the transport direction, The control unit driving the first drive roller to transport the print medium at a constant transport speed; driving the second drive roller so that a first target tension value and a tension detected by the tension sensor coincide with each other; At least while the splice portion is positioned in the drying section, the second drive roller is driven so that the tension applied to the splice portion coincides with a second target tension value that is lower than the first target tension value by a predetermined value. A printing device characterized by:

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