Liquid ejecting apparatus

Abstract

To provide a liquid jetting apparatus capable of detecting abnormality of a fixing device based on a change in the shape of a recording medium.SOLUTION: The printer 100 includes two transport rollers 4 that are located apart from each other in the transport direction and transport the media M in the transport direction, two rotary encoders RE1 and RE2 that output the rotation amounts of the two transport rollers 4, a head assembly 1A that ejects UV curable ink onto the media M, a UV light irradiator 1A that is located downstream of the head assembly 2A in the transport direction and fixes the UV curable ink to the media, a notification unit 6, and a controller 5. The controller 5 calculates the difference between the shape of the media M in the transport direction and the reference shape of the media M based on the output of the rotary encoders RE1 and RE2. When the calculated difference exceeds a predetermined range, the controller 5 causes the notification unit 6 to notify an abnormality.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a fluid ejection device configured to eject fluid to print images on a medium. [Background technology]

[0002] Conventionally, there is a liquid ejection device that includes first and second conveyance rollers, first and second rotary encoders, a liquid ejection head, and a controller (see Patent Document 1). In this liquid ejection device, the first and second conveyance rollers rotate together with the conveyance of a long recording medium. The first and second rotary encoders detect the rotational states of the first and second conveyance rollers, respectively. The liquid ejection head has nozzles that eject liquid. The controller adjusts the timing at which liquid is ejected from the nozzles of the liquid ejection head onto the long recording medium, based on the rotational states of the first and second conveyance rollers detected by the first and second rotary encoders, respectively. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-196787 Summary of the Invention [Problem to be solved by the invention]

[0004] When printing on a recording medium that is difficult for ink to penetrate, the process may include a step of fixing the ink that has been ejected from the head and landed on the recording medium onto the recording medium. For example, if the ink is UV-curable ink, a UV light irradiation device is used as a fixator that fixes the UV-curable ink onto the recording medium.

[0005] However, if an abnormality occurs in the UV light irradiation device, the fixing energy applied from the UV light irradiation device to the ink on the recording medium may become excessive or insufficient. However, it is difficult to visually confirm an abnormality in the UV light irradiation device. Furthermore, if the fixing energy applied to the ink on the recording medium becomes excessive or insufficient, the ink cannot be properly fixed on the recording medium.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a liquid ejecting apparatus that can detect an abnormality in a fixing unit based on a change in the shape of a recording medium. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a liquid ejection device including: a conveyor having two rollers spaced apart in a conveyance direction and conveying a medium in the conveyance direction, two rotary encoders outputting the rotation amounts of the two rollers, a liquid ejection head positioned between the two rollers in the conveyance direction and ejecting a liquid onto the medium being conveyed in the conveyance direction, a fuser positioned downstream of the liquid ejection head in the conveyance direction and fixing the liquid ejected onto the medium, an alarm unit, and a controller connected to the two rotary encoders, the liquid ejection head, the fuser, and the alarm unit. During conveyance of the medium by the conveyor, after the fuser starts fixing the liquid ejected onto the medium, the controller calculates a difference between the shape of the medium in the conveyance direction and a reference shape of the medium based on outputs from the two rotary encoders, and if the difference between the shape of the medium in the conveyance direction and the reference shape of the medium exceeds a predetermined range, causes the alarm unit to issue an abnormality alert. [Effects of the Invention]

[0008] In a liquid ejection device according to an aspect of the present invention, a controller calculates the difference between the shape of the medium in the transport direction and a reference shape of the medium based on outputs from two rotary encoders while the medium is being transported by the transport device and after the fixing device has started fixing the liquid ejected onto the medium.The controller then causes the notification unit to notify of an abnormality if the calculated difference in shape in the transport direction exceeds a predetermined range.In other words, a liquid ejection device according to an aspect of the present invention can detect an abnormality in the fixing device based on a change in the shape of the recording medium. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating the overall configuration of a printer 100. FIG. [Figure 2] FIG. 2 is a plan view showing an outline of a head assembly 1A. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of the printer 100. [Figure 4] 2 is a diagram showing a schematic configuration of a flow path member 12 and an actuator member 13. FIG. [Figure 5] 10 is a table showing an example of a reference expansion / contraction ratio of a medium M. [Figure 6] 10 is a flowchart showing the flow of processing executed by the CPU 51 of the controller 5 when printing an image on the medium M. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Overall configuration of printer 100] As shown in FIG. 1, the printer 100 mainly includes head assemblies 1A to 1H, UV light irradiators 2A and 2B, a supply roller 3A, a recovery roller 3B, a feed roller 3C, a plurality of transport rollers 4, and a controller 5. The printer 100 further includes rotary encoders RE1 and RE2, rollers RL1 and RL2, and a tension sensor TS. A notification unit 6 (see FIG. 2) for notifying the user of information is disposed on the housing of the printer 100. The notification unit 6 may be, for example, a liquid crystal panel. The combination of the head assemblies 1A to 1H, the UV light irradiators 2A and 2B, the plurality of transport rollers 4, the controller 5, the notification unit 6, and the rotary encoders RE1 and RE2 of the printer 100 is an example of a liquid ejection apparatus of the present invention.

[0011] In FIG. 1, the transport direction is the direction from the supply roller 3A to the recovery roller 3B. The medium width direction is perpendicular to the transport direction and the vertical direction and is the direction along the width of the medium M. The head assemblies 1A to 1H are arranged in this order from the downstream side in the transport direction. The head assemblies 1A to 1H are each long in the medium width direction. The length of the head assemblies 1A to 1H in the medium width direction is longer than the width of the medium M. Each of the head assemblies 1A to 1H is a line type that ejects ink onto the medium M while remaining fixed in position. For example, black, cyan, violet, magenta, orange, and yellow inks are supplied to the head assemblies 1A to 1F, respectively, and white ink is supplied to the head assemblies 1G and 1H. For each color of ink, ultraviolet-curable ink (UV-curable ink) that is cured by exposure to ultraviolet light (UV light) is used. Each of the head assemblies 1A to 1H is an example of a liquid jet head of the present invention.

[0012] As an example, ten heads 1 are positioned at the vertically lower end of each of the head assemblies 1A to 1H. As shown in FIG. 2 as an example of head assembly 1A, the ten heads 1 are arranged in a staggered pattern in the width direction of the medium with their lower surfaces positioned on the same plane. A plurality of nozzles N are opened in the lower surface of each head 1. In the lower surface of each head 1, the plurality of nozzles N form two nozzle rows aligned in the transport direction. Each nozzle row extends in the width direction of the medium. In this embodiment, each head 1 has two nozzle rows formed therein, but the number of nozzle rows may be one, three or more.

[0013] As shown in FIG. 1, the UV light irradiators 2A and 2B are aligned in the transport direction. The UV light irradiator 2A is located downstream of the head assembly 1A in the transport direction. The UV light irradiator 2B is located between the head assembly 1F and the head assembly 1G. The UV light irradiators 2A and 2B each extend in the medium width direction. The lengths of the UV light irradiators 2A and 2B in the medium width direction are each longer than the width of the medium M.

[0014] At the lower vertical end of each of the UV light irradiators 2A and 2B, an LED radiation surface is located, which radiates UV light for curing the UV-curable ink. The UV light irradiators 2A and 2B irradiate the UV-curable ink sprayed onto the medium M from the head assemblies 1A to 1H with UV light. This fixes the UV-curable ink onto the medium M. The UV light irradiator 2A is an example of a fixing device of the present invention.

[0015] As shown in Figure 1, the supply roller 3A, feed roller 3C, and collection roller 3B are arranged in this order from the upstream side in the transport direction. The multiple transport rollers 4 are also arranged in the transport direction. The supply roller 3A, collection roller 3B, feed roller 3C, and multiple transport rollers 4 all extend in the medium width direction and rotate around a rotation axis that extends in the medium width direction. The lengths of the supply roller 3A, collection roller 3B, feed roller 3C, and multiple transport rollers 4 in the medium width direction are all longer than the width of the medium M. The multiple transport rollers 4 are an example of a transport device of the present invention.

[0016] The supply roller 3A and the collection roller 3B are each rotated by a drive motor (not shown). The feed roller 3C and the plurality of transport rollers 4 each rotate in conjunction with the transport of the medium M. A long medium M is wrapped around the supply roller 3A in the transport direction. The medium M may be, for example, a PET film.

[0017] The medium M wound around the supply roller 3A is fed from the supply roller 3A by the rotation of the supply roller 3A. The medium M fed from the supply roller 3A is transported while being in partial contact with the circumferential surfaces of the feed roller 3C, roller RL1, tension sensor TS, the plurality of transport rollers 4, and roller RL2, and is then taken up by the recovery roller 3B.

[0018] Each of the rollers RL1 and RL2 has a drive motor (not shown). The drive motors each of the rollers RL1 and RL2 drive the rollers RL1 and RL2 based on a signal indicating the tension of the medium M output from the tension sensor TS, thereby controlling the transport speed and tension of the medium M. As a result, the medium M is transported in the transport direction below the head assemblies 1A to 1H and the UV light irradiators 2A and 2B while contacting the upper portions of the circumferential surfaces of the plurality of transport rollers 4.

[0019] Of the multiple conveying rollers 4, a rotary encoder RE1 is attached to the rotation shaft (not shown) of the conveying roller 4 located most upstream in the conveying direction. Furthermore, a rotary encoder RE2 is attached to the rotation shaft (not shown) of the conveying roller 4 located most downstream in the conveying direction. The rotary encoder RE1 outputs the amount of rotation of the conveying roller 4 located most upstream in the conveying direction. The rotary encoder RE2 outputs the amount of rotation of the conveying roller 4 located most downstream in the conveying direction. The detection method of the rotary encoders RE1 and RE2 may be optical or magnetic.

[0020] In the transport direction, head assemblies 1A to 1H and UV light irradiators 2A and 2B are located between the transport roller 4 located most upstream and the transport roller 4 located most downstream.

[0021] 3, the controller 5 includes a CPU 51, a ROM 52, and a RAM 53. The controller 5 is electrically connected to a driver IC 14, UV light irradiators 2A and 2B, rotary encoders RE1 and RE2, and a notification unit 6, which will be described later.

[0022] 1 or an input unit (not shown), and in accordance with programs and data stored in ROM 52 and RAM 53, the CPU 51 controls the driver IC 14, the UV light irradiators 2A and 2B, the rotary encoders RE1 and RE2, the notification unit 6, etc. The external device EX is, for example, a PC.

[0023] The ROM 52 stores programs and data for the CPU 51 to perform various controls. The RAM 53 temporarily stores data used when the CPU 51 executes the programs.

[0024] The controller 5 is electrically connected to each head 1 included in each of the head assemblies 1A to 1H via a driver IC 14. The controller 5 controls each head 1 via the driver IC 14, causing the multiple nozzles N of each head 1 to eject UV-curable ink toward the medium M being transported in the transport direction. Furthermore, the controller 5 controls the UV light irradiators 2A and 2B to irradiate UV light onto the UV-curable ink ejected onto the medium M. This causes an image to be printed on the medium M.

[0025] Next, a description will be given of the flow path member 12 and the actuator member 13 that constitute each head 1 with reference to Fig. 4. Note that the structures of the flow path member 12 and the actuator member 13 are common to the ten heads 1 included in each of the head assemblies 1A to 1H, so only the flow path member 12 and the actuator member 13 in one head 1 will be described.

[0026] As shown in FIG. 4, the flow path member 12 is formed by a plurality of metal plates and a nozzle plate NP stacked in the vertical direction. Ink flow paths such as individual flow paths 12B including pressure chambers P and supply manifolds 12A are formed in the plurality of metal plates by etching. The nozzle plate NP is formed from a polymer synthetic resin material such as polyimide, and is bonded to the lower surfaces of the stacked metal plates with an adhesive. The lower surface of the nozzle plate NP forms a nozzle surface, which serves as an ink ejection surface, where nozzles N open. The nozzle plate NP may also be formed from a metal material such as stainless steel.

[0027] Inside the flow path member 12, individual flow paths 12B communicating with each nozzle N and a supply manifold 12A communicating with the individual flow paths 12B are formed. Although not shown, the supply manifold 12A extends in the medium width direction (the direction perpendicular to the paper surface in FIG. 4). The supply manifold 12A is connected to a tank (not shown) located outside the head 1 via an ink supply port (not shown) formed in the flow path member 12. Ink coming out of the tank flows into the supply manifold 12A via the ink supply port, and is supplied from the supply manifold 12A to the individual flow paths 12B.

[0028] Although not shown, the flow path member 12 is formed with a plurality of pressure chambers P that communicate with the plurality of nozzles N, respectively. The plurality of pressure chambers P open to the upper surface of the flow path member 12. The flow path member 12 is also formed with two rows of individual flow paths that extend in the medium width direction, corresponding to the two rows of nozzles that extend in the medium width direction. The supply manifold 12A communicates with a plurality of individual flow paths 12B that make up the two rows of individual flow path rows. The number of supply manifolds 12A formed in the flow path member 12 is adjusted according to the number of nozzles N. When a plurality of supply manifolds 12A are formed, the number of individual flow paths 12B that communicate with each supply manifold 12A is also adjusted according to the number of nozzles N.

[0029] 4, the actuator member 13 is fixed to the upper surface of the flow path member 12. The actuator member 13 includes a metallic vibration plate 13A, a piezoelectric layer 13B, and a plurality of individual electrodes 13C.

[0030] The actuator member 13 is formed by sequentially depositing a thin film that will become the piezoelectric layer 13B and a thin film that will become the individual electrode 13C on the upper surface of the diaphragm 13A.

[0031] The diaphragm 13A is disposed on the upper surface of the flow path member 12 so as to cover all of the pressure chambers P. The diaphragm 13A is a metal plate having a substantially rectangular shape in a plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. The upper surface of the conductive diaphragm 13A is located below the piezoelectric layer 13B. Therefore, the upper surface of the diaphragm 13A can also serve as a common electrode. The diaphragm 13A as a common electrode is connected to the ground wiring of the driver IC 14 that drives the actuator member 13 and is always maintained at ground potential. Note that the diaphragm 13A does not necessarily have to be a metal plate. For example, the diaphragm 13A may be formed from the same piezoelectric material as the piezoelectric layer 13B, with a metal film formed on its upper surface as a common electrode.

[0032] The piezoelectric layer 13B is disposed on the upper surface of the vibration plate 13A. The piezoelectric layer 13B is formed of a piezoelectric material whose main component is lead zirconate titanate (PZT), a ferroelectric solid solution of lead titanate and lead zirconate. The piezoelectric layer 13B is polarized in the vertical direction at least in the region facing the pressure chamber P (the portion sandwiched between the individual electrode 13C and the vibration plate 13A).

[0033] The individual electrode 13C is disposed on the upper surface of the piezoelectric layer 13B so as to overlap the pressure chamber P in the vertical direction. The vibration plate 13A as a common electrode, the individual electrode 13C, and a portion of the piezoelectric layer 12B sandwiched between the individual electrode 13C and the vibration plate 13A form one driving element 13X.

[0034] Next, we will explain the operation of the drive element 13X of the actuator member 13 during ink ejection. When a predetermined drive potential is applied to a certain individual electrode 13C from the driver IC 14, a potential difference is generated between the individual electrode 13C to which the drive potential is applied and the diaphragm 13A, which is held at ground potential. This generates an electric field in the thickness direction on the piezoelectric layer 13B sandwiched between the individual electrode 13C and the diaphragm 13A. The direction of this electric field is parallel to the polarization direction of the piezoelectric layer 13B. As a result, the region of the piezoelectric layer 13B facing the individual electrode 13C (active region) contracts in a planar direction perpendicular to the thickness direction. Here, the diaphragm 13A below the piezoelectric layer 13B is fixed to the flow path member 12. Therefore, as the piezoelectric layer 13B located on the upper surface of the diaphragm 13A contracts in the planar direction, the portion of the diaphragm 13A covering the pressure chamber P deforms so as to become convex toward the pressure chamber P (unimorph deformation). At this time, the volume inside the pressure chamber P decreases, so the ink pressure inside the pressure chamber P increases, and ink is ejected from the nozzle N communicating with this pressure chamber P.

[0035] When UV light is irradiated onto the UV-curable ink that has been ejected from each nozzle N and landed on the medium M, the UV-curable ink hardens and becomes fixed to the medium M. At this time, the UV-curable ink shrinks. Therefore, if a PET film is used as the medium M, the PET film also shrinks as the UV-curable ink shrinks. As a result of the shrinkage of the PET film, the length of the PET film in the transport direction becomes shorter.

[0036] Meanwhile, a certain amount of tension is applied in the transport direction by rollers RL1 and RL2 to medium M. For this reason, when the PET film serving as medium M softens due to radiant heat from UV light irradiators 2A and 2B or heat transmitted from the UV-curable ink as it hardens, the PET film stretches in the transport direction.

[0037] That is, when UV light is irradiated to fix UV-curable ink on a PET film, the PET film is subjected to a force that shrinks the PET film in the conveying direction and a force that stretches the PET film in the conveying direction. Therefore, the PET film shrinks or stretches in the conveying direction depending on the magnitude relationship between the force that shrinks the PET film in the conveying direction and the force that stretches the PET film in the conveying direction. In other words, if the force that shrinks the PET film in the conveying direction and the force that stretches the PET film in the conveying direction are not balanced, the PET film will deform in the conveying direction.

[0038] When the PET film is deformed, the amount of deformation in the conveying direction can be calculated based on the rotation amount R1 output by rotary encoder RE1 and the rotation amount R2 output by rotary encoder RE2. That is, when the PET film is stretched in the conveying direction, the rotation amount R2 of the conveying roller 4 located most downstream in the conveying direction is greater than the rotation amount R1 of the conveying roller 4 located most upstream in the conveying direction. That is, the expansion / contraction ratio expressed as (R2 / R1) is greater than 1. Conversely, when the PET film is contracted in the conveying direction, the rotation amount R2 of the conveying roller 4 located most downstream in the conveying direction is less than the rotation amount R1 of the conveying roller 4 located most upstream in the conveying direction. That is, the expansion / contraction ratio expressed as (R2 / R1) is less than 1. When the PET film is not stretched in the conveying direction, the expansion / contraction ratio expressed as (R2 / R1) is 1.

[0039] Furthermore, the expansion / contraction rate of the medium M in the transport direction varies depending on the print duty and the illuminance of the LEDs of the UV light irradiators 2A and 2B. Furthermore, the expansion / contraction rate of the medium M in the transport direction also varies depending on the type of medium M. Therefore, in this embodiment, before actual printing, test printing is performed using the medium M to be used in actual printing with the UV light irradiators 2A and 2B in a normal state. In the test printing, printing is performed while changing the print duty and the illuminance of the LEDs. This calculates the expansion / contraction rate (R2 / R1) of the medium M for each combination of print duty and LED illuminance. The calculated expansion / contraction rate (R2 / R1) of the medium M is then stored in ROM 53 as the reference expansion / contraction rate of the medium M in the transport direction. The illuminance of the LEDs is an example of the expected output energy of the present invention. The reference expansion / contraction rate is an example of the reference shape of the present invention.

[0040] FIG. 5 is a table showing an example of the reference expansion / contraction ratio of medium M in the transport direction when medium M is a PET film. For example, under conditions where the printing duty is 50% and the LED illuminance is 50%, the expansion / contraction ratio (R2 / R1) of medium M in the transport direction is 0.99. This means that medium M has shrunk in the transport direction. The value 0.99 is then stored in ROM 53 as the reference expansion / contraction ratio of medium M in the transport direction when the printing duty is 50% and the LED illuminance is 50%. Note that the LED illuminance in FIG. 5 represents the ratio of the actual illuminance to the maximum illuminance of the LED.

[0041] Furthermore, if an abnormality occurs in the UV light irradiators 2A and 2B, the fixing energy applied from the UV light irradiators 2A and 2B to the UV-curable ink on the PET film may be excessive or insufficient. For example, if the fixing energy is excessive, the impact of radiant heat from the UV light irradiators 2A and 2B will be greater. This is likely to result in a larger amount of deformation of the PET film than when the UV light irradiators 2A and 2B are normal. On the other hand, if the fixing energy is insufficient, the amount of shrinkage of the UV-curable ink on the PET film will be smaller. This is likely to result in a smaller amount of deformation of the PET film than when the UV light irradiators 2A and 2B are normal.

[0042] Therefore, when the difference between the calculated shrinkage rate of the PET film and the reference shrinkage rate exceeds a predetermined range, the controller 5 determines that an abnormality has occurred in at least one of the UV light irradiators 2A, 2B. In this case, the controller 5 causes the alarm unit 6 to notify the abnormality of at least one of the UV light irradiators 2A, 2B.

[0043] Next, the flow of processing executed by the CPU 51 of the controller 5 when UV-curable ink is ejected from the head assemblies 1A to 1H onto the medium M being transported in the transport direction to print an image will be described with reference to FIG.

[0044] 6 after receiving a print job from, for example, the external device EX and starting the transport of the medium M. When the transport of the medium M starts, the CPU 51 determines whether the transport speed of the medium M has reached a predetermined value based on the amount of rotation output by the rotary encoders RE1 and RE2 (step S101).

[0045] If it is determined that the transport speed of the medium M has not reached the predetermined value (step S101: No), the CPU 51 repeats the processing of step S101. If it is determined that the transport speed of the medium M has reached the predetermined value (step S101: Yes), the CPU 51 starts printing based on the print job (step S102). That is, the CPU 51 controls the driver IC 14 and the UV light irradiators 2A and 2B based on the print job to start ejecting UV-curable ink onto the medium M and irradiating the UV-curable ink that has landed on the medium M with UV light.

[0046] Next, the CPU 51 calculates the expansion / contraction ratio of the medium M in the transport direction based on the amount of rotation output by the rotary encoders RE1 and RE2. Then, the CPU 51 calculates the difference between the calculated expansion / contraction ratio of the medium M and a reference expansion / contraction ratio that matches the print duty and LED illuminance of the print job currently being executed, among the reference expansion / contraction ratios of the medium M stored in the ROM 53 (step S103). Note that the expansion / contraction ratio of the medium M in the transport direction calculated based on the amount of rotation output by the rotary encoders RE1 and RE2 is an example of the shape of the medium of the present invention.

[0047] Then, the CPU 51 determines whether the difference in the expansion / contraction ratio calculated in step S103 is within a predetermined range, for example, between −0.1 and +0.1 (step S104).

[0048] If it is determined that the difference in the expansion / contraction rate calculated in step S103 is within a predetermined range (step S104: Yes), the CPU 51 adjusts the timing of ejecting UV-curable ink from each nozzle N based on the expansion / contraction rate of the medium M calculated in step S103 (step S105). When the medium M is expanding, that is, when (R2 / R1)>1, the timing at which the medium M reaches directly below each nozzle N is earlier than when (R2 / R1)=1. Therefore, the CPU 51 advances the ejection timing of each nozzle N compared to when (R2 / R1)=1. Furthermore, the CPU 51 advances the ejection timing of a nozzle N located more downstream in the transport direction. On the other hand, when the medium M is contracting, that is, when (R2 / R1)<1, the timing at which the medium M reaches directly below each nozzle N is later than when (R2 / R1)=1. Therefore, the CPU 51 delays the ejection timing of each nozzle N compared to when (R2 / R1)=1. Furthermore, the CPU 51 delays the ejection timing of the nozzles N that are located on the downstream side in the transport direction.

[0049] In step S105, when adjusting the timing of ejecting UV-curable ink from each nozzle N, the CPU 51 uses the output from one of the two rotary encoders RE1 and RE2 as a reference, depending on the material of the medium M. For example, if the medium M is made of a material that easily stretches, such as PET film, the CPU 51 adjusts the ejection timing from each nozzle N based on the output of the rotary encoder RE1 located upstream in the transport direction. On the other hand, if the medium M is made of a material that does not easily stretch, such as paper, the CPU 51 adjusts the ejection timing from each nozzle N based on the output of the rotary encoder RE2 located downstream in the transport direction. This is because the head assembly 1A that ejects black ink is located at the most downstream side in the transport direction, and the ejection timing of inks of other colors is adjusted based on the ejection timing of the black ink.

[0050] Next, the CPU 51 determines whether printing based on the print job has been completed (step S106). If it determines that printing based on the print job has not been completed (step S106: No), the CPU 51 executes the processes from step S103 onwards. If it determines that printing based on the print job has been completed (step S106: Yes), the CPU 51 updates the reference expansion / contraction ratio of the medium M stored in the ROM 53 to the expansion / contraction ratio of the medium M calculated in step S103, and ends the series of processes.

[0051] On the other hand, if it is determined that the difference in the expansion / contraction ratio calculated in step S103 exceeds the predetermined range (step S104: No), the CPU 51 causes the notification unit 6 to notify the user of an abnormality in at least one of the UV light irradiators 2A, 2B (step S108). Specifically, the CPU 51 causes the liquid crystal panel serving as the notification unit 6 to display a message notifying the user of an abnormality in at least one of the UV light irradiators 2A, 2B. Furthermore, the CPU 51 controls the driver IC 14 and the UV light irradiators 2A, 2B to stop printing based on the print job (step S109), and ends the series of processes.

[0052] According to the above embodiment, the CPU 51 calculates the expansion / contraction rate of the medium M based on the amount of rotation output by the rotary encoders RE1 and RE2. If the CPU 51 determines that the difference between the calculated expansion / contraction rate of the medium M and the reference expansion / contraction rate of the medium M stored in the ROM 53 exceeds a predetermined range, the CPU 51 causes the notification unit 6 to notify the abnormality of at least one of the UV light irradiators 2A and 2B. This makes it possible to detect and notify an abnormality in the UV light irradiators 2A and 2B that is difficult to confirm visually, and to prevent printing from continuing in a state in which the UV-curable ink has not been properly fixed to the medium M.

[0053] The above-described embodiment is illustrative in all respects and is not restrictive. Not all of the components shown in the above-described embodiment are essential, and the components can be changed or omitted as necessary.

[0054] In the above embodiment, the number of head assemblies was eight, but the number and arrangement of the head assemblies can be changed as appropriate. Similarly, the number and arrangement of the heads 1 included in one head assembly can be changed as appropriate. Furthermore, the number and arrangement of the nozzles N included in each head 1 can also be changed as appropriate.

[0055] In the above embodiment, the printer 100 includes head assemblies 1A to 1H and is configured to eject ink of seven colors: black, cyan, violet, magenta, orange, yellow, and white. However, the present invention is not limited to this configuration, and the printer 100 may be configured to eject ink of any appropriate color.

[0056] In the above embodiment, the number of UV irradiators is two, but the number of UV irradiators may be one or three or more depending on the number of head assemblies. In either case, one UV irradiator may be located downstream in the transport direction from the head assembly located most downstream in the transport direction. Furthermore, when the number of UV irradiators is three or more, the UV irradiators other than the one UV irradiator may be located between two head assemblies adjacent to each other in the transport direction.

[0057] The controller 5 may be electrically connected to a drive motor (not shown) that drives the supply roller 3A and the collection roller 3B, a drive motor (not shown) that drives the rollers RL1 and RL2, and a tension sensor TS. The controller 5 may then control the drive motor (not shown) that drives the supply roller 3A and the collection roller 3B, and the drive motor (not shown) that drives the rollers RL1 and RL2, based on a signal output from the tension sensor TS.

[0058] The medium M is not limited to a PET film, but may be, for example, a PP film, paper, or a medium made of paper coated with resin.

[0059] In the above embodiment, UV-curable ink is used as the liquid ejected from the nozzle N, but the liquid is not limited to UV-curable ink. For example, water-based ink may also be used as the liquid. In this case, a heater, for example, may be used as a fixator that fixes the water-based ink to the medium M.

[0060] In the above embodiment, the CPU 51 calculates the expansion / contraction rate in the transport direction of the medium M based on the amount of rotation output by the rotary encoders RE1 and RE2, but this is not limited to this. The CPU 51 may also calculate the amount of change in the length of the medium M in the transport direction, i.e., the amount of expansion / contraction of the medium M in the transport direction, based on the amount of rotation output by the rotary encoders RE1 and RE2. In this case, the amount of expansion / contraction of the medium M in the transport direction is an example of the shape of the medium of the present invention. Furthermore, in test printing, the CPU 51 may also calculate the amount of expansion / contraction of the medium M in the transport direction based on the amount of rotation output by the rotary encoders RE1 and RE2. Then, the amount of expansion / contraction of the medium M in the transport direction calculated in the test printing may be stored in the ROM 53 as the reference amount of expansion / contraction of the medium M in the transport direction. In this case, the reference amount of expansion / contraction is an example of the reference shape of the present invention.

[0061] In the above embodiment, the CPU 51 calculates the difference between the expansion / contraction rate of the medium M and the reference expansion / contraction rate in step S103 after starting the ejection of UV-curable ink and the irradiation of UV light in step S102. However, this is not limited to this. For example, the CPU 51 may calculate the difference between the expansion / contraction rate of the medium M and the reference expansion / contraction rate after the conveyance speed reaches a predetermined value (step S101: Yes) and before starting the ejection of UV-curable ink and the irradiation of UV light in step S102. Before starting the ejection of UV-curable ink and the irradiation of UV light, the UV light irradiators 2A and 2B are not yet in use. Therefore, it is unlikely that at least one of the UV light irradiators 2A and 2B is abnormal. However, because the conveyance of the medium M has started, the tension sensor TS is operating, and there is a possibility that an abnormality has occurred in the tension sensor TS. If an abnormality has occurred in the tension sensor TS, the medium M may not be given appropriate tension, and the difference between the expansion / contraction rate of the medium M and the reference expansion / contraction rate may exceed the predetermined range. Therefore, after the conveying speed reaches a predetermined value, if the difference between the expansion / contraction rate of the medium M and the reference expansion / contraction rate exceeds a predetermined range before the ejection of UV-curable ink and the irradiation of UV light begin, the CPU 51 may cause the alarm unit 6 to alarm about an abnormality in the tension sensor TS.

[0062] In the above embodiment, the CPU 51 displays a message on the liquid crystal panel serving as the notification unit 6 to notify the user of an abnormality in at least one of the UV light irradiators 2A, 2B. However, this is not limiting. For example, the CPU 51 may display an error code on the liquid crystal panel to notify the user of an abnormality in at least one of the UV light irradiators 2A, 2B. Alternatively, the CPU 51 may light or flash a lamp serving as the notification unit 6, or may sound an alarm from a speaker serving as the notification unit 6. Alternatively, the CPU 51 may execute a program that displays a message indicating an abnormality in at least one of the UV light irradiators 2A, 2B on the display unit of the external device EX. In this case, the program that displays a message indicating an abnormality on the display unit of the external device EX is an example of a notification unit of the present invention.

[0063] In the above embodiment, after the abnormality of the UV light irradiator is notified in step S108, printing based on the print job is stopped in step S109. However, the order of notifying the abnormality and stopping printing is not limited to this. For example, the abnormality of the UV light irradiator may be notified after printing based on the print job is stopped, or the abnormality of the UV light irradiator may be notified and printing based on the print job may be stopped in parallel. [Explanation of symbols]

[0064] 1 head 1A~1H Head Assembly 2A, 2B UV light irradiation machine 3A Supply Roller 3B Collection roller 3C Feed Roller 4 Conveyor roller 5 Controller 6. Notification Department 100 printers RE1, RE2 rotary encoders RL1, RL2 rollers TS tension sensor

Claims

1. a conveyor having two rollers spaced apart from each other in a conveyance direction, and conveying the medium in the conveyance direction; two rotary encoders for outputting the rotation amounts of the two rollers, respectively; a liquid ejection head positioned between the two rollers in the transport direction and configured to eject liquid onto the medium being transported in the transport direction; a fixing unit located downstream of the liquid ejection head in the transport direction, the fixing unit fixing the liquid ejected onto the medium onto the medium; The notification department, a controller connected to the two rotary encoders, the liquid ejection head, the fixing unit, and the notification unit; The controller, during the conveyance of the medium by the conveyance device, after the fixing of the liquid sprayed onto the medium by the fixing device has started, calculating a difference between the shape of the medium and a reference shape of the medium in the transport direction based on outputs from the two rotary encoders; The liquid ejecting device causes the notifying unit to notify an abnormality when a difference between the shape of the medium and a reference shape of the medium in the transport direction exceeds a predetermined range.

2. 2. The liquid ejection device according to claim 1, wherein the controller adjusts the ejection timing of the liquid ejection head based on the difference between the shape of the medium and the reference shape of the medium in the transport direction when the difference between the shape of the medium and the reference shape of the medium in the transport direction is within the predetermined range.

3. The liquid ejecting apparatus according to claim 2 , further comprising a memory in which the reference shape of the medium in the transport direction is stored.

4. 4. The liquid ejecting apparatus according to claim 1, wherein the abnormality is an abnormality in the fixing unit.

5. 4. The liquid ejection device of claim 3, wherein, when the difference between the shape of the medium and the reference shape of the medium in the transport direction is within the specified range, the controller updates the reference shape of the medium stored in the memory to the shape of the medium after the liquid ejection head has finished ejecting the liquid onto the medium and the fixation of the liquid onto the medium by the fixation device has finished.

6. The liquid ejecting apparatus according to claim 1 , wherein the reference shape of the medium is determined based on the type of the medium, a planned output energy of the fixing unit, and a print duty.

7. The liquid ejection apparatus according to claim 2 , wherein the controller determines the ejection timing of the liquid ejection head based on an output from one of the two rotary encoders that is located upstream in the transport direction.

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