Liquid ejection device and liquid ejection method

Abstract

To provide a liquid discharging apparatus excellent in liquid discharge accuracy.SOLUTION: A liquid discharging apparatus according to one aspect of the present invention is a liquid discharging apparatus that discharges liquid onto a long recording medium that is conveyed, the liquid ejecting apparatus including: a plurality of liquid discharging means that discharges liquid onto the recording medium that is conveyed; a plurality of imaging means that are provided corresponding to positions of the liquid discharging means and outputs captured images obtained by imaging the recording medium that is conveyed. The image forming apparatus includes control means for controlling liquid discharging timing by the plurality of liquid discharging means on the basis of an effective image region in each of the plurality of captured images output from the plurality of imaging means; and changing means for changing at least one of a position, a shape, and size of the effective image region on the basis of an expansion / contraction state of the recording medium.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus and a liquid ejection method. [Background technology]

[0002] Conventionally, liquid ejection devices that eject liquid onto a conveyed long recording medium are known. Such liquid ejection devices are used in applications such as image forming devices that form an image on a long recording medium such as continuous paper using the ejected liquid.

[0003] In a liquid ejection device, a configuration is disclosed in which the timing of liquid ejection by multiple liquid ejection units is controlled based on the transport amount error in the transport direction of a long recording medium, which is detected by multiple detection units provided corresponding to the positions of each of the multiple liquid ejection units (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid ejection device, the precision of liquid ejection may be reduced due to expansion and contraction of the recording medium being transported.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection device that has excellent liquid ejection accuracy. [Means for solving the problem]

[0006] A liquid ejection device according to one aspect of the present invention is a liquid ejection device that ejects liquid onto a long recording medium being transported, and includes: a plurality of liquid ejection means that eject liquid onto the recording medium being transported; a plurality of image capture means that are provided corresponding to the positions of the liquid ejection means and output captured images of the recording medium being transported; and a plurality of liquid ejection means that output captured images of the recording medium being transported based on an effective image area of ​​each of the captured images output from the plurality of image capture means. meansand a change unit that changes at least one of the position, shape, and size of the effective image area based on the expansion and contraction state of the recording medium. The number of the plurality of imaging means is less than the number of the plurality of liquid ejection means, and one of the plurality of imaging means is disposed at a position corresponding to the position of the liquid ejection means disposed most upstream in the conveying direction among the plurality of liquid ejection means. . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a liquid ejection device that has excellent liquid ejection accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a liquid ejection device according to an embodiment; [Figure 2] FIG. 2 is a block diagram illustrating the configuration of the periphery of a liquid ejection unit according to the embodiment. [Figure 3] FIG. 2 is a block diagram illustrating an example of a functional configuration of a control IC according to an embodiment. [Figure 4] 10 is a flowchart of an example of processing by a control IC according to the embodiment. [Figure 5] 10A and 10B are diagrams illustrating an example of the relationship between a captured image and an effective image area. [Figure 6] FIG. 10 is a diagram illustrating an example of an effective imaging area before a position change. [Figure 7] FIG. 10 is a diagram illustrating an example of an effective imaging area after a position change. [Figure 8] FIG. 1 is a first diagram showing an example of expansion and contraction of continuous paper depending on the ink application area. [Figure 9] FIG. 2 is a second diagram showing an example of expansion and contraction of continuous paper depending on the ink application area. [Figure 10] 10A and 10B are diagrams illustrating examples of changes in the shape of the effective imaging area according to the expansion and contraction state of the continuous paper. [Figure 11] 10A and 10B are diagrams illustrating an example of image data correction according to the expansion and contraction state of continuous paper. [Figure 12] FIG. 10 is a diagram illustrating an example of the configuration of a liquid ejection device according to a first modified example. [Figure 13] FIG. 10 is a diagram illustrating an example of the configuration of a liquid ejection device according to a second modified example. [Figure 14]FIG. 10 is a diagram illustrating the configuration of a liquid ejection device according to a third modified example. [Figure 15] FIG. 10 is a diagram illustrating an example of the configuration of a liquid ejection device according to a fourth modified example. [Figure 16] FIG. 10 is a diagram illustrating an example of the configuration of a liquid ejection device according to a fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0010] Furthermore, the embodiments shown below are examples of liquid ejection devices that embody the technical concepts of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the shapes of the components described below, their relative locations, parameter values, etc. are intended to be illustrative and not to limit the scope of the present invention. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity of explanation.

[0011] The liquid ejection device according to the embodiment ejects liquid onto a conveyed long recording medium. In the embodiment, an inkjet liquid ejection device that ejects ink onto continuous paper, which is a long sheet of paper, to form an image is described as an example. Here, continuous paper is an example of a long recording medium, and ink is an example of a liquid. Note that the terms image formation, printing, printing, and recording in the embodiment are all synonymous.

[0012] <Configuration example of liquid ejection device 1> FIG. 1 is a diagram illustrating the configuration of a liquid ejection device 1 according to an embodiment.

[0013] In this embodiment, the liquid ejection devices 210K, 210Y, 210M, and 210C each eject ink and apply the ink to the continuous paper 120 to form an image. When there is no need to distinguish between the liquid ejection devices 210K, 210Y, 210M, and 210C, they will be referred to as liquid ejection device 210.

[0014] The liquid ejection means 210K ejects black ink, the liquid ejection means 210Y ejects yellow ink, the liquid ejection means 210M ejects magenta ink, and the liquid ejection means 210C ejects cyan ink. Each color ink forms a color image on the continuous paper 120. In the following, for ease of explanation, black may be referred to as K, yellow as Y, magenta as M, and cyan as C.

[0015] 1, liquid ejection devices 210K, 210Y, 210M, and 210C are provided around the continuous paper 120. The liquid ejection devices 210K, 210Y, 210M, and 210C eject ink onto the continuous paper 120 as it is transported.

[0016] The continuous web 120 is stretched across a drive roller 230 and eight support rollers 220. The continuous web 120 is driven by the drive roller 230 and moves along a conveying direction 2. The conveying direction 2 is the direction in which the continuous web 120 moves as the drive roller 230 rotates.

[0017] Eight support rollers 220 provided opposite the liquid discharge means 210 maintain the tension state of the continuous paper 120 when ink is discharged from the liquid discharge means 210 .

[0018] The imaging means 52A and 52C are provided corresponding to the positions of the liquid discharge means 210K and 210M, and output images of the continuous paper 120 being conveyed.

[0019] In this embodiment, the imaging means 52A is positioned upstream in the conveying direction of the continuous paper 120 from the ejection position where ink is ejected from the liquid ejection means 210K. The imaging means 52C is positioned at a position corresponding to the position of the liquid ejection means 210M. The position corresponding to the position of the liquid ejection means 210M is, for example, immediately below the position where the liquid ejection means 210M ejects ink onto the continuous paper 120.

[0020] There are four liquid dischargers 210 and two imaging devices 52A and 52B, so the number of imaging devices 52A and 52B is less than the number of liquid dischargers 210. Of the imaging devices 52A and 52B, imaging device 52A is disposed at a position corresponding to the position of liquid discharger 210K, which is disposed most upstream in conveyance direction 2 among the four liquid dischargers 210. The position corresponding to the position of liquid discharger 210K is, for example, immediately below the position where liquid discharger 210K discharges ink onto the continuous paper 120.

[0021] The imaging units 52A and 52C each include an LED (Light Emitting Diode) and an imaging element, which may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) including a plurality of pixels.

[0022] The imaging means 52A and 52C irradiate the continuous paper 120 with light from the LED, capture an image of a predetermined imaged area of ​​the continuous paper 120 using the imaging element, and output the captured images Sa and Sc to the control means 520. The predetermined imaged area corresponds to an area on the continuous paper 120 that can be imaged by each of the imaging means 52A and 52C.

[0023] The surface of the continuous paper 120 includes a background pattern due to paper fibers and the like, and the pattern of the background pattern varies depending on the position on the continuous paper 120. The imaging means 52A and 52C, for example, image this background pattern on the continuous paper 120. However, the object imaged by the imaging means 52A and 52C is not limited to the background pattern, and the imaging object may also be a mark provided in advance on the continuous paper 120, or a speckle pattern that occurs when laser light is irradiated onto the continuous paper 120.

[0024] The control means 520 controls the ink ejection timing of the liquid ejection means 210K, 210Y, 210M, and 210C based on the effective image areas included in the captured images Sa and Sc, respectively.

[0025] Specifically, the control means 520 detects the transport distance error of the continuous paper 120 in the transport direction 2 based on the effective image area in each of the captured images Sa and Sc, and controls the ink ejection timing of the liquid ejection means 210K, 210Y, 210M, and 210C in accordance with this transport distance error. Here, the effective image area refers to a portion of the image area in each of the captured images Sa and Sc that is used to detect the transport distance error.

[0026] The control means 520 can also control the transport of the continuous paper 120, in addition to controlling the timing of ink ejection by the liquid ejection means 210Y, 210M, and 210C.

[0027] <Configuration example of the liquid ejection means 210 and its surroundings> Fig. 2 is a block diagram illustrating an example of the configuration around the liquid discharge means 210. Note that, since the liquid discharge means 210K, 210C, 210M, and 210Y all have the same configuration, Fig. 2 will explain one liquid discharge means 210 as an example.

[0028] 2, the liquid ejection means 210 has a head substrate 201, a piezoelectric element support substrate 202, a piezoelectric element driving IC (Integrated Circuit) 203, and a plurality of piezoelectric elements 204. The piezoelectric element driving IC 203 also has a plurality of switching circuits 205 that are paired with the plurality of piezoelectric elements 204.

[0029] The liquid discharge means 210 is communicably connected to a head drive substrate 100 that drives the liquid discharge means 210. The head drive substrate 100 is communicably connected to an external PC (Personal Computer) 300. In this embodiment, the head drive substrate 100 is included in the control means 520, but may be provided separately from the control means 520.

[0030] The liquid ejection means 210 is provided with a plurality of liquid chambers for storing ink, and each of the plurality of liquid chambers is provided with a nozzle for ejecting ink. A plurality of piezoelectric elements 204 are provided in pairs in the plurality of liquid chambers.

[0031] The piezoelectric elements 204 expand and contract in response to the drive waveform signals, generating pressure that is applied to the ink in the liquid chamber, causing the ink to be ejected from the nozzle. Each of the switching circuits 205 is an electric circuit that switches between an ink ejection state and a non-ejection state of the piezoelectric elements 204.

[0032] The head drive circuit board 100 has a control IC 101, drive waveform generation means 102A and 102B, and a memory 103. The control IC 101 receives image data Im, which is the basis for image formation by the liquid ejection device 1, from an external PC 300, and transmits this image data Im and an ejection timing signal tt to the liquid ejection means 210. The ejection timing signal tt is a signal that corresponds to the timing at which ink is ejected by the liquid ejection means 210.

[0033] The control IC 101 determines the ink ejection timing based on the captured images Sa and Sc captured by the imaging units 52 A and 52 C. The control IC 101 outputs an ejection timing signal tt to the liquid ejection unit 210 according to the determined ink ejection timing.

[0034] The drive waveform generating means 102A outputs a drive waveform signal VcomA generated in accordance with image data Im received via the control IC 101 to the liquid ejection means 210. The drive waveform generating means 102B outputs a drive waveform signal VcomB generated in accordance with image data Im received via the control IC 101 to the liquid ejection means 210.

[0035] The memory 103 is a storage device such as a read only memory (ROM), a hard disk drive (HDD), or a solid state drive (SSD).

[0036] In response to image data Im and an ejection timing signal tt, the multiple switching circuits 205 output drive waveform signals VcomA and VcomB to the piezoelectric elements 204 to be put into an ejection state among the multiple piezoelectric elements 204. The piezoelectric elements 204 that are put into an ejection state apply pressure to the ink in the liquid chamber in response to the input drive waveform signals VcomA and VcomB, causing ink to be ejected from the nozzles at the ink ejection timing in accordance with the ejection timing signal tt.

[0037] <Example of control IC101 function configuration> Fig. 3 is a block diagram illustrating an example of the functional configuration of the control IC 101. As shown in Fig. 3, the control IC 101 has a detection unit 111, a determination unit 112, a communication unit 113, an acquisition unit 114, a change unit 115, a correction unit 116, and an ejection control unit 117. Note that Fig. 3 shows the main components of the control IC 101, but the control IC 101 may have components other than those shown in Fig. 3.

[0038] The control IC 101 detects the transport distance error of the continuous paper 120 in the transport direction 2 using the detection unit 111, and determines the ink ejection timing of each of the liquid ejection means 210C, 210M, and 210Y based on the detected transport distance error using the determination unit 112. The control IC 101 causes the liquid ejection means 210K, 210C, 210M, and 210Y to eject ink at the determined ink ejection timing using the ejection control unit 117.

[0039] Control IC 101 also receives a print job including image data Im from external PC 300 via communication unit 113, and acquires, via acquisition unit 114, information on the internal device temperature constant T1, drying process temperature constant T2, humidity constant H1, continuous paper type constant P1, ink type constant In1, ink ejection amount constant In2 onto the front (first side) of continuous paper 120, and tension constant Te. Based on the information acquired via acquisition unit 114, control IC 101 controls the driving of movement mechanisms 53A and 53C via change unit 115, and controls the positions of imaging means 52A mounted on movement mechanism 53A and imaging means 52C mounted on movement mechanism 53C.

[0040] Furthermore, the control IC 101 corrects the image data Im using the correction unit 116 based on the various information acquired by the acquisition unit 114, and causes the ejection control unit 117 to eject ink from the liquid ejection means 210 based on the corrected image data Im'.

[0041] A more detailed explanation will be given below. If the distance between imaging means 52A and imaging means 52C in conveying direction 2 is D [m] and the conveying speed of continuous paper 120 is V [m / s], then a predetermined imaged area of ​​continuous paper 120 passes the position where imaging means 52A is located, and then passes the position where imaging means 52C is located after the passage of time T (=D / V [s]).

[0042] However, this time T will be offset if there is an error in the amount of transport of the continuous paper 120 by the liquid ejection device 1. The control IC 101 captures the imaged area of ​​the continuous paper 120 using the imaging means 52A and outputs the captured image Sa, and then, after the elapse of the time T, captures the imaged area of ​​the continuous paper 120 using the imaging means 52C and outputs the captured image Sc.

[0043] If there is a transport distance error in the continuous paper 120, the image of the captured area of ​​the continuous paper 120 in the captured image Sc will be shifted in the transport direction 2 relative to the image of the captured area of ​​the continuous paper 120 in the captured image Sa according to the transport distance error.

[0044] The detection unit 111 performs a cross-correlation calculation between the captured image Sa and the captured image Sc, and calculates the amount of deviation Δ of the captured image Sc relative to the captured image Sa in the conveying direction 2. From the calculated amount of deviation Δ, the detection unit 111 detects the conveying distance error ΔDm of the continuous paper 120 at the position of the liquid discharge means 210M.

[0045] Here, with respect to the reference liquid discharge means 210K, each of the liquid discharge means 210C, 210M, and 210Y is disposed at a distance y apart in the transport direction 2. This distance y can be expressed by the following equation (1). y=a×x+b+T1+T2+H1+P1+I1+I2+Te...(1)

[0046] The distance x represents a predetermined distance from the liquid discharge means 210K. The multiple liquid discharge means 210 are arranged at equal intervals d. Therefore, ideally, the distance xc at the position of the liquid discharge means 210C is equal to the interval d, the distance xm at the position of the liquid discharge means 210M is equal to twice the interval d, and the distance xy at the position of the liquid discharge means 210Y is equal to three times the interval d.

[0047] However, the actual positions of the liquid dischargers 210C, 210M, and 210K may deviate from the ideal positions due to manufacturing errors in the liquid discharger 1. In this embodiment, the actual positions of the liquid dischargers 210C, 210M, and 210K can be expressed by the above formula (1) using predetermined constants a, b, T1, T2, H1, P1, I1, I2, and Te.

[0048] Constant a is the ratio error of the distances among the plurality of liquid discharge means 210. Constant b is the variation error among the plurality of liquid discharge means 210. The ratio error and variation error occur during the manufacturing process of the liquid discharge device 1, and are therefore measured during the manufacturing process and stored in memory 103. Detection unit 111 detects the transport amount error using the ratio error and variation error stored in memory 103.

[0049] The constants T1, T2, H1, P1, I1, I2 and Te represent the amount of expansion and contraction according to the expansion and contraction state of the continuous paper 120, and are acquired by the acquisition unit 114 described later and provided from the acquisition unit 114 to the detection unit 111.

[0050] The detection unit 111 calculates the transport distance error ΔDc at the position of the liquid discharger 210C other than the transport distance error ΔDm at the position of the liquid discharger 210M using the following equation (2), and calculates the transport distance error ΔDy at the position of the liquid discharger 210Y using the following equation (3). The detection unit 111 outputs the calculated transport distance errors ΔDc, ΔDm, and ΔDy to the determination unit 112. ΔDc=a×(ΔDm / 2)+b+T1+T2+H1+P1+I1+I2+Te...(2) ΔDy=a×(3×ΔDm / 2)+b+T1+T2+H1+P1+I1+I2+Te...(3)

[0051] Based on the transport distance errors ΔDc, ΔDm, and ΔDy input from the detection unit 111, the determination unit 112 determines the ink ejection timing of each of the liquid ejection means 210C, 210M, and 210Y relative to the ejection of the liquid ejection means 210K.

[0052] For example, the determination unit 112 counts the number of clock pulses of a fixed clock signal output by a rotary encoder provided on the drive roller 230, triggered by the timing when the liquid discharger 210K discharges ink. The determination unit 112 determines the ink discharge timing to be the timing when the number of clock pulses reaches the target pulse number corresponding to each of the liquid dischargers 210C, 210M, and 210Y, corrected for the conveyance distance errors ΔDc, ΔDm, and ΔDy. The determination unit 112 outputs a discharge timing signal tt corresponding to the determined ink discharge timing to the discharge control unit 117.

[0053] The communication unit 113 controls communication between the external PC 300 and the control IC 101. In this embodiment, the control IC 101 receives image data Im, which is the source of the image to be formed on the continuous form 120, from the external PC 300 via the communication unit 113.

[0054] The acquisition unit 114 inputs in-apparatus temperature information t1 from an apparatus temperature sensor 54 disposed within the liquid ejection apparatus 1, inputs drying process temperature information t2 from a drying process temperature sensor 55 disposed in a drying apparatus provided downstream of the liquid ejection apparatus 1, and inputs humidity information h1 from a humidity sensor 56 disposed within the liquid ejection apparatus 1. The acquisition unit 114 also inputs tension information te from a tension sensor 57 disposed within the liquid ejection apparatus 1 that detects the tension applied to the continuous paper 120, and inputs continuous paper type information p1, ink type information in1, and ink ejection amount information in2 onto the second side of the continuous paper 120 from the print job. This information is collectively referred to as stretch state information U. Based on the input stretch state information U, the acquisition unit 114 references memory 103 in which correspondence information 130 is stored to acquire constant information V.

[0055] The constant information V is information that represents a plurality of constants according to the expansion and contraction state of the continuous paper 120. The constant information V includes a constant T1, a constant T2, a constant H1, a constant Te, a constant P1, a constant In1, and a constant In2.

[0056] Correspondence information 130 includes information indicating the correspondence relationship between internal device temperature information t1 and constant T1, the correspondence relationship between drying process temperature information t2 and constant T2, the correspondence relationship between humidity information h1 and constant H1, and the correspondence relationship between tension information te and constant Te. Correspondence information 130 also includes information indicating the correspondence relationship between continuous paper type information p1 and constant P1, the correspondence relationship between ink type information in1 and constant In1, and the correspondence relationship between ink discharge amount information in2 for the second side of continuous paper 120 and constant In2. Each correspondence relationship is determined in advance through experiments, simulations, etc.

[0057] The meaning of each constant included in the constant information V is shown in Table 1 below. [Table 1]

[0058] The acquisition unit 114 outputs the acquired constant information V to the detection unit 111, the change unit 115, and the correction unit 116, respectively.

[0059] The modification unit 115 is an example of a modification means that modifies at least one of the position, shape, and size of the effective image area on the continuous paper 120 based on the expansion / contraction state of the continuous paper 120. In this embodiment, the modification unit 115 modifies at least one of the position, shape, and size of the effective image area when the amount of expansion / contraction of the continuous paper 120 is equal to or greater than a predetermined expansion / contraction threshold.

[0060] In this embodiment, the change unit 115 drives the moving mechanism 53A that movably mounts the imaging means 52A in accordance with constant information V based on the expansion / contraction state information U of the continuous paper 120, and changes the position of the imaging means 52A, thereby changing the position of the effective image area in the captured image Sa. The change unit 115 also drives the moving mechanism 53C that movably mounts the imaging means 52C in accordance with constant information V based on the expansion / contraction state information U of the continuous paper 120, and changes the position of the imaging means 52C, thereby changing the position of the effective image area in the captured image Sc.

[0061] The change unit 115 can change the positions of the imaging means 52A and 52C in at least one of the conveyance direction 2 and the width direction of the continuous paper 120 that intersects with the conveyance direction 2.

[0062] When the liquid ejection means 210K, 210C, 210M and 210Y eject ink onto the front surface (first side) of the continuous paper 120 and then eject ink onto the back surface (second side) of the continuous paper 120, which is the side opposite to the front surface, i.e., when double-sided printing is performed, the modification unit 115 can change the position of the effective image area based on correspondence information 130 corresponding to the drying state of the continuous paper 120 onto which ink has been ejected onto the front surface of the continuous paper 120 before the liquid ejection means 210K, 210C, 210M and 210Y eject ink onto the back surface of the continuous paper 120.

[0063] The change of the effective image area by the change unit 115 is not limited to changing the positions of the imaging means 52A and 52C, but may change at least one of the position, shape, and size of the effective image area.

[0064] The correction unit 116 corrects the image data Im according to constant information V based on the expansion / contraction state information U of the continuous paper 120, and outputs the corrected image data Im' to the discharge control unit 117. For example, the correction unit 116 can correct the image data Im by performing image processing on the image data Im to reduce the image data according to the reduced state when the continuous paper 120 has been reduced, image processing to expand the image data according to the expanded state when the continuous paper 120 has been expanded, and image processing to shift the image data according to the positional displacement when the continuous paper 120 has been displaced according to the expansion / contraction state.

[0065] The ejection control unit 117 ejects ink from each of the plurality of liquid ejection means 210 based on the corrected image data Im' and the ejection timing signal tt. The liquid ejection device 1 can form an image on the continuous paper 120 by applying ink ejected from the plurality of liquid ejection means 210 to the continuous paper 120.

[0066] <Processing example by control IC101> Fig. 4 is a flowchart showing an example of processing by the control IC 101. The control IC 101 starts the processing in Fig. 4 when a print job is received from the external PC 300, or when a user inputs an operation to start image formation using an operation unit of the liquid ejection device 1.

[0067] First, in step S41, the control IC 101 inputs, via the acquisition unit 114, the expansion / contraction state information U from the device temperature sensor 54, the drying process temperature sensor 55, the humidity sensor 56, the tension sensor 57, and the print job.

[0068] Next, in step S42, the control IC 101 acquires constant information V by the acquisition unit 114, based on the stretch state information U, by referring to the correspondence information 130 stored in the memory 103. The acquisition unit 114 outputs the constant information V to the change unit 115, the correction unit 116, and the detection unit 111.

[0069] Next, in step S43, the control IC 101 determines, by the change unit 115, whether or not the amount of expansion / contraction of the continuous paper 120 is equal to or greater than a predetermined expansion / contraction threshold value.

[0070] In step S43, if it is determined that the expansion / contraction threshold value is not exceeded (step S43, No), the control IC 101 proceeds to step S45.

[0071] On the other hand, if it is determined in step S43 that the expansion / contraction threshold is equal to or greater than the expansion / contraction threshold (step S43, Yes), in step S44, the control IC 101 causes the change unit 115 to drive the moving mechanism 53A that movably mounts the imaging means 52A in accordance with the constant information V, thereby changing the position of the imaging means 52A. Also, the control IC 101 causes the change unit 115 to drive the moving mechanism 53C that movably mounts the imaging means 52C in accordance with the constant information V, thereby changing the position of the imaging means 52C.

[0072] Subsequently, in step S45, the control IC 101 corrects the image data Im in accordance with the constant information V, and outputs the corrected image data Im′ to the discharge control unit 117.

[0073] The order of steps S44 and S45 may be reversed as appropriate, or both steps may be performed in parallel.

[0074] Subsequently, in step S46, the control IC 101 inputs, via the detection unit 111, the captured images Sa and Sc captured by the imaging means 52A and 52C at the changed positions.

[0075] Subsequently, in step S47, the control IC 101 detects the transport distance errors ΔDc, ΔDm, and ΔDy based on the captured images Sa and Sc using the detection unit 111. The detection unit 111 outputs the detected transport distance errors ΔDc, ΔDm, and ΔDy to the determination unit 112.

[0076] Next, in step S48, the control IC 101 determines, via the determination unit 112, the ink ejection timing of each of the liquid ejection means 210C, 210M, and 210Y relative to the ejection of the liquid ejection means 210K, based on the conveyance distance errors ΔDc, ΔDm, and ΔDy input from the detection unit 111. The determination unit 112 outputs, to the ejection control unit 117, an ejection timing signal tt corresponding to the determined ink ejection timing.

[0077] Subsequently, in step S49, the control IC 101 causes the ejection control unit 117 to eject ink from each of the plurality of liquid ejection means 210 based on the corrected image data Im' and the ejection timing signal tt.

[0078] Next, in step S50, the control IC 101 determines whether to end the process. This determination can be made based on whether all ejection based on the corrected image data Im' has been completed, or whether the user has performed an operation input to end image formation using the operation unit.

[0079] If it is determined in step S50 that the process is to be ended (step S50, Yes), the control IC 101 ends the process. On the other hand, if it is determined that the process is not to be ended (step S50, No), the control IC 101 performs the process from step S41 onwards again.

[0080] In this manner, the control IC 101 can eject ink onto the continuous paper 120 to form an image.

[0081] <Example of changing the position of the effective image area Vc according to the expansion / contraction state of the continuous paper 120> An example of changing the position of the imaged area 71 in accordance with the expansion and contraction state of the continuous paper 120 will be described with reference to FIGS.

[0082] Fig. 5 is a diagram illustrating an example of the relationship between the captured image Sc and the effective image area Vc. Note that, although the captured image Sc and the effective image area Vc are described as examples in Fig. 5, the same applies to the captured image Sa and the effective image area Va, and therefore the symbols for the captured image Sa and the effective image area Va are written in parentheses.

[0083] 5, the effective image area Vc is a partial area included in the captured image Sc. When the detection unit 111 performs a cross-correlation calculation, the entire captured image Sc is not used, and only this effective image area Vc is used.

[0084] The larger the effective image area Vc, the wider the detection range of the conveyance amount error Dc by cross-correlation calculation, but the lower the detection accuracy of the conveyance amount error Dc. Therefore, the size of the effective image area Vc is determined in advance as appropriate according to the required detection accuracy and detection range of the conveyance amount error Dc.

[0085] Furthermore, in the cross-correlation calculation, the amount of deviation of a characteristic image area of ​​the captured image Sc relative to the characteristic image area of ​​the captured image Sa is detected as the deviation amount Δ. In other words, the characteristic image area affects the accuracy of detection of the transport distance error by the cross-correlation calculation. However, if the characteristic image area is no longer included in the image areas of the captured images Sa and Sc due to expansion or contraction of the continuous paper 120, the deviation amount Δ cannot be detected, and therefore the transport distance error D may not be detected.

[0086] Figures 6 and 7 are diagrams illustrating an example of changing the position of the effective imaging area 72 in accordance with the expansion and contraction state of the continuous paper 120. Figures 6 and 7 show the continuous paper 120 viewed in a plan view from its normal direction. Figure 6 is a diagram illustrating the effective imaging area 72 before the position is changed, and Figure 7 is a diagram illustrating the effective imaging area 72 after the position is changed.

[0087] As shown in Figures 6 and 7, on the continuous paper 120, the effective imaging area 72 is included in the imaged area 71. The image of the imaged area 71 corresponds to the captured image Sc, and the image of the effective imaging area 72 corresponds to the effective image area Vc. The feature area 73 is a characteristic area in the imaged area 71, and corresponds to a characteristic image area that affects the detection accuracy of the transport amount error by cross-correlation calculation. Note that Figures 6 and 7 show the feature area 73 in a simplified manner.

[0088] 6, in the state before the change, if the characteristic area 73 is located at the edge of the effective image capturing area 72 within the imaged area 71, the characteristic image area may be outside the image area of ​​either the captured image Sa or Sc. In this case, the detection unit 111 cannot detect the deviation amount Δ of the image area, and therefore cannot detect the conveyance distance error D.

[0089] In this embodiment, the change unit 115 moves the imaging devices 52A and 52C along the movement direction 63 in accordance with the expansion / contraction state of the continuous paper 120, thereby changing the positions of the imaging devices 52A and 52C. This change in position allows the feature region 73 to be positioned in an area other than the ends of the effective imaging area 72, for example, in the central area of ​​the effective imaging area 72, as shown in Figure 7. By positioning the feature region 73 in the central area of ​​the effective imaging area 72, the feature image region is included within the image areas of the effective image areas Va and Vc of the captured images Sa and Sc, respectively, making it possible to detect the conveyance distance error D.

[0090] <Example of expansion and contraction of continuous paper 120 according to ink application area> Figures 8 and 9 are diagrams showing an example of expansion and contraction of the continuous paper 120 depending on the ink application area, with Figure 8 being Figure 1 and Figure 6 being Figure 2. Figures 8 and 9 show the continuous paper 120 as viewed in a plan view from its normal direction.

[0091] 8 and 9, the ink application area 61 shown by dot hatching represents the area where ink is applied to the continuous paper 120 by being ejected from the liquid ejection means 210. The expansion / contraction direction 62 shown by the arrow represents the direction in which the continuous paper 120 expands as a result of the application of ink.

[0092] As shown in Figure 8, when ink is applied to the central region of the continuous paper 120, the continuous paper 120 stretches in a substantially uniform direction from the central region where the ink is applied toward the periphery. On the other hand, as shown in Figure 9, when ink is applied to an edge region in the width direction of the continuous paper 120 that intersects with the conveying direction 2, the continuous paper 120 does not stretch uniformly from the edge region where the ink is applied toward the periphery. In other words, the continuous paper 120 does not stretch in a direction where the continuous paper 120 does not exist outside the edge region where the ink is applied.

[0093] As described above, the elongation state of the continuous paper 120 differs depending on the position of the ink-application area on the continuous paper 120. Because the ink-application area is determined by image data Im, the liquid ejection device 1 can grasp the difference in the elongation state depending on the position of the ink-application area based on the image data Im, and can reflect this in the change by the change unit 115 of at least one of the position, shape, and size of the effective image area.

[0094] <Example of changing the shape of the effective image area Vc according to the stretch state of the continuous paper 120> Fig. 10 is a diagram showing an example of a change in the shape of the effective image area Vc according to the expansion / contraction state of the continuous paper 120. Fig. 10 shows the continuous paper 120 as viewed in a plan view from its normal direction.

[0095] 10, continuous paper 120a represents continuous paper 120 that has shrunk along conveying direction 2. Modification unit 115 can change the shape of effective image area Vc so that effective imaging area 72a shrinks along conveying direction 2 in accordance with the shrinkage of continuous paper 120a.

[0096] The continuous paper 120b represents the continuous paper 120 stretched along the conveying direction 2. The modification unit 115 can modify the shape of the effective image area Vc so that the effective imaging area 72b stretches along the conveying direction 2 in accordance with the stretching of the continuous paper 120b.

[0097] The change unit 115 can also change the size of the effective image area Vc so that the characteristic image area is included in the effective image area Vc.

[0098] <Example of correction of image data Im according to the expansion / contraction state of continuous paper 120> Figure 11 is a diagram showing an example of image data correction according to the expansion / contraction state of the continuous paper 120. Figure 11 shows the continuous paper 120 viewed in a plan view from its normal direction, as well as image data Im and corrected image data Im'.

[0099] In FIG. 11, continuous paper 120a represents continuous paper 120 that has shrunk along conveyance direction 2, and continuous paper 120b represents continuous paper 120 that has expanded along conveyance direction 2.

[0100] When the continuous paper 120 shrinks along the conveying direction 2, as in the case of the continuous paper 120a, the correction unit 116 can output corrected image data Ima' obtained by correcting the image data Im to expand in the direction corresponding to the conveying direction 2. Furthermore, when the continuous paper 120 expands along the conveying direction 2, as in the case of the continuous paper 120b, the correction unit 116 can output corrected image data Imb' obtained by correcting the image data Im to shrink in the direction corresponding to the conveying direction 2.

[0101] <Modification> In this embodiment, the liquid ejection device 1 is exemplified as having an imaging means 52A arranged immediately below the liquid ejection means 210K and an imaging means 52C arranged immediately below the liquid ejection means 210M, but this configuration is not limited to this and various modifications are possible.

[0102] 12 to 16 are diagrams illustrating the configuration of liquid ejection devices according to various modifications. Fig. 12 shows a first example, Fig. 13 shows a second example, Fig. 14 shows a third example, Fig. 15 shows a fourth example, and Fig. 16 shows a fifth example.

[0103] 12, the liquid discharger 1a has an imaging means 52A arranged immediately below the liquid discharger 210K and an imaging means 52D arranged immediately below the liquid discharger 210Y. The imaging means 52D outputs an image Sd obtained by imaging the continuous paper 120 at a position corresponding to the liquid discharger 210Y.

[0104] 13, liquid discharger 1b has imaging means 52A arranged immediately below liquid discharger 210K and imaging means 52B arranged immediately below liquid discharger 210C. Imaging means 52B outputs an image Sb obtained by imaging continuous paper 120 at a position corresponding to liquid discharger 210C.

[0105] 14, liquid discharger 1c has imaging means 52A arranged in the vicinity immediately below liquid discharger 210K, imaging means 52B arranged in the vicinity immediately below liquid discharger 210C, and imaging means 52C arranged in the vicinity immediately below liquid discharger 210M. Imaging means 52B outputs an image Sb obtained by imaging continuous paper 120 at a position corresponding to liquid discharger 210C, and imaging means 52C outputs an image Sc obtained by imaging continuous paper 120 at a position corresponding to liquid discharger 210M.

[0106] 15, liquid discharger 1d has imaging means 52A arranged immediately below liquid discharger 210K, imaging means 52B arranged immediately below liquid discharger 210C, and imaging means 52D arranged immediately below liquid discharger 210Y. Imaging means 52B outputs an image Sb of continuous paper 120 taken at a position corresponding to liquid discharger 210C, and imaging means 52D outputs an image Sd of continuous paper 120 taken at a position corresponding to liquid discharger 210Y.

[0107] 16, liquid discharger 1e has imaging means 52A arranged immediately below liquid discharger 210K, imaging means 52C arranged immediately below liquid discharger 210M, and imaging means 52D arranged immediately below liquid discharger 210Y. Imaging means 52C outputs an image Sc obtained by imaging continuous paper 120 at a position corresponding to liquid discharger 210M, and imaging means 52D outputs an image Sd obtained by imaging continuous paper 120 at a position corresponding to liquid discharger 210Y.

[0108] The liquid ejection devices 1a, 1b, 1c, 1d, and 1e described above also provide the same effects as those of the liquid ejection device 1.

[0109] <Effects of the liquid ejection device 1> As described above, the liquid ejection device 1 ejects ink (liquid) onto the transported continuous paper 120 (long recording medium). The liquid ejection device 1 has liquid ejection means 210K, 210C, 210M, and 210Y (plurality of liquid ejection means) that eject ink onto the transported continuous paper 120, and imaging means 52A and 52C (plurality of imaging means) that are provided corresponding to the positions of the liquid ejection means 210K, 210C, 210M, and 210Y and that output captured images Sa and Sc of the transported continuous paper 120. The liquid ejection device 1 also has control means 520 that controls the ink ejection timing (liquid ejection timing) of the liquid ejection means 210K, 210C, 210M, and 210Y based on the effective image areas Va and Vc of the captured images Sa and Sc (plurality of captured images) output from the imaging means 52A and 52C, respectively. Furthermore, the liquid ejection device 1 has a change unit 115 (change means) that changes at least one of the position, shape, and size of the effective image areas Va and Vc based on the expansion and contraction state of the continuous paper 120.

[0110] The liquid ejection device 1 changes at least one of the position, shape, and size of the effective image areas Va and Vc based on the expansion / contraction state of the continuous paper 120, so that even if the continuous paper 120 expands or contracts, the effective image areas Va and Vc contain characteristic image areas that affect the detection accuracy by cross-correlation calculation, making it possible to detect errors in the transport amount of the continuous paper 120. In this embodiment, by making it possible to detect errors in the transport amount of the continuous paper 120, a liquid ejection device 1 can be provided that has excellent control accuracy of the ink ejection timing and excellent ink ejection accuracy.

[0111] Furthermore, in this embodiment, the number of imaging means 52A and 52C is smaller than the number of liquid dischargers 210K, 210C, 210M, and 210Y. Of the imaging means 52A and 52C, imaging means 52A is disposed at a position corresponding to the position of liquid discharger 210K, which is disposed most upstream in conveyance direction 2, among liquid dischargers 210K, 210C, 210M, and 210Y. In this embodiment, the number of imaging means 52A and 52C is reduced, which simplifies the configuration of liquid discharger 1 and also reduces device costs.

[0112] Furthermore, in this embodiment, when the amount of expansion or contraction of the continuous paper 120 is equal to or greater than a predetermined expansion or contraction threshold, at least one of the position, shape, and size of the effective image areas Va and Vc is changed. The liquid ejection device 1 performs changes by the change unit 115 only when the amount of expansion or contraction of the continuous paper 120 is equal to or greater than a predetermined expansion or contraction threshold, so the processing load for changes by the change unit 115 can be reduced.

[0113] Furthermore, in this embodiment, the expansion / contraction state of the continuous paper 120 includes an expansion / contraction state corresponding to at least one of the amount of ink ejected onto the continuous paper 120, the humidity around the continuous paper 120, the type of continuous paper 120, the type of ink, the dryness state of the ink ejected onto the continuous paper 120, and the tension applied to the continuous paper 120. Because the expansion / contraction information includes this information, the liquid ejection device 1 can detect an error in the transport amount of the continuous paper 120 even if the continuous paper 120 expands or contracts due to various factors.

[0114] Furthermore, in this embodiment, the modification unit 115 modifies at least one of the position, shape, and size of the effective image areas Va and Vc based on predetermined correspondence information 130 that indicates the correspondence between the expansion / contraction state of the continuous paper 120 and at least one of the position, shape, and size of the effective image areas Va and Vc. The liquid ejection device 1 does not need to calculate the above-mentioned equation (1) using the modification unit 115 every time the expansion / contraction state of the continuous paper 120 changes, thereby reducing the calculation load.

[0115] Furthermore, in this embodiment, the liquid ejection devices 210K, 210C, 210M, and 210Y eject ink onto the front surface (first surface) of the continuous paper 120, and then eject ink onto the back surface (second surface) of the continuous paper 120. Before the liquid ejection devices 210K, 210C, 210M, and 210Y eject ink onto the back surface, the change unit 115 changes at least one of the position, shape, and size of the effective image areas Va and Vc based on correspondence information 130 corresponding to the dryness state of the continuous paper 120 onto which the ink has been ejected onto the front surface of the continuous paper 120. Because the change unit 115 makes changes based on correspondence information 130 corresponding to the dryness state of the continuous paper 120 onto which the ink has been ejected onto the front surface of the continuous paper 120, the liquid ejection device 1 can detect a transport distance error of the continuous paper 120 even if the continuous paper 120 expands or contracts due to the ink applied to the front surface during double-sided printing.

[0116] Furthermore, in this embodiment, the change unit 115 changes at least one of the position, shape, and size of the effective image areas Va and Vc by changing the position of the imaging means 52A and 52C in at least one of the conveyance direction 2 and the width direction of the continuous paper 120. Because the liquid ejection device 1 changes the positions of the imaging means 52A and 52C in both the conveyance direction 2 and the width direction of the continuous paper 120 using the change unit 115, it is possible to detect errors in the conveyance amount of the continuous paper 120 even if the continuous paper 120 expands or contracts in both the conveyance direction 2 and the width direction of the continuous paper 120.

[0117] Furthermore, in this embodiment, the liquid ejection devices 210K, 210C, 210M, and 210Y eject ink onto the continuous paper 120 based on image data Im' corrected in accordance with the expansion and contraction state of the continuous paper 120. If an image is formed on the continuous paper 120 while the continuous paper 120 is in a temporarily expanded or contracted state, and the continuous paper 120 subsequently returns to its pre-expansion state, the image formed on the continuous paper 120 may be distorted. The liquid ejection device 1 corrects the image data in accordance with the expansion and contraction state of the continuous paper 120, and therefore can prevent deformation of the image formed on the continuous paper 120.

[0118] Although the embodiments have been described above, the present invention is not limited to the specifically disclosed above embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0119] In the embodiments, the terms image formation, recording, printing, copying, and printing are all synonymous. Recording media include media such as paper, recording paper, recording sheet, plain paper, glossy paper, film, and cloth. The recording media may be made of paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or other materials that can accept liquid even temporarily. The recording media is not limited to sheet-like shapes, and may be structures such as walls and ceilings, or the sides, bottom, or top of cardboard. The recording media may also be the surface of a three-dimensional object fixed to the ground or a facility.

[0120] The liquid may have any viscosity and surface tension that allows it to be ejected from the liquid ejection unit, and is not particularly limited. However, it is preferable that the viscosity of the liquid be 30 mPa·s or less at room temperature and normal pressure, or upon heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, or the like containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, or an edible material such as a natural dye. These liquids can be used, for example, in inkjet inks, surface treatment solutions, components of electronic devices and light-emitting devices, and solutions for forming electronic circuit resist patterns.

[0121] The liquid ejection unit is a functional component that ejects and sprays liquid from a nozzle. Energy sources for ejecting liquid include piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators that consist of a vibration plate and an opposing electrode.

[0122] The embodiments also include a liquid ejection method. For example, the liquid ejection method is a liquid ejection method using a liquid ejection device that ejects liquid onto a long recording medium being transported, in which the liquid ejection device ejects liquid onto the recording medium being transported using multiple liquid ejection units, multiple imaging units provided corresponding to the positions of the liquid ejection units capture images of the recording medium being transported and output them, a control unit controls the liquid ejection timing of the multiple liquid ejection units based on an effective image area in each of the multiple captured images output by the multiple imaging units, and a change unit changes at least one of the position, shape, and size of the effective image area based on the expansion / contraction state of the recording medium. Such a liquid ejection method can achieve the same effects as the liquid ejection device described above.

[0123] Furthermore, all ordinal numbers, quantitative numbers, etc. used above are merely examples for specifically explaining the technology of the present invention, and the present invention is not limited to the exemplified numbers. Furthermore, the connection relationships between the components are merely examples for specifically explaining the technology of the present invention, and the connection relationships for realizing the functions of the present invention are not limited to these.

[0124] Each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and conventional circuit modules designed to perform each of the above-described functions. [Explanation of symbols]

[0125] 1 Liquid discharge device 2 Conveying direction 52A, 52B, 52C, 52D Imaging means 53A, 53C movement mechanism 61 Ink application area 62 Stretch direction 63 Direction of movement 71 Imaged area 72 Effective imaging area 73 Feature Areas 100 Head drive board 101 Control IC 102A, 102B drive waveform generating means 103 memory 111 Detection unit 112 Decision Section 113 Communications Department 114 Acquisition Department 115 Change section (change means) 116 Correction unit 117 Discharge control section 120 Continuous paper (long recording medium) 130 Compatibility Information 201 Head board 202 Piezoelectric element support substrate 203 Piezoelectric element driver IC 204 Piezoelectric element 205 Switching circuit 210, 210K, 210C, 210M, 210Y Liquid discharge means 220 Support roller 300 external PC 520 Control means Im image data Im' Corrected image data tt Discharge timing signal Sa, Sc captured images U Stretch status information V constant information Vc, Va Effective image area t1 Temperature information inside the device t2 Drying process temperature information h1 Humidity information p1 Continuous paper type information In1 ink type information in2 Ink discharge amount information on the surface te tension information a, b, T1, T2, H1, P1, I1, I2, Te constant [Prior art documents] [Patent documents]

[0126] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-170889

Claims

1. A liquid ejection device that ejects liquid onto a long recording medium being conveyed, a plurality of liquid ejection means for ejecting liquid onto the recording medium being conveyed; a plurality of image capturing means provided corresponding to the positions of the liquid ejection means, the image capturing means capturing an image of the recording medium being conveyed, and outputting the captured image; a control unit that controls the timing of liquid ejection by the plurality of liquid ejection units based on an effective image area in each of the plurality of captured images output from the plurality of imaging units; a change unit that changes at least one of the position, shape, and size of the effective image area based on the expansion / contraction state of the recording medium, the number of the plurality of imaging means is less than the number of the plurality of liquid ejection means, A liquid ejection device, wherein one of the plurality of imaging means is arranged at a position corresponding to the position of the liquid ejection means that is arranged most upstream in the transport direction among the plurality of liquid ejection means.

2. 2. The liquid ejection device according to claim 1, wherein the change unit changes at least one of the position, shape, and size of the effective image area when the amount of expansion or contraction of the recording medium is equal to or greater than a predetermined expansion or contraction threshold.

3. 3. The liquid ejection device according to claim 1, wherein the expansion / contraction state of the recording medium includes an expansion / contraction state corresponding to at least one of the amount of the liquid ejected onto the recording medium, the humidity around the recording medium, the type of the recording medium, the type of the liquid, the dryness state of the liquid ejected onto the recording medium, and the tension applied to the recording medium.

4. A liquid ejection device described in any one of claims 1 to 3, wherein the modification means modifies at least one of the position, shape and size of the effective image area based on predetermined correspondence information indicating the correspondence between the expansion / contraction state of the recording medium and at least one of the position, shape and size of the effective image area.

5. the plurality of liquid ejection means eject the liquid onto a first surface of the recording medium, and then eject the liquid onto a second surface of the recording medium, the second surface being an opposite surface to the first surface; 5. The liquid ejection device according to claim 4, wherein the modification means modifies at least one of the position, shape, and size of the effective image area based on the correspondence information corresponding to the dryness state of the recording medium onto which the liquid has been ejected onto the first surface before the plurality of liquid ejection means eject the liquid onto the second surface.

6. A liquid ejection device described in any one of claims 1 to 5, wherein the change means changes at least one of the position, shape, and size of the effective image area by changing the position of each of the multiple imaging means in at least one of the transport direction of the recording medium and the width direction of the recording medium that intersects the transport direction.

7. 7. The liquid ejection device according to claim 1, wherein the plurality of liquid ejection devices eject the liquid onto the recording medium based on image data corrected in accordance with the expansion / contraction state of the recording medium.

8. A liquid ejection method using a liquid ejection device that ejects liquid onto a long recording medium being conveyed, the liquid ejection device comprising: A plurality of liquid ejection means eject liquid onto the recording medium being conveyed; outputting captured images of the recording medium being conveyed by a plurality of imaging means provided corresponding to the positions of the liquid discharge means; a control unit that controls the timing of liquid ejection by the plurality of liquid ejection units based on an effective image area in each of the plurality of captured images output from the plurality of imaging units; a change unit that changes at least one of the position, shape, and size of the effective image area based on the expansion / contraction state of the recording medium; the number of the plurality of imaging means is less than the number of the plurality of liquid ejection means, A liquid ejection method, wherein one of the plurality of imaging means is arranged at a position corresponding to the position of the liquid ejection means arranged most upstream in the transport direction among the plurality of liquid ejection means.

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