Liquid discharging device

Abstract

To provide a technique of correcting a magnification deviation of an image formed by droplets when a liquid is discharged onto a recording medium transported using a transportation drum.SOLUTION: A liquid discharging device includes: a drum-like member for transporting a recording medium; a discharge head which is arranged so as to face the drum-like member and discharges a liquid onto the recording medium; timing generation means for generating a discharge timing signal of instructing a timing of discharging the liquid from the discharge head according to a rotation amount of the drum-like member; storage means for storing a correction value for correcting the outer diameter of the drum-like member; magnitude calculation means for calculating image magnification of an image formed on the recording medium, on the basis of the correction value; and formation image deformation means for changing the timing so as to deform the image formed on the recording medium on the basis of the image magnification.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an apparatus for discharging liquid. [Background technology]

[0002] There is known an apparatus that ejects liquid onto a recording medium that is being conveyed, and among such apparatuses, there is known an apparatus that ejects liquid onto a sheet-shaped recording medium, conveys the sheet-shaped recording medium along the outer peripheral surface of a drum-shaped member, and forms an image on the recording medium.

[0003] The processing accuracy and axial alignment accuracy of the drum-shaped member (hereinafter referred to as the transport drum) used to transport the recording medium affect the conditions under which the ejected droplets land on the recording medium, which ultimately affects the quality of the image formed on the recording medium transported along the outer surface of the drum-shaped member.

[0004] A technology has been disclosed that makes the dot pitch between each dot in the main scanning direction constant by generating a dot clock of a predetermined frequency according to the position at which each dot is to be formed, in order to correct internal expansion and contraction of a replicated image, even if the processing precision of the transport drum is low, or even if the axis alignment work is simplified to increase precision (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] The technique disclosed in Patent Document 1 is one that eliminates internal expansion and contraction in the main scanning direction of a duplicated image recorded on a photosensitive material, even if there is a change in the relative scanning speed between the recording surface of the photosensitive material and a drawing device.

[0006] When an image is formed by ejecting droplets onto a recording medium transported using a transport drum, the accuracy of the position at which the droplets adhere to the medium is affected by more than just the fluctuation in the scanning speed relative to the droplet adhesion surface of the medium and the ejection head that ejects the droplets, as described in Patent Document 1.

[0007] For example, the accuracy of the position where the droplets ejected from the ejection head adhere to the medium is affected by the external shape error of the transport drum and the thickness of the recording medium. In particular, it affects the direction in which the image magnification changes in the sub-scanning direction. That is, the recording medium is placed on the cylindrical part of the transport drum, and the timing of ejecting the liquid is controlled by the rotation angle of the transport drum, so if the rotation radius changes due to the drum shape or the thickness of the recording medium, the image magnification changes.

[0008] To correct the variation in image magnification caused as described above, there is a method in which a reading mechanism for reading the surface of the recording medium is arranged in the double-sided path after image formation, and a correction value is calculated by reading the formed image, thereby making a correction at the time of the next image formation. However, even if such a method is adopted, it is not possible to make corrections due to the drum shape or the thickness of the recording medium. In other words, in the conventional technology, there is another problem to be solved in that the image position accuracy decreases in image formation using a device that ejects liquid.

[0009] The present invention aims to provide a technique for correcting magnification deviation of an image formed by droplets when liquid is ejected onto a recording medium transported by a transport drum in a liquid ejecting device. [Means for solving the problem]

[0010] In order to solve the above problem, one aspect of the present invention relates to a liquid ejecting device, comprising: a drum-shaped member for transporting a recording medium; an ejection head arranged opposite the drum-shaped member for ejecting liquid onto the recording medium; a timing generation means for generating an ejection timing signal indicating the timing of ejecting the liquid from the ejection head in accordance with the amount of rotation of the drum-shaped member; a storage means for storing a correction value for correcting the outer diameter of the drum-shaped member; a magnification calculation means for calculating an image magnification of an image formed on the recording medium based on the correction value; and an image deformation means for changing the timing so as to deform the image formed on the recording medium based on the image magnification. Effect of the Invention

[0011] According to the present invention, it is possible to correct the magnification deviation of an image formed by droplets of liquid ejected onto a recording medium transported by a transport drum. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an inkjet recording apparatus as an embodiment of an apparatus for discharging liquid according to the present invention; [Diagram 2] 5A and 5B are diagrams for explaining the correlation between the relationship between the drum-shaped member and the liquid ejection portion provided in the embodiment, and the image forming area. [Diagram 3] 5A and 5B are diagrams for explaining the correlation between the relationship between the drum-shaped member and the liquid ejection portion provided in the embodiment, and the image forming area. [Figure 4] 5A to 5C are diagrams illustrating the characteristics of a recording medium transported by the drum-shaped member. [Diagram 5] FIG. 2 is a diagram showing an example of an image reading device provided in the embodiment. [Figure 6] 5 is a diagram showing a flow of image correction in the embodiment. [Figure 7] FIG. 2 is a hardware configuration diagram for executing the control process executed in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram of an inkjet recording apparatus 1, which is an example of an apparatus for ejecting liquid.

[0014] 1, the inkjet recording apparatus 1 includes an input section 10, an image forming section 20, a drying section 30, and a discharge section 40. The inkjet recording apparatus 1 forms an image by causing the image forming section 20 to eject ink onto a sheet of paper P (medium) that is input from the input section 10. Then, the inkjet recording apparatus 1 dries the ink attached to the sheet of paper P in the drying section 30, and then discharges the sheet of paper P to the discharge section 40.

[0015] Additionally, an upstream transport path Ph1 and a downstream transport path Ph2 are formed inside the inkjet recording apparatus 1. The upstream transport path Ph1 and the downstream transport path Ph2 refer to spaces through which the paper P passes inside the inkjet recording apparatus 1. The upstream transport path Ph1 is a transport path upstream of the image forming unit 20 in the transport direction of the paper P (i.e., from the loading unit 10 to the image forming unit 20). The downstream transport path Ph2 is a transport path downstream of the image forming unit 20 in the transport direction of the paper P (i.e., from the image forming unit 20 to the discharge unit 40 via the drying unit 30).

[0016] The conveying direction of the paper P is the direction along the conveying paths Ph1 and Ph2 from the entrance section 10 through the image forming section 20 and the drying section 30 to the discharge section 40. The upstream conveying path Ph1 and the downstream conveying path Ph2 may extend linearly or curvedly in the conveying direction of the paper P, or may be configured as a combination of these. More specifically, the portion of the downstream conveying path Ph2 from the opposing position of the drum 51 as a drum-shaped member described later and the transfer cylinder 25 to the outer circumferential surface of the transfer cylinder 25 is a curved conveying path curved in the conveying direction.

[0017] The carry-in section 10 includes an input tray 11 on which a plurality of sheets P are stacked, a feeding device 12 that separates and sends out the sheets P one by one from the input tray 11, and a pair of registration rollers 13 that sends the sheets P through an upstream transport path Ph1 to the image forming section 20. The feeding device 12 can be any known feeding device having a feeding function, such as a device using rollers or a device using air suction.

[0018] The paper P sent from the input tray 11 to the upstream transport path Ph1 by the feeding device 12 has its leading edge reaching the pair of registration rollers 13, and then the pair of registration rollers 13 is driven at a predetermined timing to be conveyed into the image forming unit 20. In this embodiment, the configuration of the input unit 10 is not particularly limited as long as it has a function of sending out the paper P to the image forming unit 20.

[0019] The image forming section 20 forms an image on the paper P carried in by the carry-in section 10, and discharges the paper P on which the image has been formed to the drying section 30. The image forming section 20 includes a sheet transport device 21 that transports the paper P, an ejection unit 22 that ejects liquid onto the paper P transported by the sheet transport device 21, a receiving drum 24, and a delivery drum 25 (medium transport device).

[0020] The sheet conveying device 21 includes a drum 51 that rotates while supporting the paper P on its peripheral surface, and a suction device 52 that is a suction means that generates a suction force on the peripheral surface of the drum 51. The receiving cylinder 24 receives the paper P from the carry-in section 10 and delivers it to the drum 51. The delivery cylinder 25 receives the paper P on which an image has been formed from the drum 51 and delivers it to the drying section 30.

[0021] The paper P transported from the carry-in section 10 to the image forming section 20 has its leading edge gripped by a gripper provided on the surface of the receiving drum 24, and is transported as the surface of the receiving drum 24 moves. The paper P transported by the receiving drum 24 is delivered to the drum 51 at a position opposite the drum 51.

[0022] A gripper is also provided on the surface of the drum 51, and the leading edge of the paper P is gripped by the gripper. In addition, a plurality of suction holes are formed and dispersed on the surface of the drum 51. A suction device 52 generates a suction air current toward the inside of the drum 51 at each suction hole. The paper P is adsorbed to the surface of the drum 51 by this suction air current. The leading edge of the paper P transferred from the receiving cylinder 24 to the drum 51 is gripped by the gripper, and the paper P is adsorbed to the surface of the drum 51 by the suction air current, and is transported as the surface of the drum 51 moves.

[0023] The discharge unit 22 includes discharge units 22 (23A to 23F) which are liquid discharge means and constitute a discharge head. For example, the discharge unit 22A discharges cyan (C) liquid, the discharge unit 22B discharges magenta (M) liquid, the discharge unit 22C discharges yellow (Y) liquid, and the discharge unit 22D discharges black (K) liquid. Discharge units 22E and 23F are used to discharge any of YMCK, or special liquids such as white and gold (silver). Furthermore, a discharge unit that discharges a treatment liquid such as a surface coating liquid can also be provided.

[0024] The ejection unit 22 is, for example, a full-line type head in which a plurality of liquid ejection units (hereinafter simply referred to as "heads") having a nozzle row in which a plurality of nozzles are arranged are arranged on a base member. The ejection operation of the ejection unit 22 is controlled by a drive signal corresponding to image data. When the paper P transported by the drum 51 passes through an area facing the ejection unit 22, each color ink is ejected from the nozzles provided on the lower surface (nozzle surface) of each of the ejection units 22. As a result, an image corresponding to the image data is formed on the paper P.

[0025] In this embodiment, the image forming unit 20 only needs to have a function of depositing liquid onto the paper P to form an image, and the configuration for ejecting or depositing the liquid is not particularly limited.

[0026] Moreover, the image forming unit 20 according to this embodiment can form an image in an image forming area in the center of the paper P. In other words, the paper P on which an image is formed by the image forming unit 20 has so-called "margins" where no image is formed at both ends in the width direction. The width direction of the paper P is a direction perpendicular to the transport direction of the paper P and the thickness direction of the paper P. The left and right margins shown in FIG. 5 are located on opposite sides of the image forming area in the width direction of the paper P. Moreover, the left and right margins are areas having a predetermined length in the width direction of the paper P. Furthermore, the left and right margins are areas provided over the entire area of ​​the paper P in the transport direction of the paper P.

[0027] The paper P transported by the drum 51 (in other words, the paper P on which an image has been formed by the image forming unit 20) is delivered to the transfer cylinder 25 at a position facing the drum 51. More specifically, the leading edge of the paper P is gripped by a gripper provided on the surface of the transfer cylinder 25, and the paper P is transported as the surface of the transfer cylinder 25 moves. At this time, the surface of the paper P on which the image has been formed (the inner peripheral surface of the paper P transported along the curved transport path) faces the transfer cylinder 25. The paper P transported by the transfer cylinder 25 is delivered to the drying unit 30 through the downstream transport path Ph2.

[0028] The drying section 30 includes a drying mechanism section 31 and a suction transport mechanism section 32. The drying mechanism section 31 dries the ink attached to the paper P in the image forming section 20. The suction transport mechanism section 32 transports the paper P transferred from the transfer drum 25 to the discharge section 40 side along the downstream transport path Ph2. That is, the paper P transferred from the image forming section 20 through the transfer drum 25 is received by the suction transport mechanism section 32, and then transported by the suction transport mechanism section 32 to pass through the drying mechanism section 31 and transferred to the discharge section 40. When passing through the drying mechanism section 31, the ink on the paper P is subjected to a drying process, and liquid components such as water in the ink evaporate, the ink is fixed on the paper P, and curling of the paper P is suppressed.

[0029] The discharge section 40 includes a discharge tray 41 on which a plurality of sheets of paper P are stacked. The sheets of paper P transported from the drying section 30 by the suction transport mechanism 32 are sequentially stacked and held on the discharge tray 41. In this embodiment, the discharge section 40 only needs to have a function of discharging the sheets of paper P, and the configuration of the discharge section 40 is not particularly limited.

[0030] The inkjet recording apparatus 1 of the present embodiment is composed of an input unit 10, an image forming unit 20, a drying unit 30, and a discharging unit 40, but other functional units may be added as appropriate. For example, the inkjet recording apparatus 1 may be provided with a pre-processing unit between the input unit 10 and the image forming unit 20 that performs pre-processing of the image formation, or a post-processing unit between the drying unit 30 and the discharging unit 40 that performs post-processing of the image formation.

[0031] An example of the pre-processing section is a section that performs a processing liquid application process in which processing liquid that reacts with the ink to suppress bleeding is applied to the paper P. However, the content of the pre-processing is not limited to the above-mentioned example. An example of the post-processing section is a paper inversion and transport process in which the paper P on which an image has been formed in the image forming section 20 is inverted and sent back to the image forming section 20 to form images on both sides of the paper P, or a process of binding multiple sheets of paper P on which images have been formed. However, the content of the post-processing is not limited to the above-mentioned example.

[0032] In this embodiment, the inkjet recording device 1 is described as an example of an image forming device that is a "device that ejects liquid." However, the device that ejects liquid is not limited to one that visualizes meaningful images such as characters and figures with the ejected droplets, as long as it is equipped with a droplet ejection unit that ejects liquid toward the surface of the sheet material to be dried. As another example, the device that ejects liquid may form a pattern that does not have a meaning in itself.

[0033] The medium is not limited to a specific material, and may be any material to which the liquid can be attached even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, or ceramics. The medium may be, for example, a film product, a cloth product for clothing, a building material such as wallpaper or flooring, or a leather product. In this embodiment, anything to which the liquid can be attached even temporarily is referred to as a "medium." In addition, a specific example of the "droplet" is not limited to the ink ejected from the ejection unit 22, and may be a processing liquid used in a pre-processing unit. In other words, the present invention can be widely applied to a droplet ejection device that ejects droplets at a target position.

[0034] Moreover, the term "ejection head" refers to a functional component that ejects or sprays liquid from an ejection hole (nozzle). As an energy generation source for ejecting liquid, ejection energy generation means such as a piezoelectric actuator, a thermal actuator using an electrothermal conversion element such as a heating resistor, and an electrostatic actuator consisting of a vibration plate and a counter electrode can be used. However, the ejection energy generation means used is not limited to the above examples.

[0035] [Relationship between the radius of the drum 51, the thickness of the paper P, and the image formation accuracy] Fig. 2 is an enlarged view of the opposing arrangement position of the ejection unit 22 and the drum 51, and is an enlarged view of how the paper P is transported along the outer periphery of the drum 51. Fig. 2(b) is a diagram for explaining the length in the sub-scanning direction (image formation range length) of the image formation range, which is the range in which an image is formed when an image formation process is performed on the paper P.

[0036] 2(a), the paper P is attracted to and held in a fixed state on the outer circumferential surface 511 of the drum 51. The drum 51 holding the paper P rotates to transport the paper P. As the paper P is being transported by the drum 51, liquid ink is ejected from the ejection unit 22 toward the paper P in the form of droplets, and adheres to the surface of the paper P to form an image.

[0037] The position where the droplets adhere to the paper P is controlled by the ejection timing of the ejection head 23. Therefore, a predetermined image can be formed by ejecting liquid as droplets from a predetermined ejection head 23 at a predetermined ejection timing according to the transport state of the paper P, i.e., the amount of rotation of the drum 51. The amount of rotation of the drum 51 is determined based on the rotation angle of the drum 51 detected by a rotary encoder 63a (see FIG. 7) provided on the rotation shaft of the drum 51.

[0038] When the drum 51 is used as a conveying member and image formation processing is performed while the paper P is conveyed by the drum 51, the conveying path of the paper P is the cylindrical surface of the drum 51, and the image formation range as the range to which droplets are attached is also determined by the rotation angle of the drum 51. That is, when the outer diameter of the drum 51 differs from the ideal design value, the circumferential length of the drum 51 also differs. In that case, even if the rotation angle of the drum 51 is the same, the distance that a certain position on the circumference of the drum 51 moves will differ. That is, the paper P conveyed by the rotation of the drum 51 along the circumference of the drum 51 will have an image formation range that is different when the outer diameter of the drum 51 is the ideal value and an image formation range based on the actual outer diameter of the drum 51. That is, the magnification of the image G to be formed in the sub-scanning direction will differ due to the outer diameter of the drum 51.

[0039] 2(a), the ideal design value of the outside diameter of the drum 51 is defined as "ideal outside diameter R." Also, the actual measurement value of the outside diameter of the drum 51 is defined as "actual outside diameter R'."

[0040] 2(b), the image formation range length, which is the length in the sub-scanning direction of the image formation range on the circumference (ideal circumference) of drum 51 when the outer diameter of drum 51 is assumed to be ideal outer diameter R, is defined as "ideal position L." Similarly, the sub-scanning direction length of the image formation range on the circumference (actual circumference) of drum 51 when the outer diameter is assumed to be actual measured outer diameter R' is defined as "actual position L'."

[0041] In this case, when "ideal outer diameter R<actual outer diameter R'" as exemplified in Fig. 2(a), that is, when the actual outer diameter R' of the drum 51 is smaller than the ideal outer diameter R, the actual position L' in the sub-scanning direction of the image forming position in the inkjet recording apparatus 1 becomes shorter than the ideal position L, as exemplified in Fig. 2(b). In other words, when "ideal outer diameter R<actual outer diameter R'", the sub-scanning direction portion of the image forming range is shorter, and therefore the image formed in the image forming range becomes smaller (reduced) in accordance with this degree than when the ideal outer diameter R.

[0042] On the other hand, as shown in Fig. 3(a), when "ideal outer diameter R>actual outer diameter R'", that is, when the actual outer diameter R' of the drum 51 is larger than the ideal outer diameter R, as shown in Fig. 3(b), the image forming position in the inkjet recording apparatus 1, the actual position L' in the sub-scanning direction, is longer than the ideal position L. In other words, when "ideal outer diameter R>actual outer diameter R'", the sub-scanning direction portion of the image forming range is longer, and accordingly, the image formed in the image forming range becomes larger (expanded) than when the ideal outer diameter R.

[0043] That is, the measured outer diameter R' is used as a correction value, and the relationship between this measured outer diameter R' and a predefined ideal outer diameter R is used to define an image magnification a for correcting the magnification of image G in the sub-scanning direction, as described below.

[0044] 1, the inkjet recording apparatus 1 is provided with an operation input panel 90 as an outer diameter input means with which the user inputs the outer diameter (actual outer diameter R') of the drum 51. The operation input panel 90 is disposed on a side surface of the inkjet recording apparatus 1, and is a user interface with which the user can input the actual outer diameter R'. The input actual outer diameter R' is stored in a storage means provided in the controller 100, which will be described later.

[0045] When the inkjet recording device 1 performs an image forming process on the paper P, the image magnification a used in the image forming process in the sub-scanning direction of a predefined image forming range is calculated by "actual outer diameter R' / ideal outer diameter R" based on the actual outer diameter R' (correction value) stored in the storage means. The image G is transformed using the image magnification a that can be calculated by the above division, and then the image forming process is performed. This control is performed by the controller 100, which will be described later, and therefore the controller 100 corresponds to a timing generating means that controls the liquid ejection timing.

[0046] When there is an image whose image formation range length in the sub-scanning direction is "Lx", by changing the length of the image in the sub-scanning direction to "Lx / a" and forming the image, the image that is actually formed is formed to be longer by the outer diameter of the drum 51. In other words, since this is a process equivalent to "a×Lx / a", as a result, an image of a predetermined length can be formed as the image formation range length (Lx).

[0047] As described above, the image magnification deviation when an image is formed on the drum can be corrected by deforming the image to be formed using the image magnification a to account for the deformation of the image formation position in the sub-scanning direction caused by the outer diameter of the drum 51.

[0048] Furthermore, the variation in the image forming range length caused by conveying the paper P along the circumferential surface of the drum 51 is caused by the thickness component (thickness value) of the paper P as well as the deviation of the outer diameter of the drum 51 from the ideal value.

[0049] 4 is an enlarged view of the state of the paper P when it is transported along the drum 51. As illustrated in FIG. 4, when the paper P is transported along the circumference of the drum 51, the length of the paper P is an outer paper length PLo that is longer than the actual length of the paper P on the surface of the paper P on which the image G is formed. On the other hand, the inner surface of the paper P that is in contact with the drum 51 is an inner paper length PLi that is shorter than the actual length of the paper P. When the paper P is discharged from the inkjet recording device 1, both the outer paper length PLo and the inner paper length PLi return to the same value as the paper length.

[0050] Therefore, when the thickness of the paper P is taken into consideration, the length of the image forming area during image formation is affected by the actual outer diameter R' of the drum 51 plus the thickness value. In other words, the length of the image forming area is extended (the image is extended) by an amount equivalent to the thickness value of the paper P.

[0051] The thickness t of the paper P can be input by the user via the operation input panel 90. The input thickness t is stored in a storage means provided in the controller 100. This makes it possible to accommodate various types of paper P and correct image magnification deviation in the image forming process using the drum 51. Moreover, by correcting the thickness of the paper P in addition to correcting the outer diameter of the drum 51, a target image can be obtained with higher accuracy.

[0052] Specifically, as described above, when the paper P is held on the outer peripheral surface of the drum 51, the thickness t of the paper P expands on the front side (the side on which the image G is formed) and contracts on the back side. Then, when the paper P is separated from the drum 51, the shape returns to its original state. Therefore, half of the thickness t of the paper P affects the radius of the drum 51. Thus, the image magnification a when performing the image forming process in the inkjet recording device 1 can be calculated by "(R'+t / 2) / R". By similarly applying the reciprocal to the image G to be formed with the image magnification a, the target image can be obtained with high accuracy.

[0053] [Adjustment chart reader] The correction value due to the outer diameter of the drum 51 may be calculated by the user inputting the measured outer diameter R' as described above, but it can also be obtained by using an adjustment chart. The adjustment chart used as an adjustment image in the inkjet recording apparatus 1 is, for example, formed of two line segments spaced at a fixed interval in the transport direction. By measuring the interval between the two lines, the image magnification a for the image formation range length can be calculated.

[0054] 5 illustrates an example of the arrangement of a reading device 80 as an image reading means provided in the inkjet recording apparatus 1. The reading device 80 is a device that reads an adjustment chart formed on the surface of the paper P transported along the outer circumferential surface of the drum 51. Therefore, it is disposed downstream of the ejection head 23 in the transport direction.

[0055] Although the details of the reading device 80 are not shown, multiple CCDs (Charge Coupled Devices) are arranged in the main scanning direction (width direction of the paper P), and multiple arrays are lined up in parallel in the direction perpendicular to the transport direction. The CCDs can read the image G (adjustment chart) formed on the surface of the paper P by shining light on the paper P and measuring the brightness of the reflected light.

[0056] A signal (image reading signal) based on the image G read by the reading device 80 is notified to the controller 100 as the reading result, and the distance between the two lines, which is the measured shape, is calculated based on the measurement. That is, the measured shape has at least two locations. Since the measured distance between the two lines (measurement distance Lm) can be considered to be the same as the above-mentioned "actual measurement position L'", the image magnification a can be calculated by "measurement distance Lm / ideal position L".

[0057] Here, if the thickness t of the paper P on which the adjustment chart is formed is t0, the image magnification a is (R'+t0 / 2) / R. From this, it is calculated as "R'=R·Lm / L-t0 / 2".

[0058] It should be noted that when the adjustment chart is read by the reading device 80, the above calculation can be automatically performed and the image magnification a can be stored in the storage means.

[0059] In the above example, the image magnification a is calculated from the distance between two points on the adjustment chart, but it is also possible to measure three or more lines (at multiple measurement points), measure the positions of each line, and use the least squares method to find the inclination that reduces the deviation from the target value, and use the inclination as the image magnification a. In this case, the calculation error of the correction value can be further reduced.

[0060] According to the above embodiment, the controller 100 can calculate the actual outer diameter R' of the drum 51 based on the error in the image formation range without directly measuring the actual diameter of the drum 51. In other words, the controller 100 constitutes a correction value calculation means.

[0061] Fig. 6 is an image diagram showing a correction value when the drum diameter is corrected and a method of processing the thickness t of the paper P in the inkjet recording device 1 according to this embodiment. As shown in Fig. 6, after the image magnification a is calculated, the process of modifying the image to be formed on the paper P is executed before front side printing (image forming process on the front side of the paper P) and before back side printing (image forming process on the back side of the paper P).

[0062] [Control block of inkjet recording device 1] Next, the control block configuration of the inkjet recording apparatus 1 will be described with reference to Fig. 7. Fig. 12 is a hardware configuration diagram for executing control processing executed in the inkjet recording apparatus 1. As shown in Fig. 7, the inkjet recording apparatus 1 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a ROM (Read Only Memory) 103, a HDD (Hard Disk Drive) 104, and an I / F 105, which are connected via a common bus 109.

[0063] The CPU 101 is a calculation means and controls the overall operation of the inkjet recording apparatus 1. The RAM 102 is a volatile storage medium capable of reading and writing information at high speed, and is used as a working area when the CPU 101 processes information. The ROM 103 is a read-only non-volatile storage medium in which programs such as firmware are stored. The HDD 104 is a non-volatile storage medium capable of reading and writing information and having a large storage capacity, and in which an OS (Operating System), various control programs, application programs, etc. are stored. Either the RAM 102 or the HDD 104, or both, constitute the storage means according to this embodiment.

[0064] Inkjet recording apparatus 1 processes a control program stored in ROM 103, an information processing program (application program) loaded from a storage medium such as HDD 104 to RAM 102, and the like, using a calculation function provided in CPU 101. This processing constitutes a software control unit including various functional modules of inkjet recording apparatus 1. The combination of the software control unit thus constituted and hardware resources mounted on inkjet recording apparatus 1 constitutes functional blocks that realize the functions of inkjet recording apparatus 1. In other words, CPU 101, RAM 102, ROM 103, and HDD 104 constitute controller 100 as control means for controlling the operation of inkjet recording apparatus 1.

[0065] That is, a magnification calculation means for calculating an image magnification a and a formed image deformation means for executing an image deformation process for correcting the timing of an ejection timing signal in an image formation process are realized in the controller 100. The magnification calculation means can calculate a value equivalent to the actual outer diameter R' based on the result of the adjustment chart read by the reading device 80, and calculate the image magnification a based on this actual outer diameter R'.

[0066] The I / F 105 is an interface that connects the drum rotation motor 63, the suction device 52, the discharge unit 22, the operation input panel 90, the reading device 80, and the rotary encoder 63a to a common bus 109. The controller 100 operates the drum rotation motor 63, the suction device 52, the discharge unit 22, and the reading device 80 through the I / F 105, and acquires the detection results of the rotary encoder 63a and the reading device 80. Note that while FIG. 7 mainly illustrates only the components of the image forming unit 20, the loading unit 10, the drying unit 30, and the discharge unit 40 are also controlled by the controller 100 in the same manner.

[0067] The rotary encoder 63a outputs a pulse signal indicating the amount of rotation of the drum rotating motor 63 to the controller 100. That is, the controller 100 can grasp the amount of rotation of the drum rotating motor 63 by counting the pulse signals output from the rotary encoder 63a.

[0068] The controller 100 generates a discharge timing signal that indicates the discharge timing of the multiple discharge heads 23 included in the discharge unit 22 based on the rotation amount of the drum rotation motor 63, and notifies each discharge head 23 of the signal.

[0069] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the present invention. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

[0070] For example, aspects of the present invention are as follows. <1> A drum-shaped member that transports a recording medium; an ejection head disposed opposite the drum-shaped member and configured to eject liquid onto the recording medium; a timing generating means for generating an ejection timing signal indicative of a timing for ejecting the liquid from the ejection head in accordance with an amount of rotation of the drum-shaped member; a storage means for storing a correction value for correcting the outer diameter of the drum-shaped member; a magnification calculation means for calculating an image magnification of an image to be formed on the recording medium based on the correction value; a formed image modification unit that changes the timing so as to modify the image formed on the recording medium based on the image magnification; The present invention relates to a liquid ejection device comprising: <2> The storage means also stores a thickness value indicating the thickness of the recording medium, the magnification calculation means calculates the image magnification based on the correction value and the thickness value. <1> The present invention relates to an apparatus for discharging the liquid described above. <3> An outer diameter input means for inputting the outer diameter; a correction value calculation means for calculating the correction value by dividing the input outer diameter by an ideal outer diameter of the drum-shaped member; having The storage means stores the calculated correction value. <1> or <2> The present invention relates to an apparatus for discharging the liquid described above. <4> an image reading means for reading an adjustment image for adjusting the timing; calculating an actual outer diameter of the drum-shaped member based on a result of reading the adjustment image by the image reading means; <1> ~ <3> 1 is a liquid ejection device according to any one of claims 1 to 9. <5> the adjustment image has a plurality of measurement shapes in a sub-scanning direction, the magnification calculation means calculates the correction value based on the result of the measurement shape detected by the image reading means and the ideal outer diameter of the drum-shaped member; <4> The present invention relates to an apparatus for discharging the liquid described above. <6> There are a plurality of measurement shapes, the magnification calculation means calculates the correction value for the ideal outer diameter by using a least squares method based on the reading results of the measurement shape at at least two points. <5> The present invention relates to an apparatus for discharging the liquid described above. <7> the magnification calculation means calculates the correction value taking into account a thickness value of a recording medium on which the adjusted image is formed. <4> ~ <6> 1 is a liquid ejection device according to any one of claims 1 to 9. [Explanation of symbols]

[0071] 1: Inkjet recording device 20: Image forming section 22: Discharge unit 51: Drums 52:Suction device 63: Drum rotation motor 63a: Rotary encoder 80: Reading device 90: Operation input panel 100: Controller 101: CPU 102: RAM 103: ROM 104: HDD 105: Interface 109: Common bus 511: Outer surface [Prior art documents] [Patent documents]

[0072] [Patent Document 1] Patent Publication No. 2021-146648

Claims

1. A drum-shaped member that transports a recording medium; an ejection head disposed opposite the drum-shaped member and configured to eject liquid onto the recording medium; a timing generating means for generating an ejection timing signal indicative of a timing for ejecting the liquid from the ejection head in accordance with an amount of rotation of the drum-shaped member; a storage means for storing a correction value for correcting the outer diameter of the drum-shaped member; a magnification calculation means for calculating an image magnification of an image to be formed on the recording medium based on the correction value; a formed image modification unit that changes the timing so as to modify the image formed on the recording medium based on the image magnification; A liquid ejection device comprising:

2. The storage means also stores a thickness value indicating the thickness of the recording medium, the magnification calculation means calculates the image magnification based on the correction value and the thickness value. The liquid dispensing device according to claim 1 .

3. An outer diameter input means for inputting the outer diameter; a correction value calculation means for calculating the correction value by dividing the input outer diameter by an ideal outer diameter of the drum-shaped member; having The storage means stores the calculated correction value.

3. A liquid ejection device according to claim 1 or 2.

4. an image reading means for reading an adjustment image for adjusting the timing; calculating an actual outer diameter of the drum-shaped member based on a result of reading the adjustment image by the image reading means; The liquid dispensing device according to claim 1 .

5. the adjustment image has a plurality of measurement shapes in a sub-scanning direction, the magnification calculation means calculates the correction value based on the result of the measurement shape detected by the image reading means and the ideal outer diameter of the drum-shaped member; 5. The liquid dispensing device according to claim 4.

6. There are a plurality of measurement shapes, the magnification calculation means calculates the correction value for the ideal outer diameter by using a least squares method based on the reading results of the measurement shape at at least two points.

6. The liquid dispensing device according to claim 5.

7. the magnification calculation means calculates the correction value taking into account a thickness value of a recording medium on which the adjusted image is formed. A liquid dispensing device according to any one of claims 4 to 6.

Images