Liquid discharge device, and image formation apparatus

Abstract

To provide a liquid discharge device that can complete correction of an impact position in short time, and to provide an image formation apparatus.SOLUTION: A liquid discharge device includes: a plurality of liquid discharge head units that are provided at different positions on a path in a conveyance direction along which a conveyed object is conveyed; image sensors for imaging a region of the conveyed object on which liquid has been discharged by the liquid discharge head units; a detection processing part for detecting a deviation amount between positions where liquid has been discharged by the plurality of liquid discharge head units, based on the image information imaged by each of the image sensors; a correction part for correcting a timing of discharging liquid from the liquid discharge head units, based on the deviation amount detected by the detection processing part; and a change part for changing a correction upper limit to be used for correcting the timing in the correction part, based on the specified conveyed object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and an image forming apparatus.

Background Art

[0002] In inkjet image forming technology, a technique has been developed to improve the landing position accuracy with respect to the conveyance direction of an object to be conveyed by correcting the ejection timing of a print head (an example of a liquid ejection head) using the detection values (position, moving speed, moving amount of the conveyed object) of a sensor mounted in front of the print head.

Summary of the Invention

Problems to be Solved by the Invention

[0003] By the way, in the above-described technique for improving the landing position accuracy, the correction amount is always constant regardless of the object to be conveyed. Further, when the object to be conveyed is paper, the paper causes expansion and contraction of pulp fibers due to humidity changes. Therefore, in the above-described technique for improving the landing position accuracy, it takes time for correction for thin paper or the like that easily stretches in the conveyance direction.

[0004] The present invention has been made in view of the above, and an object thereof is to provide a liquid ejection device and an image forming apparatus capable of completing the correction of the landing position in a short time.

Means for Solving the Problems

[0005] In order to solve the above-described problems and achieve the object, the present invention includes a plurality of liquid ejection head units provided at different positions on a path in the conveyance direction for conveying an object to be conveyed, an image sensor that images a region of the object to be conveyed where liquid has been ejected by the liquid ejection head unit, a detection processing unit that detects a deviation amount between positions where liquid has been ejected by the plurality of liquid ejection head units based on image information imaged by each image sensor, a correction unit that corrects the timing of ejecting liquid from the liquid ejection head unit based on the deviation amount detected by the detection processing unit, and a change unit that changes a correction upper limit value used for correcting the timing in the correction unit based on the specified object to be conveyed.

Advantages of the Invention

[0006] According to the present invention, there is an effect that correction of the landing position can be completed in a short time.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of a liquid ejection device and an image forming apparatus will be described in detail with reference to the accompanying drawings.

[0009] FIG. 1 is a schematic diagram showing an example of the overall configuration of an apparatus for discharging a liquid according to the present embodiment. As shown in the figure, an image forming apparatus 510 (an example of a liquid discharging apparatus) has four liquid discharging head units 210A, 210B, 210C, and 210D for discharging each of the four colors of ink. In the following description, when the liquid discharging head units 210A, 210B, 210C, and 210D are not distinguished, they may be described as a liquid discharging head unit 210 (an example of a liquid discharging unit).

[0010] Each liquid discharging head unit 210 discharges each of the liquids of each color onto a web 120 conveyed in the web direction (conveying direction). Further, it is assumed that the web 120 is conveyed by two pairs of nip rollers and a roller 230 or the like. Note that each nip roller rotates while sandwiching an object to be conveyed such as the web 120 as shown in the figure. In this way, each nip roller and the roller 230 are mechanisms for conveying the web 120 or the like in a predetermined direction.

[0011] Hereinafter, in the overall configuration example to be illustrated, it is assumed that each liquid ejection head unit 210 is installed in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side to the downstream side in the web direction. The liquid ejection head unit installed on the most upstream side (hereinafter referred to as the black liquid ejection head unit 210A) is for black (K). The liquid ejection head unit installed next to this black liquid ejection head unit 210A (hereinafter referred to as the cyan liquid ejection head unit 210B) is for cyan (C). Further, the liquid ejection head unit installed next to the cyan liquid ejection head unit 210B (hereinafter referred to as the magenta liquid ejection head unit 210C) is for magenta (M). Subsequently, the liquid ejection head unit installed on the most downstream side (hereinafter referred to as the yellow liquid ejection head unit 210D) is for yellow (Y). That is, the liquid ejection head units 210A, 210B, 210C, and 210D are an example of a plurality of liquid ejection head units provided at different positions on the path in the conveyance direction (web direction) for conveying the web 120 (an example of an object to be conveyed).

[0012] Based on image data or the like, each liquid ejection head unit 210 ejects inks of respective colors to predetermined positions on the web 120. The position where this ink is ejected (hereinafter referred to as the landing position) is substantially equal to the position where the liquid ejected from the liquid ejection head unit 210 lands on the recording medium. That is, the landing position is directly below the liquid ejection head unit 210 or the like. Hereinafter, an example will be described in which the processing position processed by the liquid ejection head unit 210 is taken as the landing position.

[0013] In this example, the black ink is ejected to the landing position of the black liquid ejection head unit 210A. Similarly, the cyan ink is ejected to the landing position of the cyan liquid ejection head unit 210B. Further, the magenta ink is ejected to the landing position of the magenta liquid ejection head unit 210C. Also, the yellow ink is ejected to the landing position of the yellow liquid ejection head unit 210D.

[0014] Note that the controller 520 connected to each liquid ejection head unit 210 controls the respective timings at which each liquid ejection head unit 210 ejects ink. Further, the controller 520 controls the timing based on the detection result of the image sensor 52 and the like.

[0015] The liquid ejection head unit 210 may be a liquid ejection unit in which a liquid ejection head and a head tank are integrated. The liquid ejection head of the liquid ejection head unit 210 ejects liquids of respective colors such as yellow (Y), cyan (C), magenta (M), and black (K), for example. Further, the liquid ejection head is arranged in a nozzle row composed of a plurality of nozzles in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ejection direction facing downward.

[0016] Also, the pressure generating means used for the liquid ejection head is not limited. For example, in addition to a piezoelectric actuator (which may use a laminated piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a diaphragm and a counter electrode, or the like may be used.

[0017] Also, in the terms of the present embodiment, image formation, recording, printing, imprinting, printing, shaping, etc. are all synonymous.

[0018] The liquid ejection head unit 210 is an integration of a liquid ejection head with functional components and mechanisms, and is an assembly of components related to liquid ejection. For example, the liquid ejection head unit 210 includes at least one of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism combined with the liquid ejection head.

[0019] Here, the integration includes, for example, those in which the liquid ejection head and the functional components and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., and those in which one is held movably with respect to the other. Also, the liquid ejection head and the functional components and mechanisms may be configured to be detachable from each other.

[0020] For example, as the liquid ejection head unit 210, there is one in which a liquid ejection head and a head tank are integrated. Also, there is one in which a liquid ejection head and a head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter can also be added between the head tank and the liquid ejection head of these liquid ejection head units 210.

[0021] Also, as the liquid ejection head unit 210, there is one in which a liquid ejection head and a carriage are integrated.

[0022] Also, as the liquid ejection head unit 210, there is one in which a liquid ejection head is movably held by a guide member that constitutes a part of a scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated. Also, there is one in which a liquid ejection head, a carriage, and a main scanning movement mechanism are integrated.

[0023] Also, as the liquid ejection head unit 210, there is one in which a cap member that is a part of a maintenance and recovery mechanism is fixed to a carriage to which a liquid ejection head is attached, and the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated.

[0024] Also, as the liquid ejection head unit 210, there is one in which a tube is connected to a liquid ejection head to which a head tank or a flow path component is attached, and the liquid ejection head and a supply mechanism are integrated. Through this tube, the liquid in the liquid storage source is supplied to the liquid ejection head.

[0025] The main scanning movement mechanism shall also include a single guide member. Also, the supply mechanism shall include a single tube and a single loading unit.

[0026] The image sensor 52 is arranged in the conveyance direction of the web 120 in the order of the image sensor 52A, the image sensor 52B, the image sensor 52C, and the image sensor 52D from the upstream side. The image sensor 52A is a device such as a detection device installed for the black liquid ejection head unit 210A. Similarly, the image sensor 52B is a device such as a detection device installed for the cyan liquid ejection head unit 210B. Further, the image sensor 52C is a device such as a detection device installed for the magenta liquid ejection head unit 210C. Further, the image sensor 52D is a device such as a detection device installed for the yellow liquid ejection head unit 210D. In the following description, the image sensor 52A, the image sensor 52B, the image sensor 52C, and the image sensor 52D may be simply referred to as the image sensor 52 in total. That is, the image sensor 52 is an example of an image sensor that images the area of the web 120 where liquid is ejected by the liquid ejection head unit 210.

[0027] In the following description, the position where the image sensor 52 is installed refers to the position where detection and the like are performed. Therefore, it is not necessary to install all devices such as detection devices at the position where the image sensor 52 is installed, and they may be connected by a cable or the like, and devices other than the image sensor 52 may be installed at other positions. Note that the image sensor 52A, the image sensor 52B, the image sensor 52C, and the image sensor 52D illustrated in FIG. 1 show examples of positions where the image sensor 52 is installed.

[0028] The image sensor processing unit 53 independently receives a shutter trigger (camera trigger) from the controller 520 and captures the image data of each of the image sensors 52A, 52B, 52C, and 52D. The image sensor processing unit 53 calculates the phase-limited correlation of the image data of the downstream image sensors 52B, 52C, and 52D with respect to the most upstream image sensor 52A. Here, the phase-limited correlation may be the relative position of the image data captured by each of the image sensors 52B, 52C, and 52D with respect to the image sensor 52A (the detection (imaging) position of the image sensor 52A).

[0029] Also, based on the calculation result of the position-limited correlation, the image sensor processing unit 53 outputs the paper position among the image sensors 52A, 52B, 52C, and 52D to the controller 520. Here, the paper position among the image sensors 52A, 52B, 52C, and 52D may be the relative position of the web 120 among the image sensors 52A, 52B, 52C, and 52D.

[0030] In the controller 520, based on pulses (encoder pulses) from an encoder provided on the roller 230, the ejection timings of the respective liquid ejection heads 210A, 210B, 210C, and 210D are generated. Further, the controller 520 corrects the ejection timing based on the paper position output from the image sensor processing unit 53.

[0031] Specifically, the controller 520 includes a correction unit 520a, a change unit 520b, and a detection processing unit 520c. The detection processing unit 520c is an example of a detection processing unit that detects the amount of deviation (position deviation amount) between the positions (landing positions) where a liquid such as ink is ejected by the plurality of liquid ejection head units 210A, 210B, 210C, and 210D based on the image data (an example of image information) captured by the respective image sensors 52A, 52B, 52C, and 52. In the present embodiment, the detection processing unit 520c detects the position deviation amount based on the encoder of the roller 230 based on the paper position output from the image sensor processing unit 53.

[0032] The correction unit 520a is an example of a correction unit that corrects the ejection timing (an example of timing) for ejecting ink from the liquid ejection head units 210A, 210B, 210C, and 210D based on the amount of position deviation detected by the image sensor processing unit 53.

[0033] The change unit 520b is an example of a change unit that changes the correction upper limit value used for correcting the ejection timing in the correction unit 520a based on the object to be conveyed (web 120) specified by the user or the like. By changing the correction upper limit value according to the object to be conveyed, the landing position can be corrected according to the amount of deviation in the web direction. For example, for an object to be conveyed with a large amount of deviation, the correction can be completed in a short time.

[0034] Further, the change unit 520b may change the correction upper limit value at a timing that does not affect the ejection of ink from the liquid ejection head units 210A, 210B, 210C, and 210D. By greatly changing the correction upper limit value during the inter-page or intermittent operation, it becomes possible to adjust the landing positions between the plurality of liquid ejection head units 210A, 210B, 210C, and 210D in a short time.

[0035] Furthermore, the change unit 520b may greatly change the correction upper limit value during the inter-page or intermittent operation. This enables adjustment of the landing position in a short time, so that even for the same paper type, a correction upper limit value taking into account other composite factors can be used.

[0036] The external storage device 600 may be an example of a recording unit that records a plurality of correction upper limit values. In this case, the change unit 520b changes to the correction upper limit value corresponding to the specified object to be conveyed (web 120) among the plurality of correction upper limit values stored in the external storage device 600. For example, as shown in Table 1 below, when correcting the ejection timing, for an object to be conveyed with a large amount of deviation in the web direction (for example, plain paper), the change unit 520b increases the correction upper limit value. This allows the correction to be completed in a short time. Conversely, as shown in Table 1 below, for an object to be conveyed with a small amount of deviation in the web direction (for example, coated paper), the change unit 520b can also prevent image quality degradation (for example, streaks) by reducing the correction upper limit value.

Table 1

[0037] FIG. 2 is a flowchart showing an example of the flow of correction processing for the amount of deviation in the landing position between a plurality of liquid ejection head units in a conventional image forming apparatus. First, the conventional image forming apparatus detects the position, moving speed, or moving amount of an object to be conveyed (recording medium) (step S201). Next, the conventional image forming apparatus calculates the conveyance time required for a predetermined portion of the recording medium to be conveyed to the next landing position based on the position, moving speed, or moving amount of the recording medium (step S202).

[0038] Next, the conventional image forming apparatus detects a predetermined portion conveyed to the landing position (step S203). Then, the conventional image forming apparatus detects the amount of positional deviation in the conveyance of the recording medium to the landing position based on the calculated conveyance time and the detection result of the predetermined portion, and adjusts (corrects) the deviation of the recording medium conveyed to the landing position based on the amount of positional deviation (step S204).

[0039] FIG. 3 is a flowchart showing an example of the flow of correction processing for the amount of deviation in the landing position between a plurality of liquid ejection head units in the image forming apparatus according to the present embodiment. First, in the present embodiment, the controller 520 detects the position, moving speed, or moving amount of an object to be conveyed (recording medium) (step S301). Next, the controller 520 calculates the conveyance time required for a predetermined portion of the recording medium to be conveyed to the next landing position based on the position, moving speed, or moving amount of the recording medium (step S302).

[0040] Next, the image forming apparatus 510 detects a predetermined portion conveyed to the landing position by the image sensor 52 (step S303). Then, the changing unit 520b changes the correction upper limit value based on the correction upper limit value stored in the external storage device 600 and the designated object to be conveyed. Next, the correction unit 520a adjusts (corrects) the amount of positional deviation detected by the detection processing unit 520c based on the changed correction upper limit value (step S304).

[0041] FIG. 4 is a timing chart for explaining an example of the correction upper limit value change process in the image forming apparatus according to the present embodiment. The detection processing unit 520c of the controller 520 calculates a positional deviation amount (for example, "12") based on the sheet position between the image sensors 52 detected by the image sensor processing unit 53. As shown in FIG. 4, the correction unit 520a corrects the ejection timing within the correction upper limit value based on the encoder reference. In the conventional means, as shown in FIG. 4, the correction upper limit value (for example, "1") is constant regardless of the object to be conveyed. On the other hand, in the present embodiment, as shown in FIG. 4, the changing unit 520b changes the correction upper limit value (for example, "4") based on the designated object to be conveyed, so that the correction of the ejection timing can be completed in a short time.

[0042] As described above, according to the image forming apparatus 510 according to the present embodiment, by changing the correction upper limit value according to the object to be conveyed, the landing position can be corrected according to the amount of positional deviation in the web direction. Therefore, for example, for an object to be conveyed with a large amount of positional deviation, the correction can be completed in a short time.

[0043] In the present embodiment, a liquid ejection apparatus such as the image forming apparatus 510 includes a liquid ejection head or a liquid ejection head unit 210, and is an apparatus that drives the liquid ejection head to eject liquid. The liquid ejection apparatus includes not only an apparatus capable of ejecting liquid onto an object to which liquid can adhere, but also an apparatus that ejects liquid into the air or liquid.

[0044] This liquid ejection apparatus can also include means related to the feeding, conveying, and paper discharging of objects to which liquid can adhere, as well as a pre-processing apparatus, a post-processing apparatus, and the like.

[0045] For example, as the liquid ejection apparatus, there are an image forming apparatus that ejects ink to form an image on a sheet, and a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that ejects a modeling liquid onto a powder layer formed in a layer shape of powder in order to model a three-dimensional object (three-dimensional object).

[0046] Further, the liquid ejection device is not limited to one in which a significant image such as characters or figures is visualized by the ejected liquid. For example, those that form a pattern having no meaning by itself, those that create a three-dimensional image, etc. are also included.

[0047] The above-mentioned thing to which the liquid can adhere means a thing to which the liquid can adhere at least temporarily, and means a thing that adheres and adheres firmly, a thing that adheres and penetrates, etc. Specific examples include recording media such as paper, recording paper, recording paper, film, cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as test cells, etc., and all things to which the liquid adheres are included unless otherwise particularly limited.

[0048] The material of the above-mentioned thing to which the liquid can adhere may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. as long as the liquid can adhere even temporarily.

[0049] Further, the liquid may have a viscosity and surface tension that can be ejected from the head, and is not particularly limited, but it is preferably one whose viscosity becomes 30 mPa·s or less at normal temperature and normal pressure, or by heating or cooling. More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, calcium, edible materials such as natural pigments, etc. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light-emitting elements, and liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0050] Further, there is a liquid ejection device in which the liquid ejection head and the thing to which the liquid can adhere move relatively, but it is not limited to this. Specific examples include serial type devices that move the liquid ejection head and line type devices that do not move the liquid ejection head.

[0051] In addition, as other liquid ejection devices, there are also a treatment liquid application device that ejects a treatment liquid onto a sheet for the purpose of modifying the surface of the sheet, an injection granulation device that injects a composition liquid in which raw materials are dispersed in a solution through a nozzle to granulate fine particles of the raw materials, and the like.

[0052] In the above embodiment, an example in which the image forming apparatus of the present invention is applied to a multifunction device having at least two functions among a copying function, a printer function, a scanner function, and a facsimile function has been described. However, the present invention can be applied to any image forming apparatus such as a copying machine, a printer, a scanner device, a facsimile device, etc.

[0053] Aspects of the present invention are as follows, for example. <1> A plurality of liquid ejection head units provided at different positions on a path in the conveyance direction for conveying an object to be conveyed, An image sensor that images a region of the object to be conveyed onto which liquid has been ejected by the liquid ejection head unit, A detection processing unit that detects a deviation amount between positions where liquid has been ejected by the plurality of liquid ejection head units based on image information imaged by each image sensor, A correction unit that corrects the timing of ejecting liquid from the liquid ejection head unit based on the deviation amount detected by the detection processing unit, A change unit that changes a correction upper limit value used for correcting the timing in the correction unit based on the specified object to be conveyed, A liquid ejection device comprising: <2> Further comprising a recording unit that records a plurality of the correction upper limit values, The change unit changes to the correction upper limit value corresponding to the specified object to be conveyed among the plurality of correction upper limit values recorded in the recording unit, the liquid ejection device according to <1>. <3> The change unit changes the correction upper limit value in the correction unit at a timing that does not affect the ejection of liquid from the liquid ejection head unit, the liquid ejection device according to <1> or <2>. <4> The liquid ejection device according to <3>, wherein the changing unit increases the correction upper limit value during inter-page or intermittent operation. <5> The liquid ejection device according to any one of <1> to <4>, wherein the changing unit increases the correction upper limit value for an object to be conveyed having a large amount of deviation with respect to the conveyance direction. <6> The liquid ejection device according to any one of <1> to <5>, wherein the changing unit decreases the correction upper limit value for an object to be conveyed having a small amount of deviation with respect to the conveyance direction. <7> A plurality of liquid ejection head units provided at different positions on a path in the conveyance direction for conveying an object to be conveyed, An image sensor that images a region of the object to be conveyed from which liquid has been ejected by the liquid ejection head unit, A detection processing unit that detects a deviation amount between positions where liquid is ejected by the plurality of liquid ejection head units based on image information imaged by each image sensor, A correction unit that corrects the timing of ejecting liquid from the liquid ejection head unit based on the deviation amount detected by the detection processing unit, A changing unit that changes a correction upper limit value used for correcting the timing in the correction unit based on the specified object to be conveyed, An image forming apparatus comprising:

Description of the reference numerals

[0054] 52 Image sensor 53 Image sensor processing unit 120 Web 210 Liquid ejection head unit 230 Roller 520 Controller 520a Correction unit 520b Changing unit 520c Detection processing unit 600 External storage device

Prior art documents

Patent documents

[0055]

Patent Document 1

Claims

1. A plurality of liquid ejection head units provided at different positions on a path in a conveyance direction for conveying an object to be conveyed, an image sensor that images a region of the object to be conveyed where liquid has been ejected by the liquid ejection head unit, a detection processing unit that detects a deviation amount between positions where liquid has been ejected by the plurality of liquid ejection head units based on image information captured by each image sensor, a correction unit that corrects the timing of ejecting liquid from the liquid ejection head unit based on the deviation amount detected by the detection processing unit, a change unit that changes a correction upper limit value used for the timing correction in the correction unit based on the specified object to be conveyed, A liquid ejection device comprising:

2. Further comprising a recording unit that records a plurality of the correction upper limit values, The liquid ejection device according to claim 1, wherein the change unit changes to the correction upper limit value corresponding to the specified object to be conveyed among the plurality of correction upper limit values recorded in the recording unit.

3. The liquid ejection device according to claim 1 or 2, wherein the change unit changes the correction upper limit value in the correction unit at a timing that does not affect the ejection of liquid from the liquid ejection head unit.

4. The liquid ejection device according to claim 3, wherein the change unit increases the correction upper limit value during inter-page or intermittent operation.

5. The liquid ejection device according to claim 1, wherein the change unit increases the correction upper limit value for an object to be conveyed having a large deviation amount with respect to the conveyance direction.

6. The liquid ejection device according to claim 1, wherein the change unit decreases the correction upper limit value for an object to be conveyed having a small deviation amount with respect to the conveyance direction.

7. A plurality of liquid ejection head units provided at different positions on a path in a conveyance direction for conveying an object to be conveyed, an image sensor that images a region of the object to be conveyed where liquid has been ejected by the liquid ejection head unit, a detection processing unit that detects a deviation amount between positions where liquid has been ejected by the plurality of liquid ejection head units based on image information captured by each image sensor, a correction unit that corrects the timing of ejecting liquid from the liquid ejection head unit based on the deviation amount detected by the detection processing unit, a change unit that changes a correction upper limit value used for the timing correction in the correction unit based on the specified object to be conveyed, An image forming device comprising:

Images