JP7415435B2 - inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device.

An inkjet recording apparatus includes a recording head unit having an inkjet head, and forms (records) an image on a recording medium by ejecting ink from the inkjet head. At this time, the inkjet head of the recording head unit is placed close to the recording surface of the recording medium, so if the recording medium is lifted, the recording medium may come into contact with the inkjet head, potentially damaging the inkjet head. .

Patent Document 1 describes a technique for stopping the conveyance of a recording medium when a conveyance abnormality due to floating of the recording medium is detected.

Japanese Patent Application Publication No. 2002-113910

However, in the technology described in Patent Document 1, even if an attempt is made to immediately stop the conveyance of the recording medium after detecting a conveyance abnormality due to the floating of the recording medium, the recording medium will not be able to move due to the inertial force acting on the recording medium conveyance means such as the conveyance drum. The movement of the inkjet head cannot be stopped immediately, and there is a risk that the recording medium may come into contact with the inkjet head.

The present invention has been made to solve the above problems, and an object thereof is to provide an inkjet recording device that can effectively suppress damage to an inkjet head due to contact with a recording medium. .

The present invention has a plurality of recording head units provided for each color of ink and each having an inkjet head, and a mounting surface on which a recording medium is placed, and the recording head unit is provided for each color of ink, and the recording head unit has a mounting surface on which a recording medium is mounted, and the recording head unit is provided for each color of ink. A conveyance unit that conveys the medium along a conveyance path passing through image recording positions by a plurality of recording head units, and only the recording head unit that is disposed most upstream in the conveyance direction of the recording medium among the plurality of recording head units. In order to support the unit so that it can move between a normal position close to the image recording position and a retracted position retracted from the normal position, only the recording head unit disposed on the most upstream side in the conveyance direction of the recording medium is supported. A single head unit moving mechanism is provided, but is not provided for other recording head units, and a recording head unit that is not used in a print job among multiple recording head units is the most upstream in the recording medium conveyance direction. control for controlling the head unit moving mechanism so that only the print head unit placed furthest upstream in the conveyance direction of the print medium is evacuated from the normal position to the evacuation position when the print head unit is placed on the side; This is an inkjet recording apparatus including a section.

According to the present invention, damage to an inkjet head due to contact with a recording medium can be effectively suppressed.

1 is a schematic perspective view of an inkjet recording apparatus according to a first embodiment of the present invention. 2 is a schematic side view showing the internal structure of the inkjet recording apparatus shown in FIG. 1. FIG. 1 is a schematic side view enlarging a part of an image forming section included in an inkjet recording apparatus according to a first embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a control system of an inkjet recording apparatus according to a first embodiment of the present invention. 1 is a flowchart showing a processing procedure of an inkjet recording apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic perspective view enlarging a part of an image forming section included in an inkjet recording apparatus according to a second embodiment of the present invention. FIG. 3 is a schematic perspective view showing a state in which a cover is attached to the recording head unit. It is a flowchart which shows the processing procedure of the inkjet recording device based on 2nd Embodiment of this invention.

≪First embodiment≫
<Configuration of inkjet recording device>
FIG. 1 is a schematic perspective view of an inkjet recording apparatus according to a first embodiment of the present invention.
As shown in FIG. 1, the inkjet recording apparatus 10 includes a paper feed section 11, an image forming section 12, a paper discharge section 13, and an ink supply tank 14. The paper feed section 11 is a section that supplies paper as a recording medium. The image forming section 12 is a section that forms an image on paper using ink. The paper ejection section 13 is a part that ejects paper on which an image has been formed. The ink supply tank 14 is a tank for storing a predetermined amount of ink and supplying this ink to the image forming section 12.

FIG. 2 is a schematic side view showing the internal structure of the inkjet recording apparatus shown in FIG.
As shown in FIG. 2, the paper feed section 11 is provided with a paper feed tray 11a. Paper 15 before forming an image is stacked on the paper feed tray 11a. The paper feed unit 11 separates and feeds the sheets 15 stacked on the paper feed tray 11a one by one starting from the top.

The image forming section 12 includes a transport drum 20 as a transport section, a plurality of recording head units 21W, 21Y, 21M, 21C, and 21K, a mist catcher 22, an ultraviolet irradiation section 23, an inline sensor 24, and a reversing section. 25, and two large and small conveyance rollers 26a and 26b.

The conveyance drum 20 is rotatably provided. The transport drum 20 rotates while wrapping the paper 15 supplied from the paper feed section 11 around the outer peripheral surface 20a of the transport drum 20. The transport drum 20 transports the paper 15 in the transport direction A by adsorbing the paper 15 to the outer peripheral surface 20a of the transport drum 20 by suctioning air, for example, and rotating in this state. In order to realize such a transport method, a large number of air suction holes (not shown) are formed in the outer peripheral surface 20a of the transport drum 20. The outer circumferential surface 20a of the transport drum 20 corresponds to a mounting surface on which the paper 15, which is a recording medium, is placed.

The plurality of recording head units 21W, 21Y, 21M, 21C, and 21K form (record) images on paper 15, which is a recording medium, using ink of a corresponding color. Specifically, the recording head unit 21W forms an image using white (W) ink, and the recording head unit 21Y forms an image using yellow (Y) ink. Further, the recording head unit 21M forms an image using magenta (M) ink, the recording head unit 21C forms an image using cyan (C) ink, and the recording head unit 21K forms an image using black (K) ink. An image is formed using ink. In this embodiment, as an example, ultraviolet curable ink is used.

Each of the recording head units 21W, 21Y, 21M, 21C, and 21K is arranged to face the upper outer peripheral surface 20a of the transport drum 20. Further, the respective recording head units 21W, 21Y, 21M, 21C, and 21K are arranged with their positions shifted in the circumferential direction of the conveyance drum 20. In this embodiment, as an example, five recording head units 21W, 21Y, 21M, 21C, and 21K are provided in the image forming section 12.

The mist catcher 22 is disposed on the downstream side of the recording head unit 21K in the conveyance direction A of the paper 15 by the conveyance drum 20. The mist catcher 22 collects mist generated by ejection of ink from the inkjet heads provided in each of the recording head units 21W, 21Y, 21M, 21C, and 21K. The ultraviolet irradiation unit 23 is arranged downstream of the mist catcher 22 in the conveyance direction A of the paper 15. The ultraviolet irradiation unit 23 cures the ink forming the image on the paper 15 by irradiating the paper 15 transported by the rotation of the transport drum 20 with ultraviolet rays. The ultraviolet irradiation unit 23 functions as a fixing unit that fixes the image formed on the paper 15 using ink to the paper 15. The fixing of the image by the fixing unit is not limited to the one that irradiates ultraviolet rays, but also the one that irradiates energy rays that can harden the ink depending on the properties of the ink, or the one that dries the ink by heating the paper 15. There may be.

The in-line sensor 24 is arranged downstream of the ultraviolet irradiation section 23 in the transport direction A of the paper 15. The in-line sensor 24 is a sensor for reading an image formed on the paper 15 while being transported by the transport drum 20 and inspecting the color density, inclination, etc. of this image. The reversing unit 25 is a portion that inverts the front and back of the paper 15 in order to form images on both sides of the paper 15 or to eject the paper 15 with the image formed on one side of the paper 15 facing downward. The conveyance rollers 26a and 26b are rollers that convey the paper 15 on which the image has been formed toward the paper discharge section 13.

The paper ejection section 13 is provided with a paper ejection tray 13a. The sheets 15 on which images have been formed are sequentially discharged to the paper discharge tray 13a.

<Operation of inkjet recording device>
Next, the operation of the inkjet recording apparatus 10 having the above configuration will be explained.
Print jobs performed by the inkjet recording apparatus 10 are roughly divided into three print jobs depending on which color ink is used to form an image. The first print job is a print job that forms an image on the paper 15 using ink of five colors (white, yellow, magenta, cyan, and black). The second print job is a print job in which an image is formed on the paper 15 using four colors of ink except white. The third print job is a print job that forms an image on paper 15 using only black ink.

Here, the operation of the inkjet recording apparatus 10 when executing the first print job will be described.
First, the sheets 15 stacked on the paper feed tray 11a of the paper feed section 11 are separated one by one from the top and supplied to the image forming section 12. The leading edge of the paper 15 supplied to the image forming section 12 is gripped by a transport claw (not shown). The transport claw feeds the paper 15 to the transport drum 20 at a predetermined timing. As a result, the paper 15 is attracted to the outer peripheral surface 20a of the transport drum 20, and in this state, the paper 15 is transported in the transport direction A as the transport drum 20 rotates.

On the other hand, the inkjet heads provided in each of the recording head units 21W, 21Y, 21M, 21C, and 21K apply ink to a predetermined position at a predetermined timing on the paper 15 transported by the rotation of the transport drum 20. Exhale. As a result, an image is formed on the paper 15. Thereafter, the paper 15 is irradiated with ultraviolet rays by the ultraviolet irradiator 23. When the paper 15 is irradiated with ultraviolet rays, the ink forming the image on the paper 15 is cured.

The paper 15 on which the image has been formed is then transported by transport rollers 26a and 26b, and sent to the paper discharge section 13. The sheets 15 fed into the sheet discharge section 13 are sequentially discharged onto the sheet discharge tray 13a. Through the above operations, a sheet 15 on which an image has been formed is obtained.

FIG. 3 is an enlarged schematic side view of a part of the image forming section included in the inkjet recording apparatus according to the first embodiment of the present invention. In the following description, the ink colors W, Y, M, C, Omit the subscript of K.

As shown in FIG. 3, a conveyance path (indicated by a broken line in the figure) 31 for conveying the recording medium is formed on the outer peripheral surface 20a of the conveyance drum 20. Paper 15 (see FIG. 2) as a recording medium is conveyed as the conveyance drum 20 rotates while being attracted to the outer peripheral surface 20a of the conveyance drum 20. Therefore, the conveyance path 31 is formed along the outer peripheral surface 20a of the conveyance drum 20.

In the middle of the conveyance path 31, there are image recording positions P1, P2, P3, P4, and P5 by the respective recording head units 21W, 21Y, 21M, 21C, and 21K. The image recording position P1 is a position where an image is recorded (formed) by the recording head unit 21W, and the image recording position P2 is a position where an image is recorded by the recording head unit 21Y. Further, the image recording position P3 is a position where an image is recorded by the recording head unit 21M, and the image recording position P4 is a position where an image is recorded by the recording head unit 21C. Further, the image recording position P5 is a position where an image is recorded by the recording head unit 21K.

When the paper 15 is conveyed along the conveyance path 31, the leading edge of the paper 15 first passes the image recording position P1 by the recording head unit 21W, and then the image is recorded by the other recording head units 21Y, 21M, 21C, and 21K. It passes through positions P2, P3, P4, and P5 in order. When executing the first print job described above, each of the recording head units 21W, 21Y, 21M, 21C, and 21K is located at a position (hereinafter referred to as , referred to as the "normal position"). Then, when ink is ejected from the five recording head units 21W, 21Y, 21M, 21C, and 21K at predetermined timings, the white ink adheres to the paper 15 at the image recording position P1, and the yellow ink adheres to the paper 15 at the image recording position P2. It adheres to the paper 15. Furthermore, magenta ink adheres to the paper 15 at the image recording position P3, cyan ink adheres to the paper 15 at the image recording position P4, and black ink adheres to the paper 15 at the image recording position P5.

The recording head unit 21W includes an inkjet head 32W and a carriage 33W that holds the inkjet head 32W. The inkjet head 32W has an ink ejection surface 34W, and ejects ink from nozzles (not shown) provided on the ink ejection surface 34W. The ink ejection surface 34W of the inkjet head 32W is arranged to face the outer peripheral surface 20a of the transport drum 20. When the recording head unit 21W is placed at the normal position Pa, a predetermined gap is formed between the ink ejection surface 34W of the inkjet head 32W and the outer peripheral surface 20a of the transport drum 20. The normal position Pa is a position suitable for forming an image on the paper 15 by ejecting ink from the inkjet head 32W. The predetermined gap is set to, for example, about 1 mm.

Similar to the recording head unit 21W described above, the recording head unit 21Y includes an inkjet head 32Y and a carriage 33Y that holds this inkjet head 32Y, and the recording head unit 21M includes an inkjet head 32M and a carriage 33Y that holds this inkjet head 32Y. A carriage 33M for holding. The recording head unit 21C includes an inkjet head 32C and a carriage 33C that holds the inkjet head 32C, and the recording head unit 21K includes an inkjet head 32K and a carriage 33K that holds the inkjet head 32K. There is.

Among the five recording head units 21W, 21Y, 21M, 21C, and 21K, the recording head unit 21W, which is disposed most upstream in the transport direction A, is provided so as to be movable in the direction B by a head unit moving mechanism 41. . The B direction, which is the moving direction of the recording head unit 21W, is a direction along the radial direction of the transport drum 20. The head unit moving mechanism 41 moves the recording head unit between a normal position (position indicated by a solid line) Pa close to the image recording position P1 and an evacuation position (position indicated by a two-dot chain line) Pb evacuated from the normal position Pa. This is a mechanism that movably supports 21W. In this embodiment, as an example, it is assumed that the head unit moving mechanism 41 operates using a motor as a driving source.

The retreat position Pb is set so that the recording head unit 21W is moved to the normal position Pa (image recording position This is the position set for evacuation from P1). In the first embodiment of the present invention, when retracting the recording head unit 21W from the normal position Pa to the evacuation position Pb, the head unit moving mechanism 41 moves the recording head unit 21W in a direction away from the transport path 31. The structure is as follows. Therefore, when the recording head unit 21W is retracted to the retracted position Pb, the distance between the ink ejection surface 34W of the inkjet head 32W and the outer circumferential surface 20a of the transport drum 20 is larger than the above-mentioned predetermined gap (for example, , several tens of mm).

A floating detection section 45 and a pressing roller 46 are provided around the conveyance drum 20. The floating detection unit 45 detects floating of the paper 15 conveyed by the conveying drum 20. The floating detection section 45 is arranged upstream in the transport direction A from the image recording positions P1, P2, P3, P4, and P5 by the respective recording head units 21W, 21Y, 21M, 21C, and 21K. The floating of the paper 15 is caused by the fact that when the paper 15 is placed on the outer peripheral surface 20a of the transport drum 20 and transported, the paper 15 does not attract (closely adhere to) the outer peripheral surface 20a of the transport drum 20, and the paper 15 does not stick to the outer peripheral surface 20a of the transport drum 20. This is a phenomenon in which the objects float.

The floating detection section 45 can be configured using a contact type sensor or a non-contact type sensor (not shown). When using a contact type sensor, for example, a contactor is brought into contact with the paper 15 transported by the transport drum 20, and the position of the contactor changes as the paper 15 floats. can be detected. When using a non-contact type sensor, for example, a light emitting element is placed at one end of the conveyance drum 20 in the direction of the central axis (in the depth direction in FIG. 3) and a light receiving element is placed at the other end. The floating of the paper 15 can be detected by utilizing the phenomenon in which the light emitted from the paper 15 is blocked by the floating of the paper 15.

The pressing roller 46 is disposed upstream of the floating detection section 45 in the conveying direction A. The pressure roller 46 is pressed against the conveyance drum 20 with a predetermined pressure. The pressing roller 46 presses the paper 15 sent from the paper feed section 11 to the image forming section 12 against the transport drum 20, thereby causing the paper 15 to be attracted to the outer circumferential surface 20a of the transport drum 20.

FIG. 4 is a block diagram showing the configuration of the control system of the inkjet recording apparatus according to the first embodiment of the present invention.
As shown in FIG. 4, the inkjet recording apparatus 10 includes, in addition to the above-mentioned floating detection section 45, a control section 51, an operation display section 53, a head drive section 55, a transport motor 57, and a head unit movement motor 57. A motor 59 is provided. When the floating detection unit 45 detects floating of the paper 15, it provides the control unit 51 with a detection signal indicating that floating of the paper 15 has occurred.

The control unit 51 includes a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 63, and a RAM (Random Access Memory) 65. The CPU 61 reads a predetermined processing program from the ROM 63, loads it into the RAM 65, and centrally controls the operation of each part of the inkjet recording apparatus 10 according to the loaded program. The control unit 51 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network (not shown). Further, when the control unit 51 receives a print job from the operation display unit 53 or an external device, the control unit 51 operates each unit of the inkjet recording device 10 to form an image on the paper 15 based on the image data specified in the print job. control.

The control unit 51 also has a function of determining the color of ink used for printing image data in a print job (hereinafter referred to as "color determination function"). The color discrimination function can be provided to the control unit 51 by storing a color discrimination program in the ROM 63 and having the CPU 61 read the color discrimination program from the ROM 63 and develop it in the RAM 65.

The operation display unit 53 is configured by, for example, a liquid crystal display with a touch panel, and has a function of displaying various information to the user and a function of receiving various input operations from the user. The information displayed on the operation display section 53 includes various operation screens, setting screens, error notification screens, and the like. Further, input operations performed by the user using the operation display section 53 include an operation for instructing execution of a print job, an operation for selecting (designating) image data to be subjected to a print job, and an operation for selecting (specifying) image data to be used for a print job. This includes operations such as selecting (specifying) the type (size, thickness, paper quality, etc.) and selecting conditions to be applied to the print job. Further, the operation of selecting conditions to be applied to a print job includes an operation of selecting whether to permit or disable execution of the evacuation operation of the recording head unit. The retracting operation of the recording head unit refers to an operation of retracting the recording head unit from the normal position to the retracted position.

Thereby, when executing a print job that does not use the recording head unit 21W, the user can select whether or not to perform the evacuation operation of the recording head unit 21W by operating the operation display section 53. In this case, the operation display section 53 has a function as a selection section. Further, among the sheets of paper 15 that can be handled by the inkjet recording apparatus 10, there are types of paper that float easily and sheets that do not float easily. If the paper 15 used for the print job is of a type that does not easily float, there is less need to perform the evacuation operation of the recording head unit 21W. Further, the retracting operation of the recording head unit 21W takes time. Therefore, if a user who wants to reduce the time required for the evacuation operation specifies a type of paper that does not easily float in a print job, before instructing the execution of this print job, select a mode that does not allow the evacuation operation of the recording head unit 21W. (hereinafter referred to as "evacuation not permitted mode") may be selected on the operation display section 53. In this way, the present embodiment is configured such that the user can select in advance whether or not to perform the evacuation operation of the recording head unit 21W.

Note that it is also possible to provide the control section 51 with the function of the selection section instead of the operation display section 53. Specifically, when the control unit 51 receives a print job from an external device and the conditions applied to this print job include a condition that does not permit execution of the evacuation operation of the recording head unit 21W, It is possible to adopt a configuration in which the control unit 51 selects the evacuation non-permission mode according to the conditions.

The head drive section 55 independently drives each of the inkjet heads 32W, 32Y, 32M, 32C, and 32K based on control commands given from the control section 51. The transport motor 57 is a motor for transporting the paper 15 and includes a motor that rotates the transport drum 20. The head unit moving motor 59 is a motor that serves as a drive source for the head unit moving mechanism 41 described above. The transport motor 57 and the head unit moving motor 59 are individually controlled by the control section 51 .

FIG. 5 is a flowchart showing the processing procedure of the inkjet recording apparatus according to the first embodiment of the present invention. The processing shown in the flowchart of FIG. 5 is performed under the control of the control unit 51.

First, the control unit 51 determines whether or not a print job has been accepted (step S1), and if the print job is accepted via an external device or the operation display unit 53, the process proceeds to step S2. The print job includes image data to be printed, conditions to be applied when printing this image data on paper 15, and the like.

Next, the control unit 51 determines whether or not to perform the evacuation operation of the recording head unit (step S2). In the first embodiment of the present invention, since the target of the evacuation operation is the recording head unit 21W, the control section 51 determines whether or not to perform the evacuation operation of the recording head unit 21W in step S2. If the user has previously selected the evacuation disallowed mode using the operation display section 53, the determination is YES in step S2 and the process proceeds to step S6; if the user has not selected the evacuation disallowed mode, A negative determination is made in step S2, and the process proceeds to step S3.

In step S3, the control unit 51 performs color determination processing to determine the color of ink used in the print job. If the print job accepted in step S1 is the first print job, it is determined that the ink colors used to print the image data are five colors: white, yellow, magenta, cyan, and black. Furthermore, if the print job accepted in step S1 above is the second print job, it is determined that the ink colors used to print the image data are four colors excluding white, and the third print job is If so, it is determined that the color of the ink used to print the image data is only black.

Next, the control unit 51 determines whether white (W) ink is not used in the print job (step S4). This determination is made based on the determination result of the color determination process in step S3. Specifically, if the ink colors used to print the image data are four colors excluding white, or only black, YES is determined in step S4 and the process proceeds to step S5. Further, if the ink colors used to print the image data are five colors, white, yellow, magenta, cyan, and black, a negative determination is made in step S4, and the process proceeds to step S6.

In step S5, the control unit 51 moves the recording head unit 21W whose ink color is white (W) from the normal position Pa to the retreat position Pb. At this time, the control section 51 drives the head unit moving motor 59 to operate the head unit moving mechanism 41, thereby causing the recording head unit 21W to retreat. As a result, the recording head unit 21W retreats (separates) from the image recording position P1, so there is a gap between the outer circumferential surface 20a of the transport drum 20 and the inkjet head 32W of the recording head unit 21W due to the protrusion of the paper surface due to the lifting of the paper 15. A separation distance greater than the dimensions is ensured. In this case, the recording head unit 21W corresponds to a recording head unit that is not used in a print job.

Next, the control unit 51 drives the transport motor 57 to start transporting the paper 15 (step S6). At this time, the conveyance drum 20 rotates according to the drive of the conveyance motor 57. Then, when the paper 15 is attracted to the outer peripheral surface 20a of the transport drum 20 through the pressure roller 46, the transport drum 20 transports the paper 15 along the transport path 31 shown in FIG.

Next, the control unit 51 determines whether the floating detection unit 45 has detected floating of the paper 15 (step S7). When the floating detection unit 45 detects floating of the paper 15, it provides a detection signal to that effect to the control unit 51.The control unit 51 receives this detection signal so that the floating detection unit 45 detects floating of the paper 15. I judge that I did. If the control unit 51 determines that the floating detection unit 45 has detected floating of the paper 15, the process proceeds to step S8, and if it determines that the floating detection unit 54 has not detected the floating of the paper 15, the process proceeds to step S10.

In step S8, the control unit 51 stops the conveyance of the paper 15 by the conveyance drum 20 by stopping the drive of the conveyance motor 57. At this time, even if the control unit 51 stops driving the transport motor 57, the transport drum 20 rotates by a predetermined amount due to the inertia force acting on the drum itself, and then stops. Next, the control unit 51 executes a notification process to notify the user that a conveyance error has occurred (step S9), and then ends the series of processes. In the notification process, an error notification screen is displayed on the operation display section 53 to notify the user of the occurrence of a transport error. It is preferable that a message for resolving the transport error is displayed on the error notification screen together with the details of the transport error. As a message for resolving a conveyance error, for example, a message such as "Please remove the paper from the conveyance path." can be considered.

On the other hand, in step S10, the control section 51 drives the head drive section 55 to start printing. At this time, if the ink colors used to print the image data are five colors, white, yellow, magenta, cyan, and black, the control unit 51 controls all the inkjet heads 32W, 32Y, 32M, 32C, and 32K. The head driving section 55 is controlled to drive. Further, if the ink colors used to print the image data are four colors excluding white, the control unit 51 controls the head drive unit 55 to drive the four inkjet heads 32Y, 32M, 32C, and 32K. However, if the color of the ink used to print the image data is only black, the control unit 51 controls the head drive unit 55 to drive only the inkjet head 32K. As a result, ink is ejected from the inkjet head 32 of the recording head unit 21 used in the print job, and this ink adheres to the paper 15, thereby forming an image on the paper 15.

Next, the control unit 51 determines whether the print job is finished (step S11). The print job ends when printing (image formation) for the print pages specified in the print job is completed. In step S11, if the control unit 51 determines that the print job has not ended, the process returns to step S7 and performs the same process as described above, and if it determines that the print job has ended, the process advances to step S12. Note that if the floating detection unit 45 detects floating of the paper 15 after printing is started in step S10, the control unit 51 stops driving both the transport motor 57 and the head driving unit 55 in step S8. As a result, both conveyance of the paper 15 and printing on the paper 15 are stopped.

In step S12, the control section 51 determines whether the recording head unit 21W has retreated to the retreat position Pb. If the recording head unit 21W has been evacuated to the evacuation position Pb, the process proceeds to step S13, and if the recording head unit 21W has not been evacuated to the evacuation position Pb, the series of processes ends at that stage.

In step S13, the control unit 51 moves the recording head unit 21W from the retracted position Pb to the normal position Pa by driving the head unit moving motor 59 and operating the head unit moving mechanism 41, and then Finish processing. Thereby, the recording head unit 21W returns to a state close to the image recording position P1.

In the first embodiment of the present invention described above, when the recording head unit 21W is not used in a print job, the control unit 51 moves the recording head unit 21W from the normal position Pa to the retracted position Pb by driving the head unit moving mechanism 41. The structure is such that it can be evacuated to Therefore, even if the paper 15 that has passed between the conveyance drum 20 and the pressure roller 46 is lifted, if the recording head unit 21W is evacuated to the evacuation position Pb, the inkjet head 32W of the recording head unit 21W can be There is no possibility that the paper 15 will come into contact with it. Therefore, damage to the inkjet head 32 due to contact with the paper 15 can be effectively suppressed.

Furthermore, in the first embodiment of the present invention, the recording head unit 21W, which is not used in a print job, is retracted from the normal position Pa to the evacuation position Pb before the transport drum 20 starts transporting the paper 15. ing. Thereby, contact between the inkjet head 32W of the recording head unit 21W and the paper 15 can be more reliably avoided.

Further, in the first embodiment of the present invention, the recording head unit 21W that ejects white ink is disposed at the most upstream side in the transport direction A. Generally, as an ink color used in a print job, white is used less frequently than yellow, magenta, cyan, and black, so the most upstream recording head unit 21W is evacuated less frequently by the process shown in FIG. 5 above. It gets expensive. When the most upstream recording head unit 21W is retracted, in order to avoid contact between the paper 15 and the recording head unit 21, the floating detection section 45 detects the floating of the paper 15 until the movement of the paper 15 is completely stopped. The allowable paper movement distance becomes longer. Specifically, when the recording head unit 21W is not retracted, the allowable paper movement distance is limited to the distance between the floating detection section 45 and the recording head unit 21W; In this case, the allowable paper movement distance is extended to the distance between the floating detection section 45 and the recording head unit 21Y. That is, the allowable paper movement distance becomes longer by the distance between the recording head unit 21W and the recording head unit 21Y. Therefore, by arranging the recording head unit 21W at the most upstream side in the transport direction A, damage to the inkjet head 32 due to contact with the paper 15 can be more effectively suppressed.

Further, in the first embodiment of the present invention, the control unit 51 controls the head unit moving mechanism 41 so that the retracting operation of the recording head unit 21W that is not used in a print job is executed between print jobs. Therefore, contact between the inkjet head 32W and the paper 15 can be avoided without interfering with the printing operations of the recording head units 21Y, 21M, 21C, and 21K. Note that "between print jobs" preferably refers to the period from the end of printing in the current print job until the start of printing in the next print job, and more preferably, the recording head unit 21W is not used. This refers to the period from the end of printing in a print job until the start of printing in a print job using the recording head unit 21W.

Further, in the first embodiment of the present invention, a configuration is adopted in which it is possible to select whether or not to perform a retracting operation of the recording head unit 21W that is not used in a print job by operating the operation display section 53. Thereby, the user can select whether or not to execute the evacuation operation of the recording head unit 21W depending on the type of paper 15 specified in the print job. If the user selects the evacuation disallow mode and executes a print job so that the evacuation operation of the recording head unit 21W is not permitted, even if the recording head unit 21W is not used in the print job, the recording head unit 21W Evacuation operation is not performed. Therefore, when executing a print job by specifying a type of paper that does not easily float, the time required for the evacuation operation of the recording head unit 21W can be reduced, and the inkjet recording apparatus 10 can be operated with priority given to printing efficiency. .

≪Second embodiment≫
Next, a second embodiment of the present invention will be described. In the second embodiment of the present invention, the same reference numerals are given to the same or corresponding parts as the constituent parts mentioned in the first embodiment described above, and redundant explanation will be omitted.

FIG. 6 is a schematic perspective view enlarging a part of an image forming section included in an inkjet recording apparatus according to a second embodiment of the present invention.
The second embodiment of the present invention is different from the first embodiment in that it includes a head unit moving mechanism 41 that supports the recording head unit 21W so that it can move between the normal position Pa and the retracted position Pb. Although it is similar, the moving direction of the recording head unit 21W by the head unit moving mechanism 41 and the retracted position Pb of the recording head unit 21W are different.

A moving direction J of the recording head unit 21W by the head unit moving mechanism 41 (hereinafter referred to as a "head unit moving direction") is set in a direction parallel to the central axis of the transport drum 20. Since the paper 15 serving as a recording medium is transported in the transport direction A according to the rotation of the transport drum 20 while being attracted to the outer circumferential surface 20a of the transport drum 20, the head unit movement direction J is determined by the movement of the paper 15 by the transport drum 20. The direction is perpendicular to the transport direction A.

The head unit moving mechanism 41 also moves the recording head unit 21W out of the transport area, thereby retracting the recording head unit 21W from the normal position Pa to the retreat position Pb. Therefore, the retracted position Pb of the recording head unit 21W is set outside the transport area away from the transport path 31 (see FIG. 3) for the paper 15. The term "outside the transport area" means an area outside the outer circumferential surface 20a of the transport drum 20 in the head unit movement direction J. Therefore, when the recording head unit 21W is moved from the normal position Pa to the retracted position Pb, the inkjet head 32W (see FIG. 3) of the recording head unit 21W no longer faces the outer peripheral surface 20a of the transport drum 20. Therefore, even if the paper 15 transported by the transport drum 20 is lifted, contact between the paper 15 and the recording head unit 21W can be avoided by retracting the recording head unit 21W to the evacuation position Pb in advance. can.

Further, in the second embodiment of the present invention, as shown in FIG. 7, the above-mentioned point is that a cover 28 is provided to cover the ink ejection surface 34W (see FIG. 3) of the recording head unit 21W that has been retracted to the retracted position Pb. This is different from the first embodiment. The cover 28 is attached to the recording head unit 21W by the cover attachment/detachment mechanism 29 when the recording head unit 21W is moved from the normal position Pa to the retracted position Pb. The cover 28 is made of resin, for example, and is formed in a rectangular tray shape so as to shield and protect the inkjet head 32W (see FIG. 3) of the recording head unit 21W from the outside. The cover 28 suppresses drying of ink in the inkjet head 32W by covering the ink ejection surface 34W of the recording head unit 21W.

The configuration of the control system of the inkjet recording apparatus according to the second embodiment of the present invention is the same as that of the first embodiment, except that the operation (drive) of the cover attachment/detachment mechanism 29 is controlled by the control section 51. (See FIG. 4), so the explanation will be omitted.

FIG. 8 is a flowchart showing the processing procedure of the inkjet recording apparatus according to the second embodiment of the present invention. The processing shown in the flowchart of FIG. 8 is performed under the control of the control unit 51.

First, the control unit 51 determines whether or not a print job has been accepted (step S21), and if the print job is accepted via the external device or the operation display unit 53, the process proceeds to step S22.

Next, the control unit 51 determines whether or not to perform the evacuation operation of the recording head unit (step S22). If the user has previously selected the evacuation not permitted mode using the operation display unit 53, the determination is YES in step S22 and the process proceeds to step S27; if the user has not selected the evacuation not permitted mode, A negative determination is made in step S22, and the process proceeds to step S23.

In step S23, the control unit 51 performs color discrimination processing. Next, the control unit 51 determines whether white (W) ink is not used in the print job (step S24). Then, if the white ink is not used, the process proceeds to step S25, and if the white ink is not used, the process proceeds to step S27.

In step S25, the control unit 51 moves the recording head unit 21W whose ink color is white (W) from the normal position Pa to the retreat position Pb. Next, the control section 51 attaches the cover 28 to the recording head unit 21W by driving the cover attachment/detachment mechanism 29 (step S26).

Subsequently, the control unit 51 drives the transport motor 57 to start transporting the paper 15 (step S27), and then determines whether the floating detection unit 45 detects floating of the paper 15 (step S28). ). If the floating detection unit 45 detects floating of the paper 15, it is determined YES in step S28 and the process moves to step S29, and if the floating detection unit 45 does not detect floating of the paper 15, it is determined NO in step S28. The process then proceeds to step S31.

In step S29, the control unit 51 stops the transport of the paper 15 by the transport drum 20 by stopping the transport motor 57. Next, the control unit 51 executes a notification process to notify the user that a conveyance error has occurred (step S30), and then ends the series of processes.

On the other hand, in step S31, the control unit 51 drives the head drive unit 55 to start printing, and then determines whether the print job is finished (step S32). If it is determined that the print job has not been completed, the process returns to step S28 and the same process as described above is performed; if it is determined that the print job has been completed, the process proceeds to step S33. Note that if the floating detection unit 45 detects floating of the paper 15 after printing is started in step S31, the control unit 51 stops driving both the transport motor 57 and the head driving unit 55 in step S29. As a result, both conveyance of the paper 15 and printing on the paper 15 are stopped.

In step S33, the control unit 51 determines whether the recording head unit 21W has retreated to the retreat position Pb. If the recording head unit 21W has not retreated to the retreat position Pb, the series of processes ends at that stage. On the other hand, if the recording head unit 21W is retracted to the retracted position Pb, the control section 51 removes the cover 28 from the recording head unit 21W by driving the cover attachment/detachment mechanism 29 (step S34).

Next, the control section 51 causes the recording head unit 21W to perform an ink ejection operation by driving the head driving section 55 (step S35). Next, the control unit 51 moves the recording head unit 21W from the retreat position Pb to the normal position Pa by driving the head unit movement motor 59 to operate the head unit movement mechanism 41 (step S36 ), the series of processing is completed.

In the second embodiment of the present invention described above, in addition to the same effects as the first embodiment, the following unique effects can be obtained.
That is, in the second embodiment of the present invention, by setting the retraction position Pb outside the transport area outside the transport path 31 and attaching the cover 28 to the recording head unit 21W that has been moved to the retraction position Pb, The ink ejection surface 34W of the recording head unit 21W is covered with a cover 28. Therefore, while the recording head unit 21W is retracted to the retracted position Pb, drying of ink in the inkjet head 32W can be suppressed by the cover 28. Therefore, the occurrence of ejection failure due to ink drying can be suppressed.

In addition, in the second embodiment of the present invention, between the time when the recording head unit 21W that is not used in a print job is moved to the retreat position Pb and the time when it is returned to the normal position Pa, the recording head unit 21W at the retreat position Pb is moved to the retreat position Pb. The control unit 51 is configured to control the head drive unit 55 so as to perform an ink ejection operation. Thereby, the nozzles of the inkjet head 32W are cleaned by ejecting ink. Therefore, when the recording head unit 21W is returned from the retracted position Pb to the normal position Pa and a print job is executed using white ink, the ink is smoothly ejected from the nozzles of the inkjet head 32W to produce a good image. can be formed.

Note that the ink ejection operation of the recording head unit 21W may be performed at least once after the recording head unit 21W is moved to the retracted position Pb and before it is returned to the normal position Pa. Further, the ink ejecting operation of the recording head unit 21W may be performed two or more times as necessary. In that case, a timer (not shown) starts measuring time starting from the timing when the recording head unit 21W is moved to the retracted position Pb, and every time a certain period of time elapses, the recording head unit 21W performs an ink ejection operation. Just let it happen. As a result, the ink ejection operation of the recording head unit 21W is performed periodically, so even if the time from moving the recording head unit 21W to the retracted position Pb to returning it to the normal position Pa is long, the inkjet head 32W The nozzle can be maintained in a clean state.

<Modified examples, etc.>
The technical scope of the present invention is not limited to the embodiments described above, but also includes various modifications and improvements within the scope of deriving specific effects obtained by the constituent elements of the invention and their combinations.

For example, in the embodiment described above, the recording head unit 21W is movably supported by the head unit moving mechanism 41, and when the recording head unit 21W is not used in a print job, only the recording head unit 21W is supported by the head unit moving mechanism 41. Although the movement is made from the normal position Pa to the retreat position Pb, the present invention is not limited thereto. For example, when executing a print job in which four recording head units 21W, 21Y, 21M, and 21C are movably supported by their corresponding head unit moving mechanisms 41 and an image is formed using only black ink, , the four recording head units 21W, 21Y, 21M, and 21C may be moved from the normal position Pa to the retreat position Pb. In this case, before the transport drum 20 starts transporting the paper 15, the four recording head units 21W, 21Y, 21M, and 21C are retracted to the retracted position Pb. Therefore, even if the paper 15 that has passed between the transport drum 20 and the pressure roller 46 is lifted, there is no risk that the paper 15 will come into contact with the inkjet heads 32W, 32Y, 32M, and 32C. Therefore, damage to the inkjet head 32 due to contact with the paper 15 can be more effectively suppressed.

Further, in the embodiment described above, the recording head unit 21 disposed on the most upstream side in the transport direction A is configured to eject white ink, but the present invention is not limited to this, and the present invention is not limited to this, and the recording head unit 21 is arranged to eject white ink. Alternatively, it may be possible to eject ink of another color other than black, for example, a transparent color. Furthermore, the number of recording head units 21 that the inkjet recording apparatus 10 has is not limited to five, but may be six or more. If there are two or more recording head units 21 that are not used for a print job, the most upstream recording head unit 21 may be preferentially evacuated, or the most upstream recording head unit 21 may be evacuated with priority. Two or more recording head units 21 may be evacuated.

Further, in the above embodiment, the configuration in which the paper 15 serving as a recording medium is conveyed by the conveyance drum 20 has been described as an example, but the present invention is not limited to this, and the present invention is not limited to this. It is also applicable to inkjet recording devices.

Further, in the above embodiment, the paper 15 is used as an example of a recording medium, but the present invention is not limited to this, and can also be applied to an inkjet recording apparatus using a cloth, a resin film, or the like as a recording medium, for example.

10... Inkjet recording device 15... Paper (recording medium)
20...Conveyance drum (conveyance section)
20a...Outer peripheral surface (placement surface)
21W, 21Y, 21M, 21C, 21K... Recording head unit 28... Cover 31... Conveyance path 32W, 32Y, 32M, 32C, 32K... Inkjet head 34W... Ink ejection surface 41... Head unit movement mechanism 45... Lifting detection section 51... Control section 53...Operation display section (selection section)
P1, P2, P3, P4, P5...Image recording position Pa...Normal position Pb...Evacuation position

Claims (11)

a plurality of recording head units provided for each color of ink and each having an inkjet head;
a conveyance unit having a placement surface on which a recording medium is placed, and conveying the recording medium placed on the placement surface along a conveyance path passing through image recording positions by the plurality of recording head units; ,
Of the plurality of recording head units, only the recording head unit disposed most upstream in the conveyance direction of the recording medium is moved between a normal position close to the image recording position and a retracted position retracted from the normal position. A single head unit that is provided only for the print head unit disposed on the most upstream side in the conveyance direction of the print medium and not provided for other print head units so as to be movably supported. a moving mechanism;
If a recording head unit that is not used in a print job among the plurality of recording head units is a recording head unit disposed most upstream in the conveyance direction of the recording medium, the recording head unit is disposed most upstream in the conveyance direction of the recording medium. an inkjet recording apparatus, comprising: a control section that controls the head unit moving mechanism so that only the recording head unit that has been moved is retracted from the normal position to the retracted position. The control unit controls the head unit moving mechanism to retract a recording head unit that is not used in the print job from the normal position to the retracted position before the transport unit starts transporting the recording medium. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus controls: comprising a floating detection unit that detects floating of the recording medium conveyed by the conveying unit from the placement surface,
The control unit controls the transport unit so as to stop transporting the recording medium by the transport unit when the floating detection unit detects the floating of the recording medium. inkjet recording device. The head unit moving mechanism moves the recording head unit from the normal position to the retracted position by moving only the recording head unit located most upstream in the conveyance direction of the recording medium in a direction away from the conveyance path. The inkjet recording apparatus according to any one of claims 1 to 3, wherein the inkjet recording apparatus is evacuated to a. The head unit moving mechanism moves the recording head unit from the normal position by moving only the recording head unit disposed most upstream in the conveyance direction of the recording medium out of the conveyance area away from the conveyance path. The inkjet recording apparatus according to any one of claims 1 to 3, wherein the inkjet recording apparatus is retracted to the retracted position. The inkjet recording apparatus according to claim 5, further comprising a cover that covers an ink ejection surface of the recording head unit that is retracted to the retracted position. The control unit performs at least one ink ejection operation on the recording head unit in the retracted position after moving the recording head unit that is not used in the print job to the retracted position and before returning it to the normal position. The inkjet recording apparatus according to claim 5 or 6. The control unit controls the head unit moving mechanism to perform an operation of retracting a recording head unit not used in the print job from the normal position to the evacuation position between the print jobs. 8. The inkjet recording device according to any one of items 7 to 7. Among the plurality of printhead units, the printhead unit disposed most upstream in the conveyance direction of the print medium is a printhead unit that ejects ink of a predetermined color other than yellow, magenta, cyan, and black. ,
The head unit moving mechanism supports the recording head unit that discharges ink of the predetermined color so as to be movable between the normal position and the retracted position. Inkjet recording device. The inkjet recording device according to claim 9, wherein the predetermined color is white. The inkjet recording apparatus according to any one of claims 1 to 10, further comprising a selection unit that allows selection of whether to perform an operation of retracting a recording head unit that is not used in the print job from the normal position to the retracted position.

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