JP2024071971A - Droplet ejection device, program, and image forming system - Google Patents

Abstract

A droplet ejection device, a program, and an image forming system are provided that are capable of detecting whether a pretreatment agent has been sufficiently applied while efficiently recording an image.
[Solution] The droplet ejection device 1 includes an image forming unit 12 that forms an image by ejecting droplets onto a recording surface P1 that is coated with a pretreatment agent that prevents the penetration of droplets, a detection unit 13 that detects the density of a transport surface P2, which is the surface opposite the recording surface P1, during transport of the recording medium P on which an image has been formed by the image forming unit 12, and a control unit 15 which is a judgment unit that judges whether the pretreatment agent has been normally applied to the recording surface P1 based on the density of the transport surface P2 detected by the detection unit 13.
[Selected figure] Figure 2

Description

The present invention relates to a droplet ejection device, a program, and an image forming system.

Conventionally, there is known a droplet ejection device that ejects droplets onto the recording surface of a recording medium to record an image. In this droplet ejection device, droplets are ejected at appropriate timing from the nozzles of a droplet ejection head onto a recording surface that has been coated with a pretreatment agent that prevents the droplets from penetrating.

As shown in FIG. 10A, when droplets are ejected onto a recording medium whose recording surface has been sufficiently coated with the pretreatment agent, the droplets remain on the recording surface, making it possible to form a clear image.
10B, when droplets are discharged onto a recording medium whose recording surface is not sufficiently coated with the pretreatment agent, the droplets do not remain on the recording surface but penetrate to the opposite surface, the transport surface, resulting in a decrease in the density of the image formed on the recording surface, resulting in poor quality.
Therefore, before an image recording operation, it is necessary to check whether a sufficient amount of pretreatment liquid has been applied to the recording surface, but because the pretreatment liquid is colorless and transparent, it is difficult to detect with the naked eye.

In response to this, a droplet ejection device is known that is equipped with a light emitting element and a light receiving element, and detects the presence or absence of a missing nozzle based on whether a light beam is blocked by the ejected droplets (see, for example, Patent Document 1). With such a droplet ejection device, when a pretreatment agent is ejected from a nozzle to be applied, it is possible to detect whether the pretreatment agent has been sufficiently applied to the recording surface.
Furthermore, a droplet ejection device is known that inverts a printed sheet of paper and measures the show-through density using a CCD (see, for example, Patent Document 2). With such a droplet ejection device, it is possible to detect whether the pretreatment agent has been applied correctly based on the measured show-through density.

JP 2006-240119 A JP 2007-130924 A

However, the droplet ejection device of JP-A-2003-133662 detects ejection defects by moving the carriage outside the printing area before ejecting droplets, which reduces productivity.
In addition, the droplet ejection device of Patent Document 2 measures the show-through density by inverting the paper using a reversing path after single-sided printing. Therefore, the paper must be reversed even though it is single-sided printing, which is inefficient in terms of productivity. In addition, a transport path is required to reverse the paper, which is also inefficient in terms of cost.

The present invention has been made in consideration of these circumstances. Its purpose is to provide a droplet ejection device, program, and image forming system that can efficiently detect defective application of a pretreatment agent.

In order to solve the above problems, the present invention provides a droplet ejection device, comprising:
an image forming unit that forms an image by ejecting droplets onto a recording surface of a recording medium on which a pretreatment agent that prevents the penetration of droplets has been applied;
a detection unit that detects the density of a conveyance surface of the recording medium on the opposite side to the recording surface, the conveyance surface having an image formed thereon by the image forming unit during conveyance of the recording medium;
and a determination unit that determines whether the pretreatment agent is normally applied to the recording surface based on the concentration of the pretreatment agent on the transport surface detected by the detection unit.

The present invention relates to a droplet ejection device, comprising:
The image forming apparatus further includes an application section that is provided upstream of the image forming section in a transport direction and applies the pretreatment agent to the recording surface of the recording medium.

The present invention relates to a droplet ejection device, comprising:
the application unit applies a pretreatment agent by ejecting the pretreatment agent from a nozzle;
The determination unit determines whether or not the application unit has a missing nozzle.

The invention according to claim 4 is the droplet ejection device according to any one of claims 1 to 3,
the image forming unit includes a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted;
The image forming unit forms an image by scanning the carriage in a width direction perpendicular to a conveying direction of the recording medium.

The invention according to claim 5 is the droplet ejection device according to claim 4,
the image forming unit forms a color band image by discharging droplets from the droplet discharge head at the end in the width direction of the image forming area of the recording medium during image formation;
The detection unit detects the density of the color stripe image on the transport surface side.

The present invention according to claim 6 is the droplet ejection device according to claim 5,
The detection portion has a length equal to or greater than the length of the image that is scanned and printed by the carriage.

A seventh aspect of the present invention provides the droplet ejection device according to any one of the first to third aspects,
the image forming unit includes a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted;
The image forming unit forms an image by fixing the carriage.

The invention according to claim 8 is the droplet ejection device according to claim 7,
the image forming unit forms a color stripe image by discharging droplets from the droplet discharging head before starting a recording operation;
The detection unit detects the density of the color stripe image on the transport surface side.

The invention according to claim 9 is the droplet ejection device according to claim 8,
The detection unit is disposed below an extension line of the transport direction of the image forming unit so that the length of the width direction perpendicular to the transport direction of the recording medium is the same as the length of the width direction of the image forming area of the recording medium.

According to a tenth aspect of the present invention, there is provided a droplet ejection device according to any one of the first to third aspects,
The determining unit determines that a coating defect of the pretreatment agent has occurred when the density of the transport surface detected by the detecting unit is equal to or greater than a predetermined threshold value.

The present invention according to claim 11 provides the droplet ejection device according to claim 10,
The device includes an operation receiving unit that can arbitrarily set the threshold value.

The present invention according to claim 12 is the droplet ejection device according to claim 10,
The threshold value differs depending on the type of recording medium.

The present invention according to claim 13 provides the droplet ejection device according to claim 10,
The image forming apparatus further includes a control unit that, when the determining unit determines that defective application of the pretreatment agent has occurred, stops image formation and notifies a user of a warning.

The invention described in claim 14 is a droplet ejection device according to claim 10, which recites claim 3,
a cleaning unit that cleans the ejection surfaces of the image forming unit and the application unit;
and a control unit that, when the determination unit determines that defective application of the pretreatment agent has occurred, interrupts image formation and causes the cleaning unit to clean the ejection surface of the application unit.

According to a fifteenth aspect of the present invention, there is provided a droplet ejection device according to any one of the first to third aspects,
The recording medium is a fabric.

According to a sixteenth aspect of the present invention, there is provided a droplet ejection device according to any one of the first to third aspects,
the detection unit includes a light source that irradiates light onto the transport surface of the recording medium, and a light receiving unit that receives light that is irradiated by the light source and reflected by the transport surface;
The density of the transport surface is detected from the intensity of the reflected light received by the light receiving section.

The invention according to claim 17 is a program comprising:
A computer of a droplet ejection device including an image forming unit that ejects droplets onto a recording surface of a recording medium coated with a pretreatment agent that prevents the penetration of droplets to form an image, and a detection unit that detects the density of a conveyance surface of the recording medium, the conveyance surface being the opposite side to the recording surface and on which an image is formed by the image forming unit, during conveyance of the recording medium,
The liquid ejection device functions as a determination unit that determines whether the pretreatment agent is normally applied to the recording surface based on the density of the pretreatment agent on the transport surface detected by the detection unit.

The present invention relates to an image forming system, comprising:
The droplet ejection device according to claim 1 ;
and a coating device including a coating section that coats the pretreatment agent on the recording surface of the recording medium.

The present invention makes it possible to efficiently detect improper application of pretreatment agents.

1 is a block diagram of a droplet ejection device and a coating device in an image forming system according to a first embodiment. 1 is a side view of a droplet ejection device in an image forming system according to a first embodiment. FIG. 4 is a bottom view showing an example of a detection unit. 11 is a graph showing the change in ink amount and density on the recording surface and the transport surface when ink is ejected onto a recording medium whose recording surface has been normally coated with a pretreatment agent. 11 is a graph showing the change in ink amount and density on the recording surface and the transport surface when ink is ejected onto a recording medium on which a pretreatment liquid is not applied. 5 is a flowchart showing a flow of operations of the droplet ejection device in the image forming system according to the first embodiment. FIG. 11 is a block diagram of a droplet ejection device in an image forming system according to a second embodiment. FIG. 11 is a side view of a droplet ejection device in an image forming system according to a second embodiment. 10 is a flowchart showing a flow of operations of a droplet ejection device in an image forming system according to a second embodiment. FIG. 11 is a bottom view showing an example of a detection unit according to a modified example. 1 is a schematic diagram of a recording medium on which droplets are ejected onto a recording surface onto which a pretreatment agent has been applied. 1 is a schematic diagram of a recording medium on which droplets are ejected to a recording surface on which a pretreatment agent is not applied.

One embodiment of the present invention will be described below with reference to the drawings. The following description is merely an example of one embodiment of the present invention and is not intended to limit the present invention.

[Overall Configuration of Image Forming System]
[First embodiment]
Fig. 1 is a block diagram showing the functional configuration of an inkjet recording apparatus 1 and a coating apparatus 2. Fig. 2 is a side view of the inkjet recording apparatus 1.
The image forming system 100 includes at least an inkjet recording apparatus 1 which is a droplet ejection apparatus.
1, an image forming system 100 according to the present embodiment includes an inkjet recording apparatus 1 and an application apparatus 2. That is, the image forming system 100 according to the present embodiment employs a method of applying a pretreatment agent in advance.

[Inkjet recording device]
First, we will disclose an example of the configuration of an inkjet recording apparatus 1. The inkjet recording apparatus 1 is an apparatus that forms an image by ejecting ink from an inkjet head 121, which is a droplet ejection head, onto a recording surface P1, which is one surface of a recording medium P.

The inkjet recording device 1 according to the first embodiment includes a conveying unit 11, an image forming unit 12, a detection unit 13, a cleaning unit 14, a control unit 15, a memory unit 16, a communication unit 17, an operation reception unit 18, and a display unit 19.

(recoding media)
In the present invention, the recording medium P is, for example, a fabric. However, the recording medium P is not limited to a fabric, and may be paper or other materials.
Furthermore, before the recording medium P according to this embodiment is loaded into the inkjet recording apparatus 1 , a pretreatment agent is applied to the recording surface P 1 in advance by the application device 2 .

(Pretreatment Agent)
The viscosity of the ink ejected by the image forming unit 12 is kept low so that it can be ejected as droplets from the nozzles. Therefore, when ink is ejected onto the recording medium P, the ink does not remain on the recording surface P1, and may penetrate to the conveying surface P2, which is the surface opposite the recording surface P1. This reduces the density of the image formed on the recording surface P1, resulting in poor quality.
In contrast, if a pretreatment agent that prevents ink penetration is applied to the recording surface P1, the ink will remain on the recording surface P1, allowing a clear image to be recorded.

The pretreatment agent may be any appropriate component depending on the ink to be ejected from the image forming unit 12. For example, in the case of reactive ink or dispersible ink, it is preferable to apply a liquid containing a glue agent as a pretreatment agent to cause the ink to remain on the recording surface P1. In addition, in the case of dry process ink containing a pigment, it is preferable to use an acidic liquid as a pretreatment agent to aggregate the anionic groups in the ink.

The amount of pretreatment agent applied (squeezing rate) depends on the type of recording medium P, but can be, for example, 0.2% to 90% by weight relative to the total weight of the recording medium P.

(Transportation section)
The transport unit 11 includes, for example, two transport rollers 111, a transport belt 112, and a transport motor 113. The transport unit 11 transports the recording medium P in a transport direction.

The transport roller 111 rotates in the transport direction around a rotation axis that extends in the width direction perpendicular to the transport direction. The transport roller 111 also supports the inside of a ring-shaped transport belt 112. The transport belt 112 is placed so that the transport surface P2 of the recording medium P is in contact with the transport surface of the transport belt 112. When the transport roller 111 rotates in response to the operation of the transport motor 113, the transport belt 112 moves in the transport direction, transporting the recording medium P in the transport direction indicated by the arrow in FIG. 2.

(Image forming section)
1, the image forming unit 12 includes an inkjet head 121, a head driving unit 122, and a carriage C. The image forming unit 12 ejects ink onto a recording surface P1 to form an image.

The inkjet head 121 has a large number of nozzles arranged in a predetermined pattern that eject ink from openings, and a piezoelectric element.

A plurality of inkjet heads 121 are arranged on a fixed carriage C to constitute an inkjet head unit. The length in the width direction of the image forming area of the inkjet head unit (i.e., the length from the nozzle at the first end in the width direction of the inkjet head unit to the nozzle at the second end) is approximately the same as the length in the width direction of the image forming area of the recording medium P.
That is, the inkjet recording apparatus 1 according to this embodiment is a so-called one-pass type inkjet recording apparatus.

The head drive unit 122 outputs a drive pulse that expands or contracts the piezoelectric element of each inkjet head 121 under the control of the control unit 15. As the piezoelectric element deforms due to the drive pulse, it deforms the ink flow path (pressure chamber) that supplies ink to the nozzle, imparting pressure fluctuations to the ink and causing it to be ejected from the nozzle.

Although not shown in FIG. 2, the image forming unit 12 may include multiple inkjet head units in the transport direction. Each inkjet head unit may eject ink of a different color, such as Y (yellow), M (magenta), C (cyan), K (black), or a special color or light color. Additionally, multiple inkjet head units may eject ink of the same color.

(Detection unit)
3, the detection unit 13 is provided below an extension of the image forming unit 12 in the transport direction so as to have the same width as the image forming area. The detection unit 13 includes a plurality of density sensors 131 arranged along the width direction and capable of acquiring the density of the transport surface P2.

The density sensor 131 includes, for example, a light source 131a and a light receiving unit 131b. The density sensor 131 receives light reflected from the light source 131a onto the transport surface P2 at the light receiving unit 131b, and obtains the density of the transport surface P2 from the intensity of the reflected light.
Then, the detection unit 13 outputs information on the density of the transport surface P2 acquired by the density sensor 131 to the control unit 15.

The method of acquiring the density of the transport surface P2 by the density sensor 131 is not limited to acquiring the reflected light intensity. For example, a light source 131a and a light receiving unit 131b may be provided at opposing positions across the recording medium P to acquire the transmitted light intensity, and the density of the transport surface P2 may be acquired from the transmitted light intensity.

Figure 4A is a graph showing the relationship between the amount of ink and the density on the recording surface P1 (solid line) and the transport surface P2 (dash line) when ink is ejected onto a recording surface P1 that has been properly coated with a pretreatment agent. Figure 4B is a graph showing the relationship between the amount of ink and the density on the recording surface P1 (thick dashed line) and the transport surface P2 (thin dashed line) when ink is ejected onto a recording surface P1 that has not been coated with a pretreatment agent.

As described above, in the recording medium P where the pretreatment liquid has been normally applied to the recording surface P1, the ink remains on the recording surface P1 and does not penetrate to the transport surface P2.
Therefore, as shown in FIG. 4A, the density of the recording surface P1 increases as the amount of ink increases.
On the other hand, because the pretreatment agent inhibits the ink from penetrating into the transport surface P2, the density on the transport surface P2 does not change even if the amount of ink is increased.

In contrast, in the case of a recording medium P in which the pretreatment liquid is not applied to the recording surface P1, the ink does not remain on the recording surface P1, but permeates to the transport surface P2.
Therefore, as shown in Fig. 4B, the density of the recording surface P1 increases as the amount of ink increases, however, the amount of increase is smaller than that in Fig. 4A.
Furthermore, as the amount of ink increases, the amount of ink that permeates also increases, and therefore, as the amount of ink increases, the density of the transport surface P2 also increases.

Thus, the density of the recording surface P1 increases whether or not the pretreatment agent is applied, although there are differences in the rate of increase. Therefore, simply detecting an increase in the density of the recording surface P1 under the image formation area does not allow one to determine whether or not the pretreatment agent is applied, and it becomes necessary to create a predetermined gradation chart image, such as a 100% image. As a result, it becomes difficult to detect abnormal application of the pretreatment agent in real time in accordance with image formation.

On the other hand, the density of the transport surface P2 does not change from the area where ink is not being ejected if the pretreatment agent is applied normally, and increases according to the amount of ink if the pretreatment agent is not applied normally. Therefore, by acquiring the density of the transport surface P2, it is easier to detect whether or not the pretreatment agent has been abnormally applied on the recording surface P1 than by acquiring the density of the recording surface P1. In other words, since it is no longer necessary to create a gradation chart image, it becomes possible to detect in real time whether or not the pretreatment agent has been abnormally applied during image formation.

(Cleaning Department)
Returning to FIG. 1 , the cleaning unit 14 includes a drive unit 141 and a wiping member 142 .
The cleaning unit 14 cleans the ejection surface of the inkjet head 121 on which the nozzle openings are arranged.

The driving unit 141 operates the wiping member 142 to wipe away ink and solidified ink adhering to the ejection surface.
The wiping member 142 is not particularly limited, but may be, for example, a nonwoven fabric that absorbs ink, or a resin member on a blade that scrapes off solid matter.

(Control Unit)
The control unit 15 is a processor that controls the overall operation of the inkjet recording apparatus 1 .
The control unit 15 includes, for example, a CPU 151 (Central Processing Unit) and a RAM 152 (Random Access Memory).

The CPU 151 executes various control processes through calculations. The RAM 152 provides a working memory space for the CPU 151 and stores temporary data.
In addition, the control unit 15 executes a predetermined program to function as a judgment unit that judges whether the pretreatment agent has been normally applied to the recording surface P1 based on the concentration of the transport surface P2 detected by the detection unit 13.

Specifically, for example, the control unit 15 compares whether the density of the transport surface P2 below the image formation area detected by the density sensor 131 is equal to or greater than a predetermined threshold based on the density of the transport surface P2 before image formation. If the density of the transport surface P2 is less than the predetermined threshold, it determines that the pretreatment agent has been applied normally and continues the recording operation. If the density of the transport surface P2 is equal to or greater than the predetermined threshold, it determines that there is a problem with the application of the pretreatment agent, displays a warning about the poor application of the pretreatment agent on the display unit 19, and interrupts the recording operation.

The predetermined threshold value is not limited to a preset value, and may be changed to any value by the user through operation of the operation reception unit 18, for example.
In addition, it is preferable that the density of the transport surface P2 before the image formation is stored in advance in the storage unit 16, but is not limited to this. For example, the recording medium P before the image formation may be transported and the density sensor 131 may acquire the density of the transport surface P2.
It is also preferable that different threshold values corresponding to the types of recording media P are stored in the storage unit 16 .

(Memory unit)
The storage unit 16 stores image data to be recorded, processing data thereof, other setting data, and programs. Image data may be stored in, for example, a dynamic random access memory (DRAM) capable of temporarily storing large amounts of data and outputting them at high speed. The setting data and programs are stored in a non-volatile memory such as a flash memory and/or a hard disk drive (HDD).
In this way, even if the power supply to the inkjet recording apparatus 1 is stopped, the setting data can be stored.

(Communications Department)
The communication unit 17 controls the transmission and reception of data in accordance with a predetermined communication standard, for example, TCP/IP (Transmission Control Protocol/Internet Protocol).
The communication unit 17 may be connected to a local area network (LAN) and may be connectable to the external Internet via a router, or may be directly connectable to the external Internet via a universal serial bus (USB) cable connected to a USB terminal.

(Operation reception unit)
The operation reception unit 18 receives an input operation by the user, and outputs the received content to the control unit 15 as an input signal.
The operation reception unit 18 includes, for example, a touch panel and a push button switch. The touch panel is positioned so as to overlap with the display screen of the display unit 19, and the operation content may be specified in synchronization with the display content on the display screen.

(Display)
The display unit 19 displays status and selection menus to the user.
The display unit 19 has, for example, a display screen and an indicator (lamp). The indicator may be, for example, an LED (Light Emitting Diode) lamp that is used to indicate the presence or absence of power supply or the presence or absence of an operational abnormality.
The display unit 19 has, for example, a liquid crystal display, and can display various characters and figures on the display screen in a dot matrix format.

[Coating device]
The coating device 2 is a device for coating the recording medium P with a pretreatment agent.
The coating device 2 includes a control unit 21 and a coating unit 22 .
The control unit 21 includes, for example, a CPU and a RAM, and controls the application of the pretreatment agent by the application unit 22 .

(Applying part)
The coating section 22 applies a pretreatment agent to an image forming area of the recording surface P1.
Examples of the method for applying the pretreatment agent by the application unit 22 include a pad method, a coating method, a spray method, etc. The method for applying the pretreatment agent by the application unit 22 is not limited to these, and may be any known method.

Note that, although FIG. 1 illustrates an example in which the inkjet recording device 1 and the coating device 2 are connected in a system manner, this is not limited to this.

[Operation of Inkjet Recording Apparatus]
Next, the operation of the inkjet recording apparatus 1 according to this embodiment will be described.
FIG. 5 is a flow chart showing the flow of operations of the inkjet recording apparatus 1.

When an image recording instruction from a user is received via the operation receiving unit 18, the inkjet recording apparatus 1 conveys the recording medium P by the continuous operation of the conveying unit 11 (step S101).
The recording medium P is a recording medium P on whose recording surface P1 a pretreatment agent has been applied in advance by the application device 2.

The control section 15 judges whether or not the color band forming area of the recording medium P has reached the area below the image forming section 12 (step S102).
In this embodiment, the color band forming area is provided along the width direction at the downstream end in the transport direction of the image forming area.
When the control unit 15 determines that the color stripe formation region has not reached the area below the image forming unit 12 (step S102; No), the control unit 15 transitions to step S102 again. Then, the control unit 15 waits until the color stripe formation region reaches the area below the image forming unit 12.

When the control unit 15 determines that the color band formation area has reached the area below the image forming unit 12 (step S102; Yes), it outputs a drive pulse to the head driving unit 122. Then, it ejects ink from all the nozzles of the inkjet head unit onto the color band formation area to form a color band image (step S103).

Since ink dries quickly, in nozzles that have not ejected ink for a certain period of time, the ink evaporates and thickens. This causes a phenomenon called decap, in which the nozzle is unable to eject ink, or the ejection speed decreases even if the ink is able to be ejected. To prevent this, ink is ejected from all nozzles to form a color band image before forming an image based on an image recording command, which allows for good ink ejection.
In the following description, an image formed in an image forming area excluding color band forming areas based on an image recording instruction is referred to as a recorded image in order to distinguish it from a color band image.

After the color band image is formed, the control unit 15 determines whether the color band forming area has reached the detection unit 13 (step S104).
When the control unit 15 determines that the color band formation region has not reached the detection unit 13 (step S104; No), the control unit 15 transitions to step S104 again. Then, the control unit 15 waits until the color band formation region reaches the detection unit 13.

When the control unit 15 determines that the color band formation area has reached the detection unit 13 (step S104; Yes), it causes the density sensor 131 to acquire the density of the transport surface P2 below the color band formation area (step S105).

The control unit 15, as a determination unit, determines whether or not there is a defective application of the pretreatment agent from the density of the transport surface P2 below the color band formation area acquired by the density sensor 131 (step S106). If the control unit 15 determines that there is a defective application of the pretreatment agent (step S106; Yes), it interrupts the image recording operation (step S107). In addition, the control unit 15 causes the display unit 19 to display a warning about the defective application of the pretreatment agent (step S108), and ends the operation.

Note that it is not necessary to execute both steps S107 and S108. It is sufficient to execute at least one of steps S107 and S108.

When a low-density recorded image is formed, even if there is a coating defect in the pretreatment agent, the amount of ink that penetrates to the transport surface P2 may be small. As a result, the increase in density on the transport surface P2 is small, and the coating defect in the pretreatment agent may not be detected.
In contrast, the color band image has a high density, and if there is a coating defect in the pretreatment liquid, the amount of increase in density on the transport surface P2 is large.

In this way, the presence or absence of defective application of the pretreatment agent can be more easily detected on the transport surface P2 below the color stripe image. Therefore, it is preferable to detect the presence or absence of defective application of the pretreatment agent not only on the transport surface P2 below the recorded image but also on the transport surface P2 below the color stripe image.
However, detecting the presence or absence of defective application of the pretreatment agent based on the density of the transport surface P2 below the color band image is not an essential operation in the inkjet recording apparatus 1. Therefore, it is also possible to transition from step S103 to step S109, which will be described later.

When the control unit 15 determines that there is no application defect of the pretreatment agent (step S106; No), it starts image formation of the recording image (step S109). Specifically, the control unit 15 forms the recording image by ejecting ink from the image forming unit 12 onto the recording surface P1 based on the image data stored in the storage unit 16.

During the formation of the recorded image, the detection unit 13 sequentially acquires the density of the transport surface P2, and the control unit 15 determines whether or not there is a coating defect in the pretreatment agent from the density (step S110). If the control unit 15 determines that there is a coating defect in the pretreatment agent (step S110; Yes), it transitions to step S107 or step S108 and ends the operation.

When the control unit 15 determines that there is no defective application of the pretreatment agent (step S110; No), it determines whether the formation of the recorded image is complete (step S111). When the control unit 15 determines that the formation of the recorded image is not complete (step S111; No), it transitions to step S109 and continues forming the recorded image. When the control unit 15 determines that the formation of the recorded image is complete (step S111; Yes), it ends the recording operation. After the recording operation is completed, the recording medium P is dried by a dryer (not shown) and the recording medium P is stored by a winder (not shown).

[Effects of the First Embodiment]
As described above, the inkjet recording apparatus 1 according to the first embodiment includes an image forming unit 12 that forms an image by ejecting droplets onto a recording surface P1 that has been coated with a pretreatment agent. The inkjet recording apparatus 1 also includes a detection unit 13 that detects the density of a transport surface P2, which is the surface opposite to the recording surface P1, while the recording medium P on which an image has been formed by the image forming unit 12 is being transported. The inkjet recording apparatus 1 also includes a control unit 15 that determines whether the pretreatment agent has been normally applied to the recording surface P1, based on the density of the transport surface P2 detected by the detection unit 13.
According to this configuration, it is easier to determine whether the pretreatment agent has been applied normally than when measuring the density of the recording surface P1, and therefore it is possible to efficiently detect whether the pretreatment agent has been applied sufficiently.

The image forming unit 12 also includes an inkjet head 121 that ejects droplets from nozzles, and a carriage C on which the inkjet head 121 is mounted. The image forming unit 12 forms an image by fixing the carriage C. In other words, the inkjet recording apparatus 1 is of a one-pass type.
According to this configuration, image formation is completed in one continuous scan, resulting in high productivity.

Furthermore, before the start of a recording operation, the image forming unit 12 forms a color stripe image by ejecting droplets from the inkjet head 121. Then, the detection unit 13 detects the density of the color stripe image on the transport surface P2 side.
According to this configuration, the presence or absence of a coating defect of the pretreatment agent can be determined before the formation of the recorded image, which is more efficient. Also, the presence or absence of a coating defect of the pretreatment agent can be suitably determined regardless of the density of the recorded image. Also, the formation of the color band image reduces nozzle ejection defects.

The detection unit 13 is provided below the extension line of the image forming unit 12 so that the length in the width direction of the detection unit 13 is the same as the length in the width direction of the image forming area of the recording medium P.
According to this configuration, the detection unit 13 can detect the density of the transport surface P2 over the entire image forming area.

Furthermore, when the density on the transport surface P2 detected by the detection unit 13 is equal to or greater than a predetermined threshold value, the control unit 15 determines that a coating defect of the pretreatment agent has occurred.
According to this configuration, it is possible to prevent erroneous detection due to a difference in concentration on the transport surface P2 that is not due to defective application of the pretreatment agent.

The inkjet recording apparatus 1 also includes an operation reception unit 18 that allows the threshold value to be set arbitrarily.
According to this configuration, it becomes possible to perform a recording operation according to the required image quality.

Furthermore, the storage unit 16 of the inkjet recording apparatus 1 stores a different threshold value for each type of recording medium P.
According to this configuration, various recording media P can be used in the inkjet recording apparatus 1 .

Furthermore, if the control unit 15 determines that a pretreatment agent application defect has occurred, the control unit 15 suspends image formation and notifies the user of a warning.
According to this configuration, it is possible to prevent an increase in costs caused by continuing the recording operation on the recording medium P on which the pretreatment liquid has been imperfectly applied.

[Second embodiment]
Next, an image forming system 100 according to a second embodiment will be described in detail with reference to FIGS.
In the following description, the same components as those in the image forming system 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.
The image forming system 100 according to the second embodiment includes only the inkjet recording apparatus 1 and does not include the coating apparatus 2 .

Fig. 6 is a block diagram showing the functional configuration of the inkjet recording apparatus 1 according to the second embodiment, and Fig. 7 is a side view of the inkjet recording apparatus 1 according to the second embodiment.
7, the inkjet recording apparatus 1 according to the second embodiment includes a coating unit 22 located upstream in the transport direction from the image forming unit 12. That is, the image forming system 100 according to the second embodiment employs an in-line system for the pretreatment agent.

(Applying part)
The coating unit 22 coats the recording medium P transported by the transport unit 11 with a pretreatment agent.
Specifically, the coating unit 22 has a configuration similar to that of an inkjet head unit, for example, and applies the pretreatment agent to the recording medium P based on a drive pulse from a head drive unit 122 .

[Operation of Droplet Discharge Device]
Next, the operation of the inkjet recording apparatus 1 according to the second embodiment will be described.
FIG. 8 is a flow chart showing the flow of operations of the inkjet recording apparatus 1.

When an image recording instruction is received from a user, the inkjet recording device 1 transports the recording medium P by the transport unit 11 (step S201).

The control unit 15 determines whether the leading edge of the image forming area of the recording medium P has reached the coating unit 22 (step S202). If the leading edge of the image forming area has not reached the coating unit 22 (step S202; No), the control unit 15 waits until the leading edge of the image forming area reaches the coating unit 22.

When the leading edge of the image forming area reaches under the application unit 22 (step S202; Yes), the control unit 15 causes the head drive unit 122 to output a drive pulse to eject the pretreatment agent (step S203).

The subsequent steps S204 to S213 are similar to steps S102 to S111 in the first embodiment, so detailed explanations will be omitted.

When the image recording operation is interrupted in step S209, the control unit 15 may perform a process of cleaning the ejection surface of the application unit 22 using the cleaning unit 14.

[Effects of the second embodiment]
As described above, the inkjet recording apparatus 1 according to the second embodiment includes the coating unit 22 provided upstream in the transport direction from the image forming unit 12. The coating unit 22 applies the pretreatment agent by, for example, ejecting it from a nozzle, and the control unit 15 determines whether the coating unit 22 has a missing nozzle.
According to this configuration, even if the coating device 2 is not provided separately from the inkjet recording device 1, a clear image can be recorded on the recording medium P coated with the pretreatment liquid.

The inkjet recording apparatus 1 also includes a cleaning unit 14 that cleans the image forming unit 12 and the ejection surface of the application unit 22. When the control unit 15 determines that defective application of the pretreatment agent has occurred, it interrupts image formation and causes the cleaning unit 14 to clean the ejection surface of the application unit 22.
According to this configuration, image formation can be resumed after the cleaning operation is completed.

[Other configurations]
In the above, in step S202, when the leading edge of the image forming area reaches below the coating unit 22, the coating unit 22 applies the pretreatment agent, but this is not limited to this. In other words, a configuration in which the coating unit 22 applies the pretreatment agent when the leading edge of the recording medium P reaches below the coating unit 22 may be adopted.

In the above, the application unit 22 of the second embodiment is described as having the same configuration as the inkjet head unit, but this is not limited to this. The application unit 22 of the second embodiment may also apply the pretreatment agent by a pad method, a coating method, a spray method, or the like, similar to the application unit 22 of the application device 2 of the first embodiment.

In addition, in the above, the width direction length of the image forming area of the inkjet head unit is approximately the same as the width direction length of the image forming area of the recording medium P, and the carriage C is fixed as a one-pass type, but this is not limited to this.
The length in the width direction of the area where an image can be formed by the inkjet head unit may be shorter than the length in the width direction of the image forming area of the recording medium P, and the carriage C may be movable in the width direction.
That is, the inkjet recording apparatus 1 may be of a so-called scan type, in which the recording operation is performed by moving the carriage C in the width direction.

In the scan-type inkjet recording device 1, the transport unit 11 does not transport the recording medium P by continuous operation, but transports the recording medium P by intermittent operation. Specifically, for example, each time the carriage C moves from the first end to the second end in the width direction of the image forming area to form an image, the transport unit 11 transports the recording medium P a predetermined distance in the transport direction.

In addition, in the scan-type inkjet recording device 1, the color band formation area is the first end in the width direction of the image formation area of the recording medium P. And the color band formation operation is performed during image formation, not before the recording operation.

Furthermore, in the scan-type inkjet recording device 1, the detection unit 13 does not have to be equal in width to the image forming area. The detection unit 13 only needs to be at least as long as the length of the image printed by scanning the carriage C. With this configuration, it is possible to detect defective application of the pretreatment agent when the image forming unit 12 forms an image.
Also, as shown in FIG. 9, a configuration may be adopted in which only one density sensor 131 is provided, rather than the multiple density sensors 131 .

In the above, the image forming system 100 is configured to include the inkjet recording device 1 and the coating device 2, but this is not limited to this. For example, the image forming system 100 may include other devices having configurations such as an operation reception unit 18 and a display unit 19.

In addition, in the above, the inkjet recording apparatus 1 is described as performing single-sided printing, but the present invention is not limited to this. The inkjet recording apparatus 1 may perform double-sided printing.
In addition, after the inkjet recording device 1 forms a recording image on the first surface of the recording medium P, when the recording medium P is flipped over to form a recording image on the second surface, it goes without saying that the second surface becomes the recording surface P1 and the first surface becomes the transport surface P2.

In addition, in the above, the droplet ejection head 121 is described as an inkjet head, but the droplets ejected from the droplet ejection head 121 are not limited to ink droplets.

In addition, in the above, examples have been disclosed in which a hard disk or a non-volatile semiconductor memory is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to these examples. Portable recording media such as CD-ROMs can be used as other computer-readable media. Furthermore, carrier waves can also be used as a medium for providing data for the program according to the present invention via a communication line.

100 Image forming system 1 Inkjet recording device (droplet ejection device)
12 Image forming unit 121 Inkjet head (droplet ejection head)
C Carriage 13 Detection unit 131a Light source 131b Light receiving unit 14 Cleaning unit 15 Control unit (determination unit)
18 Operation reception unit 2 Coating device 22 Coating unit P Recording medium P1 Recording surface P2 Transport surface

Claims (18)

an image forming unit that forms an image by ejecting droplets onto a recording surface of a recording medium on which a pretreatment agent that prevents the penetration of droplets has been applied;
a detection unit that detects the density of a conveyance surface of the recording medium on the opposite side to the recording surface, the conveyance surface having an image formed thereon by the image forming unit during conveyance of the recording medium;
a determination unit that determines whether the pretreatment agent is normally applied to the recording surface based on the concentration of the pretreatment agent on the conveying surface detected by the detection unit;
A droplet ejection device comprising: The droplet ejection device according to claim 1, further comprising an application section that is provided upstream of the image forming section in the transport direction and applies the pretreatment agent to the recording surface of the recording medium. the application unit applies a pretreatment agent by ejecting the pretreatment agent from a nozzle;
The droplet ejection device according to claim 2 , wherein the determining unit determines whether or not the application unit is missing a nozzle. the image forming unit includes a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted;
The droplet ejection device according to claim 1 , wherein the image forming section forms an image by scanning the carriage in a width direction perpendicular to a transport direction of the recording medium. the image forming unit forms a color stripe image by discharging droplets from the droplet discharge head at the end in the width direction of the image forming area of the recording medium during image formation;
The droplet ejection device according to claim 4 , wherein the detection section detects the density of the color stripe image on the transport surface side. The droplet ejection device according to claim 5, wherein the detection unit has a length equal to or greater than the length of the image scanned and printed by the carriage. the image forming unit includes a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted;
The droplet ejection device according to claim 1 , wherein the image forming section forms an image by fixing the carriage. the image forming unit forms a color stripe image by discharging droplets from the droplet discharging head before starting a recording operation;
The droplet ejection device according to claim 7 , wherein the detection unit detects the density of the color stripe image on the transport surface side. The droplet ejection device according to claim 8, wherein the detection unit is provided below an extension of the conveying direction of the image forming unit so that the length of the width direction perpendicular to the conveying direction of the recording medium is the same as the length of the image forming area of the recording medium in the width direction. The droplet ejection device according to any one of claims 1 to 3, wherein the determination unit determines that a coating defect of the pretreatment agent has occurred when the density of the transport surface detected by the detection unit is equal to or greater than a predetermined threshold value. The droplet ejection device according to claim 10, further comprising an operation reception unit capable of arbitrarily setting the threshold value. The droplet ejection device according to claim 10, wherein the threshold value differs for each type of recording medium. The droplet ejection device according to claim 10, further comprising a control unit that interrupts image formation and issues a warning to a user when the determination unit determines that a coating defect in the pretreatment agent has occurred. a cleaning unit that cleans the ejection surfaces of the image forming unit and the application unit;
The droplet ejection device according to claim 10, which recites claim 3, further comprising a control unit that, when the determination unit determines that defective application of the pretreatment agent has occurred, interrupts image formation and causes the cleaning unit to clean the ejection surface of the application unit. The droplet ejection device according to any one of claims 1 to 3, wherein the recording medium is a fabric. the detection unit includes a light source that irradiates light onto the transport surface of the recording medium, and a light receiving unit that receives light that is irradiated by the light source and reflected by the transport surface;
4. The droplet ejection device according to claim 1, wherein the density of the transport surface is detected from the intensity of the reflected light received by the light receiving section. A computer of a droplet ejection device including an image forming unit that ejects droplets onto a recording surface of a recording medium coated with a pretreatment agent that prevents the penetration of droplets to form an image, and a detection unit that detects the density of a conveyance surface of the recording medium, the conveyance surface being the opposite side to the recording surface and on which an image is formed by the image forming unit, during conveyance of the recording medium,
a program that causes the program to function as a determination unit that determines whether the pretreatment agent is normally applied to the recording surface, based on the density of the pretreatment agent on the transport surface detected by the detection unit. The droplet ejection device according to claim 1 ;
an application device including an application section that applies a pretreatment agent to the recording surface of the recording medium;

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