WO2018139238A1 - Maintenance device, maintenance method, and liquid discharge device - Google Patents

Abstract

Provided are a maintenance device, maintenance method, and liquid discharge device that make it possible to curb deterioration of a liquid discharge surface during a process for wiping the liquid discharge surface. The present invention is provided with: a discharge state information acquisition unit for acquiring discharge state information representative of whether a discharge element is a malfunctioning discharge element or normal discharge element; a discharge element determination unit for determining a malfunctioning discharge element to be a non-discharging element and a normal discharge element to be a discharging element, in the case of a liquid containing particles having a Mohs scale of mineral hardness greater than 0.5; and a preliminary discharge unit for executing a preliminary discharge with a liquid discharge head in which liquid is to be discharged from the discharging element and liquid is not to be discharged from the non-discharging element.

Description

MAINTENANCE DEVICE, MAINTENANCE METHOD, AND LIQUID DISCHARGE DEVICE

The present invention relates to a maintenance device, a maintenance method, and a liquid ejection device, and more particularly to wiping of a liquid ejection head.

2. Description of the Related Art A liquid discharge apparatus including an inkjet liquid discharge head is known. Due to ejection abnormality of the nozzle portion provided in the ink jet type liquid ejection head, ejection unevenness or missing ejection may occur.

Patent Document 1 describes a liquid ejection device that periodically inspects whether there is an abnormality in a nozzle portion and disables a nozzle portion that is determined to be abnormal.

The liquid discharge head in this specification corresponds to the print head in Patent Document 1. The liquid ejection apparatus in this specification corresponds to the image recording apparatus in Patent Document 1. The nozzle portion in this specification corresponds to the recording element in Patent Document 1.

In order to cope with a discharge abnormality of the liquid discharge head, a maintenance process is performed on the liquid discharge head in order to keep the discharge performance of the liquid discharge head in a good state.

Patent Document 2 describes a liquid discharge apparatus that performs cleaning of a liquid discharge head as maintenance of the liquid discharge head. The liquid ejection device described in Patent Document 2 forcibly ejects liquid from all nozzle portions provided in the liquid ejection head as cleaning of the liquid ejection head.

The liquid discharge head in this specification corresponds to the print head in Patent Document 2. The liquid ejecting apparatus in this specification corresponds to the ink jet printer in Patent Document 2. The nozzle portion in this specification corresponds to the nozzle in Patent Document 2.

Patent Document 3 describes a liquid ejection device that obtains the dryness of each nozzle unit and determines whether or not preliminary ejection is necessary based on the dryness. The liquid ejection device described in Patent Document 3 sets the weight of the dryness according to the type of liquid.

In addition, the nozzle part in this specification corresponds to the nozzle in Patent Document 3. The liquid ejection apparatus in this specification corresponds to the image forming apparatus in Patent Document 3. The liquid in this specification corresponds to the ink in Patent Document 3.

Patent Document 4 describes a liquid ejection apparatus that measures the temperature of each of a plurality of nozzle portions in a preliminary ejection step and ejects liquid only from nozzle portions whose temperature measurement values are equal to or lower than a predetermined temperature. Yes.

In addition, the nozzle part in this specification corresponds to the nozzle in Patent Document 4. The liquid ejection device in this specification corresponds to the droplet ejection device in Patent Document 4.

Japanese Unexamined Patent Application Publication No. 2016-096331 JP 2003-191492 A JP 2010-094950 A JP 2008-114106 A

As a maintenance of the liquid discharge head, wiping processing of the liquid discharge surface is known. In the wiping process, deposits on the liquid ejection surface are removed using a wiping member such as a web. On the other hand, there is a concern that the liquid ejection surface is deteriorated due to the wiping process. The liquid discharge head is concerned about a decrease in discharge performance due to deterioration of the liquid discharge surface. One cause of the deterioration of the liquid discharge surface due to the wiping process is the composition of particles contained in the liquid.

When the preliminary discharge is executed before the wiping process of the liquid discharge surface, the liquid may adhere to the liquid discharge surface due to the execution of the preliminary discharge. In order to suppress deterioration of the liquid discharge surface, it is preferable to suppress adhesion of the liquid to the liquid discharge surface.

Patent Document 1 has no description regarding maintenance of the liquid ejection head, such as wiping processing of the liquid ejection surface. Patent Documents 2 to 4 have no description regarding means for suppressing the adhesion of liquid to the liquid ejection surface.

The present invention has been made in view of such circumstances, and an object thereof is to provide a maintenance device, a maintenance method, and a liquid ejection device capable of suppressing deterioration of the liquid ejection surface during the wiping process of the liquid ejection surface. To do.

In order to achieve the above object, the following invention modes are provided.

The maintenance device according to the first aspect is an abnormal discharge element in which an abnormal discharge has occurred or a normal discharge is possible for each of the plurality of discharge elements of the liquid discharge head including a plurality of discharge elements that discharge liquid. A discharge state information acquisition unit that acquires discharge state information that indicates whether the element is a normal discharge element, and a plurality of pieces acquired by the discharge state information acquisition unit when the liquid contains particles having a Mohs hardness exceeding 0.5. Based on the discharge state information of each of the discharge elements, the discharge element determination unit that determines the abnormal discharge element as the discharge non-execution element and determines the normal discharge element as the discharge execution element, and discharge is executed by the discharge element determination unit The liquid discharge head is configured such that liquid is discharged from the discharge element determined as the element, and liquid is not discharged from the discharge element determined as the discharge non-execution element by the discharge element determination unit. And preliminary ejection executing unit for executing the preliminary discharge, a maintenance device having a.

According to the first aspect, when a liquid containing particles having a Mohs hardness of more than 0.5 is used, a normal discharge element capable of normal discharge is determined as a discharge execution element, and the preliminary discharge of the liquid discharge head is performed. Discharge the liquid. An abnormal ejection element in which ejection abnormality has occurred is determined as an ejection non-execution element, and is not ejected during preliminary ejection of the liquid ejection head. During the preliminary ejection, the abnormal ejection element does not eject the liquid, so that the adhesion of the liquid to the liquid ejection surface during the preliminary ejection is suppressed.

Examples of the ejection element include an ejection port formed on the liquid ejection surface, a communication channel communicating with the ejection port, a pressure chamber communicating with the communication channel, and a pressure generating element that pressurizes the pressure chamber. An example of the pressure generating element is a piezoelectric element.

Examples of particles having a Mohs hardness exceeding 0.5 include pigments used for color materials of color inks. As an example of a liquid containing particles having a Mohs hardness exceeding 0.5, a color ink containing a pigment can be given.

The second aspect may be configured such that the maintenance device according to the first aspect includes a wiping processing unit that wipes the liquid ejection surface of the liquid ejection head after the preliminary ejection of the liquid ejection head is performed by the preliminary ejection execution unit.

According to the second aspect, deterioration of the liquid ejection surface is suppressed. As a result, the life of the liquid discharge head can be extended.

An example of the deterioration of the liquid discharge surface is wear.

As an example of a wiping process part, the aspect provided with a wiping member and a wiping control part is mentioned. Examples of the wiping member include a wiping sheet or a blade. An example of the wiping sheet is a wiping web.

The third aspect is liquid information for acquiring liquid information indicating whether or not the liquid ejected from the liquid ejection head contains particles having a Mohs hardness exceeding 0.5 in the maintenance apparatus of the first aspect or the second aspect. It is good also as a structure provided with the acquisition part.

According to the third aspect, when a liquid containing particles having a Mohs hardness exceeding 0.5 is used, the normal ejection element and the abnormal ejection element are reliably determined as ejection non-execution elements.

According to a fourth aspect, in the maintenance device according to the third aspect, the ejection element determination unit is configured such that the liquid information acquired by the liquid information acquisition unit is liquid information of a liquid containing particles having a Mohs hardness of 0.5 or less. The abnormal discharge element and the normal discharge element may be determined as the discharge execution elements based on the discharge state information of each of the plurality of discharge elements acquired by the discharge state information acquisition unit.

According to the fourth aspect, when ink containing particles having a Mohs hardness of 0.5 or less is used, liquid is ejected from the abnormal ejection element and the normal ejection element. As a result, the ejection performance of the abnormal ejection element and the normal ejection element can be recovered.

Examples of abnormal ejection elements include ejection elements that exceed a predetermined landing position error tolerance.

According to a fifth aspect, in the maintenance device according to the third aspect or the fourth aspect, the liquid information acquisition unit indicates whether the liquid discharged from the liquid discharge head contains particles having a Mohs hardness of 1.0 or more. It is good also as a structure which acquires information.

According to the fifth aspect, when a liquid containing pigment particles having a Mohs hardness of 1.0 or more is used, it is possible to perform a preliminary discharge in which the abnormal discharge element is not discharged and the liquid is discharged from the normal discharge element. is there.

An example of a liquid containing particles having a Mohs hardness of 1.0 or more is black ink containing carbon black.

A sixth aspect includes a discharge state information storage unit that stores discharge state information of each of the plurality of discharge elements in the maintenance device according to any one of the first to fifth aspects, and the discharge state information acquisition unit includes: A configuration may be adopted in which the discharge state information of each of the plurality of discharge elements is read from the discharge state information storage unit, and the discharge state information of each of the plurality of discharge elements is acquired.

According to the sixth aspect, the discharge state information acquisition unit can read the discharge state information of each nozzle unit stored in the discharge state information storage unit and acquire the discharge state information of each nozzle unit. .

According to a seventh aspect, in the maintenance device according to the sixth aspect, the discharge state information storage unit includes a discharge element in which one or more discharge abnormalities occur in each of the plurality of discharges of the plurality of discharge elements. It is good also as a structure memorize | stored.

According to the seventh aspect, it is possible to perform preliminary discharge in which a nozzle portion in which one or more discharge abnormalities have occurred is not discharged in a plurality of discharges.

According to an eighth aspect, in the maintenance device according to the sixth aspect or the seventh aspect, the discharge state information storage unit includes a discharge element in which at least one discharge abnormality does not occur in each of the plurality of discharges of the plurality of discharge elements. It is good also as a structure memorize | stored as a normal discharge element.

According to the eighth aspect, it is possible to perform preliminary discharge in which liquid is discharged from a nozzle portion where no discharge abnormality occurs in a plurality of discharges.

The ninth aspect is discharge element determination information determined by the discharge element determination unit in the maintenance device according to any one of the first aspect to the eighth aspect, and each of the plurality of discharge elements is a discharge execution element. Alternatively, it may be configured to include a discharge element determination information storage unit that stores discharge element determination information indicating whether a discharge non-execution element is associated with identification information of each of the plurality of discharge elements.

According to the ninth aspect, it is possible to read ejection element determination information from the ejection element determination information storage unit.

According to a tenth aspect, in the maintenance device according to the ninth aspect, when the discharge state information of a plurality of discharge elements is updated, the discharge stored in the discharge element determination information storage unit based on the updated discharge state information It is good also as a structure provided with the discharge element determination information update part which updates element determination information.

According to the tenth aspect, it is possible to update the ejection element determination information due to the update of the ejection state information.

In the maintenance method according to the eleventh aspect, each of the plurality of ejection elements of the liquid ejection head including a plurality of ejection elements for ejecting liquid is an abnormal ejection element in which ejection abnormality has occurred, or normal ejection is possible A discharge state information acquisition step for acquiring discharge state information indicating whether the element is a normal discharge element, and a plurality of pieces acquired by the discharge state information acquisition step when the liquid contains particles having a Mohs hardness exceeding 0.5. Discharge element determination step of determining an abnormal discharge element as a discharge non-execution element and determining a normal discharge element as a discharge execution element based on the discharge state information of each of the discharge elements, and discharge execution in the discharge element determination step The liquid is discharged from the discharge element determined as the element, and the liquid is not discharged from the discharge element determined as the discharge non-execution element in the discharge element determination step. And preliminary ejection executing step of executing a preliminary discharge of body discharge head, a maintenance method comprising.

According to the eleventh aspect, it is possible to obtain the same effect as in the first aspect.

In the eleventh aspect, matters similar to the matters specified in the second aspect to the tenth aspect can be appropriately combined. In that case, the component responsible for the process and function specified in the maintenance device can be grasped as the component of the maintenance method responsible for the process and function corresponding thereto.

A twelfth aspect includes a liquid information acquisition step of acquiring liquid information indicating whether or not the liquid discharged from the liquid discharge head contains particles having a Mohs hardness exceeding 0.5 in the maintenance method of the eleventh aspect. It is good also as a structure.

According to the twelfth aspect, similarly to the second aspect, when a liquid containing particles having a Mohs hardness of more than 0.5 is used, the determination of the discharge execution element and the discharge non-execution element is reliably performed. .

A thirteenth aspect is the maintenance method according to the twelfth aspect, wherein a maintenance execution request acquisition step for acquiring a maintenance execution request including a preliminary discharge execution step, and the plurality of discharge elements determined in the discharge element determination step are discharge execution elements A discharge element determination information storage step for storing discharge element determination information indicating whether the discharge element is a discharge non-execution element in association with identification information of a plurality of discharge elements, and a maintenance execution request acquisition step Before execution, the liquid information acquisition step, the discharge state information acquisition step, the discharge element determination step, and the discharge element determination information storage step may be executed.

According to the thirteenth aspect, it is possible to execute the preliminary ejection step based on the ejection element determination information updated in advance.

The liquid ejection apparatus according to the fourteenth aspect is a liquid ejection head including a plurality of ejection elements that eject liquid, and an abnormal ejection element in which ejection abnormality has occurred in each of the plurality of ejection elements, or normal ejection. Is acquired by the discharge state information acquiring unit that acquires discharge state information indicating whether the liquid is a normal discharge element, and when the liquid contains particles having a Mohs hardness exceeding 0.5. Based on the discharge state information of each of the plurality of discharge elements, the discharge element determination unit that determines the abnormal discharge element as the discharge non-execution element and determines the normal discharge element as the discharge execution element, and the discharge element determination unit Liquid is discharged from the discharge element determined as the discharge execution element, and liquid is not discharged from the discharge element determined as the discharge non-execution element by the discharge element determination unit. And preliminary ejection executing unit for executing the preliminary ejection, which is a liquid ejecting apparatus having a.

According to the fourteenth aspect, it is possible to obtain the same effect as in the first aspect.

In the fourteenth aspect, matters similar to the matters specified in the second aspect to the tenth aspect can be appropriately combined. In that case, the component responsible for the processing and function specified in the maintenance device can be grasped as the component of the liquid ejection device responsible for the processing and function corresponding thereto.

According to a fifteenth aspect, in the liquid ejection device according to the fourteenth aspect, a liquid information acquisition unit that acquires liquid information indicating whether or not the liquid ejected from the liquid ejection head contains particles having a Mohs hardness exceeding 0.5. It is good also as a structure provided.

According to the fifteenth aspect, similarly to the second aspect, when a liquid containing particles having a Mohs hardness of more than 0.5 is used, the determination of the discharge execution element and the discharge non-execution element is reliably performed. .

A sixteenth aspect is a liquid ejection device according to the fourteenth aspect or the fifteenth aspect, wherein each of the plurality of ejection elements is an abnormal ejection element in which ejection abnormality has occurred, or a normal ejection element capable of normal ejection. An abnormality determination unit that determines whether or not there is provided, and the discharge state information acquisition unit may acquire the determination result of the abnormality determination unit as discharge state information.

According to the sixteenth aspect, whether each of the plurality of ejection elements is an abnormal ejection element in which an ejection abnormality has occurred or a normal ejection element capable of normal ejection is detected as a detection result of the ejection state detection unit. It is possible to obtain.

According to a seventeenth aspect, in the liquid ejection device according to the sixteenth aspect, the abnormality determination unit uses, as an abnormal ejection element, an ejection element in which one or more ejection abnormalities have occurred in each of a plurality of ejections of the plurality of ejection elements. It is good also as a structure to determine.

According to the seventeenth aspect, it is possible to determine an abnormal ejection element.

According to the present invention, when a liquid containing particles having a Mohs hardness of more than 0.5 is used, the normal discharge element capable of normal discharge is determined as the discharge execution element, and the liquid is discharged during the preliminary discharge of the liquid discharge head. To discharge. An abnormal ejection element in which ejection abnormality has occurred is determined as an ejection non-execution element, and is not ejected during preliminary ejection of the liquid ejection head. During the preliminary ejection, the abnormal ejection element does not eject the liquid, so that the adhesion of the liquid to the liquid ejection surface during the preliminary ejection is suppressed.

FIG. 1 is an overall configuration diagram of an ink jet recording apparatus. FIG. 2 is a front view of the drawing unit of the ink jet recording apparatus. FIG. 3 is a block diagram of a control system of the ink jet recording apparatus according to the first embodiment. FIG. 4 is a perspective plan view showing an example of the structure of an inkjet head. FIG. 5 is a perspective view of the head module and includes a partial cross-sectional view. FIG. 6 is a perspective plan view showing an example of the structure of an inkjet head. FIG. 7 is a sectional view showing the internal structure of the head module. FIG. 8 is a flowchart showing a control flow of the maintenance method according to the first embodiment. FIG. 9 is a block diagram of a control system of the ink jet recording apparatus according to the second embodiment. FIG. 10 is a flowchart showing the flow of control of the method for determining the ejection execution element and the ejection non-execution element. FIG. 11 is a flowchart showing a control flow of the maintenance method according to the second embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, the same components are denoted by the same reference numerals, and redundant description is omitted.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus. The ink jet recording apparatus 10 illustrated in FIG. 1 includes a paper feed unit 12, a drawing unit 14, a paper discharge unit 16, and a maintenance unit. In FIG. 1, the illustration of the maintenance unit is omitted. The maintenance unit is illustrated in FIG.

<Paper Feeder>
The paper feed unit 12 includes a paper feed drum 30. The paper supply drum 30 has a cylindrical shape. The sheet feeding drum 30 is installed horizontally with respect to the horizontal plane 1 by pivotally supporting a rotating shaft 32 provided protruding from both ends in the longitudinal direction on a bearing provided on a main body frame of the inkjet recording apparatus 10. . In FIG. 1, the main body frame and the bearing are not shown. The main body frame is shown in FIG.

A motor (not shown) is connected to the rotary shaft 32 via a rotation transmission mechanism (not shown). The paper feed drum 30 is driven by a motor (not shown) and rotates. A curved line with an arrow shown in the paper supply drum 30 represents the rotation direction of the paper supply drum 30.

The paper feed drum 30 includes a gripper 36 on the peripheral surface 34. The leading edge of the sheet S is held by the gripper 36 and supported by the peripheral surface 34 of the sheet feeding drum 30. The paper S supported by the paper supply drum 30 is conveyed along the peripheral surface 34 of the paper supply drum 30 due to the rotation of the paper supply drum 30. The sheet S is synonymous with a medium.

The leading edge of the paper S is an area including the leading edge of the paper S. The leading edge of the paper S has a certain length from the leading edge of the paper S. The certain length is at least longer than the length that can be gripped by using the gripper 36.

The gripper 36 includes a plurality of claws, a plurality of claw bases, and a claw support member. A plurality of claws, a plurality of claw stands, and a claw support member are not shown. The plurality of claws and the plurality of claw bases are arranged along a direction parallel to the rotation axis of the sheet feeding drum 30.

The term “parallel” in this specification includes a substantial parallel that intersects but can obtain the same effect as the parallel. In addition, the term “orthogonal” in this specification includes substantial orthogonality that intersects at an angle of less than 90 degrees or greater than 90 degrees, but can obtain the same effect as the orthogonality.

The gripper 36 grips the paper S between a plurality of claws and a claw base. The plurality of claws are supported by a claw support member so as to be opened and closed. The plurality of claw bases may have an integral structure.

The paper feeding unit 12 includes a paper feeding cassette (not shown) and a sheet feeder (not shown). A sheet cassette S stores a sheet S of paper. The sheet feeder is disposed between the paper feed cassette and the paper feed drum 30.

The sheet feeder corrects the posture of the paper S taken out from the paper feed cassette. The sheet S whose posture is corrected is sent toward the sheet feeding drum 30.

<Drawing part>
The drawing unit 14 includes a drawing drum 40. The drawing drum 40 has a cylindrical shape. The drawing drum 40 is rotatably supported using the main body frame of the inkjet recording apparatus 10.

FIG. 2 is a front view of the drawing unit of the ink jet recording apparatus. The drawing drum 40 is installed horizontally with respect to the horizontal plane 1 by pivotally supporting a rotating shaft 42 provided protruding from both ends in the longitudinal direction on a bearing 22 provided on the main body frame 21 of the inkjet recording apparatus 10. Yes.

A motor (not shown) is connected to the rotation shaft 42 via a rotation transmission mechanism (not shown). The drawing drum 40 is driven to rotate by a motor (not shown). A curve with an arrow shown in the drawing drum 40 represents the rotation direction of the drawing drum 40.

The gripper 46 is disposed at two locations on the peripheral surface 44 of the drawing drum 40. The gripper 46 of the drawing drum 40 has the same structure as the gripper 36 of the paper feed drum 30. The arrangement positions of the two grippers 46 are separated from each other by a half circumference on the peripheral surface 44 of the drawing drum 40.

The drawing drum 40 has a plurality of suction holes arranged in a paper support area for supporting the paper S on the peripheral surface 44. The plurality of suction holes are connected to a pump (not shown) through a flow path (not shown) formed inside the drawing drum 40. The illustration of the plurality of suction holes is omitted.

動作 Operate a pump (not shown) to generate negative pressure in multiple suction holes. The sheet S gripped at the leading end using the gripper 46 is sucked and supported by the peripheral surface 44 of the drawing drum 40 using negative pressure generated in the plurality of sucking holes.

The drawing unit 14 includes the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG. The inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K are line-type heads. Details of the line type head will be described later. An inkjet head is an example of a liquid ejection head that includes a plurality of ejection elements that eject liquid.

The inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K are radially arranged on the concentric circle with the rotation axis 42 of the drawing drum 40 as the center. The inkjet head 48 </ b> C, the inkjet head 48 </ b> M, the inkjet head 48 </ b> Y, and the inkjet head 48 </ b> K are supported using the head support frame 50.

As shown in FIG. 2, the head support frame 50 includes a side plate 82 </ b> L, a side plate 82 </ b> R, and a connecting frame 84 that are orthogonal to the rotation shaft 42 of the drawing drum 40. The upper end portion of the side plate 82L and the upper end portion of the side plate 82R are connected using a connecting frame 84.

The upper term in the present specification represents a direction having a component in the direction opposite to the direction of gravity. Moreover, the lower term in this specification represents the direction which has a component of a gravitational direction. Although the same term in this specification has a difference, it includes the substantially same thing which can acquire the same effect.

The side plate 82L and the side plate 82R are formed in a plate shape. The side plate 82L and the side plate 82R are arranged at positions facing each other with the drawing drum 40 interposed therebetween. A mounting portion 86Y for mounting the inkjet head 48Y, a mounting portion 86K for mounting the inkjet head 48K, and the inkjet head 48C shown in FIG. 1 are mounted on the inner surface of the side plate 82L and the inner surface of the side plate 82R. A mounting portion and a mounting portion (not shown) for mounting the inkjet head 48M shown in FIG. 1 are provided.

A mounting portion (not shown) for mounting the inkjet head 48C shown in FIG. 1, a mounting portion (not shown) for mounting the inkjet head 48M shown in FIG. 1, and a mounting portion 86Y and a mounting portion 86K shown in FIG. The drums 40 are arranged radially at a constant interval on a concentric circle around the rotation shaft 42.

The inkjet head 48C shown in FIG. 1 is attached to the head support frame 50 due to fixing the attached parts (not shown) provided at both ends in the longitudinal direction to the attaching parts (not shown).

The inkjet head 48M shown in FIG. 1 is attached to the head support frame 50 due to fixing the attached parts (not shown) provided at both ends in the longitudinal direction to the attaching parts (not shown).

The inkjet head 48Y shown in FIG. 2 is attached to the head support frame 50 due to fixing the attached portions 88Y provided at both ends in the longitudinal direction to the attachment portions 86Y.

The ink jet head 48K shown in FIG. 2 is attached to the head support frame 50 due to fixing the attached portions 88K provided at both ends in the longitudinal direction to the attaching portion 86K.

The ink-jet head 48C, the ink-jet head 48M, the ink-jet head 48Y, and the ink-jet head 48K shown in FIG. 1 are concentrically centered on the rotation axis 42 of the drawing drum 40 due to being attached to the head support frame 50 They are arranged radially at regular intervals.

As shown in FIG. 1, the inkjet head 48 </ b> C and the inkjet head 48 </ b> K are arranged symmetrically with respect to a line parallel to the direction of gravity passing through the center of the drawing drum 40. Similarly, the inkjet head 48M and the inkjet head 48Y are arranged symmetrically with respect to a line passing through the center of the drawing drum 40 and parallel to the vertical direction.

The inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K are the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the inkjet head 48K. The liquid discharge surface 277K is disposed to face the peripheral surface 44 of the drawing drum 40.

Further, the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the liquid ejection surface 277K of the inkjet head 48K are determined in advance from the peripheral surface 44 of the drawing drum 40. It is located at the specified height.

In other words, the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, the liquid ejection surface 277K of the inkjet head 48K, and the peripheral surface 44 of the drawing drum 40 A gap of the same distance is formed between them.

Further, the liquid discharge surface 277C of the ink jet head 48C, the liquid discharge surface 277M of the ink jet head 48M, the liquid discharge surface 277Y of the ink jet head 48Y, and the liquid discharge surface 277K of the ink jet head 48K are arranged orthogonal to the transport direction of the paper S. Is done.

A liquid repellent film may be formed on the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the liquid ejection surface 277K of the inkjet head 48K.

As an example of the liquid repellent film, there may be mentioned a mode in which a silicon dioxide film is formed on a silicon substrate, and a film of perfluorodecyltrichlorosilane is formed by CVD using the silicon dioxide film as an adhesive layer. The liquid repellent film is sometimes called a water repellent film.

Note that CVD is an abbreviation for chemical vapor deposition which is an English notation for chemical vapor deposition. Chemical vapor deposition is sometimes referred to as chemical vapor deposition or chemical vapor deposition.

Hereinafter, unless otherwise specified, the term liquid discharge surface in this specification is used as a general term for both a liquid repellent film formed on the liquid discharge surface and a liquid discharge surface on which no liquid repellent film is formed. And

In addition, the liquid ejection surface 277 or the code is a generic term for the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the liquid ejection surface 277K of the inkjet head 48K. An omitted liquid discharge surface may be used.

The inkjet head 48 </ b> C causes the cyan ink to be ejected onto the paper S conveyed using the drawing drum 40. The inkjet head 48M ejects magenta ink onto the paper S conveyed using the drawing drum 40.

The inkjet head 48Y causes yellow ink to be ejected onto the paper S conveyed using the drawing drum 40. The inkjet head 48 </ b> K ejects black ink onto the paper S that is transported using the drawing drum 40.

The image forming surface of the sheet S conveyed using the drawing drum 40 has cyan ink ejected from the inkjet head 48C, magenta ink ejected from the inkjet head 48M, yellow ink ejected from the inkjet head 48Y, and the inkjet head. A color image is drawn using black ink discharged from 48K. Note that the image forming surface of the sheet S is the surface opposite to the surface supported by the drawing drum 40. The image forming surface of the sheet S is a surface facing the liquid ejection surface 277C of the inkjet head 48C, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the liquid ejection surface 277K of the inkjet head 48K. .

The head support frame 50 is guided by a guide rail (not shown) and is slidable in a direction parallel to the rotation shaft 42 of the drawing drum 40. The direction parallel to the rotation axis 42 of the drawing drum 40 is a direction parallel to the horizontal plane 1.

The head support frame 50 is driven using a linear actuator (not shown). The ink jet head 48C, the ink jet head 48M, the ink jet head 48Y, and the ink jet head 48K supported by the head support frame 50 are arranged between a drawing position indicated by a solid line in FIG. 2 and a maintenance position indicated by a broken line in FIG. It is configured to be movable.

Due to the head support frame 50 being positioned at the drawing position, the inkjet head 48C, inkjet head 48M, inkjet head 48Y, and inkjet head 48K shown in FIG. It becomes a state.

<Output section>
The paper discharge unit 16 includes a chain gripper 60. The chain gripper 60 includes a pair of first sprockets 62, a pair of second sprockets (not shown), and a pair of chains 64.

FIG. 1 shows one of the pair of first sprockets 62. In addition, one of the pair of chains 64 is illustrated. The pair of first sprockets 62 or the pair of second sprockets (not shown) are connected to a motor (not shown) via a connection mechanism (not shown). Due to the operation of a motor (not shown), the pair of chains 64 travel.

The chain 64 is provided with a plurality of grippers 66 along the running direction of the chain 64. FIG. 1 shows a part of the plurality of grippers 66. The gripper 66 has the same structure as the gripper 36 of the paper supply drum 30 and the gripper 46 of the drawing drum 40.

The sheet S whose leading end is gripped using the gripper 66 is conveyed along the traveling direction of the chain 64 due to the traveling of the chain 64. The paper S conveyed using the paper discharge unit 16 is sent to a stacking unit (not shown). A stacking unit (not shown) stacks the sheets S on which images are formed.

[Operation of inkjet recording apparatus]
The paper S is conveyed to the drawing drum 40 using the paper supply drum 30. At the transfer position of the paper S between the paper supply drum 30 and the drawing drum 40, the paper is transferred from the paper supply drum 30 to the drawing drum 40. The gripper 36 of the paper feed drum 30 is configured to be able to change the paper S between the gripper 46 of the drawing drum 40.

The paper S delivered to the drawing drum 40 is conveyed using the drawing drum 40. The ink jet head 48C, the ink jet head 48M, the ink jet head 48Y, and the ink jet head 48K cause ink to be ejected toward the paper S when the paper S passes through the respective ejection regions.

On the paper S, a color image is formed using ink ejected from the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K.

The paper S on which the color image is formed is transferred from the drawing drum 40 to the chain gripper 60 at the paper transfer position between the drawing drum 40 and the chain gripper 60. The gripper 46 of the drawing drum 40 is configured to be able to change the paper S between the gripper 66 of the chain gripper 60 and the gripper 66.

The paper S delivered from the drawing drum 40 to the chain gripper 60 is transported using the chain gripper 60.

[Maintenance Department]
When the head support frame 50 shown in FIG. 2 is positioned at the maintenance position, the ink jet head 48C, the ink jet head 48M, the ink jet head 48Y, and the ink jet head 48K shown in FIG.

The moisturizing unit 90 is arranged at the maintenance position. When the inkjet head 48C, inkjet head 48M, inkjet head 48Y, and inkjet head 48K shown in FIG. 1 are not used for a long time, the head support frame 50 is positioned at the maintenance position.

The ink jet head 48C, the ink jet head 48M, the ink jet head 48Y, and the ink jet head 48K shown in FIG. 1 are moisturized using the moisturizing unit 90 shown in FIG. Thereby, the discharge abnormality resulting from drying is suppressed.

The moisturizing unit 90 functions as an ink receiver when performing preliminary ejection of the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG.

That is, the moisturizing unit 90 functions as a cap for the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG.

The liquid ejection surface 277C of the inkjet head 48C shown in FIG. 1, the liquid ejection surface 277M of the inkjet head 48M, the liquid ejection surface 277Y of the inkjet head 48Y, and the liquid ejection surface 277K of the inkjet head 48K are shown in FIG. Due to the fact that 90 is attached, it becomes possible to perform preliminary ejection of the inkjet head 48C, inkjet head 48M, inkjet head 48Y, and inkjet head 48K shown in FIG.

Between the drawing position and the maintenance position, the liquid discharge surface 277C of the ink jet head 48C, the liquid discharge surface 277M of the ink jet head 48M, the liquid discharge surface 277Y of the ink jet head 48Y, and the liquid discharge surface of the ink jet head 48K shown in FIG. A head cleaning unit 92 for cleaning the surface 277K is provided.

The head cleaning unit 92 shown in FIG. 2 is shown with a simplified structure. The head cleaning unit 92 includes a liquid ejection surface 277C of the inkjet head 48C, a liquid ejection surface 277M of the inkjet head 48M, a liquid ejection surface 277Y of the inkjet head 48Y, and a liquid ejection surface 277K of the inkjet head 48K shown in FIG. A wiping web for wiping is provided. The head cleaning unit 92 is an example of a component of the wiping processing unit.

When the inkjet head 48K is moved from the maintenance position to the drawing position, the wiping web 94 shown in FIG. 2 contacts the liquid ejection surface 277K of the inkjet head 48K and wipes the liquid ejection surface 277K of the inkjet head 48K.

Instead of the wiping web 94, another wiping member such as a blade may be provided as a wiping member for wiping the liquid discharge surface 277K of the inkjet head 48K.

[Description of control system]
FIG. 3 is a block diagram showing a schematic configuration of the control system. As shown in FIG. 3, the ink jet recording apparatus 10 includes a system controller 100. The system controller 100 includes a CPU 100A, a ROM 100B, and a RAM 100C.

The ROM 100B and the RAM 100C shown in FIG. 3 may be provided outside the CPU. CPU is an abbreviation for Central Processing Unit. ROM is an abbreviation for Read Only Memory. RAM is an abbreviation for Random Access Memory.

The system controller 100 functions as an overall control unit that comprehensively controls each unit of the inkjet recording apparatus 10. Further, the system controller 100 functions as an arithmetic unit that performs various arithmetic processes. The system controller 100 may control each unit of the inkjet recording apparatus 10 by executing a program.

Furthermore, the system controller 100 functions as a memory controller that controls reading and writing of data in memories such as the ROM 100B and the RAM 100C.

The ink jet recording apparatus 10 includes a communication unit 102, an image memory 104, a conveyance control unit 110, a paper feed control unit 112, a drawing control unit 118, a paper discharge control unit 124, a pump control unit 126, and a maintenance control unit 128. .

The communication unit 102 includes a communication interface (not shown). The communication unit 102 can transmit and receive data to and from the host computer 103 connected to the communication interface.

The image memory 104 functions as a temporary storage unit for various data including image data. The image memory 104 reads and writes data through the system controller 100. Image data captured from the host computer 103 via the communication unit 102 is temporarily stored in the image memory 104.

The conveyance control unit 110 controls the operation of the conveyance unit 11 for the paper S in the inkjet recording apparatus 10 in accordance with a command from the system controller 100. The transport unit 11 shown in FIG. 3 includes the drawing drum 40 shown in FIG. The command here is specifically an electric signal. The following commands are the same.

The paper feed control unit 112 shown in FIG. 3 operates the paper feed unit 12 in response to a command from the system controller 100. The paper feed control unit 112 controls the paper S supply start operation, the paper S supply stop operation, and the like. The paper feed control unit 112 controls the rotation speed of the paper feed drum 30 shown in FIG. The paper feed control unit 112 shown in FIG. 3 controls the opening / closing operation of the gripper 36 shown in FIG.

The drawing control unit 118 controls the operation of the drawing unit 14 in response to a command from the system controller 100. That is, the drawing control unit 118 controls ink ejection of the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K illustrated in FIG.

The drawing control unit 118 includes an image processing unit (not shown). The image processing unit forms dot data from the input image data. The image processing unit includes a color separation processing unit, a color conversion processing unit, a correction processing unit, and a halftone processing unit (not shown).

The color separation processing unit performs color separation processing on the input image data. For example, when the input image data is expressed in RGB, the input image data is decomposed into data for each of R, G, and B colors. Here, R represents red. G represents green. B represents blue.

The color conversion processing unit converts the image data for each color separated into R, G, and B into C, M, Y, and K corresponding to the ink colors. Here, C represents cyan. M represents magenta. Y represents yellow. K represents black.

In the correction processing unit, correction processing is performed on the image data for each color converted into C, M, Y, and K. Examples of the correction processing include gamma correction processing, density unevenness correction processing, abnormal recording element correction processing, and the like.

In the halftone processing unit, for example, image data represented by a multi-gradation number such as 0 to 255 is converted into dot data represented by a binary or multi-value of three or more values less than the number of gradations of the input image data. Converted.

In the halftone processing unit, predetermined halftone processing rules are applied. Examples of the halftone processing rule include a dither method or an error diffusion method. The halftone processing rule may be changed according to image recording conditions, the contents of image data, or the like.

The drawing control unit 118 includes a waveform generation unit, a waveform storage unit, and a drive circuit (not shown). The waveform generator generates a drive voltage waveform. The waveform storage unit stores the waveform of the drive voltage. The drive circuit generates a drive voltage having a drive waveform corresponding to the dot data. The drive circuit supplies a drive voltage to the inkjet head 48C, inkjet head 48M, inkjet head 48Y, and inkjet head 48K shown in FIG.

That is, based on the dot data generated through processing using the image processing unit, the ejection timing and the ink ejection amount at each pixel position are determined, the ejection timing at each pixel position, the drive voltage corresponding to the ink ejection amount, A control signal for determining the ejection timing of each pixel is generated, this drive voltage is supplied to the inkjet head, and dots are recorded using the ink ejected from the inkjet head.

The paper discharge control unit 124 operates the paper discharge unit 16 in response to a command from the system controller 100. In the case where the paper discharge unit 16 includes a paper discharge stand including a lift mechanism (not shown), the paper discharge control unit 124 controls the operation of the lift mechanism according to the increase or decrease of the paper S.

The pump control unit 126 controls the operation of the pump 127 according to a command from the system controller 100. The pump 127 shown in FIG. 3 includes a pump that generates the adsorption pressure of the drawing drum 40 shown in FIG.

The maintenance control unit 128 controls the operation of the maintenance unit 18 in accordance with a command from the system controller 100. The maintenance unit 18 includes the moisturizing unit 90, the head cleaning unit 92, and a linear actuator (not shown) shown in FIG. The maintenance control unit 128 is an example of a component of the wiping processing unit.

3 includes an operation unit 130, a display unit 132, a parameter storage unit 134, a program storage unit 136, an in-line sensor 58, an abnormality determination unit 150, and an ejection state information storage unit 152.

The operation unit 130 includes operation members such as operation buttons, a keyboard, or a touch panel. The operation unit 130 may include a plurality of types of operation members. The illustration of the operation member is omitted.

Information input via the operation unit 130 is sent to the system controller 100. The system controller 100 executes various processes in accordance with information sent from the operation unit 130.

The display unit 132 includes a display device such as a liquid crystal panel and a display driver. Illustration of the display device and the display driver is omitted. In response to a command from the system controller 100, the display unit 132 causes the display device to display various information such as various setting information of the device or abnormality information.

The parameter storage unit 134 stores various parameters used in the inkjet recording apparatus 10. Various parameters stored in the parameter storage unit 134 are read out via the system controller 100 and set in each unit of the apparatus.

The program storage unit 136 stores a program used for each unit of the inkjet recording apparatus 10. Various programs stored in the program storage unit 136 are read out via the system controller 100 and executed in each unit of the apparatus.

The in-line sensor 58 optically reads an image formed on the paper S using the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K. The inline sensor 58 is a device that generates electronic image data indicating a read image. Image formation on the paper S is synonymous with image recording on the paper S.

The in-line sensor 58 includes an imaging device that captures an image formed on the paper S and converts it into an electrical signal indicating image information. The in-line sensor 58 may include an imaging optical device, an illumination optical system that illuminates a reading target, and a signal processing circuit that processes a signal obtained from the imaging device and generates digital image data.

The in-line sensor 58 is preferably configured to be able to read a color image. In the inline sensor 58 of this example, for example, a color CCD linear image sensor is used as an imaging device. CCD is an abbreviation for Charge-Coupled Device. CCD refers to a charge coupled device.

The color CCD linear image sensor is an image sensor in which light receiving elements having color filters of red, green, and blue are arranged in a straight line. Instead of the color CCD linear image sensor, a color CMOS linear image sensor can be used. CMOS is an abbreviation for Complementary / Metal / Oxide / Semiconductor. CMOS refers to a complementary metal oxide semiconductor.

The inline sensor 58 is arranged in the conveyance path of the paper S. As an example of the arrangement position of the in-line sensor 58, the position on the downstream side of the inkjet head 48K shown in FIG. The inline sensor 58 reads an image formed on the paper S while the paper S is transported using the drawing drum 40. The inline sensor 58 may be a camera.

The paper S on which an image is formed using the ink jet head 48C, the ink jet head 48M, the ink jet head 48Y, and the ink jet head 48K shown in FIG. 1 is formed on the paper S when passing through the reading area of the inline sensor 58. The scanned image is read.

The image formed on the paper S includes an abnormal nozzle portion detection pattern used when detecting the ejection state of each nozzle portion. The abnormal nozzle portion detection pattern may be formed on the paper S on which all user images are formed. The abnormal nozzle portion detection pattern may be formed on the paper S on which a part of the user image is formed. The nozzle portion is shown in FIG. Hereinafter, the nozzle part which is not attached | subjected code | symbol shall represent the nozzle part 281 shown in FIG.

As an example in which the abnormal nozzle portion detection pattern is formed on the paper S on which a part of the user images are formed, there is an aspect in which the abnormal nozzle portion detection pattern is formed on the paper S on which every k user images are formed. The abnormal nozzle portion detection pattern may be formed on the paper S on which the user image is not formed. Note that k is an integer of 1 or more.

The image formed on the paper S may include a print density correction test pattern, a print density unevenness correction test pattern, and other various test patterns.

The data of the read image read using the inline sensor 58 is sent to the abnormality determination unit 150. The abnormality determination unit 150 determines the presence or absence of ejection abnormality in each nozzle unit based on the data of the read image of the inline sensor 58. The presence / absence of ejection abnormality for each nozzle unit is stored in the ejection state information storage unit 152 as ejection state information.

In other words, the abnormality determination unit 150 determines whether or not all nozzle units are abnormal ejection elements in which ejection abnormality has occurred, or normal ejection elements capable of normal ejection.

The abnormality determination unit 150 can determine the presence or absence of ejection abnormality for each nozzle unit based on the amount of flight of each nozzle unit. The flying bend amount is a distance between an ideal landing position and an actual landing position. The unit of flight curve is micrometer.

The abnormality determining unit 150 can determine that there is a discharge abnormality when the amount of flight of each nozzle unit is equal to or greater than a predetermined reference value. The reference value used for determining the abnormality of each nozzle part can be determined according to the resolution in image formation.

The inkjet recording apparatus 10 illustrated in FIG. 3 includes an ink information acquisition unit 140, an ink determination unit 141, an ejection state information acquisition unit 142, a nozzle unit determination unit 144, a preliminary ejection execution unit 146, and a nozzle list storage unit 154. Yes.

The ink information acquisition unit 140 acquires ink information that is information about ink used in the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG. The ink information acquired by the ink information acquisition unit 140 includes the Mohs hardness of particles contained in the ink. Examples of the particles contained in the ink include a pigment. Ink information is an example of liquid information. The ink information acquisition unit 140 is an example of a liquid information acquisition unit.

The Mohs hardness can be determined from the type of particles. When a plurality of types of particles having different values of Mohs hardness are included, representative values such as the maximum value, median value, or average value of Mohs hardness can be adopted.

The ink information acquired by the ink information acquisition unit 140 is sent to the ink determination unit 141.

The ink determination unit 141 determines whether the ink used for the inkjet head 48 is an ink that deteriorates the liquid ejection surface 277 based on the ink information acquired by the ink information acquisition unit 140. An example of the deterioration of the liquid discharge surface 277 is wear.

Specifically, when the value of the Mohs hardness of the particles contained in the ink exceeds 0.5, the ink determination unit 141 determines that the ink deteriorates the liquid ejection surface 277. On the other hand, when the value of the Mohs hardness of the particles contained in the ink is 0.5 or less, the ink determination unit 141 determines that the ink does not deteriorate the liquid ejection surface 277. Details of the Mohs hardness of the particles contained in the ink will be described later.

Here, the inkjet head 48 is a generic term for the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG.

Hereinafter, the inkjet head 48 indicates any one of the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG.

The discharge state information acquisition unit 142 acquires discharge state information indicating the discharge states of all the nozzle units provided in the inkjet head 48. As an example of the acquisition of the discharge state information using the discharge state information acquisition unit 142, there is an aspect in which the discharge state information of each nozzle unit is read from the discharge state information storage unit 152. Table 1 below shows an example of the discharge state information stored in the discharge state information storage unit 152.

Table 1 above represents the discharge state of the past n times in the m nozzle portions provided in the inkjet head 48. The nozzle numbers in Table 1 are identification numbers from 1 to m assigned to m nozzle portions provided in the inkjet head 48. Note that n and m are integers of 1 or more. In Table 1 above, the identification number is described as the nozzle number. The identification number is an example of identification information.

A in Table 1 above indicates that normal ejection was performed. B in Table 1 above indicates that a discharge abnormality has occurred. That is, the discharge state information of each nozzle part includes the past n discharge states of each nozzle part.

From the viewpoint of accurately grasping the discharge state of each nozzle part, n is preferably 4 or more. From the viewpoint of shortening the processing period, n is preferably 4 or less. The detection of the discharge state of each nozzle unit may be executed during a print job. The detection of the ejection state of each nozzle unit may be executed at least one before the start of the print job and after the end of the print job.

The nozzle unit determination unit 144 determines the ink execution result, which is a nozzle unit that discharges ink at the time of preliminary discharge, and the ink based on the ink determination result using the ink determination unit 141 and the discharge state information of all the nozzle units. A non-ejection element that is a non-ejection nozzle is determined.

In the case of the inkjet head 48 that uses ink that degrades the liquid ejection surface 277, the nozzle unit determination unit 144 is an abnormal nozzle that is a nozzle unit in which ejection abnormality has occurred one or more times in the past n ejection states. Is determined as an ejection non-execution element. On the other hand, out of the past n discharge states, a normal nozzle portion that is a nozzle portion in which discharge abnormality does not occur one or more times is determined as a discharge execution element. The nozzle portion 281 where the ejection abnormality has occurred is an example of an abnormal ejection element. Here, the past n discharges correspond to a plurality of discharges.

Also, in the case of the inkjet head 48 that uses ink that does not deteriorate the liquid ejection surface 277, the nozzle unit determination unit 144 determines all nozzle units as ejection execution elements.

The nozzle unit determination unit 144 may create a nozzle list indicating whether each nozzle unit 281 is a discharge execution element or a discharge non-execution element. Table 2 below shows an example of the nozzle list.

In the nozzle list shown in Table 2 above, + represents a discharge execution element. -Represents a discharge non-execution element. The nozzle unit determination unit 144 may generate a preliminary discharge mask that masks the nozzle unit determined as a discharge non-execution element based on the nozzle list shown in Table 2 above. The nozzle list shown in Table 2 is stored in the nozzle list storage unit 154 shown in FIG.

The preliminary ejection execution unit 146 performs preliminary ejection of the inkjet head 48. Specifically, the preliminary discharge execution unit 146 supplies a drive voltage for preliminary discharge to the nozzle unit determined as the discharge execution element by the nozzle unit determination unit 144. On the other hand, the preliminary ejection execution unit 146 does not supply the preliminary ejection drive voltage to the nozzles determined as the ejection non-execution elements by the nozzle unit determination unit 144.

The preliminary ejection execution unit 146 may include a preliminary ejection drive voltage generation unit that generates a preliminary ejection drive voltage, and a preliminary ejection drive voltage supply unit that supplies the preliminary ejection drive voltage.

The preliminary discharge execution unit 146 operates a drive voltage supply unit (not shown) included in the drawing control unit 118 to perform preliminary discharge for the nozzle unit 281 determined as the discharge execution element by the nozzle unit determination unit 144. A driving voltage may be supplied. The preliminary discharge execution unit 146 may read the nozzle list stored in the nozzle list storage unit 154 and execute the preliminary discharge with reference to the nozzle list. The nozzle unit determination unit 144 is an example of an ejection element determination unit that determines an abnormal ejection element as an ejection non-execution element and determines a normal ejection element as an ejection execution element.

Fig. 3 lists various processing units for each function. Various processing units shown in FIG. 3 can be integrated, separated, combined, or omitted as appropriate.

The hardware structure of various processing units shown in FIG. 3 is the following various processors. Various processors include a CPU, a PLD, and an ASIC. As an example of the processing unit, the various processing units illustrated in FIG. 3 are substantially responsible for processing, but the term of the processing unit may not be used in the name. Terms such as a control unit, an execution unit, and a determination unit are also included in the concept of various processing units.

Examples of the various processing units shown in FIG. 3 include a conveyance control unit 110, a paper feed control unit 112, and a drawing control unit 118.

In addition, the control part includes what is described as processing unit using English notation. Processors include those written as processor using English notation.

CPU is a general-purpose processor that executes software and functions as various processing units. Software can be read as a program. The PLD is a processor whose circuit configuration can be changed after manufacture. An example of PLD is FPGA. PLD is an abbreviation for Programmable Logic Device. FPGA is an abbreviation for Field Programmable Gate Array.

ASIC is a processor having a circuit configuration specifically designed to execute a specific process, or a dedicated electric circuit. ASIC is an abbreviation for Application Specific Integrated Circuit.

One processing unit may be composed of one of the various processors described above. One processing unit may be configured using two or more processors of the same type, or two or more processors of different types. Examples of two or more processors of the same type include a plurality of FPGAs. An example of two or more processors of different types is a combination of a CPU and an FPGA.

Also, a plurality of processing units may be configured using a single processor. As an example of configuring a plurality of processing units using one processor, an aspect in which one processor is configured using a combination of one or more CPUs and software, and one processor functions as a plurality of processing units. Can be mentioned. Specific examples include a server and a computer such as a client.

As another example of configuring a plurality of processing units with a single processor, there is an aspect in which a processor that realizes the functions of the entire system including the plurality of processing units with a single IC chip is used. A specific example is a system on chip. System-on-chip includes those described as System On Chip or SoC using English notation. IC is an abbreviation for Integrated Circuit.

As described above, the various processing units shown in FIG. 3 are configured using one or more of the various processors described above as a hardware structure.

Furthermore, the hardware structure of the various processors described above is more specifically an electric circuit in which circuit elements such as semiconductor elements are combined. In addition, the electric circuit includes what is described as circuit using English notation.

Specific examples of the various storage units illustrated in FIG. 3 include a memory, a storage element, and a storage device. As an example of the program storage unit 136 illustrated in FIG. 3, a storage device in which various programs are stored can be given.

[Inkjet head structure]
<Overall configuration>
FIG. 4 is a perspective plan view showing a structural example of an inkjet head. The ink jet head 48 shown in FIG. 4 has a structure in which a plurality of head modules 200 are connected in the width direction of the paper S, which is a direction orthogonal to the transport direction of the paper S.

The width direction of the paper S is illustrated using an arrow line with a symbol X. The conveyance direction of the paper S is illustrated using an arrow line with a symbol Y. Hereinafter, the transport direction of the paper S may be described as a paper transport direction or a medium transport direction. In addition, the width direction of the sheet S may be described as a sheet width direction or a direction orthogonal to the medium conveyance direction.

The inkjet head 48 shown in FIG. 4 is a line-type inkjet head in which a plurality of nozzle portions are arranged over a length equal to or greater than the total length _Lmax of the paper S in the width direction of the paper S.

The same structure can be applied to the plurality of head modules 200 constituting the inkjet head 48. Further, the head module 200 can function as an ink jet head alone.

<Structure of head module>
FIG. 5 is a perspective view of the head module including a partial cross-sectional view.

The head module 200 has an ink supply unit including an ink supply chamber 232, an ink circulation chamber 236, and the like on the upper surface side in FIG. 5 which is the opposite side of the liquid ejection surface 277 of the nozzle plate 275.

The ink supply chamber 232 is connected to an ink tank (not shown) via a supply-side individual flow path 252, and the ink circulation chamber 236 is connected to a recovery tank (not shown) via a recovery-side individual flow path 256.

FIG. 6 is a perspective plan view of the liquid ejection surface of the head module. In FIG. 6, the number of nozzle openings 280 disposed on the liquid ejection surface 277 is omitted, but a two-dimensional arrangement is applied to the liquid ejection surface 277 of one head module 200 to form a plurality of nozzle openings. 280 is arranged.

The head module 200 has an end face on the long side along the V direction having an inclination of an angle β with respect to a direction orthogonal to the medium conveyance direction, and a W direction having an inclination of the angle α with respect to the medium conveyance direction. It has a parallelogram planar shape having an end surface on the short side, and a plurality of nozzle openings 280 are arranged in a matrix in the row direction along the V direction and the column direction along the W direction.

The arrangement of the nozzle openings 280 is not limited to the mode illustrated in FIG. 6, but along the row direction along the direction orthogonal to the medium conveyance direction and the column direction obliquely intersecting with the direction orthogonal to the medium conveyance direction. A plurality of nozzle openings 280 may be arranged.

The matrix arrangement of the nozzle openings 280 is a medium conveyance direction in which a plurality of nozzle openings 280 are projected in a direction orthogonal to the medium conveyance direction, and the plurality of nozzle openings 280 are arranged along a direction orthogonal to the medium conveyance direction. This is the arrangement of the nozzle openings 280 in which the arrangement intervals of the nozzle openings 280 are uniform in the orthogonal projection nozzle row.

FIG. 7 is a cross-sectional view showing the internal structure of the inkjet head. Reference numeral 214 denotes an ink supply path. Reference numeral 218 indicates a pressure chamber. Reference numeral 216 denotes an individual supply path that connects each pressure chamber 218 and the ink supply path 214.

Numeral 220 indicates a nozzle communication path that leads from the pressure chamber 218 to the nozzle opening 280. Reference numeral 226 denotes a circulation individual flow path that connects the nozzle communication path 220 and the circulation common flow path 228. The pressure chamber 218 may be referred to as a liquid chamber.

The vibration plate 266 is provided on the flow path structure 210 that forms the ink supply path 214, the individual supply path 216, the pressure chamber 218, the nozzle communication path 220, the circulation individual flow path 226, and the circulation common flow path 228. A piezoelectric element 230 having a laminated structure of a lower electrode 265, a piezoelectric layer 231, and an upper electrode 264 is disposed on the vibration plate 266 via an adhesive layer 267. The lower electrode 265 may be referred to as a common electrode, and the upper electrode 264 may be referred to as an individual electrode.

The upper electrode 264 is an individual electrode patterned according to the shape of each pressure chamber 218, and a piezoelectric element 230 is provided for each pressure chamber 218.

The ink supply path 214 is connected to the ink supply chamber 232 shown in FIG. 5, and ink is supplied from the ink supply path 214 shown in FIG. 7 to the pressure chamber 218 via the individual supply path 216.

Depending on the input image data, the piezoelectric element 230 and the diaphragm 266 are deformed due to the application of a driving voltage to the upper electrode 264 of the piezoelectric element 230 provided in the corresponding pressure chamber 218. The volume changes, and ink is ejected from the nozzle opening 280 via the nozzle communication path 220 due to a pressure change accompanying this.

Ink can be ejected from the nozzle openings 280 due to controlling the driving of the piezoelectric elements 230 corresponding to the respective nozzle openings 280 according to the dot arrangement data generated from the input image data.

A desired image is formed on the sheet S by conveying the sheet S in the medium conveyance direction at a constant speed and controlling the ink droplet ejection timing from each nozzle opening 280 according to the conveyance speed. Can be recorded.

The pressure chamber 218 provided corresponding to each nozzle opening 280 has a substantially square planar shape, and an outlet to the nozzle opening 280 is provided at one of the diagonal corners, and the other is provided at the other. An individual supply path 216 serving as an inlet for the supply ink is provided. Illustration of the planar shape of the pressure chamber 218 is omitted.

Note that the planar shape of the pressure chamber is not limited to a square. The planar shape of the pressure chamber may have various forms such as a rhombus, a quadrangle such as a rectangle, a pentagon, a hexagon and other polygons, a circle, and an ellipse.

A circulation outlet is formed in the nozzle portion 281 including the nozzle opening 280 and the nozzle communication path 220, and the nozzle portion 281 communicates with the circulation individual flow path 226 via the circulation outlet. Of the ink in the nozzle communication path 220 and the nozzle opening 280, ink that is not used for droplet ejection is collected into the circulation common flow path 228 via the circulation individual flow path 226.

The circulation common flow path 228 is connected to the ink circulation chamber 236 shown in FIG. 5, and the ink is always collected to the circulation common flow path 228 through the circulation individual flow path 226. At this time, thickening of the ink in the vicinity of the nozzle opening 280 is prevented.

As an aspect of the ejection element provided in the head module, there is an aspect in which one nozzle portion 281, a flow path such as a pressure chamber 218 communicated with one nozzle portion 281, and a piezoelectric element 230 corresponding to the nozzle portion 281 are included. Can be mentioned.

In this specification, the nozzle portion represents a concept including a nozzle opening. In the present specification, the terms “nozzle opening” and “nozzle part” can be appropriately replaced.

As an example of the piezoelectric element 230, there is a piezoelectric element 230 having a structure separated individually corresponding to the nozzle portion 281. Of course, a structure in which the piezoelectric layer 231 is integrally formed with respect to the plurality of nozzle portions 281, individual electrodes are formed corresponding to the respective nozzle portions 281, and an active region is formed for each nozzle portion 281 is applied. Also good.

A heater is provided in the pressure chamber 218 as a pressure generating element instead of a piezoelectric element, and a drive voltage is supplied to the heater to generate heat, and ink in the pressure chamber 218 is ejected from the nozzle opening 280 using a film boiling phenomenon. A thermal method may be applied.

[Description of Maintenance Method According to First Embodiment]
Next, the maintenance method according to the first embodiment will be described in detail. FIG. 8 is a flowchart showing a control flow of the maintenance method according to the first embodiment. The term “maintenance” here means at least one of a cleaning process for the inkjet head 48 and a recovery process for the inkjet head 48.

The flowchart shown in FIG. 8 is applied to all of the inkjet head 48C, the inkjet head 48M, the inkjet head 48Y, and the inkjet head 48K shown in FIG.

Maintenance of the inkjet head 48 is started. In the maintenance execution request acquisition step S10, the maintenance control unit 128 illustrated in FIG. 3 acquires a maintenance execution request for performing preliminary ejection.

As an example of maintenance for performing preliminary ejection, there is a mode in which the wiping process of the liquid ejection surface 277 of the inkjet head 48 is performed after the preliminary ejection of the inkjet head 48 is performed.

In the maintenance execution request acquisition step S10 of FIG. 8, the maintenance control unit 128 shown in FIG. 3 acquires a maintenance execution request for performing preliminary ejection, and then proceeds to the ink determination step S12 of FIG. In the ink determination step S12, the ink information acquisition unit 140 illustrated in FIG. 3 acquires ink information. The ink determination step S12 includes an ink information acquisition step. The ink information acquisition process is an example of a liquid information acquisition process.

In the ink determination step S12 shown in FIG. 8, the ink information acquisition unit 140 shown in FIG. 3 acquires the Mohs hardness of the particles contained in the ink used in the inkjet head 48 as ink information.

Further, in the ink determination step S12 of FIG. 8, the ink determination unit 141 shown in FIG. 3 uses the ink information acquired to cause the ink used for the inkjet head 48 to deteriorate the liquid ejection surface 277 of the inkjet head 48. It is determined whether or not.

In the ink determination step S12 of FIG. 8, the ink determination unit 141 determines that the ink deteriorates the liquid ejection surface 277 of the inkjet head 48 when the Mohs hardness of the particles included in the ink exceeds 0.5.

On the other hand, in the ink determination step S12 of FIG. 8, the ink determination unit 141 determines that the ink is not an ink that deteriorates the liquid ejection surface 277 of the inkjet head 48 when the Mohs hardness of the particles contained in the ink is 0.5 or less. .

8, when the ink determination unit 141 illustrated in FIG. 3 determines that the ink used for the inkjet head 48 is not an ink that deteriorates the liquid ejection surface 277 of the inkjet head 48, the ink determination unit 141 illustrated in FIG. The determination in the ink determination step S12 is NO. In the case of NO determination, the process proceeds to the all-nozzle preliminary discharge execution step S14.

In the all-nozzle preliminary discharge execution step S <b> 14, the preliminary discharge execution unit 146 shown in FIG. 3 executes preliminary discharge for discharging ink from all the nozzle units 281 provided in the inkjet head 48.

In the all-nozzle preliminary discharge execution step S14, the preliminary discharge execution unit 146 shown in FIG. 3 executes the preliminary discharge for discharging ink from all the nozzle portions 281 provided in the inkjet head 48, and then the maintenance shown in FIG. The control unit 128 ends the control of the maintenance method.

8, when the ink determination unit 141 illustrated in FIG. 3 determines that the ink used for the inkjet head 48 is an ink that deteriorates the liquid ejection surface 277 of the inkjet head 48. The determination in the ink determination step S12 of 8 is YES determination. In the case of YES determination, the process proceeds to the discharge state information acquisition step S16.

In the discharge state information acquisition step S <b> 16, the discharge state information acquisition unit 142 illustrated in FIG. 3 acquires the discharge state information of all the nozzle units 281 provided in the inkjet head 48. The discharge state information is stored in the discharge state information storage unit 152.

In the discharge state information acquisition step S16 of FIG. 8, after the discharge state information acquisition unit 142 shown in FIG. 3 acquires the discharge state information of all the nozzle units 281 provided in the inkjet head 48, the nozzle unit determination of FIG. Proceed to step S18.

In the nozzle unit determination step S18, the nozzle unit determination unit 144 shown in FIG. 3 performs one or more discharges on the discharge state information representing the previous n discharge states for all the nozzle units 281 provided in the inkjet head 48. It is determined whether or not information indicating that an abnormality has occurred is included.

In the nozzle part determination step S18 of FIG. 8, the nozzle part determination unit 144 shown in FIG. 3 has determined that the nozzle part 281 to be determined has one or more discharge abnormalities in the discharge state information representing the past n discharge states. When it is determined that the information indicating the occurrence is not included, the determination result in the nozzle part determination step S18 of FIG. 8 is NO determination. In the case of NO determination, the process proceeds to the discharge execution element determination step S20. The nozzle portion determination step S18 is an example of an ejection element determination step.

In the discharge execution element determination step S20, the nozzle unit determination unit 144 illustrated in FIG. 3 includes information indicating that one or more discharge abnormalities have occurred in the discharge state information indicating the past n discharge states. The nozzle portion 281 having no nozzle is determined as an ejection execution element that performs preliminary ejection.

In the discharge execution element determination step S20, the nozzle part determination unit 144 shown in FIG. 3 determines the determination target nozzle part 281 as the discharge execution element, and then proceeds to the determination confirmation step S24 in FIG.

On the other hand, in the nozzle part determination step S18 of FIG. 8, the nozzle part determination unit 144 shown in FIG. 3 has determined that the nozzle part 281 to be determined includes one or more discharges in the discharge state information representing the past n discharge states. When it is determined that information indicating that an abnormality has occurred is included, the determination result in the nozzle portion determination step S18 of FIG. 8 is YES. In the case of YES determination, the process proceeds to the discharge non-execution element determination step S22.

In the discharge non-execution element determination step S22, the nozzle unit determination unit 144 illustrated in FIG. 3 includes information indicating that one or more discharge abnormalities have occurred in the discharge state information indicating the past n discharge states. The nozzle unit 281 is determined as an ejection non-execution element that does not perform preliminary ejection.

In the ejection non-execution element determination step S22, the nozzle unit determination unit 144 shown in FIG. 3 determines the determination target nozzle unit 281 as an ejection non-execution element, and then proceeds to the determination confirmation step S24 in FIG.

The discharge execution element determined in the discharge execution element determination step S20 and the discharge non-execution element determined in the discharge non-execution element determination step S22 are associated with the distinction between the nozzle number and the discharge execution element or the discharge non-execution element. The nozzle list is stored in the nozzle list storage unit 154 shown in FIG.

In the determination confirmation step S24, the nozzle unit determination unit 144 illustrated in FIG. 3 determines whether all the nozzle units 281 have been determined to be ejection execution elements or ejection non-execution elements.

In the determination confirmation step S24 illustrated in FIG. 8, the nozzle unit determination unit 144 illustrated in FIG. 3 has not determined whether all the nozzle units 281 are ejection performing elements or ejection non-execution elements. In this case, the determination is NO. In the case of NO determination, the process proceeds to the nozzle part changing step S26.

In the nozzle part changing step S26, the system controller 100 shown in FIG. 3 selects the nozzle part 281 to be determined from the nozzle parts 281 that have not been determined whether the element is a discharge execution element or a discharge non-execution element. select. In the nozzle part changing step S26 of FIG. 8, after the system controller 100 shown in FIG. 3 selects the nozzle part 281 to be determined, the process proceeds to the nozzle part determining step S18.

Thereafter, in the determination confirmation step S24, each step from the nozzle portion determination step S18 to the determination confirmation step S24 is repeatedly executed until a YES determination is made.

On the other hand, in the determination confirmation step S24, YES is determined when the nozzle unit determination unit 144 illustrated in FIG. 3 determines whether all the nozzle units 281 are ejection execution elements or ejection non-execution elements. It becomes a judgment. In the case of YES determination, the process proceeds to the preliminary discharge execution step S28 in FIG.

In the preliminary discharge execution step S28, the preliminary discharge execution unit 146 shown in FIG. 3 executes the preliminary discharge using the nozzle unit 281 determined as the discharge execution element. The preliminary discharge execution unit 146 shown in FIG. 3 reads the nozzle list shown in Table 2 before executing the preliminary discharge.

In the preliminary discharge execution step S28, the preliminary discharge execution unit 146 shown in FIG. 3 supplies a preliminary discharge drive voltage for performing a predetermined number of discharges to the nozzle unit 281 determined as the discharge execution element. . The number of ejections and the ejection frequency in the preliminary ejection can be determined according to the use state of the inkjet head 48. Examples of the usage state of the inkjet head 48 include the usage period of the inkjet head 48 and the usage environment of the inkjet head 48.

In the preliminary discharge execution step S28 shown in FIG. 8, after performing preliminary discharge using the nozzle unit 281 determined as the discharge execution element, the maintenance control unit 128 shown in FIG. 3 uses the head cleaning unit 92. The wiping process S30 of FIG. 8 is performed.

In the wiping step S30, the maintenance control unit 128 shown in FIG. 3 runs the wiping web 94 of the head cleaning unit 92 and moves the inkjet head 48 from the maintenance position shown in FIG. The wiping web 94 is brought into contact with the liquid ejection surface 277 of the inkjet head 48.

In the wiping step S30, when the inkjet head 48 passes through the position of the head cleaning unit 92, the liquid ejection surface 277 of the inkjet head 48 is wiped using the wiping web 94 of the head cleaning unit 92.

8, after the wiping of the liquid discharge surface 277 of the inkjet head 48 is completed in the wiping step S30, the maintenance control unit 128 illustrated in FIG. 3 ends the maintenance of the inkjet head 48.

The maintenance control unit 128 may move the inkjet head 48 to the drawing position shown in FIG. 2 or to the maintenance position after the wiping step S30 of FIG.

[Ink that deteriorates the liquid ejection surface]
Table 3 below shows the relationship between the number of wiping operations and the contact angle of pure water on the liquid ejection surface, which is caused by the type of particles contained in the ink. The types of particles contained in the ink are distinguished using the Mohs hardness of the particles.

<Measurement method of contact angle>
As the inkjet head, an inkjet head mounted on a jet press 720 manufactured by FUJIFILM Corporation was used. On the liquid discharge surface of the inkjet head, a silicon dioxide film is formed as an adhesion layer on a silicon substrate, and perfluorodecyltrichlorosilane is formed on the silicon dioxide film. The CVD method is used for the film formation of perfluorodecyltrichlorosilane. Note that CVD is an abbreviation for Chemical Vapor Deposition.

Six types of ink containing particles having the Mohs hardness described in Table 3 above were used. The Mohs hardness value is a value provided by the ink manufacturer.

Preliminary ejection is performed to eject ink using all the nozzles provided in the inkjet head. The number of ejections of each nozzle part is 10,000. The discharge frequency is 25 kilohertz. The contact angle of pure water on the liquid discharge surface of the inkjet head was measured after the preliminary discharge was performed and before the wiping of the liquid discharge surface was started. Hereinafter, the term of the contact angle in this specification is a term indicating the contact angle of pure water unless otherwise specified. For the measurement of the contact angle, a contact angle meter, DM-500 manufactured by Kyowa Interface Science Co., Ltd. was used.

The reason why the contact angle of pure water was used as an index of the surface property of the liquid ejection surface is as follows. Ink jet heads use a wide variety of inks. However, it is difficult to conduct an experiment using any ink that can be used in an inkjet head.

On the other hand, if the values of the contact angles are the same, it is considered that the surface properties of the liquid ejection surface are the same regardless of the type of liquid used. Therefore, the surface property of the liquid discharge surface was measured using pure water that can be easily used in the experiment.

The measured value of the contact angle after the preliminary ejection is performed and before the wiping of the liquid ejection surface is started is a measured value of the contact angle with the number of wiping times in Table 3 being zero.

Next, wiping of the liquid discharge surface of the inkjet head is executed. The number of wiping times is 3000 times. As the wiping web, Toraysee manufactured by Toray Industries Inc. was used. The pressure with which the wiping web pressed the liquid discharge surface was 28.0 kilopascals.

After performing wiping 3000 times, the contact angle of pure water on the liquid ejection surface was measured. The measurement position is an arbitrary plurality of positions. The average value of the measurement values at a plurality of measurement positions was taken as the measurement value of the contact angle. The measured value of the contact angle after executing wiping 3000 times is the measured value of the contact angle of 3000 times of wiping in Table 3 above.

Next, wiping 2000 times is executed. The total number of wiping operations is 5000 times. The conditions for wiping are the same as for wiping 3000 times. The contact angle was measured after 2000 wipes were performed. The measurement position on the liquid ejection surface is the same as the measurement position of the contact angle after executing wiping 3000 times.

The average value of the measurement values at a plurality of measurement positions was taken as the measurement value of the contact angle. The measured value of the contact angle after executing wiping 2000 times is the measured value of the contact angle of 5000 times in Table 3 above.

Next, wiping 1000 times is executed. The total number of wipes is 6000. The conditions for wiping are the same as for wiping 3000 times. The contact angle was measured after 1000 wipes were performed. The measurement position on the liquid ejection surface is the same as the measurement position of the contact angle after executing wiping 3000 times.

The average value of the measurement values at a plurality of measurement positions was taken as the measurement value of the contact angle. The measured value of the contact angle after 1000 times of wiping is the measured value of the contact angle when the number of wiping times in Table 3 is 6000 times. The above procedure was performed for the six types of inks listed in Table 3 above.

An ink containing particles with a Mohs hardness of 0.3, an ink containing particles with a Mohs hardness of 0.4, and an ink containing particles with a Mohs hardness of 0.5 have wiping times of 0 to 6000 times. In the range, the variation range of the contact angle value is 0.3 degrees or less. The variation of the contact angle is a value obtained by subtracting the value of the contact angle with zero wiping from the maximum value or the minimum value of the contact angle.

In the case of ink containing particles with a Mohs hardness of 0.3, ink containing particles with a Mohs hardness of 0.4, and ink containing particles with a Mohs hardness of 0.5, the minimum value of the contact angle is 89.3 degrees.

That is, an ink containing particles with a Mohs hardness of 0.3, an ink containing particles with a Mohs hardness of 0.4, and an ink containing particles with a Mohs hardness of 0.5 have a contact angle of the liquid ejection surface. It is not lowered, and the deterioration of the liquid ejection surface is suppressed.

On the other hand, the ink containing particles with a Mohs hardness of 0.6 has a variation range of the contact angle value of 8.7 degrees in the range of wiping times from 0 to 6000 times. The minimum value of the contact angle is 81.1 degrees.

The ink containing particles with a Mohs hardness of 0.8 has a variation range of the contact angle value of 17.5 degrees in the range of wiping times from 0 to 6000 times. The minimum contact angle is 72.6 degrees.

In the ink containing particles having a Mohs hardness of 1.0, the variation of the contact angle value is 34.4 degrees in the range of the number of wiping times from 0 to 6000 times. The minimum value of the contact angle is 56.2 degrees or more.

That is, it is considered that the ink containing particles having a Mohs hardness of more than 0.5 has a reduced contact angle due to wiping of the liquid ejection surface, and the liquid ejection surface has deteriorated. That is, ink containing particles having a Mohs hardness of 0.5 or less is an ink that does not deteriorate the liquid ejection surface due to wiping of the liquid ejection surface. On the other hand, ink having a Mohs hardness exceeding 0.5 is ink that deteriorates the liquid ejection surface due to wiping of the liquid ejection surface.

The Mohs hardness is an index representing the hardness of particles contained in the ink. Examples of the particles having a Mohs hardness of 1.0 include carbon black used as a pigment for black ink. Carbon black is harder than pigments contained in other color inks. The liquid discharge surface is physically worn due to rubbing the liquid discharge surface using relatively hard particles. As a result of the physical wear of the liquid discharge surface, deterioration of the contact angle value of the liquid discharge surface becomes relatively small.

An example of particles having a Mohs hardness of 0.3 is a yellow ink pigment. Examples of particles having a Mohs hardness of 0.4 include a cyan ink pigment and a magenta ink pigment.

In the experiment described here, an ink jet head having a liquid ejection surface on which a water repellent film is formed is used. Since the contact angle is used as an evaluation index representing the surface property of the liquid ejection surface, it is considered that the experimental results shown in Table 3 above do not depend on the presence or absence of the water repellent film on the liquid ejection surface. Therefore, the experimental results shown in Table 3 above can also be applied to the liquid ejection surface where the water repellent film is not formed.

[Example of application to maintenance equipment]
In the present embodiment, the maintenance process of the inkjet head using the maintenance unit provided in the inkjet recording apparatus has been described. However, the maintenance unit illustrated in the present embodiment can be configured as a maintenance device for the inkjet head. is there.

That is, the moisturizing unit 90 and the head cleaning unit 92 shown in FIG. 2, and the system controller 100, the maintenance control unit 128, the ink information acquisition unit 140, the ink determination unit 141, the ejection state information acquisition unit 142, It is possible to configure a maintenance device including the nozzle unit determination unit 144 and the preliminary discharge execution unit 146. The maintenance apparatus described here can appropriately apply the various configurations shown in FIG.

[Function and effect]
According to the ink jet recording apparatus and the maintenance method configured as described above, when ink containing particles having a Mohs hardness of more than 0.5 is used, a nozzle in which ejection abnormality has occurred during preliminary ejection The unit is determined as a non-ejection element that does not eject ink. Due to the fact that ink is not ejected from the ejection non-execution element during preliminary ejection, ink adhesion to the liquid ejection surface during preliminary ejection is suppressed. Thereby, deterioration of the liquid discharge surface in the maintenance in which the liquid discharge surface is wiped after preliminary discharge is suppressed.

When black ink containing particles having a Mohs hardness of more than 0.5 is used, deterioration of the liquid ejection surface during maintenance in which the liquid ejection surface is wiped after preliminary ejection is suppressed in an inkjet head using black ink. The Due to the suppression of the deterioration of the liquid ejection surface, the life of the inkjet head is expected to be extended.

Further, when ink containing particles having a Mohs hardness of 0.5 or less is used, all the nozzle portions are determined as ejection performing elements that eject ink during preliminary ejection. Thereby, when ink containing particles having a Mohs hardness of 0.5 or less is used, the effect of recovering the ejection performance is maintained due to the execution of the preliminary ejection.

[Inkjet recording apparatus and maintenance method according to second embodiment]
Next, an ink jet recording apparatus and a maintenance method according to the second embodiment will be described.

FIG. 9 is a block diagram of a control system of the ink jet recording apparatus according to the second embodiment. The ink jet recording apparatus 10A shown in FIG. 9 has a nozzle list update unit 156 added to the ink jet recording apparatus 10 shown in FIG.

The nozzle list update unit 156 updates the nozzle list due to the presence or absence of ejection abnormality for each nozzle unit 281 changing. That is, in the discharge state detection, the nozzle list update unit 156 updates the nozzle list due to the detection of the nozzle unit 281 in which a new discharge abnormality has occurred. The nozzle list is an example of ejection element determination information. The nozzle list update unit 156 is an example of an ejection element determination information update unit.

FIG. 10 is a flowchart showing a control flow of the nozzle list updating method. In the maintenance method according to the first embodiment described above, after obtaining a maintenance execution request for performing preliminary discharge, a discharge execution element and a discharge non-execution element at the time of preliminary discharge are determined, and a nozzle list is generated. It was.

On the other hand, in the maintenance method according to the second embodiment, the nozzle list is updated regardless of whether there is a maintenance execution request. At the time of preliminary ejection, the latest nozzle list is read, and preliminary ejection is executed based on the read nozzle list.

* The nozzle list update method shown in FIG. 10 is executed before the maintenance for performing preliminary ejection. The update here includes generation of the first nozzle list.

In the nozzle list update method shown in FIG. 10, in the discharge state detection step S <b> 1, the discharge state information acquisition unit 142 shown in FIG. 9 acquires information on the discharge states of all the nozzle portions 281 of the inkjet head 48.

That is, in the discharge state detection step S1 of FIG. 10, the discharge state detection that is periodically executed or the irregular discharge state detection is executed. As an example of the ejection state detection that is periodically performed, there is ejection state detection that is performed for each sheet S or for each of a plurality of sheets S in a plurality of continuous image formations. As an example of irregular discharge state detection, there is discharge state detection that is performed irregularly in addition to the discharge state detection that is periodically performed.

In the discharge state detection step S1, after the discharge states of all the nozzle portions 281 of the inkjet head 48 are acquired, the process proceeds to the ink determination step S12. In the ink determination step S12, the same process as the ink determination step S12 shown in FIG. 8 is executed. Here, the description of the ink determination step S12 is omitted.

In the case of YES determination in the ink determination step S12, the process proceeds to the ejection state information acquisition step S16. The steps from the discharge state information acquisition step S16 to the nozzle portion change step S26 shown in FIG. 10 are the same steps as the maintenance method according to the first embodiment. The description here is omitted.

In the case of YES determination in the ink determination step S12, the process proceeds to the ejection execution element determination step S15. In the discharge execution element determination step S15, the nozzle unit determination unit 144 illustrated in FIG. 9 determines all the nozzle units 281 as discharge execution elements. After the discharge performing element determination step S15 of FIG. 9, the maintenance control unit 128 shown in FIG. 8 ends the control of the nozzle list update method.

That is, when an ink containing particles having a Mohs hardness of 0.5 or less is used, a nozzle list having all the nozzle portions 281 as discharge execution elements is created. In addition, the nozzle list in which all the nozzle portions 281 are the ejection execution elements is not updated.

In the case of YES determination in the determination confirmation step S24, the process proceeds to the nozzle portion determination information storage step S25. In the nozzle unit determination information storage step S25, the nozzle unit determination unit 144 illustrated in FIG. 9 determines, in the nozzle list storage unit 154, the nozzle number determination that represents the identification number of each nozzle unit 281 and the discharge execution element or the discharge non-execution element. Information is stored in association with information. The nozzle part determination information is an example of ejection element determination information. The nozzle list storage unit 154 is an example of an ejection element determination information storage unit. The nozzle portion determination information storage step S25 is an example of an ejection element determination information storage step.

In the decision confirmation step S24, after the nozzle list update unit 156 shown in FIG. 9 updates the nozzle list, the maintenance control unit 128 ends the control of the nozzle list update method shown in FIG.

FIG. 11 is a flowchart showing a control flow of the maintenance method according to the second embodiment. The maintenance method according to the second embodiment shown in FIG. 11 is the maintenance method according to the first embodiment shown in FIG. 8 in the maintenance execution request acquisition step S10, the ink determination step S12, and the all-nozzle preliminary discharge execution step S14. It is the same.

The maintenance method according to the second embodiment shown in FIG. 11 proceeds to the nozzle list reading step S27 when the ink determination step S12 is YES. In the nozzle list reading step S <b> 27, the preliminary discharge execution unit 146 illustrated in FIG. 9 reads the latest nozzle list from the nozzle list storage unit 154.

In the nozzle list reading step S27 of FIG. 11, the preliminary discharge execution unit 146 shown in FIG. 9 determines whether each nozzle unit 281 is a discharge execution element or a discharge non-execution element from the nozzle list storage unit 154. After reading the information, the process proceeds to the preliminary discharge execution step S28.

The preliminary discharge execution step S28 and the wiping step S30 in FIG. 11 are the same as the maintenance method according to the first embodiment.

[Function and effect]
According to the ink jet recording apparatus and the ink jet head maintenance method configured as described above, in the maintenance process, the nozzle part determining step for determining the nozzle part as either a discharge execution element or a discharge non-execution element is omitted. . Thereby, a maintenance process can be shortened compared with the aspect in which a nozzle part determination process is performed in a maintenance process.

In the present specification, a mode in which a sheet is conveyed by using a conveyance drum is illustrated, but a sheet may be conveyed by using a conveyance member such as a conveyance belt or a nip roller.

In this specification, an ink jet recording apparatus is illustrated as an example of the liquid ejecting apparatus. However, the liquid ejecting apparatus is not limited to an ink jet recording apparatus for graphic use, and performs electrical wiring formation and mask pattern formation for industrial use. The present invention can be widely applied to an ink jet type pattern forming apparatus.

In the embodiment of the present invention described above, the configuration requirements can be changed, added, and deleted as appropriate without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the field within the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Horizontal surface 10, 10A Inkjet recording device 11 Conveyance part 12 Paper feed part 14 Drawing part 16 Paper discharge part 18 Maintenance part 21 Main body frame 22 Bearing 30 Paper feed drums 32 and 42 Rotary shafts 34 and 44 Circumferential surfaces 36, 46, and 66 Gripper 40 Drawing drum 48, 48C, 48M, 48Y, 48K Inkjet head 50 Head support frame 58 Inline sensor 60 Chain gripper 62 First sprocket 64 Chain 82L, 82R Side plate 84 Connecting frame 86Y, 86K Mounting portion 88Y, 88K Mounted portion 90 Moisturizing unit 92 Head cleaning unit 94 Wiping web 100 System controller 100A CPU
100B ROM
100C RAM
102 Communication unit 103 Host computer 104 Image memory 110 Transport control unit 112 Paper feed control unit 118 Drawing control unit 124 Paper discharge control unit 126 Pump control unit 127 Pump 128 Maintenance control unit 130 Operation unit 132 Display unit 134 Parameter storage unit 136 Program storage Unit 140 ink information acquisition unit 141 ink determination unit 142 discharge state information acquisition unit 144 nozzle unit determination unit 146 preliminary discharge execution unit 150 abnormality determination unit 152 discharge state information storage unit 154 nozzle list storage unit 156 nozzle list update unit 200 head module 210 Flow path structure 214 Ink supply path 216 Individual supply path 218 Pressure chamber 220 Nozzle communication path 226 Circulation individual flow path 228 Circulation common flow path 230 Piezoelectric element 231 Piezoelectric layer 232 Ink supply chamber 236 Ink circulation chamber 252 Supply Individual channel 256 Recovery side individual channel 264 Upper electrode 265 Lower electrode 266 Vibration plate 267 Adhesive layer 275 Nozzle plate 277, 277C, 277M, 277Y, 277K Liquid ejection surface 280 Nozzle opening 281 Nozzle part S Paper S1 to S25 Nozzle list update Each step S10 to S30 of the method Each step of the maintenance method

Claims (17)

Whether each of the plurality of ejection elements of the liquid ejection head including a plurality of ejection elements for ejecting liquid is an abnormal ejection element in which ejection abnormality has occurred or is a normal ejection element capable of normal ejection A discharge state information acquisition unit for acquiring the discharge state information to be represented;
When the liquid contains particles having a Mohs hardness exceeding 0.5, the abnormal discharge element is discharged based on the discharge state information of each of the plurality of discharge elements acquired by the discharge state information acquisition unit. A discharge element determining unit that determines a non-execution element and determines the normal discharge element as a discharge execution element;
The liquid discharge head discharges liquid from the discharge element determined as the discharge execution element by the discharge element determination unit and does not discharge liquid from the discharge element determined as the discharge non-execution element by the discharge element determination unit. A preliminary discharge execution unit that executes the preliminary discharge of
Maintenance device equipped with. The maintenance device according to claim 1, further comprising a wiping processing unit that wipes a liquid ejection surface of the liquid ejection head after the preliminary ejection of the liquid ejection head is performed by the preliminary ejection execution unit. The maintenance apparatus according to claim 1 or 2, further comprising a liquid information acquisition unit that acquires liquid information indicating whether or not the liquid discharged from the liquid discharge head contains particles having a Mohs hardness exceeding 0.5. The ejection element determination unit is acquired by the ejection state information acquisition unit when the liquid information acquired by the liquid information acquisition unit is liquid information of a liquid containing particles having a Mohs hardness of 0.5 or less. The maintenance device according to claim 3, wherein the abnormal ejection element and the normal ejection element are determined as ejection execution elements based on ejection state information of the plurality of ejection elements. The maintenance device according to claim 3 or 4, wherein the liquid information acquisition unit acquires liquid information indicating whether or not the liquid discharged from the liquid discharge head contains particles having a Mohs hardness of 1.0 or more. A discharge state information storage unit for storing the discharge state information of each of the plurality of discharge elements;
The discharge state information acquisition unit reads the discharge state information of each of the plurality of discharge elements from the discharge state information storage unit, and acquires the discharge state information of each of the plurality of discharge elements. The maintenance device according to any one of the above. The maintenance according to claim 6, wherein the discharge state information storage unit stores, as the abnormal discharge element, a discharge element in which one or more discharge abnormalities occur in each of the plurality of discharges of the plurality of discharge elements. apparatus. 8. The discharge state information storage unit stores, as the normal discharge element, a discharge element in which one or more discharge abnormalities do not occur in each of the plurality of discharges of the plurality of discharge elements. Maintenance device. Discharge element determination information determined by the discharge element determination unit, the discharge element determination information indicating whether each of the plurality of discharge elements is the discharge execution element or the discharge non-execution element. The maintenance device according to any one of claims 1 to 8, further comprising: an ejection element determination information storage unit that stores information associated with identification information of each ejection element. When the discharge state information of the plurality of discharge elements is updated, the discharge element determination for updating the discharge element determination information stored in the discharge element determination information storage unit based on the updated discharge state information The maintenance apparatus according to claim 9, further comprising an information update unit. Whether each of the plurality of ejection elements of the liquid ejection head including a plurality of ejection elements for ejecting liquid is an abnormal ejection element in which ejection abnormality has occurred or is a normal ejection element capable of normal ejection A discharge state information acquisition step of acquiring discharge state information representing;
When the liquid contains particles having a Mohs hardness exceeding 0.5, the abnormal discharge element is discharged based on the discharge state information of the plurality of discharge elements acquired by the discharge state information acquisition step. A discharge element determination step for determining a non-execution element and determining the normal discharge element as a discharge execution element;
The liquid discharge head is configured to discharge liquid from the discharge element determined as the discharge execution element in the discharge element determination step and non-discharge liquid from the discharge element determined as the discharge non-execution element in the discharge element determination step. A preliminary discharge execution step of performing the preliminary discharge of
Including maintenance methods. 12. The maintenance method according to claim 11, further comprising a liquid information acquisition step of acquiring liquid information indicating whether or not the liquid discharged from the liquid discharge head contains particles having a Mohs hardness exceeding 0.5. A maintenance execution request acquisition step of acquiring a maintenance execution request including the preliminary discharge execution step;
Discharge element determination information indicating whether the plurality of discharge elements determined in the discharge element determination step is the discharge execution element or the discharge non-execution element, and identification information of the plurality of discharge elements An ejection element determination information storage step for storing the information in association with each other;
Including
The maintenance method according to claim 12, wherein the liquid information acquisition step, the discharge state information acquisition step, the discharge element determination step, and the discharge element determination information storage step are executed before the maintenance execution request acquisition step. A liquid discharge head comprising a plurality of discharge elements for discharging liquid;
For each of the plurality of ejection elements, an ejection state information obtaining unit that obtains ejection state information indicating whether the ejection abnormality is an abnormal ejection element or a normal ejection element capable of normal ejection;
When the liquid contains particles having a Mohs hardness exceeding 0.5, the abnormal discharge element is discharged based on the discharge state information of each of the plurality of discharge elements acquired by the discharge state information acquisition unit. A discharge element determining unit that determines a non-execution element and determines the normal discharge element as a discharge execution element;
The liquid is discharged from the discharge element determined as the discharge execution element by the discharge element determination unit, and the liquid is non-discharged from the discharge element determined as the discharge non-execution element using the discharge element determination unit. A preliminary discharge execution unit for performing preliminary discharge of the discharge head;
A liquid ejection device comprising: The liquid discharge apparatus according to claim 14, further comprising a liquid information acquisition unit that acquires liquid information indicating whether or not the liquid discharged from the liquid discharge head contains particles having a Mohs hardness exceeding 0.5. For each of the plurality of ejection elements, an abnormality determination unit that determines whether the ejection abnormality is an abnormal ejection element or a normal ejection element capable of normal ejection,
The liquid ejection device according to claim 14 or 15, wherein the ejection state information acquisition unit acquires a determination result of the abnormality determination unit as the ejection state information. The liquid ejection device according to claim 16, wherein the abnormality determination unit determines, as an abnormal ejection element, an ejection element in which one or more ejection abnormalities have occurred in each of a plurality of ejections of the plurality of ejection elements.

Images