WO2018110153A1 - Inkjet recording device and ink discharge control method of inkjet recording device - Google Patents

Abstract

An inkjet recording device and an ink discharge control method of an inkjet recording device are provided which make it possible to avoid contamination of an ink discharge surface due to ejection. This inkjet recording device (1) is provided with an ink discharge unit (20) which has an ink discharge surface where an ink discharge nozzle is provided, an ejection control means (30, 21) which performs ejection control for discharging ink from a nozzle not based on image data of an image to be recorded, and a storage unit (34) which stores faulty nozzle information relating to any of the nozzles that are faulty nozzles that do not discharge ink normally. In ejection control, the ejection control means can select whether or not to allow the discharge of ink from nozzles identified as faulty nozzles on the basis of the faulty nozzle information.

Description

Ink jet recording apparatus and ink discharge control method for ink jet recording apparatus

The present invention relates to an ink jet recording apparatus and an ink discharge control method for the ink jet recording apparatus.

Conventionally, there is an ink jet recording apparatus that records an image by ejecting ink to a recording medium from an opening of a nozzle provided on an ink ejection surface of an ink ejection unit. In such an ink jet recording apparatus, a foreign nozzle may flow into the nozzle from the nozzle opening or the ink may solidify in the nozzle opening, resulting in a defective nozzle that does not eject ink normally. As an aspect of ink ejection failure at a defective nozzle, there is an abnormality in the ink ejection amount and ejection direction. In addition, in a defective nozzle, a fine mist of ink (ink mist) may be generated more than a normal nozzle with an ink ejection operation.

Such a defective nozzle leads to deterioration of the image quality of the recorded image. For this reason, conventionally, ink discharge (ink discharge) that is not based on image data of an image to be recorded is performed at a predetermined timing or based on a user instruction, thereby preventing the inflow of foreign matter or ink coagulation. There is a technique for suppressing the occurrence of defective nozzles or eliminating clogging of nozzles to restore the defective nozzles to a normal state (for example, Patent Document 1).

JP 2008-149629 A

However, depending on the opening state of the nozzle opening of the defective nozzle, there is a problem that ink or ink mist abnormally ejected from the defective nozzle during the ejection is adhered to the ink ejection surface and the ink ejection surface is contaminated. When the ink discharge surface is contaminated in this way, the ink or ink mist adhering to the ink discharge surface falls onto the recording medium to contaminate the recording medium, or solidifies with a part of the nozzle opening being blocked. Cause new defective nozzles.

An object of the present invention is to provide an ink jet recording apparatus and an ink discharge control method for the ink jet recording apparatus, which can suppress contamination of the ink discharge surface due to discharge.

In order to achieve the above object, the invention of the ink jet recording apparatus according to claim 1 comprises:
An ink discharge section having an ink discharge surface provided with an opening of a nozzle for discharging ink;
A discharge control means for performing a discharge control for discharging ink from the nozzles without being based on image data of an image to be recorded;
A storage unit for storing defective nozzle information relating to defective nozzles that do not normally eject ink among the nozzles;
With
The discharge control means can select whether or not to discharge ink from the nozzle specified as a defective nozzle by the defective nozzle information among the nozzles in the discharge control.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
An ejection state detection unit for detecting an ejection state of ink from the nozzle;
A defective nozzle identifying unit that identifies a defective nozzle from the result of the detection by the discharge state detection unit, and stores the defective nozzle information in the storage unit based on the identification result of the defective nozzle;
Is provided.

The invention according to claim 3 is the ink jet recording apparatus according to claim 1 or 2,
The discharge control unit selects not to discharge ink from a nozzle specified as a defective nozzle by the defective nozzle information among the nozzles when a predetermined condition is satisfied in the discharge control. .

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect,
The discharge control unit determines that the predetermined condition is satisfied when an image is recorded after ink discharge by the discharge control.

The invention according to claim 5 is the ink jet recording apparatus according to claim 3 or 4,
A cleaning unit for cleaning the ink discharge surface;
Cleaning control means for performing a cleaning operation of the ink discharge surface by the cleaning unit;
With
The discharge control unit determines that the predetermined condition is satisfied when an image is recorded after the ink is discharged by the discharge control and before the cleaning operation is performed.

The invention according to claim 6 is the ink jet recording apparatus according to any one of claims 3 to 5,
In the discharge control, the discharge control unit determines that the predetermined condition is satisfied when ink is ejected from a nozzle outside the image recording area on the recording medium.

The invention according to claim 7 is the inkjet recording apparatus according to any one of claims 3 to 6,
The discharge control means is capable of performing a plurality of different types of discharge control, and the predetermined condition is satisfied when performing a predetermined discharge control among the plurality of types of discharge control. It is determined that

The invention according to claim 8 is the inkjet recording apparatus according to any one of claims 1 to 7,
The defective nozzle information includes initial defective nozzle information related to an initial defective nozzle associated with an initial defect of the ink ejection unit,
The storage unit includes an initial defective nozzle information storage unit that stores the initial defective nozzle information,
The initial defective nozzle information storage unit is provided integrally with the ink discharge unit.

The invention according to claim 9 is the inkjet recording apparatus according to any one of claims 1 to 8,
The defective nozzle information includes initial defective nozzle information related to an initial defective nozzle associated with an initial defect of the ink ejection unit,
In the discharge control, the discharge control unit selects not to discharge ink from a nozzle specified as an initial defective nozzle by the initial defective nozzle information.

In order to achieve the above object, an invention of an ink discharge control method for an ink jet recording apparatus according to claim 10 comprises:
Inkjet comprising: an ink ejection unit having an ink ejection surface provided with an opening of a nozzle for ejecting ink; and a storage unit for storing defective nozzle information relating to a defective nozzle that does not normally eject ink among the nozzles An ink discharge control method for a recording apparatus, comprising: a discharge step for discharging ink from the nozzles without being based on image data of an image to be recorded;
In the discharging step, it is selected whether or not to eject ink from a nozzle specified as a defective nozzle by the defective nozzle information among the nozzles.

According to the present invention, there is an effect that it is possible to suppress contamination of the ink ejection surface due to the ejection.

1 is a diagram illustrating a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the main function structures of an inkjet recording device. It is a schematic diagram which shows the structure of a cleaning roller. It is a schematic diagram which shows the structure of a test | inspection part. It is a figure explaining the detection operation of a defective nozzle. FIG. 6 is a diagram illustrating a discharge area where ink is discharged on a recording medium. It is a block diagram which shows the function structure which concerns on the discharge control in a head control part. It is a flowchart which shows the control procedure of an image recording process. 10 is a flowchart showing a control procedure of image recording processing according to Modification 1.

Hereinafter, embodiments of an ink jet recording apparatus and an ink discharge control method of the ink jet recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.

The ink jet recording apparatus 1 includes a transport unit 10, a head unit 20 (ink ejection unit), a control unit 30 (defective nozzle specifying unit, cleaning control unit), a head unit moving unit 41, a maintenance unit 42, and an inspection unit. 43 (discharge state detection unit), an operation display unit 44, an input / output interface 45, a bus 46, and the like.

The transport unit 10 includes a drive roller 11, a driven roller 12, a transport belt 13, and the like.
The drive roller 11 rotates around the rotation axis by driving a conveyance motor (not shown). The conveyor belt 13 is a ring-shaped belt that is supported on the inner side by the driving roller 11 and the driven roller 12, and moves around as the driving roller 11 rotates. The driven roller 12 rotates around a rotation axis parallel to the rotation axis of the drive roller 11 as the conveying belt 13 rotates. As the conveyor belt 13, a material that is flexibly bent at the contact surface with the driving roller 11 and the driven roller 12 and that reliably supports the recording medium M is used. For example, a belt made of resin such as rubber, A steel belt or the like can be used. Since the conveyance belt 13 has a material and / or a configuration on which the recording medium M is adsorbed, the recording medium M can be more stably placed on the conveyance belt 13. In the state where the recording medium M is placed on the conveyance surface of the conveyance belt 13, the conveyance unit 10 moves the conveyance medium 13 around the conveyance belt 13 at a speed corresponding to the rotation speed of the driving roller 11. A transport operation for transporting in 13 movement directions (transport direction: Y direction in FIG. 1) is performed. The drive shaft of the drive roller 11 is provided with an encoder (rotary encoder) (not shown) so that the circumferential movement distance of the conveyor belt 13 can be measured.
Note that the conveyance of the recording medium M may be intermittently performed, for example, in a mode in which the recording medium M is temporarily stopped during a period in which ink is ejected by the conveyance unit 10. The conveyance operation by the conveyance unit 10 includes an operation for temporarily stopping conveyance as described above.

In the present embodiment, a fabric is used as the recording medium M. The recording medium M is unwound from the roll on which the recording medium M has been wound (supplied) and supplied onto the conveying belt 13. The recording medium M has a rectangular shape whose width in the width direction (X direction in FIG. 1) perpendicular to the transport direction is about 2 [m] and whose length in the transport direction is about 4000 [m]. Note that the transport unit 10 may transport the recording medium M having a width in the width direction smaller than 2 [m]. The transport unit 10 may be configured to transport the recording medium M having a width in the width direction larger than 2 [m] (for example, about 4 [m]). The transportable recording medium M may be transported. The maximum width in the width direction may be smaller than 2 [m].
The recording medium M is not limited to the above-described fabric, and various media capable of fixing the ink ejected on the surface, such as paper and sheet-like resin, can be used.

The head unit 20 records an image on the recording medium M by ejecting ink from the nozzles on the recording medium M conveyed by the conveying unit 10 based on the image data. In the ink jet recording apparatus 1 of the present embodiment, four head units 20 corresponding to four colors of ink of yellow (Y), magenta (M), cyan (C), and black (K) are transported in the recording medium M, respectively. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side.

Each head unit 20 has a plurality (7 in this embodiment) in which a plurality of recording elements are arranged in a direction intersecting with the conveyance direction of the recording medium M (in this embodiment, the width direction orthogonal to the conveyance direction, that is, the X direction). ) Recording head 22 and a head control unit 21 for controlling the ink ejection operation by the recording head 22. Each recording head 22 has an ink ejection surface provided with an opening of a nozzle, and the ink ejection surface is disposed at a position facing the conveyance surface of the conveyance belt 13. Each head unit 20 is provided with a first storage unit 23 (storage unit, initial defective nozzle information storage unit) integrally with the head unit 20.

Each of the recording elements included in the recording head 22 includes a pressure chamber for storing ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle for discharging ink. When a drive signal is applied from the drive circuit in the recording head 22 to the piezoelectric element, the piezoelectric element is deformed in accordance with the drive signal to change the pressure in the pressure chamber, and ink is ejected from the nozzle communicating with the pressure chamber. The Hereinafter, the operation related to the ejection of ink from the nozzles according to the drive signal is also referred to as an ink ejection operation. Note that the operation when the nozzle is a defective nozzle described later and ink is not ejected according to the drive signal is also included in the ink ejection operation.
The arrangement range of the recording elements included in the head unit 20 in the X direction covers the width in the X direction of an area in which an image can be recorded in the recording medium M conveyed by the conveyance unit 10. Is used with its position fixed with respect to the transport unit 10 during image recording. That is, the inkjet recording apparatus 1 records an image by a single pass method.

In the head unit 20, when some of the nozzles are defective nozzles that do not normally eject ink when the head unit 20 is manufactured due to variations in processing at the time of nozzle formation, variations in characteristics of piezoelectric elements, and the like. There is. Further, as a result of the use of the head unit 20 in the ink jet recording apparatus 1, foreign matter flows into the nozzle from the nozzle opening and becomes clogged, or the ink is solidified in the nozzle opening, resulting in a defective nozzle later. There is a case. As an aspect of ink ejection failure in a defective nozzle, there are ink ejection failure and abnormalities in the ink ejection amount and ejection direction. In addition, in a defective nozzle having an abnormality in the ink ejection amount or ejection direction, there may be a case where more fine mist-like ink (ink mist) is generated than the normal nozzle as ink is ejected.
In the present embodiment, a head unit 20 that has been detected for defective nozzles (initial defective nozzles) related to initial defects after manufacturing is used. In the present embodiment, a defective nozzle that is detected for the first time after the detection of the initial defective nozzle is referred to as a late defective nozzle.

The initial defective nozzle is detected by an external inspection device (separate from the ink jet recording apparatus 1). For example, ink (or inspection droplets) is ejected from each nozzle of the head unit 20, and the ejected ink is photographed by the inspection apparatus from the side in the ink ejection direction to determine the ink ejection state. When ink is not detected in the shooting data, it is determined that ink is not ejected. When the ink ejection direction is bent, it is determined that the ink ejection direction is abnormal. When the ink flying speed is not normal, ink ejection is performed. It is determined that the amount is abnormal, and the nozzle for which these determinations are made is detected as an initial defective nozzle. Here, that the ink discharge direction is bent means that the ink is discharged in a direction bent with respect to the original discharge direction.

The head control unit 21 controls the head drive unit of the recording head 22 at an appropriate timing according to the control signal from the control unit 30 and the count number of pulse signals input from the rotary encoder attached to the drive roller. Various control signals and image data are output. The head driving unit of the recording head 22 supplies a driving signal for deforming the piezoelectric element to the recording element of the recording head 22 according to the control signal and image data input from the head control unit 21, and Ink is ejected from the opening. In the present embodiment, the control unit 30 and the head control unit 21 constitute a discharge control unit.

The first storage unit 23 is configured by a non-volatile memory such as a flash memory or an EEPROM (Electrically Erasable Programmable Read Only Memory), and stores the initial defective nozzle data D1 (initial defective nozzle information) related to the initial defective nozzle described above. . In the initial defective nozzle data D1, the initial defective nozzle is specified by the nozzle array number in the head unit 20. The first storage unit 23 may be constituted by a ROM (Read Only Memory).

The head unit moving unit 41 raises or lowers the head unit 20 in the Z direction (distance direction) perpendicular to the conveyance surface of the conveyance belt 13. Further, the head unit moving unit 41 moves the head unit 20 that has been raised to a predetermined position in the Z direction in the X direction to a position that faces an ink receiving unit of a maintenance unit 42 described later. Of the head unit moving unit 41, the mechanism for moving the head unit 20 up and down in the Z direction includes, for example, a column part extending in the Z direction, and the head unit 20 is fixed and can be moved in the Z direction along the column part by rotation of the stepping motor. It can be configured by a moving unit. In addition, the mechanism for moving the head unit 20 in the X direction in the head unit moving unit 41 is configured by, for example, a guide rail extending in the X direction and a slide member that is fixed and moves along the guide rail. be able to.
Four head unit moving units 41 are provided corresponding to the four head units 20 respectively.

The maintenance unit 42 includes an ink receiving unit (not shown) that receives ink ejected by discharging (flushing) ink from the nozzles of the head unit 20. Here, spitting out means that the nozzles that can be recovered to a normal state in which ink is normally ejected among the defective nozzles are restored to the normal state, or ink from the nozzles is suppressed for the purpose of suppressing the generation of new defective nozzles. This is the operation of the head unit 20 to be discharged. For this ejection, ink is ejected from the nozzles of the head unit 20 without being based on image data of an image to be recorded in the inkjet recording apparatus 1 (a normal image to be recorded by a print job, various test images, etc.). This includes all the operations that For example, in addition to the discharge performed on the ink receiving unit of the maintenance unit 42 (hereinafter, also referred to as a second discharge), during the execution of the print job, the outside of the image recording area of the recording medium M There is a discharge performed (hereinafter also referred to as a first discharge). Details of the spitting will be described later.

The maintenance unit 42 includes a cleaning roller (cleaning unit) that performs a cleaning operation (hereinafter, also referred to as “wiping”) for cleaning the ink discharge surface of the head unit 20 by wiping.

FIG. 3 is a schematic diagram illustrating the configuration of the cleaning roller 421.
The cleaning roller 421 is arranged such that a wiping cloth containing a predetermined chemical solution is wound around the outer peripheral surface, and the rotation axis is parallel to the Y direction. The maintenance unit 42 includes a rotation motor and a conveyance motor (not shown), and the cleaning roller 421 rotates according to the operation of the rotation motor and is moved in the Z direction and the X direction according to the operation of the conveyance motor. When the above-described wiping is performed, the cleaning roller 421 is moved in the Z direction by the operation of the transport motor, thereby contacting the ink discharge surface of the head unit 20 and rotating in this state by the operation of the rotary motor. The ink discharge surface of the head unit 20 is wiped by moving in the X direction according to the operation of the transport motor. Four cleaning rollers 421 are provided corresponding to the four head units 20 respectively.

The inspection unit 43 performs a predetermined measurement operation for detecting the ejection state of ink from each nozzle.

FIG. 4 is a schematic diagram illustrating the configuration of the inspection unit 43.
The inspection unit 43 includes a light emitting unit 431, a light receiving unit 432, a moving unit 433, a moving belt 434, rollers 435a and 435b, a motor 436, a linear encoder 437, and the like. The inspection unit 43 irradiates light to the ink flight path from the nozzle by the light emitting unit 431, and measures the light amount of the light by the light receiving unit 432. By discriminating whether or not the measured light amount is lowered at an appropriate position according to the nozzle by the ink, the ejection state of the ink from each nozzle is inspected. For example, as shown in FIG. 4, the measurement operation by the inspection unit 43 is performed on the head unit 20 moved to the + Z direction side by the head unit moving unit 41 from the recording operation. Alternatively, the measurement operation may be performed by moving the head unit 20 to the position of the inspection unit 43.

The light emitting unit 431 outputs light (here, visible light) in the optical axis L direction. The light receiving unit 432 detects the light output from the light emitting unit 431. The light output from the light emitting unit 431 has directivity, and most of the output light is detected by the light receiving unit 432 when there is no light shielding material, that is, ink. On the other hand, the light receiving unit 432 is narrow in a range in which the amount of light reduction when the detection target ink enters the light receiving area is equal to or greater than the ratio that can be detected with respect to the total incident light amount. In the case where a positional shift related to the rotational operation accuracy of 436 occurs, the position of the ink is determined to be wide within a range not deviating from the light receiving area.
The moving unit 433 is a plate-like member, and the light emitting unit 431 and the light receiving unit 432 are fixed on the plate surface. One end of the moving unit 433 is fixed to the moving belt 434.
The moving belt 434 has a ring shape and is rotationally driven by rollers 435a and 435b provided on the inner peripheral surface. The moving belt 434 moves the moving unit 433 in the X direction by being driven to rotate.
The motor 436 rotates the roller 435a. The rotational speed of the motor 436 can be appropriately changed based on a control signal from the control unit 30.
The linear encoder 437 outputs a signal indicating the movement of the moving unit 433. The linear encoder 437 is not particularly limited, but for example, a linear encoder that reads a scale with an optical sensor is used.

The operation display unit 44 includes a display device such as a liquid crystal display and an organic EL display, and an input device such as an operation key and a touch panel arranged on the screen of the display device. The operation display unit 44 displays various information on the display device, converts a user input operation to the input device into an operation signal, and outputs the operation signal to the control unit 30.

The input / output interface 45 is a means for transmitting / receiving data to / from the external device 2, and is configured by any one of various serial interfaces, various parallel interfaces, or a combination thereof.

The bus 46 is a path for transmitting and receiving signals between the control unit 30 and other components.

The control unit 30 includes a CPU 31 (Central Processing Unit), a RAM 32 (Random Access Memory), a ROM 33, and a second storage unit 34 (storage unit).

The CPU 31 reads various control programs and setting data stored in the ROM 33, stores them in the RAM 32, and executes the programs to perform various arithmetic processes. Thereby, the CPU 31 controls the overall operation of the inkjet recording apparatus 1. For example, the CPU 31 ejects ink from the nozzles to the recording medium M by the head unit 20 based on the image data of the image stored in the second storage unit 34 while conveying the recording medium M by the transport unit 10. To record an image.

The RAM 32 provides a working memory space to the CPU 31 and stores temporary data. The RAM 32 stores a maintenance completed flag that is used to determine the implementation status of the maintenance operation. Here, the maintenance completion flag is binary data represented by 1 bit. The RAM 32 may include a nonvolatile memory.

The ROM 33 stores various control programs executed by the CPU 31, setting data, and the like. Instead of the ROM 33, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The second storage unit 34 includes defective nozzle data D2 related to the defective nozzle including the initial defective nozzle indicated by the initial defective nozzle data D1 of the first storage unit 23 and the subsequent defective nozzle detected by the operation of the inspection unit 43. (Defective nozzle information) is stored. In the defective nozzle data D <b> 2, the defective nozzle is specified by the nozzle array number in each head unit 20. The defective nozzle data D2 is data generated in a defective nozzle detection operation described later. The defective nozzle data D2 may include only data related to defective nozzles (that is, subsequent defective nozzles) excluding the initial defective nozzle. In this case, the initial defective nozzle is specified by referring to the initial defective nozzle data D1 in the first storage unit 23.
The second storage unit 34 stores a print job (image recording command) and image data input from the external device 2 via the input / output interface 45, and image data corrected by the CPU 31. For example, an HDD (Hard Disk Drive) is used as the second storage unit 34, and a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The external device 2 is a personal computer, for example, and supplies a print job, image data, and the like to the control unit 30 via the input / output interface 45.

Next, various operations related to management of defective nozzles in the inkjet recording apparatus 1 will be described. Here, the management of defective nozzles includes detection of defective nozzles, setting for complementing non-ejection of ink from defective nozzles by correcting image data, ejection during execution of a print job, maintenance operation of the head unit 20, and Replacement of the head unit 20 is included.

First, the defective nozzle detection operation executed in the inkjet recording apparatus 1 will be described.
In the inkjet recording apparatus 1, the defective nozzle of the head unit 20 is detected when a predetermined defective nozzle detection start condition is satisfied. Here, the defective nozzle detection start condition can be, for example, that the recording operation by the head unit 20 is performed a predetermined number of times or more after the last defective nozzle detection operation. Alternatively, a predetermined amount or more of ink may be consumed after the last defective nozzle detection operation. Further, the detection of a defective nozzle may be started by a user instruction.

FIG. 5 is a diagram illustrating a defective nozzle detection operation.
In this figure, the position of the nozzle 221 on the ink ejection surface 222 of the recording head 22 is a plan view of the recording head 22 of the head unit 20 and the moving unit 433 of the inspection unit 43 as viewed from the side facing the conveyance surface of the conveyance belt 13. Is schematically shown.

When the detection of a defective nozzle is started, the head unit 20 is moved to the + Z direction side by the head unit moving unit 41 than in the recording operation, and the inspection unit 43 is arranged between the head unit 20 and the conveyor belt 13. The Alternatively, the head unit 20 may be moved to a position above the inspection unit 43.
Then, the moving unit 433 is moved to a position facing the recording head 22 based on a signal related to the measurement of the linear encoder 437. That is, the moving unit 433 is moved to a position where the optical axis L of the light output from the light emitting unit 431 and detected by the light receiving unit 432 crosses the ink flying path from the head nozzle 221. Here, the head nozzle 221 is the nozzle 221 located at the end on the + X direction side (the left end in FIG. 5) of the recording head 22 on the most + X direction side. Subsequently, while ejecting ink sequentially from each nozzle 221 of the recording head 22 for a predetermined time, the light emitting unit 431 and the light receiving unit 432 moved to positions corresponding to the nozzles 221 are operated, and the amount of light by the light receiving unit 432 is increased. Based on the measurement result, the ink ejection state is inspected. That is, when a decrease in the amount of light due to the ink is not detected at the position corresponding to the nozzle 221, non-ejection of the ink is detected, and when the position where the decrease in the amount of light is detected is shifted from the position corresponding to the nozzle 221, Bending in the discharge direction is detected. The nozzles 221 from which ink is ejected are sequentially changed one by one in the −X direction in FIG. 5 and change to the nozzle 221 at the end (right end in FIG. 5) of the print head closest to the −X direction. The change speed at this time is set to be constant, and the moving unit 433 is moved at a constant speed in accordance with the constant change speed.
The defective nozzle detection operation is performed on all nozzles including nozzles that have already been identified as defective nozzles by the defective nozzle data D2. The defective nozzle detection operation described above is performed for each of the four head units 20.

As described above, the light quantity reflecting the ink ejection state from the nozzle 221 of each head unit 20 is measured by the operation of the light emitting unit 431 and the light receiving unit 432, and the ink ejection state from the nozzle 221 is determined by the measurement result. Inspected. As a result of the inspection, when ink non-ejection or bending in the ink ejection direction is detected, the corresponding nozzle is identified as a defective nozzle. When the defective nozzle is specified, defective nozzle data D2 indicating the defective nozzle is generated based on the array number of the specified nozzle 221 in the head unit 20 and stored in the second storage unit 34.
Here, when the defective nozzle data D2 is already stored in the second storage unit 34, the new defective nozzle data D2 is overwritten on the existing defective nozzle data D2. In addition, when it is necessary to refer to the history of the occurrence of late defective nozzles, new defective nozzle data D2 that is separate from existing defective nozzle data may be generated and stored.

Next, correction of image data based on the defective nozzle data D2 will be described.
In the inkjet recording apparatus 1, when a defective nozzle is specified by the defective nozzle data D <b> 2, correction is performed on the image data of the image specified by the print job so as to prevent the recording image from being disturbed due to the defective nozzle. The image is recorded above. For example, when the nozzle 221a shown in FIG. 5 is specified as a defective nozzle, the image data of the image is corrected so that ink is not ejected from the nozzle 221a, and a nozzle adjacent to the defective nozzle (FIG. 5). The image data of the image is corrected so that the non-ejection of ink from the defective nozzle is complemented by the increase in the amount of ink ejected from the nozzle 221b) or the nozzle in the vicinity of the defective nozzle (for example, the nozzles 221b and 123c in FIG. 5). Is done. Then, ink is ejected from the head unit 20 to the recording medium M based on the corrected image data, whereby an image in which deterioration in image quality due to defective nozzles is suppressed is recorded.

In addition, when the head unit 20 is replaced and an image is recorded by the unused head unit 20, the defective nozzle data D2 related to the head unit 20 is reset. That is, since the head unit 20 is in a state where there is no late defective nozzle, defective nozzle data D2 is generated based on the initial defective nozzle data D1 stored in the first storage unit 23 of the head unit 20. It is stored in the second storage unit 34. Then, the image data of the image is corrected based on the new defective nozzle data D2. Therefore, when the head unit 20 is replaced with an unused one, it is possible to correct the image data without performing a defective nozzle detection operation, and an image is obtained based on the corrected image data. To be recorded.

Next, ink discharge (first discharge) performed during execution of a print job will be described.
In the inkjet recording apparatus 1, when the viscosity of the ink in the vicinity of the opening increases due to the evaporation of the ink solvent in the vicinity of the opening of the nozzle 221, the amount of ink ejected, the flying direction, the flying speed, and the like are set from the original settings. A defective nozzle with a defective ink discharge is generated. In particular, in the present embodiment, since a normal image to be recorded is continuously recorded on a recording medium M having a length of 4000 m, when the image recording operation is started, for example, the conveyance speed is 60 [m / min. ], The image recording operation is continued for about an hour. In this image recording operation, depending on the content of a normal image, a nozzle 221 is generated that has a very low ink discharge frequency or does not discharge ink. It is easy to become a defective nozzle due to the increased viscosity.
Therefore, in the inkjet recording apparatus 1 of the present embodiment, in order to suppress the occurrence of such defective nozzles, the ink is ejected from the nozzles 221 to the outside of the normal image recording area on the recording medium M being conveyed. 1 spitting is performed.

FIG. 6 is a diagram illustrating a discharge area where ink is discharged in the recording medium M.
As shown in FIG. 6, in the present embodiment, the first discharge is performed on the strip-shaped discharge area 52 extending in the X direction on the recording medium M. A normal image 51 is recorded on the upstream side and the downstream side of the discharge area 52 in the Y direction. That is, the discharge area 52 is set outside the recording area of the normal image 51. The normal image 51 is a long image in which a plurality of unit images in which the leading end and the trailing end in the Y direction are connected in the Y direction, and are recorded so as to be continuously connected in the recording area of the normal image 51.

The discharge area 52 includes color- specific discharge areas 52Y, 52M, 52C, and 52K in which ink is discharged by the head units 20 corresponding to Y, M, C, and K, respectively. The color discharge areas 52Y, 52M, 52C, and 52K are band-like areas that are adjacent to each other in the Y direction and extend over the recording range of the nozzles 221 in the head unit 20 in the X direction. In addition, about 1000 discharges of ink are continuously performed from the nozzles of the head unit 20 to the discharge areas 52Y, 52M, 52C, and 52K by color. The X-direction range of the discharge area 52 is equal to the X-direction recording range of the normal image 51. The reason why the discharge areas 52Y, 52M, 52C, and 52K for each color are not overlapped with each other is mainly to suppress the ink discharge amount per unit area and suppress the ink show-back. If they do not occur or do not matter, they may overlap each other.
In the first discharge, ink is ejected to a band-like (long rectangular shape) range in the Y direction on the recording medium M according to the position in the Y direction of the nozzle 221 provided in each recording head 22. The ink ejection timing is adjusted so that

Further, in the present embodiment, when ink is discharged, it is possible to select whether or not to eject ink from the nozzle 221 specified as a defective nozzle in the defective nozzle data D2. In the first discharge described above, ink is not ejected from the nozzle 221 specified as a defective nozzle in the defective nozzle data D2, and ink is ejected only from the normal nozzle 221. As a result, the ink or ink mist abnormally ejected from the defective nozzle due to the first discharge is adhered to the ink ejection surface 222, and the ink ejection surface 222 is contaminated by the ink. Occurrence of problems such as dropping onto the recording medium M at an unintended timing or solidifying in a state where a part of the nozzle opening is blocked to cause a new defective nozzle is suppressed. In particular, as shown in FIG. 6, when discharging is performed outside the recording area of the normal image 51 of the recording medium M, the normal image is not cleaned immediately after the discharging without cleaning the ink ejection surface 222. Since the 51 recording operation is performed, the contamination of the ink ejection surface 222 caused by the ink from the defective nozzle leads to the contamination of the recording medium M due to the ink dropping, but the ink is not ejected from the defective nozzle in the ejection. Generation | occurrence | production of such a malfunction is suppressed effectively.
As described above, in the present embodiment, a condition (predetermined condition) that an image is recorded after ink ejection by ejection, and a cleaning operation for cleaning the ink ejection surface 222 after ink ejection by ejection. When the condition (predetermined condition) that the image is recorded before the recording is performed, or the condition (predetermined condition) that the ink is ejected from the nozzle 221 outside the image recording area on the recording medium M is satisfied. In the discharge of ink, ink is not ejected from the nozzle 221 specified as a defective nozzle in the defective nozzle data D2.

Below, the 1st discharge control operation | movement in the inkjet recording device 1 is demonstrated.
During the execution of the print job, due to the conveyance of the recording medium M by the conveyance unit 10, a predetermined position (tip of each color discharge area 52 </ b> Y, 52 </ b> M, 52 </ b> C, 52 </ b> K) is discharged by each head unit 20. When moving to the discharge position, the discharge by each head unit 20 is started (hereinafter, the predetermined position is also referred to as a discharge start position). The movement of the discharge start position to the ink discharge position is determined by outputting a predetermined number of pulse signals for each head unit 20 from the rotary encoder attached to the drive roller.

FIG. 7 is a block diagram illustrating a functional configuration related to the control of the discharge in the head control unit 21.
As shown in FIG. 7, the head control unit 21 includes a control circuit 21a, a switching unit 21b, and an image data storage unit 21c. The head controller 21 can be configured to include, for example, a circuit board and an FPGA (Field Programmable Gate Array) mounted on the circuit board. In the present embodiment, the control circuit 21a, A switching unit 21b and an image data storage unit 21c are provided. Note that the image data storage unit 21c may be provided outside the FPGA. In addition, other semiconductor integrated circuits such as ASIC (Application Specific Integrated Circuits) may be used instead of the FPGA.

The image data storage unit 21c stores image data Da of the normal image 51 and discharge data Db used for discharge. Of these, the discharge data Db is data used to generate a drive signal for causing the nozzles 221 of each head unit 20 to discharge ink, and the gradation values of all the pixels are maximized. It is the same data as all the image data.
The image data Da and the discharge data Db are output to the switching unit 21b under the control of the control circuit 21a. From the switching unit 21b, either the image data Da or the discharge data Db is output to the head driving unit 22a of the recording head 22 in accordance with a switching control signal output from the control circuit 21a to the switching unit 21b. .

The control circuit 21a outputs a control signal for performing the ink ejection operation at an appropriate timing to the head driving unit 22a. Further, the control circuit 21a outputs a switching control signal to the switching unit 21b, and outputs either one of the image data Da and the discharge data Db for each line from the switching unit 21b to the head driving unit 22a. Let That is, when the normal image 51 is recorded, the control circuit 21a causes the switching unit 21b to output the image data Da to the head driving unit 22a. Further, the control circuit 21a switches the switching unit 21b at the start of the discharge to start the supply of the discharge data Db to the head drive unit 22a, and the discharge data Db of the discharge data Db until the end timing of the discharge operation. Continue supplying. The control circuit 21a refers to the defective nozzle data D2 stored in the second storage unit 34, and supplies a driving signal from the head driving unit 22a to the recording element having the nozzle 221 specified as the defective nozzle. A control signal is supplied to the head drive unit 22a so as not to occur.
Note that the discharge data Db is data having the same configuration as the image data composed of the same pixel data, and therefore, the discharge data Db is read from the image data storage unit 21c and supplied to the switching unit 21b. Instead, predetermined pixel data may be repeatedly supplied to the switching unit 21b under the control of the control circuit 21a.
By performing such control, the normal image 51 is recorded in the recording area of the normal image 51, while the discharge is performed outside the recording area of the normal image 51.

Next, the maintenance operation of the head unit 20 based on the defective nozzle data D2 will be described.
In the inkjet recording apparatus 1, when at least one of the number of defective nozzles in each head unit 20 indicated by the defective nozzle data D2 and the arrangement of defective nozzles in the head unit 20 satisfies a predetermined maintenance start condition, the predetermined maintenance operation is performed. Is started. In the maintenance operation of the present embodiment, the second discharge and wiping are continuously performed.
Here, the maintenance start condition relating to the number of defective nozzles may be that the number of defective nozzles indicated by the defective nozzle data D2 exceeds a predetermined first reference number. The first reference number is determined by a defective nozzle that can suppress image quality deterioration to such an extent that the defective image quality due to the defective nozzle in the recorded image is hardly recognized by complementing non-ejection of ink from the defective nozzle with the surrounding nozzles. It is preferably set within a range of numbers, and a larger value is preferable in order to reduce the frequency of maintenance operations.
Further, the maintenance start condition relating to the arrangement of the defective nozzles may be that defective nozzles exceeding a predetermined second reference number are continuous, and the defective nozzles are included in these defective nozzles. Here, the second reference number suppresses deterioration in image quality to the extent that image quality defects due to defective nozzles in the recorded image are hardly visually recognized by complementing non-ejection of ink from a plurality of adjacent defective nozzles with surrounding nozzles. Is set within the range of the number of consecutive defective nozzles.

In the maintenance operation, the second discharge is performed by discharging ink from each nozzle 221 in a state where the head unit 20 is moved to a position facing the ink receiving portion of the maintenance unit 42. The number of ink ejection operations in the second discharge is not particularly limited, but can be about 1000 as in the first discharge described above.
Here, in the second discharge, ink is ejected from all nozzles including the defective nozzle. This is because even if the ink ejection surface 222 is contaminated with ink or ink mist due to ink ejection from the defective nozzle in the second ejection, the wiping is performed following the second ejection and the ink ejection surface 222 is This is because it can be cleaned. The second discharge control operation in the inkjet recording apparatus 1 is the same as the first discharge control operation except that a drive signal is supplied to a defective nozzle to discharge ink.

In the maintenance operation, wiping is performed when the second discharge is completed. In this wiping, the head unit 20 is moved to a predetermined cleaning position where the cleaning roller 421 is disposed, and the cleaning roller 421 is moved so that the cleaning roller 421 contacts the ink ejection surface 222 of the head unit 20. From this state, the cleaning roller 421 moves in the X direction while rotating in contact with the ink discharge surface 222 according to the operation of the rotation motor and the conveyance motor of the maintenance unit 42, so that the entire ink discharge surface 222 is cleaned. Ink and foreign matter adhered to the ink discharge surface 222 and the opening of the nozzle 221 by being wiped by a wiping cloth wound around the outer peripheral surface of the ink are removed.

Since the maintenance operation of the present embodiment is to eliminate the clogging of the nozzle opening due to nozzle clogging or dirt that occurred later, there is a possibility that the maintenance operation usually recovers to a normal state. This is a late defective nozzle, and the initial defective nozzle rarely recovers to a normal state.

Next, display of head unit replacement information that prompts replacement of the head unit 20 will be described.
In the inkjet recording apparatus 1, after the above-described maintenance operation is performed and before the normal image is recorded next, defective nozzles are detected based on the inspection result by the inspection unit 43. The late defective nozzle detected as a result is a late defective nozzle that does not recover to a normal state depending on the maintenance operation (hereinafter referred to as a late defective fixed nozzle). In the inkjet recording apparatus 1, at least one of the number of subsequent defective fixed nozzles in each head unit 20 and the arrangement of the subsequent defective fixed nozzles in the head unit 20 satisfies the same predetermined condition as the condition for starting the maintenance operation. In this case, the operation display unit 44 displays head unit replacement information indicating that it is time to replace the head unit 20, and prompts the user to replace the head unit 20.
It may be determined whether or not the head unit 20 needs to be replaced based on a condition in which the number and arrangement of the initial defective nozzles are added to the number and arrangement of the subsequent defective fixed nozzles.

Next, an image recording process executed in the inkjet recording apparatus 1 will be described.

FIG. 8 is a flowchart showing the control procedure of the image recording process.
In this image recording process, image data of a normal image recorded on the recording medium M and a print job instructing recording of the normal image are supplied from the external device 2 via the input / output interface 45 and the second storage unit 34. It is started when it is stored.

When the image recording process is started, the control unit 30 determines whether an unexecuted print job is stored in the second storage unit 34 (step S101). If it is determined that an unexecuted print job is not stored in the second storage unit 34 (“NO” in step S101), the control unit 30 ends the image recording process.

When it is determined that an unexecuted print job is stored in the second storage unit 34 (“YES” in step S101), the control unit 30 determines whether or not a defective nozzle detection start condition is satisfied. Is determined (step S102). Here, for example, the control unit 30 satisfies the defective nozzle detection start condition when the image recording operation by the head unit 20 is performed a predetermined number of times or more after the last defective nozzle detection (step S103). It is determined that there is.

When it is determined that the defective nozzle detection start condition is satisfied (“YES” in step S102), the control unit 30 detects a defective nozzle (step S103). That is, the control unit 30 operates the motor of the head unit moving unit 41 to move the head unit 20 in the + Z direction, and moves the inspection unit 43 between the head unit 20 and the transport belt 13. The control unit 30 and the head control unit 21 cause the recording element to output a drive signal from the head driving unit 22 a of the recording head 22, thereby ejecting ink from the nozzle 221 of the recording element. Here, the number of ink ejections performed by the control unit 30 and the head control unit 21 from the respective nozzles 221 is several times to several tens of times, so that there is little or no contamination of the ink ejection surface. It is done. Further, the control unit 30 operates the motor 436 of the inspection unit 43 in accordance with the ink discharge to move the moving unit 433, and the light emitting unit 431 and the light receiving unit 432 are synchronized with the ink discharge timing. The detection signal of the light output from the light receiving unit 432 is obtained by operating. The control unit 30 detects the subsequent defective nozzle based on the acquired detection signal, generates defective nozzle data D2 (overwrites when there is already defective nozzle data D2), and stores it in the second storage unit 34. Let

The control unit 30 determines whether the maintenance start condition is satisfied (step S104). Here, the control unit 30 determines that the maintenance start condition related to the number of defective nozzles is satisfied when the number of defective nozzles indicated by the defective nozzle data D2 is larger than the first reference number. Further, the control unit 30 determines that the maintenance start condition related to the arrangement of the defective nozzles is satisfied when the defective nozzle data D2 indicates that the number of defective nozzles exceeding the second reference number is continuous. .

If it is determined that the maintenance start condition is not satisfied (“NO” in step S104), or if it is determined in step S102 that the defective nozzle detection start condition is not satisfied (“NO” in step S102). ), The control unit 30 determines whether any of the head units 20 has a defective nozzle (step S105).

If it is determined that there is a defective nozzle in any of the head units 20 (“YES” in step S105), the control unit 30 corrects the image data based on the defective nozzle data D2 (step S106). That is, the control unit 30 refers to the defective nozzle data D2, and image data of the normal image related to the print job so that ink is not ejected from the defective nozzle and non-ejection of ink by the defective nozzle is complemented. Is corrected and stored in the second storage unit 34.

The control unit 30 starts an image recording operation related to the print job based on the image data corrected in step S106.
That is, the control unit 30 starts the conveyance operation of the recording medium M by the conveyance unit 10. Further, when the discharge start position moves to the ink discharge position of each head unit 20, the control unit 30 and the head control unit 21 apply the discharge region 52 to the discharge region 52 by each nozzle 221 except for the defective nozzle in each head unit 20. First discharge is performed (step S107: discharge step). The control unit 30 and the head control unit 21 start ink ejection from the nozzles 221 based on the corrected image data at the timing when the recording area of the normal image 51 moves to the ink ejection position of each head unit 20. The normal image 51 is recorded on the recording medium M (step S108).
If it is determined in step S105 that all the head units 20 have no defective nozzles (“NO” in step S105), the control unit 30 corrects the image data related to the print job without correcting the image data. The normal image 51 is recorded based on the above.
When the recording of one normal image 51 is completed, the control unit 30 determines whether or not the recording of all the normal images 51 instructed by the print job is completed (step S109), and the unrecorded normal image 51 is stored. If there is, the process proceeds to step S107 (“NO” in step S109), and if all the normal images 51 have been recorded, the process proceeds to step S101 (“YES” in step S109). ").

When it is determined in step S104 that the maintenance start condition is satisfied (“YES” in step S104), the control unit 30 determines whether or not the maintenance completion flag is set to off (step S110). ).

If it is determined that the maintenance completed flag is set to OFF (“YES” in step S110), the control unit causes a predetermined maintenance operation to be performed. That is, the control unit 30 operates the head unit moving unit 41 to move the head unit 20 to a position facing the ink receiving unit of the maintenance unit 42. Then, the control unit 30 and the head control unit 21 cause the ink receiving unit to eject ink from all nozzles including defective nozzles in the head unit 20 to cause second discharge (step S111: discharge step). When the second discharge is completed, the control unit 30 moves the head unit 20 to a predetermined cleaning position, operates the rotation motor and the conveyance motor of the maintenance unit 42, and performs wiping by the cleaning roller 421 (step S112). ).

When the processing in step S112 is completed, the control unit 30 sets the maintenance completed flag to ON (step S113). When the process of step S113 ends, the control unit 30 shifts the process to step S103.

When it is determined in step S110 that the maintenance completion flag is set to ON (“NO” in step S110), the control unit 30 causes the operation display unit 44 to display the head unit replacement information (step S110). S114).
When the process of step S114 ends, the control unit 30 ends the image recording process.

In the image recording process, the control for performing the discharge in step S107 and step S111 corresponds to the discharge control by the control unit 30 and the head control unit 21.

(Modification 1)
Next, Modification 1 of the above embodiment will be described. This modification differs from the above embodiment in that the defective nozzle is detected only immediately after the maintenance operation. Other points are the same as in the above embodiment.

FIG. 9 is a flowchart showing the control procedure of the image recording process according to this modification. The image recording process shown in FIG. 9 is changed such that step S102 is changed to step S115 in the image recording process of the above-described embodiment shown in FIG. 8, and step S111 and step S112 are executed before step S103. Step S110 and step S113 are deleted. In the following, the difference from the image recording process shown in FIG. 8 will be mainly described.

When the process of step S101 is completed, the control unit 30 determines whether or not an initial maintenance start condition is satisfied (step S115). Here, the control unit 30 satisfies the initial maintenance start condition when the ink is consumed by a predetermined amount or more by recording an image in the head unit 20 after the last maintenance operation (step S111 and step S112). It is determined that When it is determined that the initial maintenance start condition is not satisfied (“NO” in step S115), the control unit 30 shifts the process to step S105.

When it is determined that the initial maintenance start condition is satisfied (“YES” in step S115), the control unit 30 performs a maintenance operation (step S111 and step S112). When the process of step S112 ends, the control unit 30 detects a defective nozzle (step S103). Further, in step S104 performed after step S103, when it is determined that the maintenance start condition is satisfied (“YES” in step S104), the control unit 30 displays the head unit replacement information on the operation display unit 44. Is displayed (step S114).

According to such an image recording process according to this modification, since the defective nozzle is detected only immediately after the maintenance operation, it is possible to suppress the frequency of detecting the defective nozzle.

(Modification 2)
Next, a second modification of the above embodiment will be described.
This modification is different from the above embodiment in that ink is not ejected from the initial defective nozzle in the second discharge. The initial defective nozzle is caused by a defect in the manufacturing process of the recording element.Therefore, unlike the defective nozzle that is generated later due to clogging of the nozzle opening portion, there is a possibility that the nozzle may be restored to a normal nozzle by discharging. Low. In view of this point, in this modification, ink discharge from the initial defective nozzle is not performed in the second discharge, thereby reducing the amount of ink consumed by the discharge.
Since the initial defective nozzle is not used in the first discharge or various image recording operations (the ink ejection operation is not performed), the initial defective nozzle of this modification is not always used and is fixed (recovered). Not) Treated as a defective nozzle. For this reason, in this modification, the initial defective nozzle may be excluded from the detection target of the defective nozzle.

As described above, the inkjet recording apparatus 1 of the present embodiment is based on the image data of the head unit 20 having the ink ejection surface 222 provided with the opening of the nozzle 221 for ejecting ink and the normal image 51 to be recorded. The control unit 30 and the head control unit 21 (discharge control unit) that perform discharge control for discharging ink from the nozzles 221 and the initial defective nozzle data D1 relating to defective nozzles that do not normally discharge ink among the nozzles 221 and A first storage unit 23 and a second storage unit 34 (storage unit) for storing the defective nozzle data D2 respectively, and the control unit 30 and the head control unit 21 are defective among the nozzles 221 in the discharge control. It is possible to select whether or not to eject ink from the nozzle 221 specified as a defective nozzle by the nozzle data D2. That (spitting discarded control means).
As a result, in the discharge control, the ink is not ejected from the defective nozzle as necessary, so that the ink ejected from the defective nozzle or the ink mist adheres to the ink ejecting surface 222 to prevent the ink ejecting surface 222 from being contaminated. Can be suppressed. As a result, the ink adhering to the ink discharge surface 222 falls on the recording medium M or the conveyance belt 13 to cause fouling, or the ink adhering to the ink discharge surface 222 is solidified with a part of the nozzle opening being blocked. Thus, it is possible to suppress the occurrence of a problem that causes a new defective nozzle.

In addition, the inkjet recording apparatus 1 includes an inspection unit 43 that detects the ejection state of ink from the nozzles 221, and the control unit 30 identifies a defective nozzle from the detection result of the inspection unit 43, and identifies the defective nozzle. Based on the above, the defective nozzle data D2 is stored in the second storage unit 34 (defective nozzle specifying means). With such a configuration, it is possible to accurately identify a defective nozzle based on the ink ejection state from the nozzle 221. Further, by referring to the defective nozzle data D2 based on the detection result of the defective nozzle and determining a defective nozzle that does not perform ink discharge in the discharge control, an appropriate discharge reflecting the detection result of the latest defective nozzle is performed. Discard control can be performed. For example, even if a nozzle has been identified as a defective nozzle in the past, it is determined that the nozzle has been restored to a normal nozzle based on the detection result of the latest defective nozzle, and ink is ejected in the discharge control to become a defective nozzle again. Can be suppressed. Further, for the nozzle newly determined as a defective nozzle based on the detection result of the most recent defective nozzle, it is possible to reliably suppress contamination of the ink ejection surface 222 by stopping the ink ejection in the discharge control.

Further, the control unit 30 and the head control unit 21 eject ink from the nozzles 221 specified as defective nozzles by the defective nozzle data D2 among the nozzles 221 when predetermined conditions are satisfied in the discharge control. It chooses not to let it (discharging control means). Thereby, the ink ejection from the defective nozzle is stopped according to the predetermined condition, both the contamination of the ink ejection surface 222 is suppressed, the generation of the defective nozzle due to the discharge and the recovery from the defective nozzle are both performed. Can be effectively realized.

In addition, the control unit 30 and the head control unit 21 determine that the predetermined condition is satisfied when the normal image 51 is recorded subsequent to the ink discharge by the discharge control (discharge control unit). . Thereby, the normal image 51 can be recorded by the head unit 20 in which the contamination of the ink ejection surface 222 is suppressed. As a result, it is possible to suppress the occurrence of a problem that the ink attached to the ink ejection surface 222 falls on the recording medium M during the recording of the normal image 51.

In addition, the inkjet recording apparatus 1 includes a cleaning roller 421 that cleans the ink ejection surface 222, and the control unit 30 causes the cleaning roller 421 to perform a cleaning operation on the ink ejection surface 222 (cleaning control unit). The head control unit 21 determines that the predetermined condition is satisfied when the normal image 51 is recorded after the ink is discharged by the discharge control and before the cleaning operation is performed (discharge control unit). . Thereby, the normal image 51 can be recorded by the head unit 20 in which the contamination of the ink ejection surface 222 is suppressed. As a result, it is possible to suppress the occurrence of a problem that the ink attached to the ink ejection surface 222 falls on the recording medium M during the recording of the normal image 51.

The control unit 30 and the head control unit 21 determine that the predetermined condition is satisfied when ink is ejected from the nozzle 221 outside the recording area of the normal image 51 on the recording medium M in the ejection control. (Discharge control means). According to this, in the case where the discharge and the normal image 51 are continuously recorded on the same recording medium M, the ink ejection surface 222 of the head unit 20 can be maintained in a state in which contamination is suppressed. As a result, it is possible to suppress the occurrence of a problem that the ink attached to the ink ejection surface 222 falls on the recording medium M during the recording of the normal image 51.

Further, the control unit 30 and the head control unit 21 can perform different types of discharge control (first and second discharges). When the discharge control (first discharge) is performed, it is determined that the predetermined condition is satisfied (discharge control means). As a result, at a timing at which contamination of the ink ejection surface 222 does not become a problem, ink can be ejected from the defective nozzle in the ejection control, and the defective nozzle can be restored to a normal nozzle.

In addition, the first storage unit 23 that stores the initial defective nozzle data D1 related to the initial defective nozzle is provided integrally with the head unit 20. Thereby, when the head unit 20 is replaced, a defective nozzle (that is, an initial defective nozzle) of the head unit 20 can be specified without detecting a defective nozzle of the head unit 20.

The defective nozzle data D2 includes information related to the initial defective nozzle associated with the initial defect of the head unit 20, and the control unit 30 and the head control unit 21 use the information related to the initial defective nozzle in the discharge control to determine the initial defective nozzle. Is selected so that ink is not ejected from the nozzles identified as (discharge control means). Accordingly, it is possible to suppress ink consumption by omitting ink ejection from an initial defective nozzle that is unlikely to recover to a normal nozzle.

In addition, the ink ejection control method of the inkjet recording apparatus 1 of the above embodiment includes a discharge step for discharging ink from the nozzle 221 without being based on the image data of the normal image 51 to be recorded. When the condition is satisfied, it is selected whether or not to eject ink from the nozzle 221 specified as a defective nozzle by the defective nozzle data D2 among the nozzles 221. Thereby, in the discharging step, the ink is not ejected from the defective nozzle as necessary, thereby preventing the ink ejection surface 222 from being contaminated by the abnormally ejected ink or ink mist from the defective nozzle. Can be suppressed.

Note that the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made.
For example, in the above-described embodiment and each modified example, the second discharge and wiping are performed as an example of the maintenance operation. However, in the maintenance operation, instead of the second discharge or the second discharge. In addition, a pressure purge for forcibly ejecting ink from the nozzles 221 may be performed. When performing the pressure purge, the maintenance unit 42 may be provided with a pressure pump, and the ink may be pressurized by a pressure pump at a predetermined pressure position in the ink supply path communicating with the pressure chamber of the recording element. By pressurizing the ink, the ink is forcibly discharged from the nozzle 221 of the recording element, and the clogging of the nozzle 221 is eliminated. The pressure purge is performed in a state where the ink discharge surface 222 of the head unit 20 faces the ink receiving portion.
Moreover, after wiping is performed following the pressure purge, further discharging may be performed. In this case, since the wiping of the ink discharge surface 222 is not normally performed after the discharge and before the recording operation of the normal image 51, the discharge is not performed so that the ink discharge surface 222 is not contaminated. It is preferable not to perform ink ejection from the defective nozzle.

Further, in the above-described embodiment and each modification, as an example of the discharge control, a discharge control for causing the first discharge to discharge ink from the normal nozzle outside the recording area of the normal image 51 on the recording medium M. In addition, although the discharge control that causes the ink receiving unit to perform the second discharge that discharges ink from all the nozzles has been described, the present invention is not limited thereto. For example, the discharge control may be one in which a small amount of ink is discharged in a recording area of the normal image 51 during a recording of the normal image 51 at a frequency that cannot be visually confirmed. . In this discharge, since the ink discharge surface 222 of the head unit 20 is in a state of facing the recording medium M, in order to prevent ink from adhering to the ink discharge surface 222 and dropping of the adhering ink onto the recording medium M. In addition, it is preferable not to eject ink from the defective nozzle.
In addition to or in place of these discharge controls, at least a part of the start condition, the number of ink discharges from each nozzle 221, the drive signal used for ink discharge, the target for ink discharge, and the like are mutually Different types of discharge control may be performed. Among these plural types of discharge control, ink discharge surface 222 is not contaminated or slightly contaminated by ink abnormally discharged from a defective nozzle, and ink is discharged at a timing when ink discharge surface 222 is later cleaned. In the discharge control for performing discharge, ink is discharged from all the nozzles 221, and in the other predetermined discharge control, the ink discharge from the defective nozzle is not performed, thereby suppressing contamination of the ink discharge surface 222. it can.

In the above embodiment and each modification, the first storage unit 23 is provided in each head unit 20 and the initial defective nozzle data D1 related to the initial defective nozzle is stored. , The defective nozzle data D2 related to the initial defective nozzle and the subsequent defective nozzle may be stored in the second storage unit 34 of the control unit 30. In this case, when the head unit 20 is replaced, the initial defective nozzle may be detected and the defective nozzle data D2 may be updated. Alternatively, defective nozzle data D <b> 2 may be generated based on information related to the initial defective nozzle detected in advance by an external detection device and stored in the second storage unit 34.

Further, in the above embodiment and each modification, the inspection unit 43 will be described using an example in which the light quantity as a physical quantity reflecting the ejection state of the ink from the nozzle 221 is measured and the subsequent defective nozzle is identified from the measurement result. However, it is not intended to be limited to this. For example, the defective nozzle is identified by recording a predetermined inspection image on the recording medium M and analyzing image data obtained by imaging the inspection image by an image reading unit such as a line sensor or an area sensor. Also good. Here, the predetermined inspection image can be, for example, a line pattern composed of a plurality of lines recorded by ink ejected from each of the plurality of nozzles 221 included in the head unit 20. In the imaging data obtained by imaging this line pattern, if there is a missing line or a line that is not recorded at an appropriate position corresponding to the nozzle 221, the nozzle 221 corresponding to the line is identified as a defective nozzle. can do.

Further, prior to detection of a defective nozzle in the inspection unit 43, the nozzles including the defective nozzle may be discharged. Thereby, it can suppress that the nozzle which restore | restores to a normal state easily is determined as a defective nozzle. In this case, it is desirable to clean the ink discharge surface 222 by wiping after discharging, but before detecting a defective nozzle. However, the ink discharge surface 222 is not contaminated, for example, when the number of ink discharges during discharging is sufficiently small. If the contamination is slight, wiping may be omitted.

In the above embodiment and the modification, the cleaning roller 421 has been described as an example of the cleaning unit that cleans the ink discharge surface 222. However, the configuration of the cleaning unit is not limited thereto, and for example, foreign matter on the ink discharge surface 222 Or a blade for scraping ink.

Further, in the above-described embodiment and modification, an example in which recording is performed on the long recording medium M that is unwound from the roll has been described, but the present invention is not limited thereto. For example, the recording medium is not limited to being unwound from a roll, and may be unwound from a state folded into ninety-nine folds, for example. The recording medium may be a short one such as a sheet.

Further, in the above-described embodiment and each modification, the description has been given using the example in which the recording medium M is conveyed by the conveyance unit 10 including the conveyance belt 13. However, the present invention is not limited to this, and the conveyance unit 10 rotates, for example. The recording medium M may be held and transported on the outer peripheral surface of the transport drum.

In the above embodiment and each modification, the single-pass inkjet recording apparatus 1 has been described as an example. However, the present invention may be applied to an inkjet recording apparatus that records an image while scanning a recording head. good.

Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, and includes the scope of the invention described in the claims and equivalents thereof. .

The present invention can be used for an ink jet recording apparatus and an ink discharge control method of the ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 External apparatus 10 Conveyance part 11 Drive roller 12 Driven roller 13 Conveyor belt 20 Head unit 21 Head control part 21a Control circuit 21b Switching part 21c Image data storage part 22 Recording head 22a Head drive part 221 Nozzle 222 Ink discharge surface 23 1st memory | storage part 30 Control part 31 CPU
32 RAM
33 ROM
34 Second storage unit 41 Head unit moving unit 42 Maintenance unit 421 Cleaning roller 43 Inspection unit 431 Light emitting unit 432 Light receiving unit 433 Moving unit 434 Moving belts 435a and 435b Roller 436 Motor 437 Linear encoder 44 Operation display unit 45 Input / output interface 46 Bus 51 Normal image 52 Discharge area 52Y, 52M, 52C, 52K Discharge image by color D1 Initial defective nozzle data D2 Defective nozzle data Da Normal image image data Db Discharge data L Optical axis M Recording medium

Claims (10)

1. An ink discharge section having an ink discharge surface provided with an opening of a nozzle for discharging ink;
   A discharge control means for performing a discharge control for discharging ink from the nozzles without being based on image data of an image to be recorded;
   A storage unit for storing defective nozzle information relating to defective nozzles that do not normally eject ink among the nozzles;
   With
   The ejection control unit can select whether or not to eject ink from a nozzle specified as a defective nozzle by the defective nozzle information among the nozzles in the ejection control.
2. An ejection state detection unit for detecting an ejection state of ink from the nozzle;
   A defective nozzle identifying unit that identifies a defective nozzle from the result of the detection by the discharge state detection unit, and stores the defective nozzle information in the storage unit based on the identification result of the defective nozzle;
   An inkjet recording apparatus according to claim 1.
3. The discharge control unit selects not to discharge ink from a nozzle specified as a defective nozzle by the defective nozzle information among the nozzles when a predetermined condition is satisfied in the discharge control. The ink jet recording apparatus according to claim 1.
4. 4. The ink jet recording apparatus according to claim 3, wherein the discharge control unit determines that the predetermined condition is satisfied when an image is recorded after ink discharge by the discharge control.
5. A cleaning unit for cleaning the ink discharge surface;
   Cleaning control means for performing a cleaning operation of the ink discharge surface by the cleaning unit;
   With
   5. The discharge control unit determines that the predetermined condition is satisfied when an image is recorded after the ink is discharged by the discharge control and before the cleaning operation is performed. 6. 2. An ink jet recording apparatus according to 1.
6. 6. The discharge control unit according to claim 3, wherein the discharge control unit determines that the predetermined condition is satisfied when ink is discharged from a nozzle outside an image recording area on the recording medium in the discharge control. The ink jet recording apparatus according to one item.
7. The discharge control means is capable of performing a plurality of different types of discharge control, and the predetermined condition is satisfied when performing a predetermined discharge control among the plurality of types of discharge control. The inkjet recording apparatus according to any one of claims 3 to 6, wherein the inkjet recording apparatus is determined to be
8. The defective nozzle information includes initial defective nozzle information related to an initial defective nozzle associated with an initial defect of the ink ejection unit,
   The storage unit includes an initial defective nozzle information storage unit that stores the initial defective nozzle information,
   The inkjet recording apparatus according to any one of claims 1 to 7, wherein the initial defective nozzle information storage unit is provided integrally with the ink discharge unit.
9. The defective nozzle information includes initial defective nozzle information related to an initial defective nozzle associated with an initial defect of the ink ejection unit,
   The discharge control unit according to any one of claims 1 to 8, wherein in the discharge control, selection is made so that ink is not discharged from a nozzle specified as an initial defective nozzle by the initial defective nozzle information. Inkjet recording device.
10. Inkjet comprising: an ink ejection unit having an ink ejection surface provided with an opening of a nozzle for ejecting ink; and a storage unit for storing defective nozzle information relating to a defective nozzle that does not normally eject ink among the nozzles An ink discharge control method for a recording apparatus, comprising: a discharge step for discharging ink from the nozzles without being based on image data of an image to be recorded;
    An ink ejection control method for an ink jet recording apparatus, wherein in the discharging step, whether or not ink is ejected from a nozzle specified as a defective nozzle by the defective nozzle information among the nozzles is selected.

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