JP2003191492A - Ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the printing quality to recording media by controlling the execution of a printing process on the basis of whether or not nozzles are in a state to be able to discharge ink. <P>SOLUTION: When a maintenance mode of executing maintenance for a printing head 10 is instructed in the ink jet printer 1, a control unit 100 detects a nozzle missing and carries out head cleaning for the printing head 10 to recover the nozzle missing by a non discharge nozzle when the non discharge nozzle not discharging ink is detected. In the case where the nozzle missing is not recovered by the head cleaning, the control unit 100 determines the non discharge nozzle as a defective nozzle. When the printing process is to be carried out by the printing head 10 including the defective nozzle, the printing process by the defective nozzle is carried out by substituting the other normal nozzle for the defective nozzle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer that prints by ejecting ink onto a recording medium.

[0002]

2. Description of the Related Art Conventionally, an ink jet type printer has been known in which ink is ejected from a print head to a sheet-like recording medium such as paper, cloth, or a plastic thin plate for recording based on input print data. There is.

[0003]

By the way, in the above-mentioned ink jet printer, the ink near the nozzle is solidified to cause clogging in the nozzle, bubbles are generated in the ink flow passage in the head, or the print head is used. There is a problem in that dust adheres to the nozzle of No. 1 and print failure occurs due to non-ejection of ink droplets. That is, since it is not possible to perform printing by a non-ejection nozzle that does not eject an ink droplet, there is a problem that a portion where printing is not performed by the non-ejection nozzle occurs in a streak shape, and color unevenness or color loss occurs. .

In order to solve the above-mentioned conventional problems, the present invention controls the execution of the printing process based on whether or not the nozzle is in a state capable of ejecting ink, and maintains the printing quality on the recording medium. The purpose is to

[0005]

In order to solve the above problems, an ink jet printer according to claim 1 is mainly a head unit having one or more print heads in which a plurality of nozzles are arranged in the sub-scanning direction. An inkjet printer including a print execution unit that scans in a scanning direction and ejects ink from a nozzle based on print data to perform printing on a recording medium, and a maintenance execution unit that performs a nozzle ejection inspection at a maintenance position. The maintenance executing means detects the non-ejection nozzle for detecting the non-ejection of the nozzle, and, when the non-ejection nozzle is detected by the non-ejection nozzle detecting means, determines the non-ejection nozzle as the defective nozzle. And a substitute nozzle determining unit that determines a substitute nozzle that substitutes the printing of the defective nozzle. Execution means, the printing by the defective nozzle is characterized in that it comprises a substitute printing control means for controlling ejection of ink from the transport and the substitute nozzles of the recording medium to perform by the substitute nozzles.

Here, the non-ejection nozzle is defined as clogging due to solidification of ink near the nozzle, adhesion of dust to the nozzle, generation of bubbles in the ink flow path of the print head, and the like. A nozzle that does not eject ink.

According to the first aspect of the present invention, it is possible to judge whether or not each nozzle of the print head is in a state where ink can be normally ejected by detecting the ejection failure of the nozzle. Therefore, the conditions of the substitute printing process can be set appropriately. Further, since the entire print area can be printed based on the print data, it is possible to prevent the occurrence of print defects due to non-ejection nozzles such as color unevenness and color loss, and to maintain the print quality on the recording medium. .

According to a second aspect of the present invention, in the ink jet printer according to the first aspect, the print executing means is based on whether or not the substitute nozzle is arranged on the carry-out direction side of the nozzle position of the defective nozzle. Thus, the execution sequence of the normal print processing and the print processing by the substitute nozzle by the substitute print control means is controlled.

According to the second aspect of the present invention, the order of execution of the normal print processing and the substitute print processing in which the print processing by the non-ejection nozzle is executed by the normal substitute nozzle is executed is controlled. According to this, it is possible to realize the printing process in consideration of the positional relationship between the non-ejection nozzle and the substitute nozzle.

Further, the invention according to claim 3 is the same as claim 1.
Alternatively, in the ink jet printer according to the second aspect, the substitute nozzle determination unit selects and determines the substitute nozzle from nozzles in which all the nozzles of the print heads that are in the same row in the main scanning direction are normal. There is.

According to the third aspect of the present invention, since all nozzles that are in a vertical positional relationship in the sub-scanning direction substitute for printing by normal nozzles, the non-ejection nozzles can be used to print the original print line. Print instead. According to this
Substitute printing can be performed without impairing the desired color appearance.

Further, the invention according to claim 4 is defined by claims 1 to 1.
In the inkjet printer described in any one of 3,
The maintenance executing means operates a head cleaning means for cleaning a print head including a non-ejection nozzle when the non-ejection nozzle detecting means detects the non-ejection nozzle, and an operation of the non-ejection nozzle detecting means. Non-ejection determining means for determining whether or not the non-ejection of the non-ejection nozzle is recovered, and the defective nozzle determining means is determined by the non-ejection determining means to not recover the non-ejection of the non-ejection nozzle. In this case, the non-ejection nozzle is a defective nozzle.

According to the fourth aspect of the present invention, when the nozzle lack is detected, it is possible to try to recover the nozzle lack by cleaning the print head provided with the non-ejection nozzle. Further, it is possible to print by using another nozzle as a substitute for the print area of the non-ejection nozzle which is determined when the nozzle lack is not solved by the head cleaning.

Further, as in the invention described in claim 5, in the ink jet printer according to claim 4, a maintenance result notification for notifying the necessity of replacement of the print head based on the judgment result by the non-ejection judging means. Means may be provided.

According to the fifth aspect of the present invention, it is possible to notify the user of a message for warning the replacement of the print head. Thus, the load of the substitute nozzle used in the substitute printing process is considered.

According to a sixth aspect of the present invention, in the ink jet printer according to the fourth or fifth aspect, the head cleaning means is a means for forcibly ejecting ink from all nozzles of the print head, and all nozzles of the print head. It is characterized in that at least three means, that is, a means for injecting the cleaning liquid and a combination of these two are provided, and the print head is cleaned by selecting a means according to the number of detected non-ejection nozzles.

According to the sixth aspect of the present invention, by selecting the means for forcibly ejecting all the nozzles, it is possible to remove air bubbles, dust, etc. that are the cause of non-ejection in the nozzles. It is possible to remove dust and ink lumps at or near the nozzle portion by selecting a means for cleaning the nozzle and its vicinity with a cleaning liquid such as water. Furthermore, by selecting a means that combines the forced ejection of ink from the nozzle and the cleaning of the nozzle and its vicinity, it is possible to effectively eliminate the cause of non-ejection of the nozzle inside and outside the nozzle. Further, the head cleaning means can be changed according to the number of detected non-ejection nozzles.

Further, as in the invention described in claim 7, in the ink jet printer according to any one of claims 1 to 6, the nozzle ejection inspection by the maintenance executing means may be automatically carried out periodically. .

According to the seventh aspect of the invention, since the maintenance of the print head can be carried out periodically, it is possible to deal with the print processing by the non-ejection nozzle according to the state of the nozzle.

Further, as in the invention described in claim 8, the ink jet printer according to any one of claims 1 to 7 further comprises selection means for selecting an inspection mode for carrying out an ejection inspection of the nozzles, When the inspection mode is selected by the selection means, the nozzle ejection inspection by the maintenance execution means may be performed.

According to the invention of claim 8, by selecting the inspection mode and executing the maintenance,
The timing of maintenance can be manually instructed. Therefore, for example, it is possible to inspect a print defect due to the nozzles included in the print head at an arbitrary timing determined from the printing condition on the recording medium.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet printer to which the present invention is applied will be described in detail below with reference to the drawings.

The ink jet printer of the present embodiment does not eject ink from the nozzle (hereinafter, "nozzle missing").
Say. When a print failure due to (1) occurs, a substitute print process is performed in which the print process by the non-ejection nozzle is executed by substituting another normal nozzle.

In the ink jet printer according to the present embodiment, when the maintenance mode for carrying out the maintenance of the print head is instructed, it is detected whether or not the nozzle is missing, and the non-ejection nozzle which does not eject the ink is detected. In that case, head cleaning is performed in order to recover the nozzle deficiency due to the non-ejection nozzle. Then, when the nozzle defect is not recovered by this head cleaning, the substitute printing process is executed for the corresponding non-ejection nozzle. This maintenance mode may be manually instructed by the user, for example, by selecting a menu or pressing a mode switching button, or may be automatically instructed to be performed periodically according to a preset cycle. May be.

FIG. 1 shows a schematic diagram of a print execution portion of the ink jet printer 1. As shown in the figure, the main configuration of the print execution portion of the inkjet printer 1 is a head unit 20 on which the print heads 10 ... Are mounted, and the head unit 20 is moved in the main scanning direction A when printing is performed or maintenance is performed. A guide shaft 30 for guiding the sheet-shaped recording medium M along the sub-scanning direction B, a nozzle lack detection unit 50, a cleaning unit 60, and the like.

FIG. 2 is a top view of the ink jet printer 1 shown in FIG. In the present embodiment, for example, the guide shaft 3 that does not overlap the print area is used.
One end side of 0 is a maintenance area, and the nozzle lack detection unit 50 and the cleaning unit 60 are arranged in this maintenance area. In the maintenance mode, the head unit 20 is drive-controlled so as to move on the maintenance region, and the nozzle lack detection unit 5
0 and the cleaning unit 60 perform maintenance processing on the target print head 10.

A plurality of print heads 10 corresponding to the number of colors required for printing are mounted on the head unit 20, and the ink contained in an ink cartridge (not shown) is supplied to the print heads 10. ing. For example, in FIG. 1, the head unit 20 includes four print heads 10 ... Which are supplied with inks of four colors of yellow (Y), magenta (M), cyan (C), and black (K), respectively. It is equipped with color printing with these four colors.

On the surface of the print head 10 facing the recording medium M (hereinafter referred to as "nozzle surface"), a plurality of nozzles for ejecting ink are arranged in the sub-scanning direction.

FIG. 3 shows an example of the nozzle arrangement arranged on the nozzle surface of the print head 10. In the figure, each of the print heads 10 has n nozzles Nz1 to Nzn.
They are arranged in rows. Hereinafter, in the present embodiment, serial numbers are assigned to the nozzles in order from the nozzles in the recording medium loading direction, and these numbers are referred to as nozzle numbers. That is,
The same nozzle number means that in each print head 10, the corresponding nozzles are located in the same row in the main scanning direction.

The nozzle deficiency detection unit 50 is particularly provided with a nozzle deficiency detection section for detecting a nozzle deficiency, and detects a nozzle deficiency by whether or not ink has been ejected from each nozzle. Further, a member for receiving ink droplets ejected to detect the nozzle shortage is provided, and the ink droplets ejected on the member are, for example, intermittently discharged to the waste liquid tank.

The cleaning unit 60 carries out cleaning for the print head 10 for which the nozzle lack detection unit 50 has detected the nozzle failure.

FIG. 4 shows a top view of the cleaning unit 60. As shown in the figure, the cleaning unit 6
In particular, 0 includes an ink receiving portion 62 that receives ink, and a head cleaning portion 64 that includes ejection nozzles JNz1 to JNzn for ejecting a cleaning liquid such as water onto the nozzle surface of the print head 10. The configuration of the cleaning unit 60 is not limited to the above-described configuration. For example, the head cleaning unit 64 may be configured by a sponge roller that has absorbed the cleaning liquid, and the sponge roller and the nozzle surface may be brought into contact with each other. The nozzle surface may be configured to be cleaned, or the nozzle surface may be configured to include a wiping portion for wiping off ink and water remaining on the nozzle surface.

Next, the functional configuration of the ink jet printer 1 will be described with reference to FIG. As shown in the figure, the inkjet printer 1 includes the print head 10, the head unit 20, and the nozzle lack detection unit 5 described above.
0, cleaning unit 60, head unit 20
A head unit driving unit 70 for moving the recording medium in the main scanning direction, a recording medium conveying unit 80 for conveying the recording medium in the sub-scanning direction, an input instruction of an operation to the inkjet printer 1, or various messages such as error messages. The display device 90, these functional units and other functional units that make up the inkjet printer 1 (not shown), and a control unit 100 that controls the overall operation of the inkjet printer 1 and the like.

The control section 100 is provided with an interface for electrically connecting the ink jet printer 1 and the functional section constituting the ink jet printer 1,
ROM: executes a process based on various control programs and control data related to the operation of each unit of the inkjet printer 1 written in a Read Only Memory (not shown) or the like, or information transferred from each connected functional unit, The operation of the inkjet printer 1 is controlled by outputting a control signal to each functional unit.

That is, the control unit 100 sends a control signal for controlling the operation of the head unit drive unit 70 so that the head unit 20 moves along the recording medium in the print area during printing. Output.

Then, when the print processing on the recording medium for the current print line is completed, the control unit 100 executes the print processing for the next print line, so that the head unit 20 is returned to the print start position. The drive unit 70 is controlled. At this time, the control unit 100
At the same time, the operation of the recording medium conveying unit 80 is controlled to convey the recording medium in the sub-scanning direction.

Further, in the maintenance mode, the control section 100 outputs a control signal for controlling the operation of the head unit drive section 70 so that the head unit 20 moves in the maintenance area.

Specifically, during execution of the nozzle deficiency detection process, the control unit 100 controls the head unit 20 to move onto the nozzle deficiency detection unit 50, and also controls the operation of the nozzle deficiency detection unit 50. Output a control signal for Further, when executing the head cleaning process, the control unit 100 controls the head unit 20 to move onto the cleaning unit 60, and outputs a control signal for controlling the operation of the cleaning unit 60.

The control unit 100 includes an ink ejection control unit 1
The ink discharge control unit 120 includes an ink discharge control signal 120 and outputs an ink discharge control signal to each print head 10 to control the discharge of ink from the nozzles provided in the print head 10. For example, at the time of executing printing, the ink ejection control unit 120 causes ink droplets to be adsorbed on the recording medium by ejecting ink droplets from the nozzles with reference to the information of each dot of the print data.

Further, the control section 100 includes a RAM; Random Access Memory 140 which forms an area for temporarily storing various control programs, control data and the like.
In M140, in particular, substitute nozzle number information 14 to be described later
2 and defective nozzle information 144 are held. Based on these pieces of information, the control unit 100 outputs a control signal for controlling the conveyance of the recording medium to the recording medium conveyance unit 80, and the ink ejection control unit 120 causes the nozzles to be ejected from each nozzle to each print head 10. Output a control signal for controlling the ejection of the ink.

Next, the operation of the ink jet printer 1 having the above-described structure will be described. In the following, for the sake of simplicity, a case where each print head 10 has six nozzles arranged in one line in the sub-scanning direction will be described as an example.

First, the operation of the ink jet printer 1 in the maintenance mode will be described with reference to the flowchart shown in FIG.

That is, when the maintenance mode is instructed, the control unit 100 first moves the head unit 20 onto the nozzle deficiency detection unit 50, and performs nozzle deficiency detection processing for all the mounted print heads 10. Is executed (step S10).

Here, a specific method of the nozzle deficiency detection processing will be described with reference to FIG.

First of all, the controller 100 controls the head unit 2
0 is moved in the main scanning direction, and as shown in FIG. 7A, ink droplets are ejected one nozzle at a time at predetermined ejection intervals to detect whether or not ink has been ejected.

FIG. 7B shows an example of the droplet signal. In the figure, the droplet signal is O while the ink is being ejected.
N. In the figure, the nozzle of nozzle number NNz3 is not ejected.

FIG. 7C shows the non-ejection detection circuit and its detection result. As shown in the same figure, the product (D) of the product of the droplet signal at the ejection timing adjusted to the synchronization pulse and the synchronization pulse, and the operation result (C) is inverted.
The nozzle shortage is determined by.

Next, the control section 100 causes the step S10.
It is determined whether or not a nozzle shortage has been detected in the nozzle shortage detection processing in (step S12). If no nozzle shortage has been detected, this processing ends.

In step S12, when the nozzle lack is detected, the control unit 100 moves the head unit 20 onto the cleaning unit 60 and targets all the print heads 10 in which the nozzle lack is detected. Head cleaning is performed (step S14).

Specifically, the control unit 100 is a means selected for each of the print heads 10 targeted for head cleaning in which nozzle deficiency is detected, according to the number of non-ejection nozzles of the print head 10. , Perform head cleaning. In the present embodiment, the head cleaning means includes means for forcibly ejecting ink from all nozzles of the corresponding print head 10 and means for ejecting cleaning liquid to all nozzles of the corresponding print head 10. Either of the means for performing both is selected and the corresponding print head 10 is cleaned.

When the means of (1) is selected, dust adhering to the nozzle, bubbles and dust generated in the ink flow path in the print head 10 are forcibly discharged from the nozzle together with the ink and removed. When the head cleaning is performed by the method in step S14, the control unit 1
00 first controls the operation of the head unit drive unit 70 to move the head unit 20 to the cleaning unit 60.
And is moved to above the ink receiving portion 62. Next, the ink ejection control unit 120 outputs an ink ejection signal to all the nozzles of the print head 10 targeted for head cleaning to eject the ink. Also in this case,
The control unit 100 may control the ink to be supplied to and ejected from the ink channel at a higher pressure than usual.

When the means is selected, dust adhering to the nozzle, ink solidified in the vicinity of the nozzle, and the like are removed by spraying a cleaning liquid on the nozzle to clean it. When the head cleaning is performed by the method in step S14, the control unit 100
First, the operation of the head unit driving unit 70 is controlled to move the head unit 20 so that the print head 10 targeted for head cleaning is located on the head cleaning unit 64 of the cleaning unit 60. Then
The cleaning unit 60 ejects the cleaning liquid from the ejection nozzles included in the head cleaning unit 64 to the nozzles included in the print head according to the drive signal from the control unit 100. In addition, print head 1 that requires head cleaning
When there are a plurality of 0s, the above-described processings are performed in order.

When the means (1) is selected, both head cleaning operations described above are performed.

Further, as described above, the control unit 100 is
The head cleaning means by is selected depending on the number of non-ejection nozzles of the print head 10. For example, when the number of defective nozzles is one, the means is selected, the means when the number of defective nozzles is two to three, the means when four or more nozzles are selected, and the head cleaning is performed.

Here, FIG. 8 shows an example of the processing result of the nozzle missing detection processing in step S12. In the figure, the nozzles Nz10 and Nz20 are detected as non-ejection nozzles. In this case, print heads C2 (C) and C3 (M) equipped with these nozzles
Is subject to head cleaning, and print head C2
Head cleaning is performed on each of (C) and C3 (M).

That is, the control section 100 first counts the number of non-ejection nozzles of the print head C2 (C) in order to perform head cleaning on the print head C2 (C). Then, the control unit 100 selects a cleaning method according to the number (= 1) of the non-ejection nozzles, and forcibly ejects ink from all the nozzles included in the print head C2 (C). Subsequently, head cleaning is similarly performed on the print head C3 (M).

All print heads 1 in which nozzle shortage is detected
After performing head cleaning for 0, the control unit 1
00 determines whether or not the nozzle shortage in the corresponding print head 10 has been recovered (step S16).

Specifically, the control unit 100 detects the nozzle lack by the same process as the nozzle lack detection process in step S12, and when the nozzle lack is not detected, it is determined that the nozzle lack is recovered. This process is finished.

If it is determined in step S16 that the nozzle shortage is not recovered, that is, if the nozzle shortage is detected again, the controller 100 executes the head cleaning process in step S14 a preset number of times. It is determined whether or not (step S18).

Specifically, the control unit 100 compares the threshold value with the number of times of head cleaning performed at the current stage, and if the number of times of head cleaning has not exceeded the threshold value, the process returns to step S14 and described above. Repeat the process. According to this, by setting the threshold value and controlling the number of times of head cleaning to be performed, it is possible to recover the nozzle shortage to the maximum, and when the head cleaning effect cannot be obtained, useless processing is repeated, It is possible to prevent wasteful use of ink.

In the present embodiment, for example, if the above-mentioned threshold value is set to 3 times and the nozzle shortage is not recovered even if the head cleaning is repeated 3 times, the control unit 100
Shifts to the processing of step S20. That is, the control unit 1
00 determines the corresponding non-ejection nozzle as a defective nozzle, and stores the nozzle number information or print head information including the nozzle number information in the defective nozzle information 144.

For example, among the non-ejection nozzles shown in FIG. 8, when the nozzle defect of the nozzle Nz20 is not finally recovered, the nozzle Nz20 is determined to be a defective nozzle.

Next, the control unit 100 determines the substitute nozzle number (step S22).

Specifically, the control unit 100 selects a nozzle number close to the nozzle number of the defective nozzle from the nozzle numbers in which all the nozzles having the same nozzle number are normal, and sets the nozzle number as the substitute nozzle number. The information 142 is stored.

For example, in FIG. 8, all the nozzles having the same nozzle number are normal, and the nozzle numbers closest to the nozzle number NNz3 of the defective nozzle are the nozzle numbers NNz2 and NNz4 adjacent to the defective nozzle. Either one of them is determined as the substitute nozzle number. For example, when it is set to select the nozzle arranged on the carry-out direction side of the defective nozzle when two adjacent substitute nozzle numbers are detected, the control unit 100
The substitute nozzle number is determined to be NNz4.

Then, the control unit 100 displays a message notifying that the corresponding print head needs to be replaced on the display device 90.
Is displayed (step S24), and this processing ends.

As described above, in the maintenance mode, the nozzle deficiency detected by the nozzle deficiency detection process is not recovered even by head cleaning. Therefore, if the non-ejection nozzle is determined to be a defective nozzle, an instruction is given after that. When the printing process is executed, the substitute printing process is performed in which the printing process of the print line by the defective nozzle is performed using the nozzle corresponding to the substitute nozzle number.
Hereinafter, this substitute printing process will be described in detail.

First, with reference to FIG. 9, a case will be described in which the determined substitute nozzle number indicates a nozzle arranged on the carry-out side of the recording medium M with respect to the defective nozzle. For example,
The nozzle Nz100 shown in FIG. 9 is a substitute nozzle, and the nozzle Nz.
Let 200 be a defective nozzle.

In this case, the control section 100 first performs the normal printing process.

That is, as shown in FIG. 9A, the control section 100 controls the operation of the recording medium conveyance section 80 to convey the recording medium M to the normal printing position. Then, the control unit 10
0 controls the operation of the head unit drive unit 70 so as to move the head unit 20 intermittently, and the ink ejection control unit 120 controls the print head 1 while the intermittent movement is stopped.
The operation of 0 is controlled to eject ink from the nozzle, and the print data of each print line is printed on the recording medium M.

By this normal printing process, as shown in FIG. 9B, print data is printed by nozzles other than the defective nozzle Nz200.

Next, the control section 100 uses the substitute nozzle to perform substitute printing processing of the print line by the defective nozzle.

That is, as shown in FIG. 9C, the control section 100 controls the operation of the recording medium carrying section 80 so that the printing position of the defective nozzle Nz200 is set to the substitute nozzle Nz100.
The recording medium M is conveyed so as to be aligned with the position. Then, the control of the movement of the head unit 20 by the control unit 100 and the control of the ink ejection by the ink ejection control unit 120 are performed in association with each other, and the print data of the print line by the defective nozzle Nz200 is printed on the recording medium M.

By this substitute printing process, as shown in FIG. 9D, the print data of the print line by the defective nozzle Nz200 is substitute printed by the substitute nozzle Nz100.

Next, with reference to FIG. 10, a case will be described in which the determined substitute nozzle number indicates a nozzle arranged on the carry-in side of the recording medium M with respect to the defective nozzle. For example, the nozzle Nz300 shown in FIG. 10 is used as a substitute nozzle.

In this case, the control section 100 first performs the substitute printing process.

That is, as shown in FIG. 10A, the control section 100 controls the operation of the recording medium conveying section 80 to set the printing position of the defective nozzle Nz200 to the substitute nozzle Nz30.
The recording medium M is conveyed so as to be aligned with the position of 0. Then, the control of the movement of the head unit 20 by the control unit 100 and the control of the ink ejection by the ink ejection control unit 120 are performed in association with each other, and the print data of the print line by the defective nozzle Nz200 is printed on the recording medium M.

By this substitute printing process, as shown in FIG. 10B, the print data of the print line by the defective nozzle Nz200 is substitute-printed by the substitute nozzle Nz300.

Then, the control section 100 carries out a normal printing process.

That is, as shown in FIG. 10C, the control section 100 controls the operation of the recording medium conveying section 80 to convey the recording medium M to the normal printing position. And the control unit 1
Control of the movement of the head unit 20 by 00 and the control of the ink ejection by the ink ejection control unit 120 are performed in tandem, and the print data of each print line other than the print line by the defective nozzle Nz200 is recorded on the recording medium M. To print.

By this normal printing process, as shown in FIG. 10D, print data is printed by nozzles other than the defective nozzle Nz200.

As described above, the head unit 20
When executing the instructed printing process when the print head 10 having the defective nozzle is present in the print head 10 mounted in the control unit 100, the control unit 100 sets the print line with the defective nozzle number to the nozzle having the same nozzle number. The substitute printing can be performed by the nozzle corresponding to the substitute nozzle number selected from the nozzle numbers that are all normal.

The present invention is not limited to the one described in the above-mentioned embodiment, but can be appropriately modified without departing from the spirit of the present invention.

For example, in the present embodiment, the printing process by the nozzle corresponding to the nozzle number of the defective nozzle is
Although the nozzle corresponding to the substitute nozzle number is used as a substitute, the printing process may be substituted for each nozzle. That is, printing with a defective nozzle
Substitute printing using a substitute nozzle.

Further, in this embodiment, the head cleaning means is changed according to the number of defective nozzles of the print head targeted for the head cleaning. It may be changed according to the number of times of head cleaning performed. That is, for example, the means for the first head cleaning, the means for the second head cleaning, and the means for the third head cleaning are selected to clean the corresponding print heads.

[0086]

According to the first aspect of the present invention, it is possible to judge whether or not each nozzle of the print head is capable of ejecting ink normally by detecting the ejection failure of the nozzle. Therefore, the conditions of the substitute printing process can be set appropriately. Further, since the entire print area can be printed based on the print data, it is possible to prevent the occurrence of print defects due to non-ejection nozzles such as color unevenness and color loss, and to maintain the print quality on the recording medium. .

According to the second aspect of the present invention, the order of execution of the normal print processing and the substitute print processing in which the print processing by the non-ejection nozzle is substituted by the normal substitute nozzle and executed is controlled. According to this, it is possible to realize the printing process in consideration of the positional relationship between the non-ejection nozzle and the substitute nozzle.

According to the third aspect of the invention, since all the nozzles in the vertical positional relationship in the sub-scanning direction are substituted by the normal nozzles, the non-ejection nozzle substitutes the print line that should be printed. Print. According to this, it is possible to perform the substitute printing without impairing the desired color appearance.

According to the fourth aspect of the present invention, when the nozzle shortage is detected, it is possible to try to recover the nozzle shortage by cleaning the print head provided with the non-ejection nozzle. Further, it is possible to print by using another nozzle as a substitute for the print area of the non-ejection nozzle which is determined when the nozzle lack is not solved by the head cleaning.

According to the invention described in claim 5, it is possible to notify the user of a message for warning the replacement of the print head. Thus, the load of the substitute nozzle used in the substitute printing process is considered.

According to the sixth aspect of the present invention, first, by selecting a means for forcibly ejecting all the nozzles, it is possible to remove air bubbles, dust, and the like that cause ejection failure in the nozzles. You can Then, by selecting a means for cleaning the nozzle and its vicinity with a cleaning liquid such as water, it is possible to remove dust and ink lumps in the nozzle portion or in the vicinity of the nozzle. Furthermore, by selecting a means that combines the forced ejection of ink from the nozzle and the cleaning of the nozzle and its vicinity, it is possible to efficiently eliminate the cause of non-ejection of the nozzle inside and outside the nozzle. Then, the head cleaning means can be changed according to the number of the non-ejection nozzles detected.

According to the invention of claim 7, the print head can be regularly maintained.
It is possible to deal with the printing process by the non-ejection nozzle according to the state of the nozzle.

According to the eighth aspect of the present invention, the maintenance timing can be manually instructed by selecting the inspection mode and executing the maintenance.
Therefore, for example, it is possible to inspect a print defect due to the nozzles included in the print head at an arbitrary timing determined from the printing condition on the recording medium.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic diagram of a print execution portion of an inkjet printer according to the present embodiment.

FIG. 2 is a diagram showing a top view of the inkjet printer 1 shown in FIG.

FIG. 3 is a diagram illustrating an example of a nozzle array arranged on a nozzle surface of a print head.

FIG. 4 is a diagram showing an example of a top view of a cleaning unit.

FIG. 5 is a diagram showing functional blocks of the inkjet printer according to the present embodiment.

FIG. 6 is a flowchart showing an example of the operation of the inkjet printer in the maintenance mode.

FIG. 7 is a diagram for explaining a nozzle missing detection process according to the present embodiment.

FIG. 8 is a diagram illustrating an example of a processing result of a nozzle deficiency detection processing.

FIG. 9 is a diagram for explaining a substitute printing process.

FIG. 10 is a diagram for explaining another example of the substitute printing process.

[Explanation of symbols]

1 inkjet printer 10 print head 20 head units 30 guide shaft 40 Guide member 50 Nozzle missing detection unit 60 cleaning unit 70 Head unit driver 80 recording medium transport unit 90 display 100 control unit 120 ink ejection control unit 140 RAM 142 Substitute nozzle number information 144 defective nozzle information

Claims (8)

[Claims] 1. A plurality of nozzles arranged in the sub-scanning direction.
A head unit equipped with one or more print heads is scanned in the main scanning direction, and a print execution unit that discharges ink from nozzles based on print data to perform printing on a recording medium and a nozzle discharge inspection at a maintenance position. An inkjet printer having maintenance performing means for performing, wherein the maintenance performing means detects a non-ejection nozzle detecting means for detecting non-ejection of a nozzle, and a non-ejection nozzle is detected by the non-ejection nozzle detecting means, A defective nozzle determining unit that determines the non-ejection nozzle as a defective nozzle; and a substitute nozzle determining unit that determines a substitute nozzle that substitutes the printing of the defective nozzle. , Controlling the conveyance of the recording medium and the ejection of ink from the substitute nozzles as is done by the substitute nozzles Jet printer, characterized in that it comprises a substitute printing control means, the that. 2. The ink jet printer according to claim 1, wherein the print execution means performs normal print processing based on whether or not the substitute nozzle is arranged on a discharge direction side from a nozzle position of a defective nozzle. An ink jet printer characterized in that the execution sequence of the printing process by the substitute nozzle is controlled by the substitute printing control means. 3. The ink jet printer according to claim 1 or 2, wherein the substitute nozzle determination means selects a substitute nozzle from nozzles in which all the nozzles of each print head having a positional relationship in the main scanning direction are normal. An inkjet printer characterized by being determined by. 4. The inkjet printer according to claim 1, wherein the maintenance execution unit includes a non-ejection nozzle when the non-ejection nozzle is detected by the non-ejection nozzle detection unit. And a non-ejection determining means for deciding whether or not the non-ejection of the non-ejection nozzle is recovered by operating the non-ejection nozzle detecting means. If the non-ejection determining means determines that the non-ejection of the non-ejection nozzle is not recovered,
An inkjet printer, wherein the non-ejection nozzle is a defective nozzle. 5. The ink jet printer according to claim 4, further comprising maintenance result notifying means for notifying whether or not the print head needs to be replaced based on the judgment result by the non-ejection judging means. . 6. The ink jet printer according to claim 4 or 5, wherein the head cleaning means is a means for forcibly ejecting ink from all nozzles of the print head, and a cleaning liquid is ejected to all nozzles of the print head. An ink jet printer comprising: a means for performing the above, and a means for combining the two, and at least three means are selected, and a means according to the number of detected non-ejection nozzles is selected to clean the print head. 7. The ink jet printer according to any one of claims 1 to 6, characterized in that the nozzle ejection inspection by the maintenance executing means is automatically carried out periodically. 8. The ink jet printer according to any one of claims 1 to 7, further comprising a selection unit for selecting an inspection mode for carrying out an ejection inspection of nozzles, when the inspection mode is selected by the selection unit. In addition, the inkjet printer is characterized in that a nozzle ejection inspection is performed by the maintenance executing means.