JP2010030184A - Inkjet printer with nozzle check function, and nozzle checking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer with a nozzle checking function, performing nozzle check so as to obtain printing throughput and printing quality in compliance with user's handleability or request in consecutive printing. <P>SOLUTION: As for the inkjet printer with a nozzle check function 1, when middle reliability and low reliability are set as reliability of nozzle check, nozzle check is not performed basically during consecutive label printing for a plurality of labels, but counted number N of passing times in consecutive printing exceeds first and second passing-time thresholds N1 and N2, interruption for nozzle check is performed even in the middle of printing. By appropriately setting the first and second passing-time thresholds N1 and N2, a printing defect caused by a defective nozzle during consecutive printing is avoided, and lowering of the printing throughput is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention provides an ink jet with a nozzle check function provided with nozzle check means for detecting whether or not an ink jet head has a nozzle that cannot eject a droplet such as ink or a nozzle that does not sufficiently eject a droplet such as ink. Regarding printers. More specifically, an ink jet printer with a nozzle check function that can avoid printing defects such as inability to eject droplets generated during continuous printing, such as when printing a large number of labels, and missing dots due to ejection defects. And a nozzle check method.

In an inkjet printer, each nozzle of the inkjet head becomes clogged due to thickening of droplets such as ink remaining in the nozzles, mixing of bubbles, adhesion of foreign matters, etc., making it impossible to eject ink droplets It may fall. In addition, the nozzle may be partially clogged, resulting in a discharge failure state in which a sufficient amount of ink droplets cannot be discharged. When printing is performed using an inkjet head including a nozzle that has fallen into such a state (hereinafter referred to as a defective nozzle), there is a risk that dot dropout or the like will occur and the print quality will deteriorate. Therefore,
It is necessary to perform the head cleaning process by moving the ink-jet head out of the printing region periodically or at a predetermined timing.

Patent Document 1 discloses a printer with a nozzle check function that performs nozzle check and head cleaning. In this printer, when power is turned on, nozzle check and head cleaning are performed as part of the startup process. Also, a nozzle check is performed to check the number of defective nozzles. If the number of defective nozzles is greater than or equal to a threshold set by the user, head cleaning corresponding to the number of defective nozzles is performed. If the number of defective nozzles is less than the threshold, head cleaning is performed. Do not do.
JP 2007-7960 A

Here, since it takes about 3 to 5 seconds to check whether each nozzle of the inkjet head is a defective nozzle or not, if the nozzle check is frequently performed, the printing throughput is greatly reduced. End up.

In particular, during continuous printing in which printing is continuously performed on a plurality of labels, there is a high possibility that foreign matters such as paper dust will adhere to the nozzles during the printing and cause defective nozzles. In order to avoid this, if nozzle check is performed during printing, for example, every time one label print is completed, the number of nozzle checks increases, and the throughput of continuous printing is greatly reduced.

In view of this point, the problem of the present invention is that a nozzle check function is provided so that the user can perform nozzle check so as to obtain print throughput and print quality according to the user's convenience or request during continuous printing. To propose an inkjet printer.

In order to solve the above problems, an inkjet printer with a nozzle check function of the present invention is
Nozzle check means for detecting whether the nozzle of the inkjet head is a defective nozzle,
A counting unit that counts the number of printing operations by the inkjet head during printing from the start to the end of a predetermined amount or a predetermined range of printing operations on the recording paper;
Control means for controlling the execution timing of the nozzle check by the nozzle check means,
The control means is characterized in that when the count value of the number of times by the counting means exceeds a predetermined threshold value, a nozzle check by the nozzle check means is executed.

In the ink jet printer with a nozzle check function of the present invention, when the number of continuous printing exceeds a predetermined threshold, the nozzle check operation is interrupted even during printing. If the threshold value is reduced, the nozzle check is performed earlier, so that a decrease in print quality can be suppressed, and if the threshold value is increased, the print throughput can be increased. Therefore, by appropriately setting the threshold value, it is possible to perform a printing operation corresponding to the user's request, the print quality required for the printed matter, and the like.

Next, the inkjet printer with a nozzle check function of the present invention is
Reliability setting means for setting the reliability of the nozzle check by the nozzle check means in at least two stages of high reliability and low reliability;
When the high reliability is set, the control unit sets the number of continuous printings to a first value.
The nozzle check is executed when the threshold value exceeds the first threshold value, and when the low reliability is set, the number of times of continuous printing exceeds the second threshold value that is larger than the first threshold value. The nozzle check is performed.

Here, the high reliability of the nozzle check means that the nozzle check is performed more strictly,
It also means that the nozzle check is performed more frequently. For example, in the case of a highly reliable nozzle check, a full nozzle check is performed, and in the case of a low reliability, a partial nozzle check is performed. In addition, a highly reliable nozzle check is performed at the end of printing of a small printing amount or printing range, for example, at the end of printing of one label, and a low reliability nozzle check is performed at a large printing amount or printing range. This is performed at the end of printing, for example, at the end of a series of print jobs.

In the ink jet printer of the present invention, the execution mode such as the frequency of nozzle check is determined based on the reliability set by the reliability setting means. For example, in the case of printing a fine image, it is possible to maintain a high print quality that does not cause image loss or the like by frequently setting the reliability of the setting and performing a nozzle check. it can. On the other hand, if you want to print characters quickly with a print quality that does not cause misreading, set the setting reliability to a low reliability to prevent unnecessary nozzle checks and maintain print throughput. Can do.

Also, when high reliability is set, a small first threshold is set, so
Compared to the case where the low reliability is set, the nozzle check operation is interrupted at an earlier point during continuous printing. Therefore, when high reliability is set, it is possible to prevent the print quality from deteriorating due to defective nozzles during printing even when printing a large number of labels continuously. , Print quality is maintained. On the other hand, when low reliability is set, when many labels are continuously printed, the nozzle check operation is interrupted less frequently during printing, so printing due to nozzle check A reduction in throughput can be prevented, and the print quality in continuous printing can also be maintained at a predetermined level or higher.

Next, the inkjet printer with a nozzle check function of the present invention is
A reliability setting means for setting the reliability of the nozzle check by the nozzle check means in at least two stages of high reliability and low reliability;
The control means includes
When the high reliability is set, the nozzle check is executed every time printing of the first printing amount or the first printing range is finished, and the count value of the number of times during the printing is determined in advance. The nozzle check is executed even when the value of 1 is exceeded,
When the low reliability is set, the nozzle check is performed every time printing of the second print amount larger than the first print amount or the second print range wider than the first print range is completed. The nozzle check is also performed when the count value of the number of times during the printing exceeds a second threshold value that is larger than the first threshold value.

According to this configuration, it is possible to avoid or suppress the occurrence of defective nozzles by setting high reliability and maintain print quality, and it is possible to ensure print throughput by setting low reliability. Further, when the low reliability is set, for example, when printing a plurality of labels continuously, when the number of continuous printing exceeds the set value,
The nozzle check operation is interrupted. Accordingly, it is possible to prevent a problem that defective nozzles are generated during printing during a continuous printing or the like and the printing quality is greatly lowered and reprinting is necessary.

Here, the reliability of the nozzle check by the nozzle check means can be set in three stages: high reliability, intermediate reliability, and low reliability.

In this case, the control means
When the high reliability is set, the nozzle check is executed each time printing of the first print amount or the first print range is completed,
When the intermediate reliability is set, the nozzle check is performed every time printing of the second print amount larger than the first print amount or the second print range wider than the first print range is completed. The nozzle check is executed even when the count value of the number of times during the printing exceeds a predetermined first value,
When the low reliability is set, the nozzle check is performed every time printing of the second print amount or the second print range is finished, and the count value of the number of times during the printing is the first count. The nozzle check may also be executed when a second value greater than 1 is exceeded.

Next, the inkjet head is periodically moved to a position facing a head cap disposed at a position outside the printing area, and a regular flushing operation for discharging ink droplets from each nozzle is performed, and an unused nozzle In the case where the regular flushing means for preventing clogging or the like is provided, the control means can execute the nozzle check by the nozzle check means after the flushing by the flashing means.

In addition, when the head cleaning unit for recovering the defective nozzle is included, the control unit is set by the result of the nozzle check and the reliability setting unit after the nozzle check is executed. It is desirable to determine whether or not to perform head cleaning by the head cleaning means based on the reliability. For example, when at least two types of reliability, that is, high reliability and low reliability, can be set in the reliability setting means, the control means detects only one defective nozzle by the nozzle check. In some cases, the head cleaning can be executed only when the set reliability is the high reliability.

In this way, it becomes possible to execute head cleaning at a frequency according to the set reliability, and in the case of high reliability, the nozzle check is frequently executed, and the head cleaning is frequently executed. Good print quality can be maintained. In the case of low reliability, the frequency of nozzle check and head cleaning is reduced, and the print quality can be reduced, but the print throughput can be increased.

In addition, the nozzle check method of the inkjet printer of the present invention,
During printing from the start to the end of a predetermined amount or a predetermined range of printing operation on the recording paper, the number of times of printing operation by the inkjet head is counted,
When the count value exceeds a predetermined threshold value,
A nozzle check for detecting whether or not the nozzle of the inkjet head is a defective nozzle is executed, and the print throughput can be increased.

Further, the reliability of the nozzle check is set to at least two stages of high reliability and low reliability,
When the high reliability is set, the nozzle check is performed when the number of times of continuous printing exceeds a first threshold, and when the low reliability is set, the continuous printing is performed. The nozzle check is executed when the number of times of printing exceeds a second threshold value that is larger than the first threshold value, and the print throughput corresponding to the set reliability can be achieved.

In the inkjet printer with a nozzle check function of the present invention, for example, during a printing operation in which a plurality of labels are continuously printed, if the number of continuous printing exceeds a predetermined threshold value, The nozzle check operation is interrupted. The print quality can be improved by reducing the threshold for interrupting the nozzle check operation, and the print throughput can be increased by increasing the threshold. By appropriately setting the threshold value, it is possible to perform a printing operation corresponding to the user's request, the print quality required for the printed matter, and the like.

Embodiments of an inkjet printer with a nozzle check function according to the present invention will be described below with reference to the drawings.

(overall structure)
FIG. 1 is an external perspective view of the ink jet printer, and FIG. 2 is an external perspective view showing a state in which the roll paper cover and the ink cartridge cover are fully opened. FIG. 3 is a perspective view showing the printer mechanism with the outer case removed to show the internal structure of the ink jet printer.

The inkjet printer 1 includes a box-shaped outer case 2, and a roll paper cover 2 a and an ink cartridge cover 2 b are lined up on the front side of the outer case 2.
Above these, a paper discharge port 3 for discharging the printed recording paper is formed. When the roll paper cover 2a is opened, as shown in FIGS. 2 and 3, the roll paper storage portion 4 formed inside the outer case 2 is opened, and the roll paper 5 stored therein is replenished. And can be exchanged. When the ink cartridge cover 2b is opened, as shown in FIG. 3, the cartridge mounting portion 7 for mounting the ink cartridge 6 enclosing the ink liquid is opened, so that the ink cartridge 6 can be mounted or removed.

As shown in FIG. 2, an opening / closing sensor for detecting that the roll paper cover 2 a is closed at the edge of the opening communicating with the roll paper storage unit 4 or the cartridge mounting unit 7 is provided on the front portion of the outer case 2. 2c and an open / close sensor 2d for detecting that the ink cartridge cover 2b is closed are attached. An impact sensor 2e for detecting an impact applied to the inkjet printer 1 from the outside is attached to a predetermined position inside the outer case 2. As the impact sensor 2e, for example, a sensor that detects the movement of a weight due to acceleration at the time of impact using a piezoelectric material or a position sensor is used.

As shown in FIG. 3, the printer mechanism unit 10 covered by the outer case 2 includes a printing mechanism 11 disposed on the upper side of the roll paper storage unit 4 and a cartridge mounted on the right side of the roll paper storage unit 4. Part 7 and a head cleaning mechanism 40 disposed on the cartridge mounting part 7. Further, as will be described later, a paper feed mechanism that transports the recording paper drawn from the roll paper 5 stored in the roll paper storage unit 4 via a printing position by the printing mechanism 11, and is positioned in the vicinity of the paper discharge port 3. Various mechanisms such as a recording paper cutting mechanism are provided.

FIG. 4 is a schematic cross-sectional view showing the internal structure of the inkjet printer 1. 3 and 4
The internal structure of the inkjet printer 1 will be described with reference to FIG. A printing mechanism 11 disposed above the roll paper storage unit 4 and the cartridge mounting unit 7 includes an inkjet head 12.
And a carriage 13 on which the inkjet head 12 is mounted, and a horizontal carriage shaft 14 for guiding the carriage 13. The carriage 13 is connected to an output shaft of a carriage motor 16 by an endless belt 15, and the eject head 12 reciprocates in the printer width direction, that is, the paper width direction of the roll paper 5 based on the rotation of the carriage motor 16.

The inkjet head 12 includes a nozzle surface 12 a on which a plurality of nozzles for ejecting ink are formed. The nozzle surface 12 a is exposed downward on the lower side of the carriage 13. A back pressure adjustment unit 17 connected to the inkjet head 12 is mounted on the upper surface of the carriage 13, and the back pressure adjustment unit 17 is connected to the tip of the ink supply tube 19 via a damper unit 18 connected to the back side thereof. It is connected to the. When the inkjet head 12 reciprocates through a printing position defined by the upper surface of the platen 20 disposed horizontally on the upper side of the roll paper storage unit 4, nozzles are formed on the recording paper 5 a sent to the upper surface of the platen 20. Printing is performed by ejecting ink droplets from each ink nozzle on the surface 12a. When printing is not performed, the inkjet head 12 moves to the right end of the carriage shaft 14 and returns to the standby position (position shown in FIG. 3) facing the head cleaning mechanism 40.

Next, the paper feeding mechanism will be described mainly with reference to FIG. 3. On the rear side of the platen 20 (upstream in the conveying direction), a rear paper feeding roller 21 and a rear paper pressing roller 22 are arranged in the printer width direction. It is stretched horizontally. A rear paper pressing roller 22 is pressed against the rear paper feeding roller 21 from above with a predetermined pressing force via the recording paper 5a. A front paper feed roller 23 and a front paper presser roller 24 are arranged on the front end side of the platen 20. Front paper feed roller 23
The front side paper pressing roller 24 is pressed from above through the recording paper 5a. The rear paper feed roller 21 and the front paper feed roller 23 are rotationally driven in synchronization by a paper feed motor 25.

The roll paper 5 is set by closing the roll paper cover 2a in a state where the length of the roll paper 5 is pulled out from the paper discharge port 3 by hand. Recording paper 5a fed out from the roll paper 5 in the roll paper storage unit 4
Is conveyed along a conveyance path passing through a printing position on the upper surface of the platen 20 in a state where a predetermined tension is applied by the tension guide 26. When the paper feed motor 25 is driven and controlled,
The rear paper feed roller 21 and the front paper feed roller 23 are rotated, and the recording paper 5a is intermittently fed for every one line printing with a constant feed amount. The inkjet head 12 is synchronized with the feeding of the recording paper 5a.
Is driven, and printing is performed on the surface of the recording paper 5a passing through the printing position. The printed recording paper 5a is stopped in a state where it is discharged from the paper discharge port 3, and the printing portion at the leading end of the recording paper 5a is cut by the recording paper cutting mechanism 8 disposed in the vicinity of the paper discharge port 3, and printed. A piece of recording paper is issued.

(Head cleaning mechanism)
FIG. 5 is a perspective view showing the head cleaning mechanism 40 taken out. The head cleaning mechanism 40 includes a head cap 41 for sealing the nozzle surface 12a of the inkjet head 12, and a wiper 4 for wiping off ink and foreign matters attached to the nozzle surface 12a.
2 and an ink suction part 43 for sucking ink remaining or clogged in the nozzles of the inkjet head head 12. Head cap 41, wiper 42
The ink suction part 43 is attached to the frame 44 of the head cleaning mechanism 40. The frame 44 is fixed to the main body frame of the inkjet printer 1 that supports the carriage shaft 14, the platen 20, and the like.

The head cap 41 is disposed directly below the nozzle surface 12a at the standby position, and includes an upward sealing surface 41a that faces the nozzle surface 12a. The head cap 41 is configured to be vertically slidable in a direction perpendicular to the nozzle surface 12 a, that is, a direction orthogonal to the carriage shaft 14 by operating a drive mechanism (not shown). Thereby, the head cap 41 moves in a direction in which the sealing surface 41a approaches or moves away from the nozzle surface 12a.

FIG. 6 is a partial cross-sectional view showing a state where the inkjet head 12 and the head cap 41 are facing each other. As shown in this figure, the head cap 41 has an edge 4 of the sealing surface 41a.
A box shape 1b stands vertically, and is formed of an elastic material such as rubber. The head cap 41 has a size and a shape that allows the head cap 41 to be in close contact with the nozzle surface 12a while covering the nozzle forming portion of the nozzle surface 12a with the edge 41b. A suction tube extending from a pump motor (not shown) provided in the ink suction portion 43 is connected to the recess 41c surrounded by the sealing surface 41a and the edge portion 41b. When the pump motor is operated with the edge 41b in close contact with the nozzle surface 12a, the sealed space surrounded by the recess 41c and the nozzle surface 12a is decompressed by the suction force of the pump motor, and remains in each nozzle of the inkjet head 12. The sucked ink is sucked and discharged into the recess 41c.

The wiper 42 is a plate-like member made of an elastic material such as rubber, and the head cleaning mechanism 4
The guide member (not shown) fixed to the zero frame 44 is slidably held up and down. The wiper 42 is configured to be movable in a direction perpendicular to the nozzle surface 12a, like the head cap 41, by operating a drive mechanism (not shown). When wiping the nozzle surface 12a with the wiper 42, the wiper 42 is lifted with the nozzle surface 12a shifted laterally from directly above the wiper 42, and the tip of the wiper 42 is slightly higher than the height of the nozzle surface 12a. In this state, the inkjet head 12 is moved along the carriage shaft 14, and the tip of the wiper 42 is brought into sliding contact with the nozzle surface 12a. As a result, foreign matter and ink adhering to the nozzle surface 12 a are scraped off by the tip of the wiper 42.

When the print job is finished and the inkjet head 12 is made to stand by at the standby position, the head cap 41 moves to a position where the edge 41b comes into close contact with the periphery of the nozzle surface 12a to block the nozzle. As a result, it is difficult to thicken the ink in the nozzles during standby, and clogging and the like are less likely to occur. Further, by wiping the wiper 42 in synchronization with the timing of moving the inkjet head 12 to the standby position side or the printing position side, a wiping process for wiping the nozzle surface 12a with the wiper 42 can be performed.

When head cleaning becomes necessary due to nozzle clogging or the like, the recess 41c is operated by operating the pump motor with the head cap 41 moved to a position where the nozzle is blocked.
And an ink suction process in which the inside of the sealed space surrounded by the ink nozzle surface 12a is sucked and ink is ejected from each ink nozzle.

Further, in order to keep the state of ink droplets in the ink nozzles appropriately, the inkjet head 1
A flushing process is periodically performed in which a predetermined amount of ink is ejected into the recess 41c of the head cap 41 from all the ink nozzles of the inkjet head 12 with the head 2 facing the head cap 41 regardless of the printing operation. Is called. Further, the flushing process for collectively ejecting a larger amount of ink droplets than the ink droplets ejected by the regular flushing process can be executed at a desired timing, thereby performing head cleaning to recover nozzle clogging and the like. .

As the cleaning process, any one of the wiping process, the ink suction process, and the flushing process, or a combination of these processes can be performed.

(Head check mechanism)
Here, before the head cleaning process is actually performed, a nozzle check process for inspecting the ejection state of ink from the ink nozzles is performed. Based on the result of the nozzle check, it is determined whether or not to perform nozzle cleaning, and a nozzle cleaning process is performed if necessary.

In order to perform this nozzle check process, the head cleaning mechanism 40 is provided with a nozzle check mechanism for detecting defective nozzles. That is, an absorbent material 41d for absorbing the discharged waste ink is disposed in the recess 41c, and a conductive material 41e is attached so as to be electrically connected to the absorbent material 41d. The electrical signal that has flowed through the conductive material 41e is taken out by wiring or the like. With this configuration, a charged ink droplet is ejected from each nozzle of the inkjet head 12, and a signal of a current change that occurs when the charged ink droplet lands on the absorber 41d can be taken out. If this signal is equal to or lower than a predetermined threshold even though ink droplets have been ejected, it can be determined that the nozzles are defectively ejected. In addition, as a method for detecting a defective nozzle, there is a method for detecting ejected ink droplets by optical means such as a laser.

Specifically, the nozzle check process discharges charged ink droplets from the nozzles of the inkjet head 12, and based on a signal of current change when the ink droplets land on the absorbent 41d in the recess 41c, The ejection state of the ink droplets from is checked. During the nozzle check process, the gap L between the nozzle surface 12a and the upper end of the edge 41b of the head cap 41
1 and the head cap 41 is positioned so that the gap L2 between the nozzle surface 12a and the surface of the absorbent material 41d has a predetermined dimension, and in this state, the inkjet head 12 and the head cap 41 have a predetermined potential difference. Then, the inkjet head 12 side is grounded, and a voltage is applied to the head cap 41 side to bring it into a predetermined electric field state. The ink ejected from the inkjet head 12 is charged with a predetermined amount of charge before landing by this electric field. When the ink lands, the charged charge flows through the conductive material 41e. In this way, it is possible to accurately inspect the ejection state of the ink droplets.

(Control system)
Next, FIG. 7 is a schematic block diagram showing a control system of the ink jet printer 1. The control system of the inkjet printer 1 is mainly configured by a control unit 30 including a CPU, a ROM, a RAM, and the like. Print data and commands are supplied to the control unit 30 from a host device such as the host device 32 via the transmission / reception unit 31. The control unit 30 controls the driving of each unit based on a print command from the host device 32 or the like, and executes a paper feeding operation and a printing operation.

The inkjet head 12 is connected to the output side of the control unit 30 via a head driver 12b. A carriage motor 16 and a paper feed motor 25 are connected via motor drivers 33 and 34. Connected to the input side of the control unit 30 are an operation input unit 30a, sensors 2c, 2d and 2e, and a sensor group 35 arranged in the recording paper transport path.
The control unit 30 controls nozzle check processing, head cleaning processing, recording paper transport processing, printing processing, and the like based on the detection output of each sensor.

The control unit 30 is connected to a storage unit 36 composed of a rewritable nonvolatile memory such as a flash ROM. Here, a recording area is provided which functions as a reliability setting unit 37 capable of setting the reliability of nozzle check by the nozzle check mechanism. In addition, a storage area is provided that functions as a threshold setting unit 38 that can set a first pass threshold value N1 and a second pass threshold value N2 that serve as a reference for determining whether or not to perform a nozzle check during continuous printing.

When the command supplied from the host device 32 is a reliability setting command, the control unit 30 sets the reliability specified by the reliability setting command in the reliability setting unit 37. For example, if high reliability is set, the nozzle check is executed in the execution mode in the high reliability mode. If intermediate reliability is set, the nozzle check is executed in the execution mode in the intermediate reliability mode. When set, the nozzle check is executed in the execution mode in the low reliability mode.

Here, the high-reliability mode is, for example, the highest print quality mode that does not allow even one-dot missing, and is a mode for maintaining the print quality. For this purpose, for example, in the case of label printing, a nozzle check is always performed every time one label is printed, and if one missing dot is detected (when one defective nozzle is detected), the nozzle is checked. Cleaning is executed.

On the other hand, the intermediate reliability mode is a mode in which printing throughput is emphasized. The intermediate reliability mode is, for example, a misreading prevention mode and is a mode that does not allow misreading of printed characters due to missing dots. For this purpose, for example, when missing two adjacent dots are detected (two adjacent missing characters). When a defective nozzle is detected, nozzle cleaning is performed. The low-reliability mode is, for example, an erroneous color prevention mode and does not allow an error in printing color due to missing dots. For this purpose, for example, when missing dots of 3 dots or more are detected. Nozzle cleaning is performed.

Next, when receiving a command for setting the first and second path threshold values N1 and N2 from the host device 32, the control unit 30 sets the values N1 and N2 received subsequently to the threshold setting unit 3.
8 is registered. The second path threshold value N2 is larger than the first path threshold value N1. When the intermediate reliability and the low reliability are set, the control unit 30 continuously prints a plurality of pages on a recording sheet, continuously prints a plurality of labels, and the like. At the time of printing, the number of passes of the inkjet head 12 (the number of scans in the recording paper width direction) is counted by the built-in counter 39, and when the intermediate reliability is set, the count pass number N exceeds the first pass threshold value N1. When the nozzle check is executed and the low reliability is set, the nozzle check is executed when the count pass number N exceeds the second pass threshold N2.

Further, the control unit 30 corresponds to a condition in which the following defective nozzles are likely to occur frequently in the recording area as a nozzle check execution time setting means, and includes control flags shown in (1) to (4). It is possible to detect that the inkjet printer 1 is in a state corresponding to the frequent occurrence condition of defective nozzles. In addition to these, a condition that the ink viscosity increases at the nozzle surface 12a may be set by detecting an environment of temperature and humidity.

(1) Timer AID flag F1
In order to be able to perform the nozzle check periodically or at a predetermined timing, the control unit 30 uses a built-in timer to indicate that a predetermined time has elapsed since the most recent nozzle check, printing process, or head cleaning process. If detected, the timer AID flag is set. The timer AID flag may be set based on an elapsed time from a predetermined process other than the nozzle check, printing process, and head cleaning process. For example, the timer AID flag may be set when 24 hours have elapsed.

(2) Impact detection flag F2
The control unit 30 detects that a predetermined impact has occurred in the ink jet printer 1.
If it is detected at e, an impact detection flag is set. If the impact of the inkjet printer 1 is further detected with the impact detection flag already set, the impact detection flag remains set.

(3) Startup processing flag F3
When the power switch of the inkjet printer 1 is turned on, the control unit 30
When a start signal or reset signal input from a host device or the like or a reset signal from the inside of the inkjet printer 1 is detected, start processing or restart processing is performed and a start processing flag is set.

(4) Cover close flag F4
When the open / close sensor 2c detects that the roll paper cover 2a of the inkjet printer 1 is closed, the control unit 30 detects that the ink cartridge cover 2b is closed.
If it is detected at d, a cover close flag is set. If the opening / closing of the roll paper cover 2a or the ink cartridge cover 2b is further detected while the cover close flag is already set, the cover close flag is kept set.

The control unit 30 periodically checks whether each of the above flags is set, and executes a nozzle check when detecting that the flag is set.

(Nozzle check and head cleaning operation control)
FIG. 8 is a schematic flowchart showing the operation of the inkjet printer 1 with a focus on nozzle check and head cleaning operations.

First, it is checked whether or not each of the above-described flags F1 to F4 is set (step ST11). If the flag is set, a nozzle check is executed (step S).
T12). If a defective nozzle that may cause a missing dot or the like is not detected, the process is terminated (step ST13 → ST14).

When a defective nozzle is detected, the set reliability is confirmed (step ST1).
3 → ST15). When the set reliability is high reliability, the operation mode is set to high reliability mode H, and head cleaning is executed (step ST16). When the set reliability is intermediate reliability, the operation mode is set to no misreading mode M,
Head cleaning is executed when two defective nozzles are detected and adjacent nozzles are both defective nozzles. If the number of detected defective nozzles is one, and if the number of defective nozzles is two but not adjacent, the process is terminated without performing head cleaning (step ST17 → ST14). When the set reliability is low reliability, the operation mode is set to the error-free mode L. In this case, the head cleaning is executed only when three or more defective nozzles are detected. (Step ST18
(→ ST16). Depending on the degree, even if there are three or more defective nozzles, it may be set so that head cleaning is unnecessary.

Next, at the time of label printing, the control unit 30 of the inkjet printer 1 executes an interrupt process for confirming the set reliability mode every time printing of one label is finished (step ST21). The end point of printing in the print data is detected based on a command such as a line feed or a page break included in the print data supplied from the host device 32 side. In this case, when the high reliability mode H is set, the process proceeds to step ST12, and as described above, the nozzle check is executed, and based on this, it is determined whether or not the head cleaning is necessary. If so, perform head cleaning. In the high reliability mode H, the nozzle check may be performed for each row in order to further increase the reliability of the nozzle check. On the other hand, when the erroneous reading prevention mode M and the erroneous color prevention mode L are set, the control unit 30 ends the process without performing the nozzle check (step ST21 → S
T14).

In addition, the control unit 30 of the inkjet printer 1 confirms the set reliability mode after the end of a series of print jobs during label printing, for example, after the end of printing a plurality of labels by batch processing or the like. Interrupt processing is executed (step ST22). The end point of the print job is detected based on a command included in the print data supplied from the host device 32. In this case, when the high reliability mode H in which the nozzle check is performed every time printing of one label is completed, the process is terminated (step ST22).
(→ ST14) If the misreading prevention mode M and the erroneous color prevention mode L in which the nozzle check is not performed every time printing of one label is completed, the process proceeds to step ST12, as described above. In addition, the nozzle check is executed, and based on this, it is determined whether or not the head cleaning is necessary, and the head cleaning is executed if necessary.

In this way, the control unit 30 provides the high reliability mode H with high reliability as the reliability of the nozzle check.
Is set, the nozzle check is executed every time the printing operation of each label is completed as an execution form of the nozzle check. On the other hand, when the erroneous reading prevention mode M and the erroneous color prevention mode L are set, the nozzle check is not performed every time one label is printed, and the nozzle check is performed after the end of a series of print jobs. Only.

In the high reliability mode H, head cleaning is always executed when even one defective nozzle is detected. On the other hand, in the erroneous reading prevention mode M and the erroneous color prevention mode L, the head cleaning is performed only when two or more adjacent defective nozzles are detected and when three or more defective nozzles are detected. Execute.

Therefore, the nozzle check frequency is high in the case of high reliability, and the nozzle check frequency is low in the case of intermediate reliability and low reliability. As a result, the head cleaning frequency is high in the case of high reliability, and the head cleaning frequency is low in the case of intermediate reliability and low reliability. As a result, for users who have absolute print quality, by selecting the high reliability mode H, it is possible to reliably prevent nozzle omission and to issue labels with extremely high print quality and high reliability. On the other hand, for users who need only print quality that does not cause misreading of characters and color, select a misreading prevention mode and a wrong color prevention mode to print printed labels with a high print throughput. Can be issued. For example, for a user who wants to guarantee the barcode print quality to a minimum, the user can issue a label in a form that realizes both print quality and print throughput by selecting the intermediate reliability mode.

(Nozzle check operation during continuous printing in the wrong reading prevention mode and wrong color prevention mode)
As described above, in the erroneous reading prevention mode M and the erroneous color prevention mode L, the print throughput is increased at the expense of some print quality. For this purpose, the nozzle check is, for example,
Label printing is not performed every time printing of one sheet is completed, but is performed when a series of print jobs are completed. Here, in the case of a print job in which printing is continued for a long time such that a large number of labels are continuously printed, there is a high possibility that defective nozzles are generated during printing. In this case, if a defective nozzle is left unattended, a missing dot may occur, and a label having a printing state that may cause misreading or a printing state that may cause a wrong color may be created. In order to prevent such an adverse effect, the control unit 30 counts the number of passes during continuous printing, and if the count pass number N exceeds the set pass thresholds N1 and N2, the nozzle check operation interrupt is performed. I try to multiply.

FIG. 9 is a flowchart showing the execution timing of the nozzle check operation when a print job for continuously printing a large number of labels is performed when the erroneous reading prevention mode M and the erroneous color prevention mode L are set. In the printing operation, the control unit 30 manages the timing for performing the regular flushing using the built-in regular flushing timer (step ST31). When the printing direction, that is, the moving direction of the inkjet head 12 during printing is a direction away from the standby position (HOME → AWAY), even if the regular flushing time is reached by the regular flushing timer, the regular flushing is not performed. The process ends (step ST32 → END). In this case the next path, namely
Periodic flushing is performed when the inkjet head returns to the standby position.

If the printing direction is the direction to return to the standby position, regular flushing is executed (step ST33). Thereafter, it is confirmed whether there is a nozzle check request (step ST34). When the high reliability mode is set, a nozzle check is requested every time printing of one label is completed, and thus the presence or absence of such a nozzle check request is confirmed. If there is no such nozzle check request, it is confirmed whether or not the setting reliability is set to the erroneous reading prevention mode M and the erroneous color prevention mode L (step ST35).

When the misreading prevention mode M is set, the number of count passes N in continuous printing is
It is confirmed whether or not a preset first pass threshold N1 is exceeded (step ST36).
If it exceeds, nozzle check is performed after regular flushing (step ST3).
7). When the erroneous color prevention mode L is set, the number of count passes N in continuous printing
Has exceeded a preset second path threshold N2 (step ST38).
). If it exceeds, nozzle check is performed after regular flushing (step S).
T37). Note that after the nozzle check, the processes after step ST13 in FIG. 8 are executed, and the head cleaning process is performed according to the set reliability.

As described above, when a large number of labels are continuously printed, the nozzle check is performed when the number of continuous printing passes is large even in the intermediate reliability misreading prevention mode M and the low reliability erroneous color prevention mode L. An interrupt is applied so that the nozzle check is performed during the regular flushing operation. Therefore, it is possible to prevent a label that needs to be reprinted from being generated due to a defective nozzle that is generated during printing during continuous printing for a long time. In other words, the print quality during continuous printing can be maintained at an acceptable level or higher.

In addition, since the nozzle check interruption is performed based on the number of continuous printing passes, the print throughput can be set to an allowable level by appropriately setting the reference first and second pass threshold values N1 and N2. Can be maintained.

(Other embodiments)
In the above example, the settable reliability has three levels of high reliability, intermediate reliability, and low reliability, but the reliability may be only two levels or four or more levels.

In addition, although the execution frequency and time are changed as the nozzle check execution mode according to the reliability, other execution modes may be used. For example, nozzle check is performed for all nozzles in the case of high reliability, and nozzle check is performed for every other nozzle in the case of low reliability. It may be possible to shorten it.

Furthermore, the case where label paper is used as the recording paper has been described as an example, but the present invention can be similarly applied to printing on normal continuous paper. For example, in the case of high reliability, the nozzle check is performed every time one page is printed on continuous paper, and in the case of intermediate reliability and low reliability, a series of print jobs, for example, printing for many pages is performed. The nozzle check may be performed at the time when the operation is completed.

1 is an external perspective view of an ink jet printer to which the present invention is applied. It is an external appearance perspective view of the state which opened the inkjet printer. It is a perspective view which shows the printer mechanism part of an inkjet printer. It is a schematic sectional drawing of an inkjet printer. It is a perspective view which shows the head cleaning mechanism of an inkjet printer. It is explanatory drawing which shows the nozzle check state of a head cleaning mechanism. It is a schematic block diagram which shows the control system of an inkjet printer. It is a schematic flowchart which shows the operation | movement of a nozzle check and head cleaning. It is a schematic flowchart which shows the nozzle check execution timing at the time of continuous printing.

Explanation of symbols

1 Inkjet printer, 2 outer case, 3 paper outlet, 4 roll paper storage unit, 5
Roll paper, 5a recording paper, 6 ink cartridge, 7 cartridge mounting section, 8 recording paper cutting mechanism, 10 printer mechanism section, 11 printing mechanism, 12 inkjet head, 1
2a Nozzle surface, 13 Carriage, 14 Carriage shaft, 15 Endless belt, 16 Carriage motor, 17 Back pressure adjustment unit, 18 Damper unit, 19 Ink supply tube, 20 Platen, 21 Rear paper feed roller, 22 Rear paper presser roller , 23 Front paper feed roller, 24 Front paper press roller, 25 Paper feed motor, 26 Tension guide, 30 Control unit, 30a Operation input unit, 31 Transmission / reception unit, 32 Host device, 33, 3
4 Motor driver, 36 storage unit, 37 reliability setting unit, 38 threshold setting unit, 39 counter, 40 head cleaning mechanism, 41 head cap, 41a sealing surface, 41
b Edge part, 41c Concave part, 41d Absorbent material, 41e Conductive material, 42 Wiper, 43 Ink suction part, 44 frame

Claims (8)

Nozzle check means for detecting whether the nozzle of the inkjet head is a defective nozzle,
A counting unit that counts the number of printing operations by the inkjet head during printing from the start to the end of a predetermined amount or a predetermined range of printing operations on the recording paper;
Control means for controlling the execution timing of the nozzle check by the nozzle check means,
The printer with a nozzle check function, wherein the control means executes a nozzle check by the nozzle check means when the count value of the number of times by the count means exceeds a predetermined threshold value. In the inkjet printer with a nozzle check function according to claim 1,
Reliability setting means for setting the reliability of the nozzle check by the nozzle check means in at least two stages of high reliability and low reliability;
When the high reliability is set, the control unit sets the number of continuous printings to a first value.
The nozzle check is executed when the threshold value exceeds the first threshold value, and when the low reliability is set, the number of times of continuous printing exceeds the second threshold value that is larger than the first threshold value. An ink jet printer with a nozzle check function, wherein the nozzle check is executed. In the inkjet printer with a nozzle check function according to claim 1,
A reliability setting means for setting the reliability of the nozzle check by the nozzle check means in at least two stages of high reliability and low reliability;
The control means includes
When the high reliability is set, the nozzle check is executed every time printing of the first printing amount or the first printing range is finished, and the count value of the number of times during the printing is determined in advance. The nozzle check is executed even when the threshold value of 1 is exceeded,
When the low reliability is set, the nozzle check is performed every time printing of the second print amount larger than the first print amount or the second print range wider than the first print range is completed. An ink jet printer with a nozzle check function, wherein the nozzle check is performed even when the count value of the number of times during the printing exceeds a second threshold value that is greater than the first threshold value. In the inkjet printer with a nozzle check function according to claim 1,
A reliability setting means for setting the reliability of the nozzle check by the nozzle check means in three stages of high reliability, intermediate reliability, and low reliability;
The control means includes
When the high reliability is set, the nozzle check is executed each time printing of the first print amount or the first print range is completed,
When the intermediate reliability is set, the nozzle check is performed every time printing of the second print amount larger than the first print amount or the second print range wider than the first print range is completed. The nozzle check is executed even when the count value of the number of times during the printing exceeds a predetermined first threshold value,
When the low reliability is set, the nozzle check is performed every time printing of the second print amount or the second print range is finished, and the count value of the number of times during the printing is the first count. An ink jet printer with a nozzle check function, wherein the nozzle check is executed even when a second threshold value greater than 1 is exceeded. In the inkjet printer with a nozzle check function according to any one of claims 1 to 4,
A head cap disposed at a position deviated from a printing region by the inkjet head;
Periodic flushing means for periodically performing flushing for moving the inkjet head to a position facing the head cap and ejecting ink droplets from each ink nozzle of the inkjet head toward the head cap;
The ink jet printer with a nozzle check function, wherein the control unit performs the nozzle check based on the number of times after the flushing by the regular flashing unit. In the inkjet printer with a nozzle check function according to any one of claims 1 to 5,
A head cleaning means for recovering the defective nozzle;
The control means determines whether or not to perform head cleaning by the head cleaning means based on the result of the nozzle check and the reliability set by the reliability setting means after execution of the nozzle check. An inkjet printer with a nozzle check function. During printing from the start to the end of a predetermined amount or a predetermined range of printing operation on the recording paper, the number of times of printing operation by the inkjet head is counted,
When the count value exceeds a predetermined threshold value,
A nozzle check method for an ink jet printer, comprising: performing a nozzle check for detecting whether or not a nozzle of the ink jet head is a defective nozzle. The nozzle check method for an inkjet printer according to claim 7,
The reliability of the nozzle check is set to at least two levels of high reliability and low reliability,
When the high reliability is set, the nozzle check is performed when the number of times of continuous printing exceeds a first threshold, and when the low reliability is set, the continuous printing is performed. A nozzle check method for an ink jet printer, wherein the nozzle check is executed when the number of times of printing exceeds a second threshold value that is greater than the first threshold value.

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