JPH11348246A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer in which deterioration of print quality due to deterioration of ejection performance of nozzle can be prevented without causing decrease of printing speed or complication of constitution. SOLUTION: At the time of printing five continuous dots, dots 61, 62, 63, 64 corresponding to normal nozzles are formed normally when no countermeasure is taken for an abnormal nozzle located in the center but a dot 65a corresponding to an abnormal nozzle is shifted from a correct position 65. On the other hand, ejection of ink drop from an abnormal nozzle is stopped based on decision results thereof and the clots 62a, 63a corresponding to adjacent normal nozzles are formed two times as large as that at the time of normal operation. According to the arrangement, deterioration of print quality due to missing of dot is prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an ink jet printer that forms dots by performing printing by ejecting ink droplets from a plurality of nozzles and landing them on a recording medium.

[0002]

2. Description of the Related Art In recent years, in order to respond to the increasing demand for high-speed and high-resolution printing for ink-jet printers, a large number of nozzles are driven at a high speed and the nozzle diameter is reduced. In. For this reason, the discharge performance is deteriorated due to nozzle clogging and the like, and non-discharge is likely to occur. Therefore, there is an increasing need to take measures to ensure the reliability of the ink jet printer.

As a countermeasure for this, there is a conventional method in which a dummy nozzle is provided in addition to a normal nozzle, and when a nozzle that cannot discharge or becomes unstable is detected, the dummy nozzle is operated instead. . This allows
Even if some of the many nozzles cannot discharge normally, it is possible to prevent missing dots, misalignment, and the like during printing, and to ensure the reliability of the inkjet printer. it can.

[0004]

However, in the ink jet head employing the above conventional method,
Since the ink is ejected from the dummy nozzle in place of the nozzle in which the operation has become abnormal, the number of scans of the ink jet head is excessively increased, so that there is a problem that the printing speed must be reduced. In addition, when the number of nozzles is large, in order to be able to cope with troubles occurring in all the nozzles, it is necessary to increase the number of dummy nozzles inevitably, or to reduce the number of nozzles while controlling the position of the inkjet head precisely. A method such as printing with a dummy nozzle must be used, and it has been difficult to avoid a reduction in printing speed and a complicated configuration.

In view of the foregoing, the present invention has been made in view of the above-described problems, and it has been possible to avoid a reduction in printing speed and a complicated configuration, and to improve the reliability of printing due to non-ejection of nozzles or deterioration of ejection performance. It is an object of the present invention to provide an ink jet head capable of effectively preventing the drop.

[0006]

According to a first aspect of the present invention, there is provided an ink jet printer, comprising: a plurality of nozzles arranged in parallel; and ink stored in an ink chamber communicating with each of the nozzles. An ink jet printer comprising a pressurizing means for pressurizing, and an ink jet head which discharges ink droplets from respective nozzles and lands at a predetermined position on a recording surface, and is formed on the recording surface by the landed ink droplets. Of the plurality of drive signals set in accordance with the size of the dot to be driven, a drive unit for driving the pressurizing unit by a selected drive signal, and ink droplets respectively ejected to the plurality of nozzles. Detects whether or not a droplet has landed normally at a predetermined position on the recording surface, and discriminates between a normal nozzle that has landed normally and an abnormal nozzle that has not landed normally. Means, and if the nozzle that ejects ink droplets corresponding to the dot for which printing is instructed is determined to be a normal nozzle by the determination means, selects a drive signal during normal operation to control the drive means. If the nozzle is determined to be an abnormal nozzle by the determination means, the ejection of ink droplets from the abnormal nozzle is stopped, and the normal nozzle adjacent to the abnormal nozzle is compared with the normal nozzle by a dot compared to the normal operation. And control means for controlling the driving means by selecting a driving signal for increasing the magnitude of the driving signal.

According to the present invention, when printing is performed by the ink jet printer, the judging means detects whether or not the ink droplets ejected from the plurality of nozzles have landed at the normal positions on the recording paper, and And the abnormal nozzle. In response to this result, the control means stops the ejection of the ink droplets from the abnormal nozzle corresponding to the dot for which printing has been instructed, and controls the specific drive signal so that the dot size increases with respect to the adjacent normal nozzle. Select In response to this drive signal, the drive unit drives the pressurizing unit to eject ink droplets from the normal nozzles, leaving blank dots on the recording paper corresponding to the abnormal nozzles, and forming large dots adjacent to them. It will be in the state that was done. Therefore, while avoiding a decrease in printing speed and complication of the configuration, missing dots,
Deterioration of print quality due to misalignment can be prevented.

According to a second aspect of the present invention, in the inkjet printer according to the first aspect, the plurality of drive signals are set with drive signals having different drive voltages in accordance with the amount of ink to be ejected. It is characterized by having been done.

According to the present invention, the amount of ink droplets ejected from the nozzles can be controlled in various sizes by a plurality of drive signals for driving the pressurizing means. Therefore, it is easy to increase the amount of ink discharged from the normal nozzles adjacent to the abnormal nozzle to increase the dot size, and it is possible to prevent the print quality from deteriorating by simple control.

According to a third aspect of the present invention, in the inkjet printer according to the second aspect, the plurality of drive signals include a drive voltage for making the amount of ink droplets to be ejected substantially double that of the normal operation. The driving signal having the following is set.

According to the present invention, the ink amount of the ink droplet ejected from the nozzle can be variably controlled to be approximately twice that in the normal operation. Therefore, by discharging the ink from the normal nozzle adjacent to the abnormal nozzle with twice the amount of ink, an appropriate dot size can be obtained, and deterioration of print quality due to missing dots can be effectively prevented.

According to a fourth aspect of the present invention, in the inkjet printer according to the first aspect, the inkjet printer forms one dot on a recording surface by landing a plurality of ink droplets. The plurality of drive signals are set to drive signals having different numbers of drive pulses corresponding to the number of ink droplets to be ejected.

According to the present invention, the number of ink droplets ejected from each nozzle can be variously controlled by a plurality of drive signals for driving the pressurizing means. Therefore, when the driving is performed by so-called multi-pulse, the number of ink droplets ejected from the normal nozzle adjacent to the abnormal nozzle can be increased, and the dot size can be easily increased. Can be prevented.

According to a fifth aspect of the present invention, in the ink jet printer according to the fourth aspect, the plurality of drive signals include a drive pulse number for making the number of ejected ink droplets approximately twice as large as that in the normal operation. The driving signal is set.

According to the present invention, the number of ink droplets ejected from the nozzles can be variably controlled to be approximately twice that in normal operation.
Therefore, by discharging the ink from the normal nozzle adjacent to the abnormal nozzle with twice the number of ink droplets, an appropriate dot size can be obtained, and deterioration of print quality due to missing dots can be effectively prevented.

According to a sixth aspect of the present invention, in the inkjet printer according to any one of the first to fifth aspects, the control means includes a nozzle for ejecting an ink droplet corresponding to a dot designated to be printed. Is determined as an abnormal nozzle by the determination means, and when printing of a dot corresponding to a normal nozzle adjacent to the abnormal nozzle is not instructed, the drive signal during the normal operation is transmitted to the normal nozzle. And controlling the driving means.

According to the present invention, when the dot corresponding to the abnormal nozzle is instructed to be printed while the dot corresponding to the normal nozzle adjacent thereto is not instructed to be printed, the control means controls the normal nozzle during normal operation. Is controlled to be driven. Therefore, for example, when printing is performed so that the periphery of one dot to be formed is blank, the dot size itself is maintained and printing is performed at a position shifted by one dot, so that fine control corresponding to the print image enables Deterioration of print quality can be effectively prevented.

According to a seventh aspect of the present invention, in the inkjet printer according to any one of the first to fifth aspects, the control means includes a nozzle for ejecting an ink droplet corresponding to a dot designated for printing. Is determined as an abnormal nozzle by the determination means, and printing of a dot corresponding to a normal nozzle adjacent to the abnormal nozzle is not instructed, and a predetermined number of dots including the dot corresponding to the abnormal nozzle In a case where printing of a continuously arranged dot group is instructed, the normal nozzle selects a drive signal during the normal operation to control the drive unit.

According to the present invention, when a dot corresponding to an abnormal nozzle and a continuous dot group including the dot are instructed to be printed, and a dot corresponding to a normal nozzle adjacent thereto is not instructed to be printed, the control means is controlled. Controls such that the normal nozzle is driven during normal operation. Therefore, for example, when printing a ruled line or the like, the dot size itself is maintained, and the ruled line or the like is printed with one dot shifted in the middle. Degradation can be effectively prevented.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

First, the structure and operation of the inkjet head of the inkjet printer according to the present embodiment will be described with reference to FIGS.

FIG. 1 is a longitudinal sectional view of the ink jet head according to this embodiment. The ink jet head shown in FIG. 1 is configured by joining a ceramic sheet 1, a piezoelectric element 2, and a nozzle plate 3.

The ceramic sheet 1 has an ink flow path formed therein, and is provided with an ink chamber 4 for supplying ink, and a plurality of pressure chambers 5 for storing ink for applying pressure for discharging ink droplets. The plurality of pressure chambers 5 are partitioned by side walls and formed in a groove shape.

The nozzle plate 3 is made of a ceramic sheet 1
It is joined to the front side. And nozzle plate 3
Are formed with a plurality of nozzles 6 for ejecting ink droplets, each of which communicates with the pressure chamber 5.
The ink droplet ejected from the nozzle 6 lands at a predetermined position on a recording paper (not shown) to form a dot.

Here, in the vicinity of the nozzle 6, clogging with foreign matter or solidified ink or the incorporation of air bubbles may occur. As a result, ink droplets cannot be ejected from the nozzle 6, or ejection becomes unstable. As a result, dots may not be formed at predetermined landing positions on recording paper. In the present embodiment, such abnormal nozzles are determined and predetermined processing is performed to maintain print quality. Details will be described later.

The piezoelectric element 2 as the ink pressurizing means includes
It is made of a sheet-shaped piezoelectric material, and is joined to the upper surface side of the ceramic sheet 1 to close an opening above the ink flow path. A drive voltage is applied to the piezoelectric element 2 by a drive unit (not shown), and the piezoelectric element 2 can be deformed in the vertical direction in FIG. 1 to pressurize the ink in the pressure chamber 5.

This will be described with reference to FIG. FIG.
FIG. 2A is a sectional view of the inkjet head taken along line XX of FIG. 1, wherein FIG. 2A illustrates a state where a driving voltage is not applied to the piezoelectric element 2, and FIG. It is.

As shown in FIG. 2A, in the upper portion of the ceramic sheet 1, it can be seen that a plurality of pressure chambers 5 are partitioned by side walls and arranged in parallel in the lateral direction. The piezoelectric element 2 bonded to the ceramic sheet 1 is provided with a large number of electrodes on an upper surface 2a and a lower surface 2b. Note that FIG.
(A) shows only three pressure chambers 5, but in practice more pressure chambers 5 can be arranged side by side.

The piezoelectric element 2 is provided with an independent electrode 20 on the upper surface 2a and an independent electrode 21 on the lower surface 2b at the upper part of each pressure chamber 5, and is provided between the two adjacent pressure chambers 5. Above the position, an independent electrode 22 on the upper surface 2a and an independent electrode 23 on the lower surface 2b are provided. In the present embodiment, the piezoelectric element 2 is driven by applying a predetermined voltage to the independent electrodes 20 and 21 and applying voltages of opposite polarities to the independent electrodes 22 and 23, respectively.

As shown in FIG. 2A, the piezoelectric element 2 is polarized in its thickness direction, and has a polarization direction shown by an arrow in FIG. 2A. That is, they are arranged so that the direction of the electric field is perpendicular to the direction of polarization, and have a so-called share mode type configuration.

In order to drive the piezoelectric element 2 configured as described above, as shown in FIG. 2B, a drive voltage is applied with the independent electrodes 20 and 21 being plus and the independent electrodes 22 and 23 being minus. . Then, the independent electrodes 20, 21
The region sandwiched between the side and the adjacent independent electrodes 22 and 23 deforms due to the occurrence of thickness slip, and acts to move the portion where the independent electrodes 20 and 21 are present to a state of being convex in the direction of the pressure chamber 5. I do. Thereby, the volume of the pressure chamber 5 decreases, the pressure of the ink in the pressure chamber 5 increases, and the ink in the pressure chamber 5 is ejected from the nozzle 6 to the outside.

At this time, as the driving voltage applied to the piezoelectric element 2 increases, the deformation amount of the pressure chamber 5 increases, and the ink amount of the ink droplet ejected from the nozzle 6 increases. This makes it possible to increase the size of a dot formed by landing an ink droplet on the recording surface. In the present embodiment, at least two drive signals can be selected in accordance with a required dot size, and each is set so that the dot size can be changed to a normal time and twice the normal size. Therefore, the voltage value of the drive signal applied to the piezoelectric element 2 can be variably controlled to approximately twice the normal value.

Subsequently, when the application of the driving voltage to the independent electrodes 20 to 23 is stopped, the deformation due to the above-mentioned thickness slip is not performed, and the operation returns to the state shown in FIG. As a result, the volume of the pressure chamber 3 returns to its original state, the pressure of the ink in the pressure chamber 5 decreases, and ink is sucked from the ink chamber 4 into the pressure chamber 5.

FIG. 3 is a block diagram showing the configuration of a control system for driving the ink jet head according to the present embodiment. As shown in FIG. 3, a controller 31 for controlling the entire control, an image data storage unit 32 for storing image data to be printed, a timing device 33 for giving a print timing to an image, A reader 34 for detecting a landing position on a recording sheet; a plurality of piezoelectric elements 2 for pressing ink;
Drivers 35 for applying the selected drive signal to
And a power supply 36 capable of supplying a sufficiently large voltage to generate a drive signal for each driver 35.

In the control block configured as described above, a process for determining a normal nozzle and an abnormal nozzle will be described with reference to a flowchart shown in FIG.
The determination process shown in FIG. 4 is a process that is performed, for example, when the power of the inkjet printer is turned on or when a predetermined interval has elapsed after startup.

When the discriminating process is started, in step S1, test printing based on a predetermined pattern is performed. Accordingly, the ink droplets ejected from each nozzle 6 land on the recording surface, and it is possible to determine whether the position is appropriate.

In step S2, the print image formed on the recording surface as a result of the test printing is read by the reader 34,
It is detected whether or not the ink droplet corresponding to each dot is properly landed. The reader 34 is, for example, a CCD
Thus, the landing of the ink droplet can be accurately read. Alternatively, the reader 34 may be constituted by a laser or the like, and the flying state of the ink droplet may be observed.

In response to the result of the detection in step S2, the controller 31 treats the nozzle 6 at which the ink droplet is ejected at the normal landing position as a normal nozzle, and does not perform the ink droplet ejection or the normal landing position. The nozzle 6 that is not ejected to the nozzle is treated as an abnormal nozzle.

In step S3, it is determined whether or not each nozzle 6 has an abnormal nozzle. That is, when an abnormal nozzle is present, it is necessary to correct the image data so that the dot corresponding to the abnormal nozzle is replaced with the normal nozzle. Therefore, a determination is made in advance in order to generate a correction parameter used in the calculation for that. is there. Printing processing using this correction parameter will be described later.

If the result of determination in step S3 is that there is an abnormal nozzle in each nozzle 6 (step S3; YE
S), the process proceeds to step S4, and a correction parameter for the abnormal nozzle is generated. This correction parameter may be in any format as long as the information can verify the positions of the abnormal nozzle and the adjacent normal nozzle with the dot positions formed in the image. Note that this correction parameter is
When the inkjet printer is started, it is initialized as if there is no abnormal nozzle.

As a result of the determination in step S3, if there is no abnormal nozzle in each nozzle 6 and all the nozzles are normal nozzles (step S3; NO), the process proceeds to step S5, and the correction parameters for the abnormal nozzle are set by the abnormal nozzle. Initialize as non-existent. As a result, for example, even in the case where the abnormal nozzle recovers its function and returns to the normal nozzle, the correction parameter is appropriately corrected.

When step S4 or step S5 is completed, in step S6, the correction parameters obtained as described above are stored in a memory means such as a RAM (not shown). Then, at the time of actual printing, the stored correction parameters are read out by the controller 31, and arithmetic processing described later is performed.

Steps S1 to S described above
The process 6 is executed by the controller 31 reading out a processing program included in a control program stored in a ROM (not shown).

Next, a printing process performed on image data will be described with reference to a flowchart shown in FIG.
The printing process illustrated in FIG. 5 is a process performed when a printing instruction is received from, for example, an externally connected host device.

When the printing process is started, step S11 is executed.
Then, image data to be printed is acquired. That is, the image data is received at the time of the print instruction, or read out when the image data is held in advance.

In step S12, the acquired image data is developed into bitmap data. The bitmap data has a data format directly corresponding to each dot of the print image. As a result, the dots to be printed are associated with the corresponding nozzles 6.

In step S13, the correction parameters already obtained are read. By comparing this correction parameter with the bitmap data, it is possible to determine how to drive and control each nozzle 6.

In step S14, the controller 31
Performs an arithmetic process based on the correction parameter and the bitmap data to determine whether or not each nozzle 6 is driven and the type of the drive signal.

Specifically, when the correction parameter indicates the presence of an abnormal nozzle, printing is not performed on the dot corresponding to the abnormal nozzle among the dots for which printing has been instructed. Instead, printing is performed from two adjacent normal nozzles.

At this time, if the printing of the dot corresponding to the adjacent normal nozzle has already been instructed, the drive signal is selected to increase the dot size for this normal nozzle and the dot printing is performed. To That is, since the driving voltage of the piezoelectric element 2 can be set to almost twice as described above, the dot size on both sides is increased to cover the missing dots.

On the other hand, when the printing of the dot corresponding to the adjacent normal nozzle is not instructed, the dot size is not increased, and the drive signal during normal operation is selected for the normal nozzle. May be printed. As a result, the area of the dots is not increased more than necessary.

Further, when the printing of the dot corresponding to the adjacent normal nozzle is not instructed, and the printing is continuously instructed in a linear shape including the dot corresponding to the abnormal nozzle, Only when the printing of the dot corresponding to the nozzle is not instructed and the printing of the dot corresponding to the abnormal nozzle is instructed in a continuous line, as described above, the normal dot size is not increased without increasing the dot size. The printing of the dots corresponding to the nozzles may be performed. Thus, the thickness of ruled lines parallel to the scanning direction or oblique ruled lines can be maintained in the printed image.

When the arithmetic processing for each dot to be printed is completed as described above, bitmap data reflecting the corrected contents can be obtained.

Next, in step S15, a drive voltage to be applied by each driver 35 to each piezoelectric element 2 is actually set in accordance with the result of the arithmetic processing. That is, one of a drive voltage when the dot size is normal and a drive voltage that is almost twice as large as that when the dot size is increased is set.

In step S16, actual printing is executed based on the developed and modified bitmap data. As a result, a print image including a large number of dots set as described above is formed on the recording paper.

The processing in steps S11 to S16 described above is also performed by the controller 3 as described above.
Numeral 1 reads out and executes a processing program included in a control program stored in a ROM (not shown).

Next, a specific example of dots actually printed as a result of performing the above-described processing will be described with reference to FIG. FIG. 6 shows an example in which five continuous dots including an abnormal nozzle at the center and normal nozzles on both sides thereof are printed.

FIG. 6A shows an example in which printing is performed as it is without taking any measures of this embodiment. The dots 61, 62, 63, and 64 of the normal nozzle are all landed at normal positions with a normal dot size. On the other hand, for the abnormal nozzle, it can be seen that the dot 65 at the position where it should be formed is not landed, but is landed as a dot 65a at a shifted position. Note that when the abnormal nozzle 65 does not discharge, the dot 65a is not landed either.

FIG. 6B shows an example of a case where printing is performed by taking measures according to the present embodiment. Normal nozzle dot 61,
6A is the same as FIG. 6A, but the dots 62a and 63a of the normal nozzle adjacent to the abnormal nozzle have the same landing position, but the dot size is almost twice as large. Recognize. Also, for the abnormal nozzle, the dot 65 that should be formed is not formed and the ejection is stopped, so that the dot 65a is not formed even at the shifted position.

Thus, when the recording paper is observed by the human eye in the state of FIG. 6B, the dots 62a and 63a corresponding to the normal nozzles adjacent to the abnormal nozzles are large, and the influence of the missing dots 65 is obtained. Figure 6
Compared to the state shown in FIG. This is effective in preventing printing performance from deteriorating due to the occurrence of abnormal nozzles. Moreover, according to the processing according to the present embodiment, the printing speed is not reduced and the configuration of the apparatus does not need to be complicated, so that the processing is more effective.

In the present embodiment described above, the case where the drive voltage for the piezoelectric element 2 is changed to twice the normal voltage is used. However, in order to increase the degree of freedom of the dot size ratio, a value other than twice is used. You may make it variable with many types of drive voltages. Further, besides varying the drive voltage, the drive waveform (rising slope, falling slope, etc.) may be varied.

In this embodiment, the case where the driving voltage is varied and the driving of the piezoelectric element 2 is controlled has been described.
In response to the use of so-called multi-pulse drive,
The driving of the piezoelectric element 2 may be controlled by varying the number of driving pulses in multiple stages. In this case, for example, in order to double the dot size, the number of drive pulses for the piezoelectric element 2 may be doubled.

In the present embodiment, the configuration using the so-called shear mode type piezoelectric element 2 arranged so that the direction of the electric field is orthogonal to the direction of polarization has been described. A configuration using a so-called unimorph type piezoelectric element 2 that is arranged so as to be in the same direction may be adopted. Further, a configuration in which the share mode type and the unimorph type are combined or a configuration in which another type of piezoelectric element 2 is used may be adopted.

Further, in the present embodiment, the configuration in which the ink is pressurized by using the piezoelectric element 2 has been described. However, bubbles are generated near the nozzle, and the ink is ejected by the force.
The present invention is applicable even when a so-called bubble jet method or another method is used.

[0065]

According to the first aspect of the present invention, since the size of the dot corresponding to the normal nozzle adjacent to the abnormal nozzle is increased, it is possible to avoid a decrease in printing speed and a complicated configuration. It is possible to prevent print quality from deteriorating due to missing dots or misalignment.

According to the second aspect of the present invention, since the ink amount can be controlled in various sizes, the dot size can be easily adjusted by increasing the ink amount from the normal nozzle adjacent to the abnormal nozzle and discharging the ink. The print quality can be increased, and the print quality can be prevented from being deteriorated by simple control.

According to the third aspect of the present invention, the normal nozzle adjacent to the abnormal nozzle ejects approximately twice the amount of ink as in normal operation, so that it is appropriate to cover missing dots and the like. The dot size is obtained, and deterioration of print quality can be effectively prevented.

According to the fourth aspect of the present invention, since the number of ink droplets can be controlled in various ways, the number of ink droplets can be increased from the normal nozzles adjacent to the abnormal nozzle and discharged easily. Can be increased, and even in the case of performing multi-pulse driving, deterioration of print quality can be prevented by simple control.

According to the fifth aspect of the present invention, the number of ink droplets is ejected from the normal nozzle adjacent to the abnormal nozzle approximately twice as many as in the normal operation. Omissions etc. are properly covered,
Deterioration of print quality can be effectively prevented.

According to the sixth aspect of the invention, when a dot corresponding to a normal nozzle adjacent to an abnormal nozzle is not instructed to be printed, a normal dot size is formed. Fine-grained control can effectively prevent print quality from deteriorating.

According to the seventh aspect of the present invention, the same control as in the sixth aspect is performed only when a print instruction of a continuous dot group including a dot corresponding to an abnormal nozzle is issued. It is possible to effectively prevent deterioration of print quality for a print image including many line drawings.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an inkjet according to an embodiment of the present invention.
FIGS. 3A and 3B are cross-sectional views taken along line XX of FIG. 3, where FIG. 3A is a diagram when a drive voltage is not applied to a piezoelectric element, and FIG.

FIG. 3 is a block diagram illustrating a configuration of a control system according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating a process of determining a normal nozzle and an abnormal nozzle in the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a printing process performed on image data in the embodiment of the present invention.

FIGS. 6A and 6B are diagrams showing specific examples of dots actually printed in the embodiment of the present invention, wherein FIG. 6A shows a case where no countermeasures are taken for abnormal nozzles, and FIG. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ceramic sheet 2 ... Piezoelectric element 3 ... Nozzle plate 4 ... Ink chamber 5 ... Pressure chamber 6 ... Nozzle 31 ... Controller 32 ... Image data storage part 33 ... Timing device 34 ... Reader 35 ... Driver 36 ... Power supply 20, 21, 22 , 23: independent electrodes 61, 62, 62a, 63, 63a, 64: dots by normal nozzles 65, 65a: dots by abnormal nozzles

Claims (7)

[Claims] 1. A printing apparatus comprising: a plurality of nozzles arranged in parallel; and a pressurizing unit configured to pressurize ink stored in an ink chamber communicating with each of the nozzles. An ink jet printer having an ink jet head that lands at a predetermined position, wherein a selected one of a plurality of drive signals set according to the size of a dot formed on a recording surface by a landed ink droplet A drive unit for driving the pressurizing unit by a drive signal, and detecting whether or not each of the ejected ink droplets has landed normally on a predetermined position on the recording surface with respect to the plurality of nozzles, and has normally landed. A discriminating unit for discriminating between a normal nozzle that has been ejected and an abnormal nozzle that has not landed normally; When it is determined that the nozzle is a normal nozzle, a drive signal during normal operation is selected to control the drive unit. When the nozzle is determined to be an abnormal nozzle by the determination unit, the abnormal nozzle is determined. Control means for stopping ejection of ink droplets from the normal nozzle adjacent to the abnormal nozzle, selecting a drive signal for increasing the dot size compared to the normal operation, and controlling the drive means, An ink jet printer comprising: 2. The inkjet printer according to claim 1, wherein the plurality of drive signals are set to drive signals having different drive voltages in accordance with the amount of ink droplets to be ejected. 3. The drive signal according to claim 2, wherein the plurality of drive signals are set to drive signals having a drive voltage that makes the amount of ink droplets to be ejected substantially double that of the normal operation. The ink-jet printer as described. 4. The inkjet printer according to claim 1, wherein one dot on the recording surface is formed by landing a plurality of ink droplets, and the plurality of drive signals are differently driven according to the number of ink droplets to be ejected. The ink jet printer according to claim 1, wherein a drive signal having a pulse number is set. 5. The drive signal according to claim 4, wherein the plurality of drive signals are set to have a drive pulse number that makes the number of ink droplets to be ejected substantially double that of the normal operation. Inkjet printer. 6. The control unit determines that a nozzle that ejects an ink droplet corresponding to a dot for which printing is instructed is determined to be an abnormal nozzle by the determination unit, and corresponds to a normal nozzle adjacent to the abnormal nozzle. The method according to any one of claims 1 to 5, wherein when the dot printing is not instructed, the normal nozzle selects a drive signal during the normal operation to control the drive unit. An inkjet printer according to item 1. 7. The control unit determines that a nozzle that ejects an ink droplet corresponding to the dot for which printing is instructed is determined to be an abnormal nozzle by the determination unit, and corresponds to a normal nozzle adjacent to the abnormal nozzle. If printing of dots is not instructed, and if printing of a predetermined number of continuously arranged dot groups including dots corresponding to the abnormal nozzle is instructed, the normal nozzle is The ink jet printer according to any one of claims 1 to 5, wherein the drive unit is controlled by selecting a drive signal during the normal operation.