JP5615574B2 - Recording apparatus and recording method - Google Patents

Description

  The present invention relates to a recording apparatus and a recording method for printing by controlling the operation of a print head. In particular, the present invention relates to an ink jet recording apparatus and a recording method.

  In a recording apparatus typified by an ink jet printer, high image quality is a major point that affects its performance as well as high printing speed. In order to achieve high image quality, it is necessary to land droplets ejected from the print head accurately and uniformly on a predetermined position on the paper.

  However, due to manufacturing variations for each nozzle of the print head, there is a problem that the print dot position is shifted due to the discharge amount, discharge direction, and nozzle position of each nozzle, and the ink does not land at the target position with high accuracy. .

  For example, Japanese Patent Laid-Open No. 2000-326497 discloses a technique that makes printing unevenness of a printed image inconspicuous by changing the dot size to be printed periodically or randomly.

JP 2000-326497 A

  The technique disclosed in Japanese Patent Laid-Open No. 2000-326497 makes it difficult for print defects to be noticeable by changing the dot size to be printed periodically or randomly to prevent ejection defects caused by nozzle variations caused by the manufacture of head nozzles. doing. Further, a line type ink jet recording apparatus that performs printing while transporting a sheet with the head position fixed is described as an example. It is also stated that the present invention is effective in a serial type ink jet recording apparatus that moves the head.

  However, in a serial type ink jet recording apparatus, an image is formed by ejecting ink from a nozzle of the head onto a sheet while fixing the head to the carriage and moving the carriage in a direction crossing the sheet conveyance direction. The dots to be formed have problems due to the movement of the carriage, in addition to the problem of positional deviation and size difference due to manufacturing variations of the nozzles of the head.

  The carriage reciprocates linearly. At this time, a plurality of bearings attached to the carriage are supported by rails. These members have not only a small amount of spring but also eccentricity and backlash, which causes vibration.

  When the carriage vibrates, the head included in the carriage vibrates similarly. It is known that the vibration has an adverse effect on the droplet discharge operation of the head. This is because the vibration of the meniscus surface, which has a large influence on the ejection operation, is affected, and the ink in the common ink chamber or actuator that secures a certain amount of ink in the head shakes. is there. Specifically, problems such as changes in the flying speed of the droplets, the size of the droplets, and the occurrence of sub-droplets discharged subsequent to the main droplets called satellites appear.

  FIG. 5A is a schematic diagram showing a printing result in a state where there is no vibration. If there is no droplet flying speed or droplet size due to vibration, each dot is relatively uniform, and as a result, it can be said that the print quality is good.

  On the other hand, FIG. 5B is a schematic diagram showing an example of a printing result when it is affected by carriage vibration. In this case, the flying speed of the droplets and the size of the droplets are periodically changed by vibration. When the flying speed of the liquid droplet is slow, the size of the liquid droplet is also reduced, so that a gap is generated between the dots and white stripes appear. On the other hand, as the flying speed of the droplet increases, the size of the droplet also increases, so that the overlap of each dot increases and black streaks appear. Even if the difference between these dots is small when compared singly, if they are ejected continuously, the difference is emphasized depending on the presence or absence of the connection between the dots, which is periodic to the human eye. It is often seen as a striped pattern. These printing defects can be said to be fatal defects as printing results.

  In order to reduce such vibrations, it is conceivable to reduce the moving speed of the carriage. However, this lowers the printing speed and reduces user productivity. This means that the performance of the printer is degraded. Further, increasing the processing accuracy of various members constituting the carriage mechanism is also effective as a measure for reducing vibration. However, in this case, there is a possibility that the cost of parts is increased.

  The present invention has been made in view of such circumstances, and a print head drive control device and a print head drive control capable of making print defects typified by stripe patterns caused by carriage vibration in a recording apparatus inconspicuous. It aims to provide a method.

The present invention relates to a print head for ejecting ink onto a recording medium, a carriage mounted with the print head and reciprocatingly scanned in the width direction of the recording medium, a reference waveform of a drive waveform of the print head, and a periodicity of the image Storage means for storing the position of a print defect, position detection means for detecting the position of the print head, random number generation means for generating a random number, and the position detected by the position detection means are stored in the storage means. If the print defect position is not present, the reference waveform is read from the storage means, the drive waveform is generated based on the reference waveform, and the position detected by the position detection means is stored in the storage means. Drive that reads the reference waveform from the storage means and generates the drive waveform based on the reference waveform and the random number. Shape generating means, and if the position detected by the position detecting means is not the position of the printing failure stored in the storage means, the fixed waveform generated by the drive waveform generating means When the print head is driven and the position detected by the position detection means is the position of the print defect stored in the storage means, the random drive waveform generated by the drive waveform generation means is used. In the recording apparatus that drives the print head, ejects the ink onto the recording medium while reciprocating the carriage, and forms an image on the recording medium, a plurality of printing modes are set according to the moving speed of the print head. has, the random number generating means, as the printing mode the moving velocity is higher of the print head, to increase the range of the random numbers to be generated And wherein the door.

The recording method of the present invention further comprises: a print head that ejects ink onto a recording medium; and a carriage that mounts the print head and reciprocates in the width direction of the recording medium, and causes the carriage to reciprocate. while discharging the ink to the recording medium, the recording method of the recording apparatus which forms an image on the recording medium, periodic defective printing position and the storage means of the reference waveform with the image of the driving waveform of the printing head Storing the print head position, detecting the position of the print head by a position detection means, generating a random number by a random number generation means, and the position detected by the position detection means is stored in the storage means When it is determined that it is not the position of the printing failure by the step of determining whether it is not the position of the printing failure or the position of the printing failure and the step of determining The position of the print defect is determined by the first drive waveform generation step of reading the reference waveform from the storage unit and generating the drive waveform based on the read reference waveform and the determination step. In this case, the reference waveform is read from the storage means, the second drive waveform generation step of generating the drive waveform based on the read reference waveform and the random number, and the position detected by the position detection means is stored in the memory If it is not the position of the print failure stored in the means, the position detected by the position detection means is stored in the storage means using the constant drive waveform generated in the first drive waveform generation step. If the position of the print failure is, the random drive waveform generated by the second drive waveform generation step is used to Possess a step of moving, wherein the recording device includes a plurality printing mode according to the moving speed of the print head, the step of generating a random number by the random number generating means, the moving speed of the print head is fast The range of the random number to be generated is increased as the printing mode is increased .

  According to the present invention, a slight change in the flying speed of a droplet generated by vibration accompanying the driving of the carriage, a slight change in droplet size, a periodic vertical stripe generated due to a slight change in satellite generation status, etc. It is possible to eliminate defects and stably achieve high print image quality.

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention. FIG. 2 is a schematic view of the carriage mechanism. FIG. 3 is a timing diagram showing an example of generating a print head drive waveform from the linear encoder. FIG. 4 is a schematic diagram showing the configuration of the carriage mechanism. FIG. 5A is a schematic diagram showing a printing result in a state where there is no vibration.

FIG. 5B is a schematic diagram illustrating an example of a printing result when affected by the vibration of the carriage.
FIG. 6 is a diagram illustrating an example of a printing result to which the embodiment of the present invention is applied. FIG. 7 is a block diagram showing the configuration of the print control unit 26 shown in FIG. FIG. 8 is a diagram showing an example in which the pulse widths of the drive waveforms are varied. FIG. 9 is a diagram illustrating an example in which the slopes of the drive waveforms at the time of state transition are varied. FIG. 10 is a diagram illustrating an example in which the peak values of the drive waveforms are varied. FIG. 11 is a diagram illustrating an example in which a drive waveform is varied by adding a preliminary pulse.

  Hereinafter, a recording apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, the recording apparatus 1 is an ink jet printer. The recording apparatus 1 includes a control unit 20 that controls the operation of the entire apparatus. The control unit 20 is a CPU 21 of a control unit that performs overall control of processing operations in the control unit 20, and a ROM 22 of a storage unit in which a program for performing a printing operation and the like are stored in advance. It is operated in the RAM 23 of the storage means used by each control unit as a work storage area during execution of the printing operation, the EEPROM 24 of the storage means constituted by a nonvolatile memory for storing the setting value and data immediately before the power is turned off, and the operation panel 44. An operation panel control unit 25 that reads the recorded state and displays information on a display unit included in the operation panel 44, a print control unit 26 that is a control unit that controls a print operation with respect to the print medium by the print head 41, and a carriage mechanism Carriage control unit 27, which is a control means for controlling the operation of 42, paper conveyance control unit 28, which is a control means for controlling the operation of the paper conveyance mechanism 43, which is composed of a grid roller or the like to convey the paper, and performs printing An image memory 30 for storing images, and an image memory book for performing writing / reading control on the image memory 30 Inclusive / control unit 31 is a control means for controlling the read, the host I / F unit 29 is an interface for input and output of host computer and the image data and control commands, with a.

  The print control unit 26 and the carriage control unit 27 control the printing operation while coordinating the print positions based on the carriage position read by the linear encoder 45.

  FIG. 2 is a schematic view of the carriage mechanism. The carriage mechanism 42 is provided with means for detecting the position of the print head 41. When ejecting droplets from the print head 41 in the recording apparatus 1, a linear encoder 45 including a case sensor attached to the carriage 420 and a linear scale 421 fixed along the travel path of the carriage 420 are used. The current position during the reciprocating operation of the carriage 420 is detected, and information is input to the control unit 20. The control unit 20 recognizes the position of the print head 41 and generates ink ejection timing, thereby improving the positional accuracy of the droplets that have landed on the paper.

  FIG. 3 is a timing diagram showing an example of generating a print head drive waveform from the linear encoder. It is an example showing the relationship between the count of the linear encoder 45 and the drive waveform of the print head 41 in the case of 2-channel output. If the rising and falling of the A phase and the B phase of the scale sensor are used as triggers, a discharge trigger signal can be generated at a cycle of 4 times the pitch carved in the linear scale 421. For example, a 720 DPI signal can be generated by a combination of a 180 LPI linear scale 421 and a linear encoder 45. By using this as a trigger and applying a print head drive waveform, it is possible to perform an ejection movement difference at a resolution of 720 DPI in the carriage scanning direction. The drive waveform shown in FIG. 3 is an example in which ejection is performed by deflecting the piezo actuator from the stationary position to both sides, and is generally called a pulling waveform. The ink drawing operation is given by the ON pulse 422, and the pushing operation is given by the OFF pulse 423. The ON pulse 422 and the OFF pulse 423 form a drive waveform for one ejection operation. In general, the pulse widths of these drive waveforms are often uniquely determined by the internal structure of the head and the type of ink to be ejected. Further, the pulse crest value is made variable according to the environmental temperature, so that the flying speed of the droplet and the size of the droplet are kept constant.

FIG. 4 is a schematic diagram showing the configuration of the carriage mechanism.
The carriage mechanism 42 includes a motor 423 for reciprocating the carriage 420 on the rail 429, a motor driving circuit, a timing belt 426, a driving pulley 424, and a driven pulley 425 for transmitting the driving force of the motor to the carriage 420. . The carriage 420 is fixed to an endless belt SUS belt 427. The SUS belt 427 is connected to the driven pulley 425 and rotates in conjunction with the driven pulley 425. The print head 41 is fixed to the carriage 420. The print head 41 ejects ink onto a paper 428 as a recording medium while moving.

  Incidentally, the carriage mechanism 42 of the large-format ink jet printer passes through many members until the rotation from the motor 423 is converted into the linear motion of the carriage 420 as shown in the example of FIG. Specifically, the timing pulley 424, the timing belt 426, the driven pulley 425, the SUS belt 427, and the like. Further, when the carriage 420 is reciprocated, a plurality of bearings 430 attached to the carriage 420 are supported by rails 427. These members have a certain amount of spring property, and also have eccentricity and backlash, which may cause periodic or sudden vibrations. This becomes more conspicuous as the large-format inkjet printer has a longer driving distance of the carriage 420. When these vibrations appear as vibrations during the traveling of the carriage 420, it is conceivable that the ejection timing of the liquid droplets ejected from the print head 41 is given periodicity. However, as described above, since the discharge trigger signal is generated based on the physical position of the carriage 420 on the travel path using the linear scale 421 and the linear encoder 45, errors in the discharge timing can be minimized. is made of.

  Here, a drive control method of the print head 41 will be described with reference to FIG. FIG. 7 is a block diagram showing the configuration of the print control unit 26 shown in FIG. Although the control unit 260 is mainly handled by the CPU 21 in FIG. 1, a part of the control unit 260 may be included in the print control unit 26. The discharge trigger generation circuit 261 outputs the discharge trigger signal of FIG. 3 generated by the linear encoder 45 to the print head 41. The discharge data transfer circuit 262 transfers print data to be output on the sheet at the time when the discharge trigger signal is generated to the print head 41 in advance. The drive waveform generation circuit 263 reads a pulse shape of a drive waveform serving as a reference determined by the internal structure of the print head 41 and the type of ink to be ejected from the memory 266 via the control unit 260, and a value generated by the random number generation circuit 265. Is output to the print head 41. The memory 266 may be provided in a specific part in the EEPROM 24 or a specific part in the RAM 23.

  FIG. 8 is a diagram showing an example in which the pulse widths of the drive waveforms are varied. FIG. 9 is a diagram illustrating an example in which the slopes of the drive waveforms at the time of state transition are varied. FIG. 10 is a diagram illustrating an example in which the peak values of the drive waveforms are varied.

  The part that randomly varies the waveform by applying a random number to the reference drive waveform is as shown by the arrow in FIG. 8, and the part that varies is the pulse width or indicated by the arrow in FIG. As can be seen, the variable part is the pulse width and the slope at the time of pulse state transition. Further, the wave height may be changed as indicated by an arrow in FIG. The drive waveform generation circuit 263 determines a pulse width according to a random number value with respect to the pulse shape of the reference drive waveform serving as a reference, and generates a drive waveform. Specifically, the pulse width is determined and stored according to the random value, the pulse width is acquired according to the random value, and the drive waveform is generated. The drive waveform generation circuit 263 determines a slope in accordance with a random number value with respect to the pulse shape of the reference drive waveform serving as a reference, and generates a drive waveform. Specifically, the inclination is determined and stored according to the value of the random number, the inclination is acquired according to the value of the random number, and the drive waveform is generated. The drive waveform generation circuit 263 is means for generating a drive waveform. The drive voltage generation circuit 264 reads a reference drive voltage value determined based on a temperature measurement value of a temperature sensor (not shown) inside the print head 41 from the memory 266 via the control means 260, and the random number generation circuit 265 generates the read drive voltage value. The value is applied and output to the print head 41. The random number applied here is a peak value of a pulse as shown in FIG. Specifically, the voltage is determined and stored according to the value of the random number, the voltage is acquired according to the value of the random number, and the drive voltage is generated. The drive voltage generation circuit 264 is means for generating a drive voltage having a drive waveform.

  In addition, as shown in FIG. 11, a method is considered in which a plurality of preliminary pulses having a narrow pulse width are added in front of a reference driving waveform for ejecting a main droplet, and the number is generated with a random number to vary the driving waveform. It is done. Although the preliminary pulse does not have energy for ejecting droplets, it can vibrate the ink meniscus surface of the nozzle. That is, since different meniscus vibrations can be given depending on the time from the preliminary pulse to the reference drive waveform and the number of preliminary pulses, it is possible to intentionally change the flying speed of the ejected droplet and the size of the droplet. it can. In this case, the gradation for each nozzle of a general inkjet head can be used. That is, the number of spare pulses to be added corresponds to the gradation of the drawing data input to the head, and it is easily expanded for each nozzle by expanding the number of bits to the width of a random number that generates 1-bit data input at the time of ejection. Variation can be brought about. This method is useful because the circuit of the head becomes complicated and large in order to provide different peak values and pulse widths simultaneously for each nozzle.

  Which part is variable with respect to the reference drive waveform is stored in advance in the memory 266 as variable part information. The variable part information is read, and a variable part is determined based on the information. A drive waveform is varied by applying a random number to the variable portion. The variable part information can be selected by a user operation on the operation panel 44 or a control command from the host computer.

  By randomly varying at least a part of the basic drive waveform, the landing position or dot size of the ejected ink can be varied randomly. Therefore, the defective print portion is less noticeable.

  The random numbers generated by the random number generation circuit 256 may be performed individually or in combination with the drive waveform generation circuit 263 and the drive voltage generation circuit 264.

  When the random number generated by the random number generation circuit 256 is applied to the drive waveform generation circuit 263 and the drive voltage generation circuit 264, the target drive waveform is an ON pulse that constitutes the drive waveform for one ejection operation of FIG. And OFF pulses may be performed individually or in combination.

  When the random number generated by the random number generation circuit 265 is applied to the drive waveform generation circuit 263 and the drive voltage generation circuit 264, it is not a good idea to increase the range indefinitely. This is because there is a possibility that the ejection operation itself may become unstable by increasing the deviation from the reference drive waveform. For this reason, it is necessary to set a random variation range only within a range in which printing defects such as periodic vertical stripes due to slight vibrations are inconspicuous. For this range, it is conceivable to store experimentally determined values in the printer firmware. However, if the degree of vibration may vary due to individual differences in the printer, it may be individually appropriate for the manufacturing process. It is also possible to adjust the range and store it in the EEPROM 24.

  In this case, at a position where there is no printing defect such as a periodic vertical stripe, the drive waveform generation circuit 263 generates the reference drive waveform as a drive waveform as it is. Alternatively, a constant variable determined with respect to the reference drive waveform is generated as the drive waveform. This generates a first drive waveform corresponding to a position where there is no printing defect such as a periodic vertical stripe by the drive waveform generation circuit 263. At a position where there is a printing defect such as a periodic vertical stripe, the drive waveform generation circuit 263 varies the variable portion of the reference drive waveform in accordance with the random number generated by the random number generation circuit 265 with respect to the reference drive waveform. Generate a drive waveform. This generates a second drive waveform corresponding to a position where there is a printing defect such as a periodic vertical stripe by the drive waveform generation circuit 263. Then, the print head 41 is driven using the first drive waveform at a position where there is no printing defect such as a periodic vertical stripe, and an image is formed, and the second drive is performed at a position where there is a printing defect such as a periodic vertical stripe. The print head 41 is driven using the waveform to form an image.

  Further, instead of applying the random number generated by the random number generation circuit 265 to the drive waveform generation circuit 263 or the drive voltage generation circuit 264, a random number sequence generated in advance is stored in the memory 266 and the ejection operation is performed. It is also conceivable that the random number is sequentially read from the random number sequence every time and the drive waveform generation circuit 263 or the drive voltage generation circuit 264 is applied when the drive waveform is output to the print head 41. Of course, the pulse shape of the drive waveform and the peak value itself may be stored. In this case, after reading the stored number, the operation of reading again from the beginning is repeated. Therefore, if the number stored in advance is small, the cycle may appear in the print result, and therefore it is necessary to store as many as possible.

  The operation of each function included in the print control unit 26 has been described individually. In practice, however, the discharge trigger generation circuit 261, the discharge data transfer circuit 262, the drive waveform generation circuit 263, the drive voltage generation circuit 264, and the like. By operating in parallel, it becomes possible to perform high-speed printing continuously.

  Here, in addition, the ejection failure position and ejection failure type are stored in advance in the memory 226 for each print mode. This stores information related to ejection defects having information specific to the device in advance, that is, information on the result of an experiment in advance or information specified in the adjustment process in the manufacturing process. Therefore, the memory 226 is constituted by a specific part of the EEPROM 24. Then, based on this information, the drive waveform is varied to make the ejection failure inconspicuous.

  The print mode includes a mode corresponding to the print speed even in a mode corresponding to image quality such as high image quality and low image quality. Even in these modes, defective ejection portions are inherently generated. The ejection failure position is a position of the print head 41 that can be determined based on the position of the carriage 420 by the linear scale 421 and the linear encoder 45. The ejection failure type is information indicating a difference between a planned landing dot and an actual landing dot. It includes at least one piece of information on the direction of displacement, the distance of displacement, and the difference in dot size. Information indicating this difference is ranked, and the range of random numbers generated by the random number generation circuit 256 is determined according to the rank.

  Specifically, a value obtained by dividing the generated random number by the number corresponding to the rank, or an integer part of this value is used, or a random number in a range corresponding to the rank is generated in advance for the random number generation circuit 256. You can ask for it. Then, a drive waveform is generated according to the random number. The range of random numbers to be generated is increased as the rank of the degree of failure is large, for example, the width of white stripes or black stripes is large, so that the degree of deformation of the drive waveform varies greatly. When the degree of failure is small, the range of random numbers to be generated is reduced, the degree of deformation of the drive waveform is reduced, and the waveform is varied in a range close to the reference waveform.

  For example, the higher the printing speed, the greater the degree of printing failure, so it is desirable to increase the range of random numbers to be generated as the printing speed increases.

  When ink is ejected at an ejection failure position, the print head 41 is driven using a drive waveform created according to the rank. The print head 41 can be driven for each nozzle.

  In addition, the function of changing the pulse shape of the drive waveform of the present invention may be provided with a switch for enabling and disabling as necessary. Strictly speaking, this function varies the droplet landing accuracy and droplet size, because this function intentionally gives an irregular change larger than the change in droplet identity caused by vibration. It will be. For example, in a high image quality mode or the like in a printer having a plurality of print modes, there is one in which the carriage moving speed is intentionally slowed to obtain high image quality in exchange for the print speed. By applying the present invention to these, it can be considered that the image quality is rather deteriorated. In this case, it is preferable to fix the basic drive waveform and apply it to the print head. In addition to assigning valid / invalid according to the print mode in advance, the user may select valid / invalid by panel operation or the like.

  FIG. 6 is a diagram illustrating an example of a printing result to which the embodiment of the present invention is applied. The change in the dot size that appeared periodically as shown in FIG. 5 (b) became dots of random size and became inconspicuous.

  As explained above, printing such as slight vertical flight stripes generated by slight changes in droplet flying speed, slight droplet size changes, and slight satellite generation conditions caused by vibrations caused by carriage drive By changing the pulse shape of the drive waveform randomly and applying it to the print head against defects, it is possible to give another irregular change and make print defects such as periodic vertical stripes inconspicuous. . As a result, it can be expected to stably achieve high print image quality.

DESCRIPTION OF SYMBOLS 1 ... Recording device, 20 ... Control part, 21 ... CPU, 22 ... ROM, 23 ... RAM, 24 ... EEPROM, 25 ... Operation panel control part, 26 ... Print control unit, 27 ... carriage control unit, 28 ... paper conveyance control unit, 29 ... host I / F unit, 30 ... image memory, 31 ... image memory write / read control unit , 41 ... print head, 42 ... carriage mechanism, 43 ... paper transport mechanism, 44 ... operation panel, 45 ... linear encoder

Claims (7)

A print head for ejecting ink onto a recording medium;
A carriage wherein the mounting the printing head, reciprocally scans in the width direction of the recording medium,
Storage means for storing a reference waveform of a drive waveform of the print head and a position of periodic printing failure of the image;
Position detecting means for detecting the position of the print head;
Random number generating means for generating random numbers;
If the position detected by the position detection means is not the position of the printing failure stored in the storage means, the reference waveform is read from the storage means, the drive waveform is generated based on the reference waveform, When the position detected by the position detection means is the position of the print failure stored in the storage means, the reference waveform is read from the storage means, and the drive waveform is generated based on the reference waveform and the random number Driving waveform generating means for
And when the position detected by the position detection means is not the position of the print failure stored in the storage means, the print head is driven by the constant drive waveform generated by the drive waveform generation means. If the position detected by the position detecting means is the position of the print failure stored in the storage means, the print head is driven by the random drive waveform generated by the drive waveform generating means. And
In the recording apparatus for ejecting the ink to the recording medium while reciprocating the carriage, and forming an image on the recording medium,
A plurality of print modes according to the moving speed of the print head;
The recording apparatus according to claim 1, wherein the random number generation means increases the range of the random number to be generated in the printing mode in which the moving speed of the print head is faster . The reference waveform has a variable portion that varies based on the random number, and a non-variable portion that does not vary,
If the position detected by the position detection means is not the position of the printing failure stored in the storage means, the drive waveform generation means reads the reference waveform from the storage means and determines the variable portion in advance. The drive waveform is generated by combining the variable portion and the non-variable portion that are variable based on the initial value, and the position detected by the position detection means is stored in the storage means In the case of a printing failure position, the drive waveform is read by reading the reference waveform from the storage means, changing the variable portion based on the random number, and combining the variable portion and the non-variable portion that are variable. The recording apparatus according to claim 1, wherein:   The drive waveform generating means can generate a non-variable portion that is a pulse for discharging a main droplet and a preliminary pulse as the variable portion before the non-variable portion, and the position detected by the position detecting means is the position detected by the position detecting means. If it is not the position of the printing failure stored in the storage means, the reference waveform is read from the storage means, the variable portion is varied based on the predetermined initial value, and the variable portion and the variable portion The drive waveform is generated by combining with a non-variable portion, and when the position detected by the position detection means is the position of the print failure stored in the storage means, the preliminary pulse is used as the random number. The recording apparatus according to claim 2, wherein the drive waveform is generated by combining the non-variable part and the variable part.   4. The recording apparatus according to claim 3, wherein the variable portion varies the number of the spare pulses based on the random number. The recording apparatus according to claim 2 , wherein the variable portion varies a rising or falling position of the reference waveform based on the random number . The printing failure is divided into a plurality of types, and further stores the type at the position together with the position of the printing failure,
The random number is the random number generating means for generating, to limit the scope of the random numbers to be generated in response to the type of the defective printing position,
The driving waveform generating means, in the defective printing position, on the basis of the said random number variable portion is generated, the change of the driving waveform is limited based on the random number which the range is limited according to the type recording apparatus according to any one of the preceding claims 2, characterized in that. A print head for ejecting ink onto a recording medium;
Mounting the print head has a carriage which reciprocally scans in the width direction of the recording medium, the carriage ejecting the ink to the recording medium while the reciprocal scanning, to form an image on said recording medium In the recording method of the recording apparatus,
Storing a reference waveform of a drive waveform of the print head and a position of periodic printing failure of the image in a storage unit;
Detecting the position of the print head by a position detecting means;
A step of generating a random number by means of random number generation;
Determining whether the position detected by the position detection means is not the position of the print failure stored in the storage means or the position of the print failure;
A first drive waveform generating step of reading the reference waveform from the storage means and generating the drive waveform based on the read reference waveform when it is determined by the determining step that the position is not the print defect position; ,
When it is determined by the determining step that the position is the printing defect position, the reference waveform is read from the storage unit, and the driving waveform is generated based on the read reference waveform and the random number. Waveform generation process;
If the position detected by the position detecting means is not the position of the printing failure stored in the storage means, the position detecting means uses the constant driving waveform generated by the first driving waveform generating step. A step of driving the print head using the random drive waveform generated by the second drive waveform generation step when the position detected by the step is a position of the print failure stored in the storage means When,
I have a,
The recording apparatus has a plurality of printing modes according to the moving speed of the print head, and the random number generating means generates the random number by generating the random number as the printing mode has a higher moving speed of the print head. A recording method characterized by enlarging the range .

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