JP2024071341A - Image forming device, image forming method, and program - Google Patents

Abstract

To provide an image forming device, an image forming method, and a program capable of correcting variations in impact among nozzles.SOLUTION: The image forming device for discharging ink from a recording head to a recording medium to form an image comprises: an acquisition unit that acquires print data; a conversion unit that converts the print data acquired by the acquisition unit into discharge data for discharging the ink from the recording head; a correction unit that applies a correction mask pattern for changing an ink discharge mode for each nozzle of a nozzle row composed of a plurality of nozzles arrayed in the sub-scanning direction of the recording head; and a discharge control unit that causes the ink to be discharged from each nozzle of the recording head to the recording medium on the basis of the discharge data to which the correction mask pattern has been applied.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image forming apparatus, an image forming method, and a program.

Inkjet printers are known that form images by discharging ink onto a recording medium while moving a recording medium relative to a recording head in which multiple nozzles that discharge ink are arranged. In such inkjet printers, images are formed by alternately repeating a main scanning operation in which ink is discharged from the nozzles onto the recording medium while moving the recording head in the main scanning direction, and a sub-scanning operation in which the recording head or the recording medium is moved in the sub-scanning direction. In this case, the printed image formed by the inkjet printer is composed of a large number of dots formed by discharging ink from the nozzle array. For this reason, if the formation position of the dots, which is the landing position of the ink on the recording medium, is shifted from the predetermined target position, it is not possible to draw a clean printed image on the recording medium such as paper. For this reason, techniques are known that correct the landing deviation caused by the transport accuracy of the recording medium or the nozzle ejection characteristics of the recording head.

As a technique for correcting such landing deviations, a configuration has been disclosed in which the ejection timing is controlled based on a determination of whether or not adjustment of the ejection timing is necessary based on the transport airflow, and on profile data that correlates the ejection frequency with the amount of landing deviation (see, for example, Patent Document 1).

However, the technology described in Patent Document 1 has the problem that it cannot address variations between nozzles because it corrects the deviation in landing position for each nozzle row of the print head.

The present invention has been made in consideration of the above, and aims to provide an image forming device, an image forming method, and a program that can correct the variation in landing of ink droplets for each nozzle.

In order to solve the above-mentioned problems and achieve the object, the present invention is an image forming device that forms an image by ejecting ink from a recording head onto a recording medium, and is characterized by comprising: an acquisition unit that acquires print data; a conversion unit that converts the print data acquired by the acquisition unit into ejection data for ejecting ink from the recording head; a correction unit that applies a correction mask pattern to the ejection data, which changes the manner in which ink is ejected, for each nozzle in a nozzle row composed of a plurality of nozzles aligned in the sub-scanning direction of the recording head; and an ejection control unit that ejects ink from each nozzle of the recording head onto the recording medium based on the ejection data to which the correction mask pattern has been applied.

The present invention makes it possible to correct the variation in landing spots for each nozzle.

FIG. 1 is a diagram showing an example of the external configuration of an image forming apparatus according to an embodiment. FIG. 2 is a diagram illustrating an example of the bottom surface of a carriage of the image forming apparatus according to the embodiment. FIG. 3 is a diagram illustrating an example of a hardware configuration of the image forming apparatus according to the embodiment. FIG. 4 is a diagram for explaining the landing positions of ink in a conventional image forming apparatus. FIG. 5 is a diagram for explaining an operation for correcting deviation in the landing position of ink in a conventional image forming apparatus. FIG. 6 is a diagram illustrating an example of the configuration of functional blocks of the image forming apparatus according to the embodiment. FIG. 7 is a diagram illustrating an operation for correcting deviation in the landing position of ink in the image forming apparatus according to the embodiment. FIG. 8 is a diagram showing an example of a drive waveform of a print head used to correct deviations in the landing position of ink in the image forming apparatus according to this embodiment. FIG. 9 is a flowchart showing an example of the flow of the entire operation of the image forming apparatus according to the embodiment. FIG. 10 is a diagram illustrating an operation of correcting deviation of ink landing positions in an image forming apparatus according to the first modified example. FIG. 11 is a diagram illustrating an operation of correcting the variation in ink diameter in the image forming apparatus according to the second modification. FIG. 12 is a diagram showing an example of a drive waveform of a print head used to correct the variation in the diameter of an ink droplet in an image forming apparatus according to the second modification.

Below, with reference to the drawings, embodiments of the image forming apparatus, image forming method, and program according to the present invention will be described in detail. Furthermore, the present invention is not limited to the following embodiments, and the components in the following embodiments include those that a person skilled in the art would easily conceive, those that are substantially the same, and those that are within the scope of what is called equivalent. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

Computer software refers to programs related to computer operation and other information used for computer processing that is equivalent to a program (hereinafter, computer software is referred to as software). Application software is a general term for software used to perform specific tasks. On the other hand, an operating system (OS) is software that controls a computer and allows application software and other software to use computer resources. An operating system performs basic management and control of a computer, such as input/output control, management of hardware such as memory and hard disks, and management of processes. Application software operates using the functions provided by the operating system. A program is an instruction to a computer that is combined to achieve a certain result. In addition, something equivalent to a program refers to something that cannot be called a program because it is not a direct instruction to a computer, but has properties similar to a program in that it specifies computer processing. For example, a data structure (a logical structure of data expressed by the interrelationships between data elements) corresponds to something equivalent to a program.

(General configuration of image forming apparatus)
Fig. 1 is a diagram showing an example of the external configuration of an image forming apparatus according to an embodiment. Fig. 2 is a diagram showing an example of the underside of a carriage of the image forming apparatus according to an embodiment. An example of the schematic configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to Figs. 1 and 2.

The image forming device 1 shown in FIG. 1 is a serial type image forming device that ejects ink from a recording head mounted on a carriage to form an image on a recording medium such as paper. As shown in FIG. 1, the image forming device 1 includes a platen 15, side plates 18a and 18b, a guide rod 19, a carriage 20, and a guide rail 29.

The platen 15 is a platform member on which the recording medium P onto which the ink is ejected (the object to be printed) is placed.

The left and right side plates 18a, 18b are plate members that support the carriage 20 together with a guide rod 19 that spans between them. The side plates 18a, 18b also serve to regulate the movement of the carriage in the main scanning direction (the X direction shown in FIG. 1).

The guide rod 19 is a member that spans between the side plates 18a and 18b, and supports the carriage 20 while guiding the movement of the carriage 20 in the main scanning direction.

The carriage 20 is a member that carries a recording head that ejects ink inside and moves back and forth in the main scanning direction along the guide rod 19. The carriage 20 can also move up and down (Z direction shown in FIG. 1) by an elevating mechanism (not shown). As shown in FIG. 2, the carriage 20 carries recording heads 30K, 30C, 30M, and 30Y. As shown in FIG. 2, the recording heads 30K, 30C, 30M, and 30Y are arranged in the main scanning direction (X direction) and are positioned so that they eject ink downward in the Z direction.

The recording head 30K includes a recording head 31K that ejects K (black) ink, a recording head 32K, and a recording head 33K. As shown in FIG. 2, the recording heads 31K, 32K, and 33K are each disposed at a different position in the sub-scanning direction, and each has a plurality of nozzles arranged in the sub-scanning direction.

The recording head 30C includes a recording head 31C that ejects C (cyan) ink, a recording head 32C, and a recording head 33C. As shown in FIG. 2, the recording heads 31C, 32C, and 33C are each disposed at a different position in the sub-scanning direction, and each has a plurality of nozzles arranged in the sub-scanning direction.

The recording head 30M includes recording head 31M, which ejects M (magenta) ink, recording head 32M, and recording head 33M. As shown in FIG. 2, recording heads 31M, 32M, and 33M are each positioned at a different position in the sub-scanning direction, and each has multiple nozzles arranged in the sub-scanning direction.

The recording head 30Y includes a recording head 31Y that ejects Y (yellow) ink, a recording head 32Y, and a recording head 33Y. As shown in FIG. 2, the recording heads 31Y, 32Y, and 33Y are each disposed at different positions in the sub-scanning direction, and each has a plurality of nozzles arranged in the sub-scanning direction.

Note that each of the recording heads 30K, 30C, 30M, and 30Y has three recording heads arranged at different positions in the sub-scanning direction, but this is not limited to this and each may have one, two, four or more recording heads.

When referring to any of the recording heads 30K, 30C, 30M, and 30Y or collectively, they may be simply referred to as "recording head 30." When referring to any of the recording heads or collectively, they may be simply referred to as "recording head 30." When referring to any of the recording heads 31K to 33K, 31C to 33C, 31M to 33M, and 31Y to 33Y or collectively, they may be simply referred to as "recording head 30."

In addition, the ink ejected from the recording head 30 is not limited to the CMYK color inks as described above, but may include, for example, transparent ink, metallic color ink, or fluorescent ink.

Each recording head 30 is equipped with a piezoelectric element as a pressure generating means, which contracts in response to a drive signal and ejects ink due to the pressure change that accompanies the contraction.

The guide rail 29 is a rail member that extends in the sub-scanning direction below the platen 15. The side plates 18a, 18b, the guide rod 19, and the carriage 20 move back and forth in the sub-scanning direction along the guide rail 29 as a unit.

In the example of the image forming device 1 shown in FIG. 1, the carriage 20 moves back and forth in the main scanning direction and the sub-scanning direction to eject ink onto the recording medium P, but this is not limited to the configuration. For example, the image forming device 1 may be configured to move the carriage 20 in the main scanning direction and transport the recording medium P in the sub-scanning direction, or may be configured to move the recording medium P in the main scanning direction and the sub-scanning direction.

In addition, the image forming device 1 is described as a serial type image forming device based on the carriage 20, but is not limited to this and may be a line type image forming device that performs printing in one pass.

(Hardware configuration of image forming apparatus)
3 is a diagram showing an example of a hardware configuration of the image forming apparatus 1 according to the embodiment of the present invention, the hardware configuration of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 3, the image forming device 1 includes a control unit 100, an operation panel 120, a sensor 130, a head driver 16, a main scanning motor 17, and a sub-scanning motor 18.

The control unit 100 is a controller that controls the overall operation and various processes of the image forming apparatus 1. The control unit 100 has a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a NVRAM (Non-Volatile RAM) 104, an ASIC (Application Specific Integrated Circuit) 105, a print control unit 106, a main scanning drive unit 107, an I/O 108, a communication I/F 109, and a sub-scanning drive unit 110.

The CPU 101 is a calculation device that controls the entire image forming apparatus 1. The ROM 102 is a non-volatile storage device that stores fixed data such as programs executed by the CPU 101. The RAM 103 is a volatile storage device that serves as a work area for calculation processing by the CPU 101. The RAM 103 also temporarily stores image data, etc.

NVRAM 104 is a non-volatile storage device that retains data, programs, etc. even when the power to image forming device 1 is cut off.

The ASIC 105 is an integrated circuit that processes various types of signals on image data, image processing such as sorting, and other input/output signals for controlling the entire image forming device 1.

The print control unit 106 is a control circuit that controls the ejection operation of the recording head 30 via the head driver 16 according to the control of the CPU 101. The print control unit 106 transfers data for driving the recording head 30 to the head driver 16. For example, the print control unit 106 transfers the ejection data as serial data, and outputs a transfer clock, a latch signal, a control signal, etc. required for transferring the ejection data to the head driver 16. The head driver 16 selectively applies a drive pulse constituting a voltage drive waveform corresponding to the ejection data received from the print control unit 106 to the pressure generating means of the recording head 30 based on the ejection data corresponding to one line of the recording head 30 inputted serially, thereby driving the recording head 30 to eject ink.

The main scanning drive unit 107 is a drive circuit that controls the operation of the main scanning motor 17 according to the control of the CPU 101. The main scanning motor 17 is a motor device that moves the carriage 20 in the main scanning direction according to the control of the main scanning drive unit 107.

I/O 108 is an interface circuit for acquiring information from sensor 130 and extracting information used to control each part of image forming device 1. Sensor 130 is, for example, an optical sensor that reads the print image formed on recording medium P, and a temperature sensor that detects the temperature of the heater during printing.

The communication I/F 109 is an interface circuit that transmits and receives data (print data, etc.) and signals to and from the PC (Personal Computer) 2. Specifically, the communication I/F 109 transmits and receives data and signals from the PC 2 via a cable or a network. When the communication I/F 109 communicates with the PC 2 via a network, it may be compliant with, for example, TCP (Transmission Control Protocol)/IP (Internet Protocol). The print data stored in the reception buffer of the communication I/F 109 is analyzed by the CPU 101, image processing and data sorting processing are performed by the ASIC 105, and the print data is transferred to the head driver 16 by the print control unit 106 as ejection data.

The sub-scanning drive unit 110 is a drive circuit that controls the rotational drive of the sub-scanning motor 18 according to the control of the CPU 101. The sub-scanning motor 18 is a motor device that moves the side plates 18a, 18b, the guide rod 19, and the carriage 20 together in a reciprocating manner along the guide rail 29 by rotating according to the control of the sub-scanning drive unit 110.

The operation panel 120 is a device such as a touch panel that inputs and outputs various information.

Note that the hardware configuration of the image forming device 1 shown in FIG. 3 is an example, and it is not necessary to include all of the components shown in FIG. 3, or it may include other components.

(Problems with the prior art)
Fig. 4 is a diagram for explaining the landing position of ink in a conventional image forming apparatus. Fig. 5 is a diagram for explaining an operation for correcting the deviation of the landing position of ink in a conventional image forming apparatus. Problems of the conventional technology will be described with reference to Figs. 4 and 5.

First, referring to FIG. 4, the landing position of ink ejected from the nozzles configured in the recording head 30 will be described. As shown in FIG. 4(a), the recording head 30 has a nozzle row in which multiple nozzles N are arranged in the sub-scanning direction, as described above. Here, the ink ejected from each nozzle N and landed on the recording medium P to be formed will be referred to as a dot D.

When ink is ejected from all nozzles N of the nozzle array at the same time, each dot D formed by ink ejected from the nozzle array of the recording head 30 should ideally be formed in a straight line in the sub-scanning direction as shown in FIG. 4(b). However, in reality, when ink is ejected from all nozzles N of the nozzle array at the same time due to variations in the ejection characteristics or formation positions of each nozzle N of the nozzle array, the dots D do not line up in a straight line, as shown in FIG. 4(c), and the landing positions are shifted. When the landing positions of the ink are shifted in this way, for example, fine characters or thin lines become blurred, and the image quality of the print image formed on the recording medium P is reduced.

For example, as shown in FIG. 5(a), when the recording head 30 is configured with recording heads 30_1, 30_2, 30_3, and 30_4 that eject different inks, the dots formed by the ink ejected from each are designated as dots D1, D2, D3, and D4. In this case, if the ink landing position is corrected for each nozzle row of the recording heads 30_1, 30_2, 30_3, and 30_4 as in the conventional technology, as shown in FIG. 5(b), the position can only be adjusted in the main scanning direction while the dots are not aligned in a straight line, and the deviation in the landing position cannot be corrected for each nozzle.

Below, we will explain in detail the functions of the image forming device 1 that can correct the deviation in landing position on a nozzle-by-nozzle basis to address the above problem.

(Configuration and Operation of Functional Blocks of Image Forming Apparatus)
Fig. 6 is a diagram showing an example of the configuration of functional blocks of an image forming apparatus according to an embodiment. Fig. 7 is a diagram explaining the operation of correcting deviation of the ink landing position in the image forming apparatus according to an embodiment. Fig. 8 is a diagram showing an example of a drive waveform of a print head used to correct deviation of the ink landing position in the image forming apparatus according to an embodiment. The configuration and operation of the functional blocks of the image forming apparatus 1 according to this embodiment will be explained with reference to Figs. 6 to 8.

As shown in FIG. 6, the image forming device 1 has a data acquisition unit 201 (acquisition unit), an image processing unit 202 (an example of a conversion unit), a correction unit 203, an ejection control unit 204, a movement control unit 205, a setting unit 206, and a memory unit 207.

The data acquisition unit 201 is a functional unit that acquires print data from the PC 2 via the communication I/F 109.

The image processing unit 202 is a functional unit that performs predetermined data processing such as CMYK conversion processing, gradation reduction processing, and image conversion processing on the print data acquired by the data acquisition unit 201, and generates ejection data for ejecting ink onto the recording medium P to form an image.

The correction unit 203 is a functional unit that applies a correction mask pattern, described later, to the ejection data generated by the image processing unit 202, and adjusts the ink ejection timing for each nozzle in the nozzle row of the recording head 30 to correct the ink landing position. In this case, the correction unit 203 refers to the correction mask pattern stored in the memory unit 207, and applies the correction mask pattern to the ejection data.

Here, the operation of the correction unit 203 will be described in detail. As shown in FIG. 7(a), the recording head 30 has a nozzle row in which a plurality of nozzles N are arranged in the sub-scanning direction, as described above. Here, the ink ejected from each nozzle N and landed on the recording medium P to form a dot D will be described. FIG. 7(b) shows a normal mask pattern MP1 applied to the ejection data. Here, for the sake of simplicity, the nozzle row has four nozzles (nozzles N1 to N4), and the number of pixels (dots) in the main scanning direction of the ejection data is four. Therefore, as shown in FIG. 7(b), the mask pattern MP1 is a 4×4 matrix, with each row corresponding to the nozzles N1 to N4, and each column indicating the ejection order of the ink. The value of each element of this mask pattern MP1 is composed of two values, 0 (no ejection) or 1 (ejection), as shown in the mask data shown in FIG. 7(c). By applying this mask pattern MP1 to the ejection data, ink is ejected according to the pixel value of the ejection data corresponding to 1 (ejection) of the mask pattern MP1, and ink is not ejected for the pixel value of the ejection data corresponding to 0 (no ejection). In other words, by applying the mask pattern MP1 to the ejection data, it is only possible to control whether or not to eject, and as a result, if there is variation in the ejection characteristics or formation position of each nozzle N of the nozzle row of the recording head 30, as shown in FIG. 7(d), the ink dots D ejected at the same timing from each nozzle N of the nozzle row of the recording head 30 do not line up in a straight line in the sub-scanning direction, and the landing position is shifted. In the example shown in FIG. 7(d), the ink dots D ejected from nozzle N2 are ejected at a slightly earlier timing than nozzle N1, so the landing position is slightly ahead, and the ink dots D ejected from nozzle N4 are ejected at an earlier timing than nozzle N1, so the landing position is ahead.

In this embodiment, the correction mask pattern MP shown in FIG. 7(e) is used instead of the above-mentioned mask pattern MP1. As shown in FIG. 7(e), the correction mask pattern MP is a 4×4 matrix, with each row corresponding to a nozzle N1 to N4, and each column indicating the ink ejection order. In this embodiment, the value of each element of this correction mask pattern MP is multivalued to a 2-bit value. That is, the value of each element of the correction mask pattern MP is composed of four values, 00 (no ejection), 01 (driving waveform (1) (delay 0 ms)), 10 (behavior waveform (2) (delay 1 ms)), and 11 (driving waveform (3) (delay 2 ms)), as shown in the mask data shown in FIG. 7(f).

The correction unit 203 applies the correction mask pattern MP to the ejection data. As a result, as described later, the ejection control unit 204 ejects ink corresponding to the pixel value of the ejection data according to the value of the element of the correction mask pattern MP corresponding to the pixel value. That is, when the value of the element is 01 (driving waveform (1) (delay 0 ms)), the ejection control unit 204 ejects ink using a driving waveform with no delay, as shown in FIG. 8. When the value of the element is 10 (driving waveform (2) (delay 1 ms)), the ejection control unit 204 ejects ink using a driving waveform with a timing delayed by 1 [ms], as shown in FIG. 8. When the value of the element is 11 (driving waveform (3) (delay 2 ms)), the ejection control unit 204 ejects ink using a driving waveform with a timing delayed by 2 [ms], as shown in FIG. 8. When the value of the element is 00 (no ejection), the ejection control unit 204 does not eject ink. In this way, the correction unit 203 applies the correction mask pattern MP to the ejection data, which makes it possible to correct for variations in the ejection characteristics or formation position of each nozzle N of the nozzle row of the recording head 30, and as shown in FIG. 7(g), the ink dots D ejected at the same timing from each nozzle N of the nozzle row of the recording head 30 are aligned in a straight line in the sub-scanning direction, and the deviation in the landing position for each nozzle can be corrected. Specifically, after correction, as shown in FIG. 7(g), the timing of ink ejection from nozzle N2 is delayed by 1 ms, and the timing of ink ejection from nozzle N4 is delayed by 2 ms, so that the ink dots D ejected at the same timing from each nozzle are aligned in a straight line in the sub-scanning direction.

In the example of the correction mask pattern shown in FIG. 7(e), the value of each element is set to a 2-bit value to make it multi-valued, but this is not limited to this, and by setting the value to 3 or more bits, even finer types of drive waveforms can be applied.

In the above, the timing of ink ejection is adjusted as an example of changing the ink ejection mode by delaying the drive waveform as shown in FIG. 8 depending on the element value of the correction mask pattern, but this is not limited to this. For example, the shape of the drive waveform of the voltage applied to the recording head 30 may be changed as an example of changing the ink ejection mode depending on the element value of the correction mask pattern. This makes it possible to correct the variation in the diameter of ink droplets caused by the variation in the nozzle diameter formed in the recording head 30, for example. Also, both the timing of ink ejection and the shape of the drive waveform may be adjusted as an example of changing the ink ejection mode depending on the element value of the correction mask pattern.

Let's go back to Figure 6 and continue the explanation.

The ejection control unit 204 is a functional unit that ejects ink from each nozzle of the recording head 30 onto the recording medium P via the print control unit 106 based on the ejection data to which the correction mask pattern has been applied by the correction unit 203. That is, as described above, the ejection control unit 204 ejects ink corresponding to the pixel value of the ejection data according to the value of the element of the correction mask pattern that corresponds to that pixel value.

The movement control unit 205 is a functional unit that controls the movement of the carriage 20 in the main scanning direction and the sub-scanning direction via the main scanning drive unit 107 and the sub-scanning drive unit 110 based on the ejection data.

The setting unit 206 is a functional unit that sets the values of each element of the correction mask pattern through an operation on the operation panel 120 or an operation on the PC 2. The setting unit 206 stores the set correction mask pattern in the storage unit 207. Here, the deviation of the landing position of the ink ejected from each nozzle of the nozzle row of the recording head 30 (deviation in the main scanning direction) may be obtained, for example, by printing and checking a chart for checking the deviation in advance, or the image forming apparatus 1 may be provided with a reading device that reads the printed chart, and the amount of deviation of the landing position may be automatically obtained based on the read data read by the reading device. Then, mask data to be associated with each dot may be determined from the deviation of the landing position obtained, and the correction mask pattern may be set by the setting unit 206. The setting unit 206 may automatically set the correction mask pattern from the read data indicating the deviation of the landing position described above.

The storage unit 207 is a functional unit that stores the correction mask pattern set by the setting unit 206. The storage unit 207 is realized by the RAM 103 or the NVRAM 104 shown in FIG. 3.

The above-mentioned data acquisition unit 201, image processing unit 202, correction unit 203, discharge control unit 204, movement control unit 205, and setting unit 206 are realized, for example, by the CPU 101 shown in FIG. 3 executing a program. Note that some or all of these functional units may be realized by a hardware circuit (integrated circuit) such as an FPGA or ASIC, rather than a software program.

Note that each functional unit of the image forming device 1 shown in FIG. 6 is a conceptual representation of the function, and is not limited to this configuration. For example, multiple functional units illustrated as independent functional units in the image forming device 1 shown in FIG. 6 may be configured as a single functional unit. On the other hand, the function of a single functional unit in the image forming device 1 shown in FIG. 6 may be divided into multiple functions and configured as multiple functional units.

(Overall Operation Flow of Image Forming Apparatus)
9 is a flow chart showing an example of the overall operation flow of the image forming apparatus 1 according to the embodiment, with reference to FIG.

<Step S11>
The setting unit 206 of the image forming apparatus 1 sets the values of the elements of the correction mask pattern through an operation on the operation panel 120 or an operation on the PC 2, and stores the correction mask pattern in the storage unit 207. Then, the process proceeds to step S12.

<Step S12>
The data acquisition unit 201 of the image forming apparatus 1 acquires the print data from the PC 2 via the communication I/F 109. Then, the process proceeds to step S13.

<Step S13>
The image processing unit 202 of the image forming apparatus 1 performs predetermined data processing such as CMYK conversion processing, gradation reduction processing, image conversion processing, etc. on the print data acquired by the data acquisition unit 201, and generates ejection data for forming an image by ejecting ink onto the recording medium P. Then, the process proceeds to step S14.

<Step S14>
The correction unit 203 of the image forming apparatus 1 applies the correction mask pattern stored in the storage unit 207 to the ejection data generated by the image processing unit 202. Then, the process proceeds to step S15.

<Step S15>
The ejection control unit 204 of the image forming apparatus 1 performs printing processing by ejecting ink from each nozzle of the recording head 30 onto the recording medium P via the print control unit 106 based on the ejection data to which the correction mask pattern has been applied by the correction unit 203. In this case, the movement control unit 205 of the image forming apparatus 1 controls the movement of the carriage 20 in the main scanning direction and the sub-scanning direction via the main scanning drive unit 107 and the sub-scanning drive unit 110 based on the ejection data. In other words, the ejection control unit 204 and the movement control unit 205 operate in cooperation with each other based on the ejection data. As a result, the ink ejection timing is adjusted for each nozzle in the nozzle row of the recording head 30, and the ink landing position is corrected.

As described above, in the image forming apparatus 1 according to this embodiment, the data acquisition unit 201 acquires print data, the image processing unit 202 converts the print data acquired by the data acquisition unit 201 into ejection data for ejecting ink from the recording head 30, the correction unit 203 applies a correction mask pattern to the ejection data to change the manner in which ink is ejected for each nozzle in a nozzle row composed of multiple nozzles aligned in the sub-scanning direction of the recording head 30, and the ejection control unit 204 ejects ink from each nozzle of the recording head 30 onto the recording medium P based on the ejection data to which the correction mask pattern has been applied. As a result, the ink dots D ejected at the same time from each nozzle N of the nozzle row of the recording head 30 are aligned in a straight line in the sub-scanning direction, and the landing variation for each nozzle can be corrected.

In addition, in the image forming device 1 according to this embodiment, the correction unit 203 can also apply a correction mask pattern that changes the timing of ink ejection for each nozzle in the nozzle row of the recording head 30. This makes it possible to correct for variations in the ejection characteristics or formation position for each nozzle in the nozzle row of the recording head 30.

In addition, in the image forming apparatus 1 according to this embodiment, the correction unit 203 can also apply a correction mask pattern that changes the drive waveform of the voltage applied to the recording head 30 for ejecting ink for each nozzle in the nozzle row of the recording head 30. This makes it possible to correct the variation in the diameter of ink droplets caused by the variation in the nozzle diameter formed in the recording head 30, etc.

(Variation 1)
The image forming apparatus 1 according to the modified example 1 will be described with a focus on the differences from the image forming apparatus 1 according to the present embodiment. Note that the overall configuration, hardware configuration, and functional block configuration of the image forming apparatus 1 according to the modified example are the same as those described in the above embodiment.

Figure 10 is a diagram illustrating the operation of correcting the deviation of the ink landing position in the image forming device according to the modified example 1. With reference to Figure 10, the operation of correcting the deviation of the ink landing position in the image forming device 1 according to this modified example will be described.

As shown in FIG. 10(a), the image forming device 1 according to this modified example includes a recording head 30A mounted on a carriage 20 for ejecting ink of color A, and a recording head 30B for ejecting ink of color B. Recording head 30A has a nozzle row in which a plurality of nozzles NA are arranged in the sub-scanning direction. Recording head 30B has a nozzle row in which a plurality of nozzles NB are arranged in the sub-scanning direction. Here, the ink ejected from each nozzle NA and each nozzle NB and landed on the recording medium P to be formed will be referred to as dots DA and dots DB, respectively.

In this modified example, the image forming apparatus 1 uses the correction mask pattern shown in FIG. 10(b) for the recording head 30A that ejects ink of color A, and the correction mask pattern shown in FIG. 10(e) for the recording head 30B that ejects ink of color B. The correction mask pattern shown in FIG. 10(b) is a 4×4 matrix, with each row corresponding to nozzles NA1 to NA4, and each column indicating the order of ink ejection. The correction mask pattern shown in FIG. 10(e) is a 4×4 matrix, with each row corresponding to nozzles NB1 to NB4, and each column indicating the order of ink ejection. In this modified example, the values of each element of these correction mask patterns are multi-valued to 2-bit values, as an example. That is, the values of each element of each correction mask pattern are composed of four values: 00 (no ejection), 01 (drive waveform (1) (delay 0 ms)), 10 (drive waveform (2) (delay 1 ms)), and 11 (drive waveform (3) (delay 2 ms)), as shown in the mask data shown in FIG. 10(c).

The correction unit 203 applies the correction mask pattern shown in FIG. 10(b) to the portion of the ejection data corresponding to the recording head 30A, and applies the correction mask pattern shown in FIG. 10(e) to the portion of the ejection data corresponding to the recording head 30B. As a result, the ejection control unit 204 ejects ink corresponding to the pixel value of the ejection data according to the value of the element of the correction mask pattern corresponding to the pixel value. That is, when the value of the element is 01 (driving waveform (1) (delay 0 ms)), the ejection control unit 204 ejects ink using a driving waveform with no delay, as shown in FIG. 8 above. When the value of the element is 10 (action waveform (2) (delay 1 ms)), the ejection control unit 204 ejects ink using a driving waveform with a timing delayed by 1 [ms], as shown in FIG. 8 above. When the value of the element is 11 (driving waveform (3) (delay 2 ms)), the ejection control unit 204 ejects ink using a driving waveform with a timing delayed by 2 [ms], as shown in FIG. 8 above. Furthermore, the ejection control unit 204 does not eject ink when the value of the element is 00 (no ejection). In this way, the correction unit 203 applies a different correction mask pattern to the ejection data for each ink color, making it possible to correct for variations in the ejection characteristics or formation position for each nozzle in the nozzle array of each of the recording heads 30A and 30B. As shown in FIG. 10(d) and FIG. 10(f), in each of the recording heads 30A and 30B, the ink dots DA and DB ejected at the same time from each nozzle N of the nozzle array are aligned in a straight line in the sub-scanning direction, and the deviation in the landing position for each nozzle of each ink color can be corrected. This improves the landing accuracy of multi-color ink.

Note that it is not limited to applying a different correction mask pattern for each ink color, but a different correction mask pattern may be applied for each recording head 30 or for each nozzle row of the recording head 30.

(Variation 2)
The image forming apparatus 1 according to the modified example 2 will be described with a focus on the differences from the image forming apparatus 1 according to the present embodiment. Note that the overall configuration, hardware configuration, and functional block configuration of the image forming apparatus 1 according to the modified example are the same as those described in the above embodiment.

Figure 11 is a diagram illustrating the operation of correcting the variation in ink diameter in an image forming apparatus according to Modification 2. Figure 12 is a diagram illustrating an example of a drive waveform of a recording head used to correct the variation in ink diameter in an image forming apparatus according to Modification 2. The operation of the correction unit 203 of the image forming apparatus 1 according to this embodiment will be described in detail with reference to Figures 11 and 12.

As shown in FIG. 11(a), the recording head 30 has a nozzle row in which a plurality of nozzles N are arranged in the sub-scanning direction. FIG. 11(b) shows a normal mask pattern MP1 to be applied to the discharge data. Here, for the sake of simplicity, the explanation will be given assuming that the nozzle row has four nozzles (nozzles N1 to N4) and the number of pixels (dots) in the main scanning direction of the discharge data is four. Therefore, as shown in FIG. 11(b), the mask pattern MP1 is a 4×4 matrix, with each row corresponding to the nozzles N1 to N4, and each column indicating the ink discharge order. The value of each element of this mask pattern MP1 is composed of two values, 0 (no discharge) or 1 (discharge), as shown in the mask data shown in FIG. 11(c). By applying this mask pattern MP1 to the discharge data, ink is discharged according to the pixel value of the discharge data corresponding to 1 (discharge) of the mask pattern MP1, and ink is not discharged for the pixel value of the discharge data corresponding to 0 (no discharge). That is, by applying the mask pattern MP1 to the ejection data, it is only possible to control whether or not to eject, and as a result, if there is variation in the nozzle diameter, etc., for each nozzle N in the nozzle row of the recording head 30, there will be variation in the diameter of the ink dots D ejected at the same time from each nozzle N in the nozzle row of the recording head 30, as shown in FIG. 11(d). In the example shown in FIG. 11(d), the diameter of the ink dots D ejected from nozzle N2 is larger than the diameters of the ink dots D ejected from nozzles N1 and N3, and the diameter of the ink dots D ejected from nozzle N4 is smaller than the diameters of the ink dots D ejected from nozzles N1 and N3.

In this modified example, instead of the above-mentioned mask pattern MP1, a correction mask pattern MPa shown in FIG. 11(e) is used. As shown in FIG. 11(e), the correction mask pattern MPa is a 4×4 matrix, with each row corresponding to a nozzle N1 to N4, and each column indicating the ink ejection order. In this modified example, the value of each element of the correction mask pattern MPa is multivalued to a 2-bit value. That is, the value of each element of the correction mask pattern MPa is composed of four values, 00 (no drive waveform (no ejection)), 01 (drive waveform (1) (dot diameter: medium)), 10 (drive waveform (2) (dot diameter: small)), and 11 (drive waveform (3) (dot diameter: large)), as shown in the mask data in FIG. 11(f).

The correction unit 203 applies the correction mask pattern MPa to the ejection data. As a result, the ejection control unit 204 ejects ink corresponding to the pixel value of the ejection data according to the value of the element of the correction mask pattern MPa corresponding to the pixel value. That is, when the value of the element is 01 (driving waveform (1) (dot diameter: medium)), the ejection control unit 204 ejects ink using a driving waveform that results in a medium dot diameter, as shown in FIG. 12, when the value of the element is 10 (driving waveform (2) (dot diameter: small)), the ejection control unit 204 ejects ink using a driving waveform that results in a small dot diameter, as shown in FIG. 12, when the value of the element is 11 (driving waveform (3) (dot diameter: large)), the ejection control unit 204 ejects ink using a driving waveform that results in a large dot diameter, as shown in FIG. 12. When the value of the element is 00 (no driving waveform (no ejection)), the ejection control unit 204 does not eject ink. In this way, the correction mask pattern MPa is applied to the ejection data by the correction unit 203, which makes it possible to correct for variations in the nozzle diameter, etc., for each nozzle N in the nozzle row of the recording head 30. As shown in FIG. 11(g), ink dots D ejected in the same amount from each nozzle N in the nozzle row of the recording head 30 are aligned in a straight line in the sub-scanning direction, and the variation in the diameter of the ink dots D for each nozzle can be corrected. Specifically, after correction, as shown in FIG. 11(g), nozzle N2 is ejected so that the ink dot diameter becomes small, and nozzle N4 is ejected so that the ink dot diameter becomes large, so that the diameter of the ink dots D ejected in the same amount from each nozzle becomes uniform.

In the example of the correction mask pattern shown in FIG. 11(e), the value of each element is set to a 2-bit value to make it multi-valued, but this is not limited to this, and by setting the value to 3 or more bits, even finer types of drive waveforms can be applied.

As described above, in the image forming device 1 according to this modified example, the correction unit 203 can also apply a correction mask pattern that changes the drive waveform of the voltage applied to the recording head 30 for ejecting ink for each nozzle in the nozzle row of the recording head 30. This makes it possible to correct the variation in the diameter of the ink dots caused by the variation in the nozzle diameter formed in the recording head 30, etc.

As an example of changing the ink ejection mode depending on the element values of the correction mask pattern, it may be possible to adjust both the ink ejection timing described in Figures 7 and 8 of the above embodiment and the ink dot diameter of this modified example.

In the above-mentioned embodiment and each modification, when at least one of the functions of the image forming device 1 and the PC 2 is realized by executing a program, the program is provided by being pre-installed in a ROM or the like. In the above-mentioned embodiment and each modification, the program executed by the image forming device 1 and the PC 2 may be provided by being recorded in an installable or executable format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disc). In the above-mentioned embodiment and each modification, the program executed by the image forming device 1 and the PC 2 may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. In the above-mentioned embodiment and each modification, the program executed by the image forming device 1 and the PC 2 may be provided or distributed via a network such as the Internet. Furthermore, in the above-described embodiment and each of the modified examples, the programs executed by the image forming device 1 and the PC 2 are modularized to include at least one of the functional units described above, and in terms of actual hardware, the CPU reads the programs from the above-described storage device and executes them, causing each of the above-described functional units to be loaded and generated on the main storage device.

The aspects of the present invention are as follows.
<1> An image forming apparatus that forms an image by ejecting ink from a recording head onto a recording medium,
An acquisition unit that acquires print data;
a conversion unit that converts the print data acquired by the acquisition unit into ejection data for ejecting ink from the recording head;
a correction unit that applies a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle in a nozzle row that is composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control unit that ejects ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
The image forming apparatus includes:
<2> The image forming apparatus according to <1>, wherein the correction unit applies the correction mask pattern that changes the timing of ink ejection for each of the nozzles in the nozzle row of the recording head.
<3> The image forming apparatus described in <1>, wherein the correction unit applies the correction mask pattern to change the driving waveform of the voltage applied to the recording head for ejecting ink, for each nozzle in the nozzle row of the recording head.
<4> a setting unit that sets the correction mask pattern in response to an operation input;
a storage unit that stores the correction mask pattern set by the setting unit;
Further equipped with
In the image forming apparatus according to any one of <1> to <3>, the correction unit applies the correction mask pattern stored in the storage unit to the ejection data.
<5> The image forming apparatus according to any one of <1> to <4>, wherein the correction unit applies a different correction mask pattern for each color of ink ejected from the recording head.
<6> The recording head is a plurality of heads,
In the image forming apparatus according to any one of <1> to <4>, the correction unit applies a different correction mask pattern to each of the recording heads.
<7> The image forming apparatus according to any one of <1> to <4>, wherein the correction unit applies a different correction mask pattern to each of the nozzle rows of the recording head.
<8> An image forming method for forming an image by ejecting ink from a recording head onto a recording medium, comprising:
An acquisition step of acquiring print data;
a conversion step of converting the acquired print data into ejection data for ejecting ink from the recording head;
a correction step of applying a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle of a nozzle array composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control step of ejecting ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
The image forming method includes the steps of:
<9> A computer that controls an image forming apparatus that forms an image by ejecting ink from a recording head onto a recording medium,
An acquisition step of acquiring print data;
a conversion step of converting the acquired print data into ejection data for ejecting ink from the recording head;
a correction step of applying a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle of a nozzle array composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control step of ejecting ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
This is a program for executing the above.

1 Image forming apparatus 2 PC
REFERENCE SIGNS LIST 15 Platen 16 Head driver 17 Main scanning motor 18 Sub-scanning motor 18a, 18b Side plate 19 Guide rod 20 Carriage 29 Guide rail 30, 30C, 30K, 30M, 30Y Recording head 30A, 30B Recording head 30_1 to 30_4 Recording head 31C to 33C Recording head 31M to 33M Recording head 31K to 33K Recording head 31Y to 33Y Recording head 100 Control unit 101 CPU
102 ROM
103 RAM
104 NVRAM
105 ASIC
106 Print control unit 107 Main scanning drive unit 108 I/O
109 Communication I/F
110 Sub-scanning drive unit 120 Operation panel 130 Sensor 201 Data acquisition unit 202 Image processing unit 203 Correction unit 204 Discharge control unit 205 Movement control unit 206 Setting unit 207 Memory unit D, D1 to D4 Dots DA, DB Dots MP, MPa Correction mask pattern MP1 Mask pattern N, NA, NB Nozzle P Recording medium

JP 2014-000724 A

Claims (9)

An image forming apparatus that forms an image by ejecting ink from a recording head onto a recording medium,
An acquisition unit that acquires print data;
a conversion unit that converts the print data acquired by the acquisition unit into ejection data for ejecting ink from the recording head;
a correction unit that applies a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle in a nozzle row that is composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control unit that ejects ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
An image forming apparatus comprising: The image forming device according to claim 1, wherein the correction unit applies the correction mask pattern that changes the timing of ink ejection for each nozzle in the nozzle row of the recording head. The image forming apparatus according to claim 1, wherein the correction unit applies the correction mask pattern to each nozzle in the nozzle row of the recording head, the correction mask pattern changing the drive waveform of the voltage applied to the recording head for ejecting ink. a setting unit for setting the correction mask pattern in response to an operation input;
a storage unit that stores the correction mask pattern set by the setting unit;
Further equipped with
The image forming apparatus according to claim 1 , wherein the correction section applies the correction mask pattern stored in the storage section to the ejection data. The image forming apparatus according to any one of claims 1 to 4, wherein the correction unit applies a different correction mask pattern for each color of ink ejected from the recording head. The recording head is a plurality of recording heads,
5. The image forming apparatus according to claim 1, wherein the correction section applies a different correction mask pattern to each of the recording heads. The image forming device according to any one of claims 1 to 4, wherein the correction unit applies a different correction mask pattern to each of the nozzle rows of the recording head. 1. An image forming method for forming an image by ejecting ink from a recording head onto a recording medium, comprising the steps of:
An acquisition step of acquiring print data;
a conversion step of converting the acquired print data into ejection data for ejecting ink from the recording head;
a correction step of applying a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle of a nozzle array composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control step of ejecting ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
The image forming method according to claim 1, A computer controls an image forming apparatus that forms an image by ejecting ink from a recording head onto a recording medium,
An acquisition step of acquiring print data;
a conversion step of converting the acquired print data into ejection data for ejecting ink from the recording head;
a correction step of applying a correction mask pattern to the ejection data, the correction mask pattern changing the manner in which ink is ejected, for each nozzle of a nozzle array composed of a plurality of nozzles aligned in a sub-scanning direction of the print head;
an ejection control step of ejecting ink from each of the nozzles of the print head onto the print medium based on the ejection data to which the correction mask pattern has been applied;
A program for executing.

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