JP2022085360A - Liquid ejection device, inkjet recording device and correction method of liquid ejection characteristics - Google Patents

Abstract

To suppress wasteful liquid consumption in observation of liquid discharge characteristics for correcting temporal change of the liquid discharge characteristics.SOLUTION: A device 1 for discharging a liquid from a plurality of nozzles 4 includes: observation means 60 for observing liquid discharge characteristics of a liquid discharged from a partial nozzle among the plurality of nozzles; and correction means 40 for correcting the liquid discharge characteristics of a group of nozzles including the partial nozzle and the other nozzles based on observation result of the observation means.SELECTED DRAWING: Figure 4

Description

The present invention relates to a liquid ejection device, an inkjet recording apparatus, and a method for correcting liquid ejection characteristics.

Conventionally, a device for discharging a liquid having a liquid discharge head including a plurality of nozzles and discharge energy generating means of each nozzle and a drive signal generating means for generating a drive signal of each discharge energy generating means is known. ..

For example, in Patent Document 1, ink (liquid) is ejected from a nozzle communicating with a pressure generating chamber by vibrating a vibrating plate with a piezoelectric vibrator (discharging energy generating means) to change the volume of the pressure generating chamber. An inkjet printer (a device that ejects a liquid) is disclosed. In this printer, the Helmholtz resonance cycle of the ink in the pressure generation chamber fluctuates due to the gradual deterioration of the vibrating plate that comes into contact with the solvent-based ink, and the ink ejection speed changes over time, and the ink landing position (ejection). Control is performed to correct the deviation (position). In this control, ink is ejected from all the nozzles to be corrected to form a test pattern on a resin film (recording material), and the ink landing position deviation is observed from the formed test pattern. Then, the current Helmholtz resonance period is calculated from the observation result, and the drive signal corresponding to all the nozzles is corrected.

However, the conventional device for discharging a liquid has a problem that the liquid is wasted in observing the liquid discharge characteristics for compensating for changes in the liquid discharge characteristics with time.

In order to solve the above-mentioned problems, the present invention is a device for discharging liquid from a plurality of nozzles, and observations for observing the liquid discharge characteristics of the liquid discharged from some of the plurality of nozzles. It is characterized by having a means and a correction means for correcting the liquid discharge characteristics of a group of nozzles including the partial nozzle and the other nozzles based on the observation result of the observation means.

According to the present invention, wasteful consumption of liquid can be suppressed in the observation of liquid discharge characteristics for compensating for changes in liquid discharge characteristics over time.

The block diagram which shows the main structure of the adjustment system which adjusts the liquid ejection characteristic of the inkjet recording apparatus in embodiment. A plan view of the inkjet recording device of the adjustment system as viewed from vertically above the recording material. It is a figure which shows the nozzle arrangement structure of the recording head which is provided more than 1 for each recording part of the head unit of the inkjet recording apparatus. The figure which shows the hardware composition of the main part of the inkjet recording apparatus. The figure which shows the hardware composition of the head drive part of the head unit. A plan view of the image pickup device of the adjustment system as viewed from above the recording material. The figure of the state which the image pickup unit of the image pickup apparatus was seen from the image pickup surface side. The block diagram which shows the hardware composition of the image pickup apparatus. A plan view of the image sensor mounted on the inkjet recording device as viewed from vertically above the recording material. The block diagram which shows the hardware composition of the arithmetic unit of the adjustment system. (A) to (d) are explanatory views showing an example of the first test chart printed on the recording material. The flowchart which shows the flow of the generation processing of the initial error correction information executed in the arithmetic unit. Explanatory drawing which shows an example of the image data of the 1st test chart. (A) to (c) are explanatory views which show an example of the correction operation of a drive waveform. The flowchart which shows the flow of the correction operation of the drive voltage of each recording head during the image formation operation. (A) to (d) are graphs for explaining the change in the liquid discharge characteristic of each nozzle due to the change with time. An explanatory plan view of the main part of the device, and FIG. 18 is an explanatory side view of the main part of the device. Explanatory view of the main part of the device. Explanatory view of the main part of the unit. Frontal explanatory view of the unit.

Hereinafter, an embodiment in which the present invention is applied to an inkjet recording device as an image forming device which is a device for discharging a liquid will be described.
In this embodiment, an image forming device that forms an image on a recording material will be described as an example of a device that discharges a liquid, but the present invention is not limited to this, and for example, a solid that discharges a liquid to form a three-dimensional object. It can also be applied to object modeling equipment.

FIG. 1 is a block diagram showing a main configuration of an adjustment system for adjusting the liquid ejection characteristics of the inkjet recording apparatus according to the present embodiment.
The adjustment system shown in FIG. 1 observes the liquid ejection characteristics of each nozzle of the inkjet recording device for each nozzle at the time of manufacturing or factory shipment, and is individual for each nozzle based on the observation result for each nozzle. Adjust each drive signal.

The adjustment system of the present embodiment mainly includes an inkjet recording device 1, an image pickup device 100, and an arithmetic unit 200. Upon adjustment, the inkjet recording apparatus 1 prints a first test chart (an example of a chart image of a specific pattern), which will be described later, on a recording material. The image pickup apparatus 100 captures (observes) the printed first test chart. The arithmetic unit 200 detects the liquid ejection characteristics such as the deviation amount of the landing position for each nozzle of the inkjet recording apparatus 1 and the droplet amount which is the ejection amount by analyzing the imaging data of the first test chart. Then, based on this detection result, the arithmetic unit 200 corrects an error (deviation) in the landing position of each nozzle, or corrects an error in the amount of droplets ejected from each nozzle. Information (hereinafter referred to as "initial error correction information") is generated and set in the inkjet recording apparatus 1. The inkjet recording device 1 controls ink ejection of each nozzle based on the set initial error correction information. As a result, it is possible to obtain a printed matter in which liquid ejection characteristics such as an error in the landing position (deviation) and an error in the amount of droplets (deviation) in each nozzle are adjusted, and high image quality can be realized.

In the example of FIG. 1, the inkjet recording device 1, the arithmetic unit 200, and the image pickup device 100 are shown as physically independent and separate devices. However, these devices may be physically one by providing the inkjet recording device 1 with the calculation function of the calculation device 200 and the image pickup function of the image pickup device 100. Alternatively, these devices may be provided with either the arithmetic function of the arithmetic unit 200 or the imaging function of the imaging apparatus 100 in the inkjet recording apparatus 1.

FIG. 2 is a plan view of the inkjet recording device 1 as viewed from vertically above the recording material P0.
The recording material P0 is, for example, paper, may be roll paper (continuous paper), cut paper, or the like, or may be various media other than paper. The recording material P0 is conveyed along the conveying direction indicated by the arrow in FIG. The head unit 2 is supported so as to face the recording surface of the recording material P0 while maintaining a predetermined distance.

The head unit 2 includes a K recording unit 2K, a C recording unit 2C, and an M recording unit for each color provided corresponding to black (K), cyan (C), magenta (M), and yellow (Y) inks. It is provided with 2M and a Y recording unit 2Y. A color image is formed on the recording material P0 by the head unit 2 ejecting ink droplets in synchronization with the paper transport speed. The number of recording heads and the color of the ink provided in the head unit 2 are arbitrary. For example, the head unit 2 may include only a black head unit and record in a black single color.

FIG. 3 is a diagram showing a nozzle arrangement configuration of a plurality of recording heads 3 provided for each recording unit of the head unit 2.
In FIG. 3, the recording heads 3 are arranged at a predetermined pitch p in a direction in which a plurality of nozzles 4 are orthogonal to the paper transport direction (hereinafter, appropriately referred to as “nozzle row direction”). In the case of the example of FIG. 3, two rows of nozzle rows are provided for one recording head 3. The first row of nozzles and the second row of nozzles are arranged with a p / 2 shift along the nozzle row direction. This enables high-resolution printing in the nozzle row direction.

FIG. 4 is a diagram showing a hardware configuration of a main part of the inkjet recording device 1.
In FIG. 4, the inkjet recording device 1 connects a control unit 40, a head unit 2, a transport drive unit 51, an operation display unit 52, an input / output interface 53, and an image sensor 60 to each other via a bus line 54. It is composed of.

The head unit 2 has a head drive unit 20 and a recording head 3. The head unit 2 supplies a drive waveform (drive signal) for deforming the piezoelectric element in the head drive unit 20 to the head drive unit 20 in response to a control signal input from the control unit 40. As a result, liquid ink is ejected from the nozzle 4 of the recording head 3.

The control unit 40 includes a CPU (Center Processing Unit) 41, a storage unit 42, a RAM (Random Access Memory) 43, and a ROM (Read Only Memory) 44. The CPU 41 reads out various control programs and setting data stored in the ROM 44, stores them in the RAM 43, executes them, and performs various arithmetic processes. Further, the CPU 41 controls the overall operation of the inkjet recording device 1.

The storage unit 42 stores a print job (image formation instruction) input from the arithmetic unit 200 via the input / output interface 53 and image data to be printed. Further, the storage unit 42 stores initial error correction information for correcting the landing position and the droplet amount (discharge amount) of each nozzle 4 generated based on the first test chart described later. Further, in the storage unit 42, correction information for correcting the landing position and the droplet amount (discharge amount) of each nozzle 4 generated based on the second test chart described later (hereinafter referred to as "time change correction information"). ) Is also remembered.

The transport drive unit 51 supplies a drive signal to the transport motor based on the control signal supplied from the control unit 40, and transports the recording material P0 at a predetermined speed and timing. The operation display unit 52 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as a touch panel arranged so as to be superimposed on the operation keys and the screen of the display device. The operation display unit 52 causes the display device to display various information, and supplies an operation signal corresponding to the user's input operation to the input device to the control unit 40.

The input / output interface 53 mediates the transmission / reception of data between an external device such as the arithmetic unit 200 and the control unit 40. The bus line 54 is a path for transmitting and receiving signals between the control unit 40 and other components.

The image sensor 60 is arranged in the inkjet recording device 1 so as to face the recording surface of the recording material P2 on which the second test chart described later is printed by the inkjet recording device 1. The image sensor 60 is composed of, for example, a line camera device, an area camera device, or the like, and captures a part of the recording material P2 in the width direction in synchronization with the transport speed of the recording material P2 to generate image data.

FIG. 5 is a diagram showing a hardware configuration of the head drive unit 20 of the head unit 2.
In FIG. 5, the head drive unit 20 includes a plurality of drive waveform correction units 21-1 to 21-N corresponding to each of the plurality of nozzles 4, a head control unit 22, a basic drive waveform generation unit 23, and drive waveform correction information. A holding portion 24 is provided.

The head control unit 22 converts the image data input from the control unit 40 into a control signal of each recording head 3-1 to 3-N (where "N" is the number of nozzles). The basic drive waveform generation unit 23 enables a reference ejection operation based on a control signal input from the head control unit 22 according to a printing environment such as an image pattern, a transport speed, and temperature and humidity. Generate a drive waveform.

The drive waveform correction information holding unit 24 stores information indicating the nozzle number of the nozzle requiring correction and correction information indicating the correction amount.

The drive waveform correction units 21-1 to 21-N read the correction information of the corresponding nozzle numbers from the drive waveform correction information holding unit 24, and are supplied from the basic drive waveform generation unit 23 based on the read correction information. Correct the basic drive waveform of the drive voltage. Then, the drive waveform correction units 21-1 to 21-N supply the corrected drive waveform to the piezoelectric elements in the corresponding recording heads 3-1 to 3-N, respectively. As a result, the liquid discharge characteristics of each nozzle 4 are appropriately corrected, the difference in the liquid discharge characteristics between the nozzles 4 is reduced, and the target liquid discharge characteristics can be obtained for any of the nozzles 4.

FIG. 6 is a plan view of the image pickup apparatus 100 as viewed from vertically above the recording material P1.
The image pickup apparatus 100 has a configuration in which two imaging units 101A and 101B are supported so as to face the recording surface of the recording material P1 on which the first test chart is printed by the inkjet recording apparatus 1. The recording material P1 on which the first test chart is printed is conveyed along the conveying direction shown in FIG. 6, and the first test chart is imaged by the image pickup units 101A and 101B. The image pickup units 101A and 101B are composed of, for example, a line camera device or an area camera device, and image the entire width direction of the recording material P1 in synchronization with the transport speed of the recording material P1 to generate image data. In the present embodiment, the two imaging units 101A and 101B are arranged at different positions in the width direction of the recording material so as to image the entire width direction of the recording material P1.

FIG. 7 is a view of the image pickup units 101A and 101B as viewed from the image pickup surface side. The two imaging units 101A and 101B have substantially the same configuration.
As shown in FIG. 7, the image pickup units 101A and 101B are provided with a plurality of image pickup elements 102 at equal intervals along the width direction of the recording material P1. The image pickup units 101A and 101B are a group of image pickup elements including the plurality of image pickup elements 102, and simultaneously image the surface of the recording material P1 to generate image data. The number of image pickup devices 102 shown in FIG. 7 is omitted from the actual number.

FIG. 8 is a block diagram showing a hardware configuration of the image pickup apparatus 100.
As shown in FIG. 8, the image pickup device 100 includes image pickup units 101A and 101B having a group of image pickup elements (image sensor group) 102 and an image processing unit 103, a control unit 140, a transfer drive unit 151, an operation display unit 152, and an image pickup device 100. , The input / output interfaces 153 are configured by connecting to each other via the bus line 154.

The image pickup units 101A and 101B image (observe) the first test chart formed on the recording material P1 conveyed by each image pickup element 102. The image processing unit 103 generates image pickup data based on the image pickup output captured by each image pickup element 102. The image pickup data of the first test chart generated by the image processing unit 103 is transmitted to the arithmetic unit 200 via the input / output interface 153. As will be described later, the arithmetic unit 200 detects the landing position and the amount of droplets for each nozzle based on the imaging data of the first test chart. Then, the arithmetic unit 200 provides correction information for correcting the basic drive waveform of the drive voltage supplied to each recording head 3-1 to 3-N based on the deviation amount of the landing position and the deviation amount of the droplet amount. calculate. This correction information is transmitted from the arithmetic unit 200 to the inkjet recording device 1 and stored in the storage unit 42 of the inkjet recording device 1.

In the present embodiment, the correction information is calculated by the arithmetic unit 200, but the correction information may be calculated by, for example, the image processing unit 103.

The control unit 140 includes a CPU 141, a storage unit 142, a RAM 143, and a ROM 144. The CPU 141 reads out various control programs and setting data stored in the ROM 144, stores them in the RAM 143 and executes them, and performs various arithmetic processes including calculation of correction information. Further, the CPU 141 controls the overall operation of the image pickup apparatus 100. The storage unit 142 stores the image pickup data of the first test chart imaged by the image pickup units 101A and 101B.

The transport drive unit 151 supplies a drive signal to the transport motor based on the control signal supplied from the control unit 140, and transports the recording material P1 at a predetermined speed and timing. The operation display unit 152 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as a touch panel arranged so as to be superimposed on the operation keys and the screen of the display device. The operation display unit 152 causes the display device to display various information, and supplies an operation signal corresponding to the user's input operation to the input device to the control unit 140.

The input / output interface 153 mediates the transmission / reception of data between an external device such as the arithmetic unit 200 and the control unit 140. The bus line 154 is a route for transmitting and receiving signals between the control unit 140 and other components.

FIG. 9 is a plan view of the image sensor 60 as an observation means mounted on the inkjet recording device 1 as viewed from vertically above the recording material P2.
The recording material P2 on which the second test chart is printed is conveyed along the conveying direction shown in FIG. 9, and the image information of the second test chart is read by the image sensor 60. The image sensor 60 is composed of, for example, a line camera device, an area camera device, or the like, and captures a part of the recording material P2 in the width direction in synchronization with the transport speed of the recording material P2 to generate image data.

The image sensor 60 of the present embodiment may be able to read the second test chart by ink droplets ejected from a specific nozzle (a nozzle of a part of a plurality of nozzles constituting the nozzle row) described later. Therefore, as shown in FIG. 9, the image sensor 60 includes three sensor units 61A to 61C that read three locations separated from each other in the width direction of the recording material, and the image unit (ink adhesion portion) of the second test chart. It is configured to read the image only in the part corresponding to. Specifically, as shown in FIG. 9, the image sensor 60 includes a first sensor unit 61A that reads image information at one end in the width direction of the recording material P2 and a second sensor that reads image information at the center in the width direction. A third sensor unit 61C for reading image information of a portion on the other end side in the width direction is provided.

The image sensor 60 of the present embodiment includes three sensor units 61A to 61C corresponding to the image portion (ink adhesion portion) of the second test chart, but the image portion of the second test chart is located. Depending on the situation, one or two sensor units or four or more sensor units may be provided.

Further, although the image sensor 60 of the present embodiment is fixedly arranged, for example, one sensor unit is configured to be movable in the width direction of the recording material, and corresponds to the image unit (ink adhesion portion) of the second test chart. The image information at the three locations may be read by the one sensor unit. As the moving mechanism for moving the image sensor 60, a known moving mechanism such as a linear stage can be adopted.

The image information read by the image sensor 60 is transmitted to the control unit 40 via the bus line 54. The control unit 40 detects the landing position and the droplet amount of the specific nozzle based on the image information of the second test chart, and each recording head 3-1 is based on the deviation amount of the landing position and the deviation amount of the droplet amount. The time-dependent change correction information for correcting the basic drive waveform of the drive voltage supplied to ~ 3-N is calculated. This time-dependent change correction information is stored in the storage unit 42 of the control unit 40.

FIG. 10 is a block diagram showing a hardware configuration of the arithmetic unit 200.
The arithmetic unit 200 of this embodiment has a CPU 201, a ROM 202, a RAM 203, an HDD 204, an operation interface (operation I / F) 205, and a communication unit 206. An operation unit such as a mouse device 207 and a keyboard device 208, which are pointing electric vices, is connected to the operation I / F 205.

In the storage unit such as ROM 202, RAM 203, or HDD 204 in the arithmetic unit 200, an arithmetic program for analyzing the imaging data of the first test chart imaged by the imaging apparatus 100 is stored. The CPU 201 reads out the arithmetic program and the setting data stored in the ROM 202, stores them in the RAM 203, and executes the operation. As a result, the CPU 201 analyzes the imaging data of the first test chart and detects the liquid ejection characteristics such as the landing position and the amount of droplets for each nozzle of the inkjet recording device 1. Then, based on this detection result, the CPU 201 first corrects an error (deviation) in the landing position of each nozzle and corrects an error (deviation) in the amount of droplets ejected from each nozzle. Generates initial error correction information, which is correction information. The generated initial error correction information is transmitted to the inkjet recording device 1 via the communication unit 206.

11 (a) to 11 (d) are explanatory views showing an example of a first test chart printed on the recording material P1.
The first test chart CH1 shown in FIG. 11A is a test consisting of independent dots formed by ink ejected from all nozzles 4 of all nozzle rows of all recording heads 3 mounted on the head unit 2. It is a chart. This first test chart CH1 is recorded by ejection control so that the dots of the ink ejected and landed from each nozzle 4 do not overlap each other and the dot positions in the recording material transport direction deviate between the adjacent nozzles. There is.

By preventing the dots of the ink ejected from each nozzle 4 from overlapping each other as in the first test chart CH1, the coordinates of the ink landing position from each nozzle 4 can be specified. It is also possible to specify the amount of ink droplets (ejection amount) of the ink ejected from each nozzle 4 from the area, diameter, or circumference of each dot.

The first test chart CH2 shown in FIG. 11B is also a test consisting of independent dots formed by ink ejected from all nozzles 4 of all nozzle rows of all recording heads 3 mounted on the head unit 2. It is a chart. This first test chart CH2 is intermittently ejected three times from the nozzles separated by a certain interval (for a certain number of nozzles), and then intermittently ejected three times by shifting to the adjacent nozzle. It is recorded by repeating the operation.

In this first test chart CH2 as well, since the dots due to the ink ejected from each nozzle 4 do not overlap each other, the coordinates of the ink landing position from each nozzle 4 can be specified. It is also possible to specify the amount of ink droplets (ejection amount) of the ink ejected from each nozzle 4 from the area, diameter, or circumference of each dot. In particular, in the first test chart CH2 shown in FIG. 11B, since a plurality of (three in this case) dots are formed for the same nozzle, the ink landing position and the amount of droplets can be determined from the average value of the plurality of dots. It can be specified, and the ink landing position and the amount of droplets with less error can be obtained.

The first test chart CH3 shown in FIG. 11C is a test chart formed by ink ejected from all nozzles 4 of all nozzle rows of all recording heads 3 mounted on the head unit 2. This first test chart CH3 repeats and records the operation of continuously ejecting from the nozzles separated by a certain interval (for a certain number of nozzles) and then shifting to the adjacent nozzle and continuously ejecting. Multiple line segments extending in the material transport direction are recorded.

In this first test chart CH3, the coordinates in the recording material width direction at the ink landing position from each nozzle 4 can be specified from the recording material width direction position of each line segment. Further, the amount of ink droplets (ejection amount) of the ink ejected from each nozzle 4 can be specified from the width of each line segment. Further, according to the first test chart CH3 shown in FIG. 11 (c), the fluctuation component of each nozzle at the time of high frequency ejection can be specified from the length from the start point to the end point of each line segment.

The first test chart CH4 shown in FIG. 11D is a test chart formed by ink ejected from all nozzles 4 of all nozzle rows of all recording heads 3 mounted on the head unit 2. In this first test chart CH4, a plurality of line segments extending in the width direction of the recording material are recorded by repeating the operation of ejecting all the nozzles in the same nozzle row all at once.

In this first test chart CH4, the coordinates of the recording material transporting direction at the ink landing position from each nozzle 4 can be specified from the recording material transporting direction position of the dot portion corresponding to each nozzle in each line segment. Further, the amount of ink droplets (ejection amount) of the ink ejected from each nozzle 4 can be specified from the width of each line segment. Further, according to the first test chart CH4 shown in FIG. 11D, it is possible to identify the variable component due to mutual interference between adjacent nozzles.

Next, a process of generating initial error correction information for correcting the basic drive waveform of the drive voltage supplied to each recording head 3-1 to 3-N will be described using the first test chart described above.
In the processing of the present embodiment, first, the first test chart described above is printed on the recording material P1 by the inkjet recording device 1 before the inkjet recording device 1 is shipped from the factory. Then, the first test chart printed on the recording material P1 is imaged by the image pickup apparatus 100. The image pickup apparatus 100 transmits the image pickup data of the first test chart imaged to the arithmetic unit 200 via the input / output interface 153. The arithmetic unit 200 executes an arithmetic program stored in a storage unit such as HDD 204 by the CPU 201, so that the amount of deviation of the landing position (discharged position) of each nozzle from the image pickup data of the first test chart and each nozzle Calculate the amount of deviation of the ink droplet amount (ejection amount) from. Then, the arithmetic unit 200 obtains initial error correction information for correcting the calculated deviation amount of the landing position of each nozzle and the deviation amount of the ink droplet amount from each nozzle, in the recording heads 3-1 to 3-. Calculated for all nozzles of N.

FIG. 12 is a flowchart showing the flow of the initial error correction information generation process executed by the arithmetic unit 200.
First, the arithmetic unit 200 acquires (receives) the imaging data of the first test chart transmitted from the imaging apparatus 100 (S101). Next, the arithmetic unit 200 specifies the coordinates of the ink landing position for each nozzle 4 and the amount of ink droplets for each nozzle 4 based on the acquired imaging data (S102). Next, the arithmetic unit 200 calculates the amount of positional deviation between the coordinates of the ink landing position of each of the specified nozzles 4 and the target landing position of each nozzle 4 for each nozzle 4 (S103). This deviation amount is, for example, the separation distance between the dot position of each nozzle 4 and the dot target position of each nozzle in the recording material transport direction. The target position may be, for example, a predetermined position, or the average value of the dot positions of a plurality of nozzles constituting the same nozzle row may be used.

Further, the arithmetic unit 200 calculates the amount of deviation between the ink droplet amount for each specified nozzle 4 and the target droplet amount for each nozzle 4 for each nozzle 4 (S104). The target droplet amount may be, for example, a predetermined droplet amount, or an average value of the droplet amounts of a plurality of nozzles constituting the same nozzle row may be used.

Next, in order to correct the drive voltage of each nozzle 4 so that the deviation amount is reduced based on the deviation amount of the ink landing position for each nozzle 4 and the deviation amount of the ink droplet amount for each nozzle 4. Initial error correction information is generated (S105). The relationship between the amount of deviation and the amount of correction can be obtained in advance by, for example, an experiment. As a specific method for generating the initial error correction information, for example, a method of storing relational expressions and table data showing the relationship between the deviation amount and the correction amount in a storage unit such as HDD 204 of the arithmetic unit 200 can be mentioned. Be done. In this method, the correction amount (initial error correction information) of each nozzle 4 is calculated from the deviation amount of the ink landing position of each nozzle 4 and the deviation amount of the ink droplet amount using the relational expression and the table data.

The arithmetic unit 200 transmits the initial error correction information of the drive voltage for each nozzle 4 thus generated to the inkjet recording device 1 via the communication unit 206. The control unit 40 of the inkjet recording device 1 transmits the initial error correction information received from the arithmetic unit 200 via the input / output interface 53 to the head drive unit 20 of the inkjet recording device 1 via the bus line 54. Based on the initial error correction information received from the control unit 40, the head control unit 22 of the head drive unit 20 outputs drive waveform correction information indicating the nozzle number of the nozzle 4 requiring correction and information indicating the correction amount. Stored in the holding unit 24. As a result, during the subsequent image forming operation, the basic drive waveform of the drive voltage of the nozzle 4 that needs to be corrected is corrected, and the deviation of the ink landing position and the deviation of the ink droplet amount are corrected.

FIG. 13 is an explanatory diagram showing an example of image data of the first test chart.
In the example of FIG. 13, the third dot from the left in the figure has a landing position shifted to the downstream side in the recording material transport direction with respect to the other dots, that is, the ink ejected from the nozzle corresponding to the third dot. Is an example of landing earlier than other nozzles. This is because the ejection timing of the nozzle corresponding to the third dot from the left in the figure is earlier than that of other nozzles, or the ejection speed of the liquid discharged from the nozzle corresponding to the third dot from the left in the figure is It means that it is faster than other nozzles.

14 (a) to 14 (c) are explanatory views showing an example of the correction operation of the drive waveform.
FIG. 14A shows an example of the basic drive waveform generated by the basic drive waveform generation unit 23 in the head drive unit 20 of the head unit 2. In FIG. 13, the drive waveform correction information holding unit 24 of the head drive unit 20 has a nozzle number (nozzle number corresponding to the third dot from the left in the figure) of the nozzle 4 that needs to be corrected based on the initial error correction information. ) And information indicating the correction amount (the amount of deviation of the landing position) are stored. In this case, as shown in FIG. 14B, the drive waveform correction unit corresponding to the nozzle corresponds the falling timing T1 of the basic drive waveform to the correction amount stored in the drive waveform correction information holding unit 24. The basic drive waveform is corrected so as to be delayed by a predetermined time (ΔT). As a result, the ink ejection timing of the nozzle is delayed, and as a result, the ink landing timing of the nozzle can be delayed, and the ink landing position of the nozzle can be aligned with the target position (for example, the ink landing position of another nozzle).

In the example of FIG. 14B, the ink landing time is delayed by changing the falling timing T1 of the basic drive waveform, but the ink landing time is not limited to this, and the ink landing time is delayed by another method. It is also possible. For example, even if the rising timings T3, T5, and T7 of the basic drive waveform are delayed, the ink ejection timing can be delayed, the landing timing can be delayed, and the ink landing timing can be delayed.

Further, as shown in FIG. 14 (c), the ink landing timing is delayed by weakening at least one magnitude of the falling voltage V2, V4, V6 of the basic drive waveform by a predetermined voltage (ΔV). It is also possible to do. In this case, since the ink ejection speed can be slowed down, the landing time can be delayed, and the ink landing time can also be delayed.

The above-mentioned correction of the falling timing and the rising timing of the basic drive waveform, the correction of the falling voltage of the basic driving waveform, or other corrections may be performed in combination with each other. Further, the example of FIG. 13 is an example of correcting the drive waveform of the nozzle whose ink landing time is early, but when correcting the drive waveform of the nozzle whose ink landing time is late, the correction opposite to the above-mentioned correction is performed. Just do it.

FIG. 15 is a flowchart showing the flow of the correction operation of the drive voltage of each recording head 3 during the image formation operation.
When a print job (image formation command) is input from the arithmetic unit 200 via the input / output interface 53, the control unit 40 of the inkjet recording device 1 receives the image data corresponding to the print job (S201). The image forming operation is started (S202). As a result, the control unit 40 transmits a control signal based on the received image data to the head drive unit 20 of the head unit 2. The head drive unit 20 applies a drive waveform corresponding to the received control signal to the recording heads 3-1 to 3-N. As a result, ink ejection control is performed according to the image information, and the ink lands on the recording material to form an image.

At this time, the drive waveform correction information holding unit 24 of the head drive unit 20 stores correction information indicating the nozzle number and the correction amount that need to be corrected based on the initial error correction information. Therefore, in the head drive unit 20, for nozzles that need to be corrected based on this correction information, individual drive waveforms (individual drive waveforms) in which the basic drive waveform is corrected by the corresponding drive waveform correction units 21-1 to 21-N. A drive signal) is generated and applied to the piezoelectric element corresponding to the nozzle. The basic drive waveform is applied as it is to the nozzles that do not require correction (nozzles in which correction information is not stored in the drive waveform correction information holding unit 24). In this way, by applying an individual drive waveform corrected as necessary to the piezoelectric element of each nozzle, deviation of the landing position due to manufacturing error, deviation of the amount of ink droplets, etc. are adjusted. The ink is ejected and a high-quality image is formed.

Even if the individual drive waveforms adjusted in advance based on the initial error correction information are used in this way, the ink landing position and ink droplet amount of each nozzle are affected by changes over time such as temperature and humidity, and changes over time of various materials. (Liquid discharge characteristics) may deviate from the target. Therefore, it is preferable to correct the individually adjusted drive waveform according to such a change with time.

Here, as with the initial error correction information, the first test chart is imaged by the image pickup apparatus 100, the liquid discharge characteristics of all the nozzles are observed, and the correction information based on the observation results is generated. For example, it is possible to obtain individual drive waveforms that have been corrected according to changes over time. However, in this case, each inkjet recording device 1 is equipped with an observation means such as an image pickup device 100 (for example, a high-resolution image pickup device such as 4800 dpi) capable of observing the liquid ejection characteristics of individual nozzles for all nozzles. There is a need to. Therefore, there is a problem that the size and cost of the inkjet recording apparatus 1 are increased. Further, in order to observe the ink, it is necessary to eject ink from all the nozzles, and there is a problem that the amount of ink consumed increases.

16 (a) to 16 (d) are graphs for explaining the change in the liquid discharge characteristic of each nozzle due to the change with time.
In these graphs, the vertical axis represents the ink ejection speed or the amount of ink droplets, which are the liquid ejection characteristics, and the horizontal axis represents the nozzle number.

The graph shown in FIG. 16A is an observation of the liquid discharge characteristics of each nozzle at the initial stage (dataA plotted with a black rectangle) and with time (dataB plotted with a cross mark). As shown in this graph, when the temperature inside the device, continuous operation time, etc. change and changes over time, all nozzles have liquid discharge characteristics, such as dataA plotted with black-painted rectangles and dataB plotted with cross marks. (Ink ejection speed or ink droplet amount) changes. At this time, the change in the liquid discharge characteristic of each nozzle shows the same tendency in all the nozzles. For example, in the example of FIG. 16A, all the nozzles are in the initial state (dataA) and in time (dataB). That is, there is a relationship that the coefficient of the time (dataB) with respect to the initial time (dataA) is the same α-fold coefficient.

That is, the change in the liquid ejection characteristics due to the change over time is not different for each nozzle, but is a constant nozzle group such as a nozzle group close to each other, a nozzle group constituting the same nozzle row, and a nozzle group provided in the same liquid ejection head. It is common to multiple nozzles that make up. Therefore, by observing the liquid discharge characteristics of at least one nozzle of the group of nozzles constituting the nozzle group, it is possible to identify changes in the liquid discharge characteristics of all the nozzles included in the nozzle group. Is. According to this, since it is sufficient that each inkjet recording device 1 is equipped with an observation means capable of observing only the liquid ejection characteristics of some nozzles (specific nozzles), the size and cost of the inkjet recording device 1 are increased. Can be suppressed. Further, since it is sufficient to eject ink from only a part of the nozzles (specific nozzles) for the observation, it is possible to suppress the ink consumption.

Therefore, in the present embodiment, when a predetermined correction start condition (for example, when the power of the inkjet recording device is turned on, when the number of continuous images formed reaches a predetermined number, etc.) is satisfied (Yes in S203), the change with time. The process of correcting the change in the liquid discharge characteristics due to the above is executed. In this process, ink is ejected from only a part of the nozzles (specific nozzles) that form dots at the locations corresponding to the three sensor units 61A to 61C of the image sensor 60 mounted on the inkjet recording device 1. Two test charts are formed (S204).

The specific nozzle may be a part of the nozzles in a group of nozzles having the same tendency of the change of the liquid discharge characteristic due to the change with time. For example, when all the nozzles of the head unit 2 of the inkjet recording device 1 show the same tendency in the change of the liquid ejection characteristics due to the change with time, some nozzles (one nozzle) in all the nozzles of the head unit 2 are used. It may be 2 or more nozzles).

Further, for example, when the changes in the liquid ejection characteristics of the nozzles due to changes with time show the same tendency in each recording unit 2K, 2C, 2M, 2Y, the specific nozzles are some nozzles in all the nozzles of each recording unit. May be good.

Further, for example, when the change in the liquid discharge characteristic of the nozzle due to the change with time shows the same tendency for each recording head 3, the specific nozzle may be a part of all the nozzles of each recording head 3.

Further, for example, when the change in the liquid discharge characteristic of the nozzle due to the change with time shows the same tendency for each nozzle row, the specific nozzle may be a part of all the nozzles in each nozzle row.

The second test chart formed by the ink ejected from the specific nozzle is read by the image sensor 60 (S205). The image information of the second test chart read by the image sensor 60 is transmitted to the control unit 40 via the bus line 54. The control unit 40 calculates the deviation amount of the ink landing position of the specific nozzle and the deviation amount of the ink droplet amount based on the image information of the second test chart (S206). Then, the control unit 40 determines whether or not the calculated deviation amount is within the specified range (within the allowable range) (S207), and if it is within the specified range (Yes in S207), the image forming operation is continued as it is. (S210).

On the other hand, when the control unit 40 determines that the calculated deviation amount is out of the specified range (within the allowable range) (No in S207), the control unit 40 performs the following processing. That is, the control unit 40 individually drives all the nozzles of the group of nozzles including the specific nozzle based on the amount of deviation of the ink landing position for the specific nozzle and the amount of deviation of the ink droplet amount. The time-dependent change correction information for uniformly correcting the waveform is calculated (S208). This time-dependent change correction information is stored in the storage unit 42 of the control unit 40, and then transmitted from the control unit 40 to the head drive unit 20 via the bus line 54. Then, the head control unit 22 of the head drive unit 20 drives the information indicating the nozzle number of the nozzle 4 requiring correction and the information indicating the correction amount based on the time-dependent change correction information received from the control unit 40. It is stored in the correction information holding unit 24. As a result, in the subsequent image forming operation, the individual drive waveforms are corrected so as to correct the deviation of the ink landing position and the deviation of the ink droplet amount due to the change with time (S209), and a high-quality image is formed. ..

For example, it is indicated by the arrow in FIG. 16 (b) based on the amount of deviation of the ink landing position and the amount of deviation of the ink droplet amount for the specific nozzle Z corresponding to the third dot from the left in FIG. 16 (b). As described above, the time-dependent change correction information that can correct the liquid discharge characteristic of the specific nozzle Z is generated. Then, by using this time-dependent change correction information for other nozzles other than the specific nozzle Z, as shown in FIG. 16 (c), the ink landing position shift and ink due to the time-dependent change also occur in the other nozzles. The deviation of the amount of droplets is corrected.

As described above, the specific nozzle may be a part of the nozzles in the group of nozzles having the same tendency of the change of the liquid discharge characteristic due to the change with time. However, the nozzle group that can be uniformly corrected may be limited by the configuration of the head drive unit 20 of the inkjet recording device 1. For example, as shown in FIG. 5, in a configuration in which drive waveform correction units 21-1 to 21-N are provided for each recording head 3-1 to 3-N, each recording head 3-1 to 3-N The time change correction information may be obtained. Further, in a configuration in which such a drive waveform correction unit is provided for each nozzle row, time-dependent change correction information may be obtained for each nozzle row.

According to this embodiment, ink is ejected from only a part of the nozzles (specific nozzles) to create a second test chart, the liquid ejection characteristics of the specific nozzle are observed, and the specific nozzle is based on the observation result. And the individual drive waveforms of a group of nozzles including other nozzles are corrected. Therefore, in order to observe the second test chart, it is sufficient to eject ink from only some nozzles (specific nozzles), and ink consumption is suppressed as compared with the case where ink is ejected from all nozzles for observation. be able to.

Further, the observation means mounted on the inkjet recording device 1 is an observation means capable of observing the liquid ejection characteristics of individual nozzles for all nozzles, such as the image pickup device 100 used for obtaining initial error correction information. Is unnecessary. As a result, the image sensor 60, which is smaller and cheaper than the image pickup device 100, can be mounted on the inkjet recording device 1 as an observation means, and the deviation due to the change with time can be corrected in real time.

In particular, when observing the amount of ink droplets in a specific nozzle, a density sensor (for example, a reflection type optical sensor), which is smaller and cheaper than an image sensor, can be used as an observation means. In this case, the amount of ink droplets ejected from the specific nozzle can be detected by the formed dot area, but since there is a high correlation between the dot area and the image density, the density data obtained by the density sensor is used. The dot area (ink droplet amount) can be calculated.

Further, when observing the ink landing position at a specific nozzle, a density sensor (for example, a reflection type optical sensor), which is smaller and cheaper than an image sensor, can be used as an observation means. In general, both the amount of ink droplets and the ink ejection speed are proportional to the voltage intensity of the drive waveform, so that there is a gap between the dot area that varies depending on the amount of ink droplets and the ink landing position that varies depending on the ink ejection speed. , There is a certain correlation. Therefore, it is also possible to estimate and calculate the ink landing position from the density data obtained by the density sensor.

Next, another example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 17 and 18.
FIG. 17 is an explanatory plan view of a main part of the device, and FIG. 18 is an explanatory view of a side surface of the main part of the device.
This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which the liquid discharge head device 404 and the head tank 441 according to the present invention are integrated. The liquid discharge head device 404 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K), as in the head unit 2 of the above-described embodiment. It is equipped with a recording unit. Further, in the recording unit of each color in the liquid discharge head device 404, the recording heads 3 having a nozzle row composed of a plurality of nozzles are arranged in a staggered manner, as in the recording unit 2K, 2C, 2M, 2Y of the above-described embodiment. ing. Further, the recording unit and its nozzle row direction are along the sub-scanning direction (head width direction) orthogonal to the main scanning direction, and are mounted with the ejection direction facing downward.

The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head device 404 to the liquid discharge head device 404.

The supply mechanism 494 includes a cartridge holder 451 which is a filling part for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is delivered from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

This device includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head device 404. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head device 404 is arranged on the side of the transport belt 412.

The maintenance / recovery mechanism 420 includes, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head device 404, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In this apparatus configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyor belt 412.

Therefore, the liquid ejection head device 404 is driven in response to the image signal while moving the carriage 403 in the main scanning direction, so that the liquid is ejected onto the stopped paper 410 to form an image.

As described above, since this device includes the liquid discharge head according to the present invention, it is possible to stably form a high-quality image.

Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG.
FIG. 19 is an explanatory plan view of a main part of the unit.

This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid among the members constituting the device for discharging the liquid. It is composed of a discharge head device 404.

It should be noted that a liquid discharge unit may be configured in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.

Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG.
FIG. 20 is a front explanatory view of the unit.

This liquid discharge unit includes a liquid discharge head device 404 to which the flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 that electrically connects to the liquid discharge head device 404 is provided on the upper part of the flow path component 444.

In the present application, the "device for discharging a liquid" is a device including a liquid discharge head, a liquid discharge head device, or a liquid discharge unit, and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or into the liquid.

The "device for discharging the liquid" may include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming device that is a device that ejects ink to form an image on paper, and a three-dimensional model (three-dimensional model) are formed in layers in order to form a three-dimensional model. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "thing to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as a material to which the liquid adheres and adheres, and a material to which the liquid adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recorded materials such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, and includes everything to which the liquid adheres, unless otherwise specified.

The material of the "material to which liquid can adhere" is temporary liquid such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, building materials such as wallpaper and flooring, and textiles for clothing. But it is good if it can be attached.

The "liquid" also includes inks, treatment liquids, DNA samples, resists, pattern materials, binders, modeling liquids, or solutions and dispersions containing amino acids, proteins, and calcium.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials. There is an injection granulator that granulates fine particles of raw materials by injecting a composition liquid dispersed in a solution.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and is a collection of parts related to liquid discharge. For example, the "liquid discharge unit" includes a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, a main scanning movement mechanism in which at least one of the configurations is combined with a liquid discharge head, and the like.

Here, the term "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, bonding, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

For example, as a liquid discharge unit, there is a liquid discharge head and a head tank integrated, such as the liquid discharge unit 440 shown in FIG. In some cases, the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a unit in which a liquid discharge head and a carriage are integrated.

Further, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member constituting a part of the scanning movement mechanism. Further, as shown in FIG. 19, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, as shown in FIG. 20, a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. ..

The main scanning movement mechanism shall include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

Further, the actuator used for the "liquid discharge head" is not limited. For example, the "liquid discharge head" includes a thermal actuator using an electric heat conversion element such as a heat generating resistor, and vibration, in addition to the piezoelectric element (which may use a laminated piezoelectric element) as described in the above embodiment. An electrostatic actuator composed of a plate and a counter electrode may be used.

Further, in the terms of the present application, image formation, recording, printing, printing, printing, modeling, etc. are all synonymous.

Finally, the embodiments described above are presented as an example and are not intended to limit the scope of the invention. Each of the novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Such embodiments and modifications of the embodiments are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

What has been described above is an example, and has a unique effect in each of the following aspects.
[First aspect]
The first aspect is a device for ejecting a liquid from a plurality of nozzles 4 (for example, an inkjet recording device 1), and the liquid is ejected from a part of the nozzles (for example, a specific nozzle) among the plurality of nozzles. A group of nozzles including an observation means (for example, an image sensor 60) for observing characteristics (for example, an ink landing position and an ink droplet amount) and a part of the nozzles and another nozzle based on the observation result of the observation means. It is characterized by having a correction means (for example, a control unit 40) for correcting the liquid discharge characteristic of the above.
Liquid discharge characteristics such as the discharge speed and the discharge amount of the liquid discharged from each nozzle are generally different for each nozzle. Therefore, for example, at the time of manufacture or factory shipment, the liquid discharge characteristics of each nozzle are observed for each nozzle, and the liquid discharge characteristics of each nozzle are adjusted based on the observation results for each nozzle. As a result, at the time of use, the liquid can be discharged from each nozzle with the liquid discharge characteristics adjusted in advance, so that the liquid can be discharged from any nozzle with the target liquid discharge characteristics.
Here, even if the liquid discharge characteristics are adjusted in advance in this way, the liquid discharge characteristics of each nozzle may deviate from the target liquid discharge characteristics due to changes over time such as temperature and humidity, and changes over time of various materials. .. Therefore, even after use, it is preferable to correct the liquid discharge characteristics adjusted in advance according to such a change with time.
In the conventional device, the liquid is discharged from all the nozzles to be corrected and the liquid discharge characteristics are observed, and the liquid discharge characteristics for each nozzle to be corrected are corrected based on the observation result. However, the change in the liquid ejection characteristics due to the change over time after use is not different for each nozzle, but is constant, such as a group of nozzles that are close to each other, a group of nozzles that form the same nozzle row, and a group of nozzles that are provided in the same liquid ejection head. It is common to a plurality of nozzles constituting the nozzle group of. Therefore, by observing the liquid discharge characteristics of at least one nozzle of the group of nozzles constituting the nozzle group, it is possible to identify changes in the liquid discharge characteristics of all the nozzles included in the nozzle group. Is. That is, in order to specify the change in the liquid discharge characteristics of all the nozzles to be corrected, discharging the liquid from all the nozzles to be corrected wastefully consumes the liquid.
Therefore, in this embodiment, the liquid discharge characteristics of some of the plurality of nozzles are observed, and based on the observation results, a group of nozzles including the part of the nozzles and other nozzles (correction target). Correct the liquid discharge characteristics of each nozzle). According to this, the nozzles that discharge the liquid for observing the liquid discharge characteristics are only some of the nozzles in the group of nozzles to be corrected, and the liquid at the time of the observation is more than the conventional device. Wasteful consumption can be suppressed.

[Second aspect]
The second aspect is a storage means for storing initial correction information (for example, initial error correction information) for correcting the liquid discharge characteristic of each nozzle based on the observation result of the initial liquid discharge characteristic of each nozzle in the first aspect. It has (for example, a storage unit 42, a drive waveform correction information holding unit 24), and the correction means is characterized in that it corrects the liquid discharge characteristics of the group of nozzles by using the initial correction information as well. ..
According to this, even if the target liquid discharge characteristic is not obtained from the initial time due to a manufacturing error or the like, the liquid can be discharged with the target liquid discharge characteristic.

[Third aspect]
A third aspect is characterized in that, in the first or second aspect, the group of nozzles is all nozzles (for example, all nozzles of the head unit 2) mounted on the device for discharging the liquid. ..
According to this, it is possible to correct the deviation of the liquid discharge characteristic due to the change with time for all the nozzles in the device for discharging the liquid from the observation result of the liquid discharge characteristic for some nozzles.

[Fourth aspect]
In the fourth aspect, in the first or second aspect, the group of nozzles is all the nozzles of the liquid discharge head (for example, the recording head 3) provided with the partial nozzles (for example, all the nozzles for each recording head 3). It is characterized by being.
According to this, it is possible to correct the deviation of the liquid discharge characteristics due to the change with time for all the nozzles in the liquid discharge head from the observation result of the liquid discharge characteristics for some nozzles.

[Fifth aspect]
A fifth aspect has, in the first or second aspect, a liquid ejection head (eg, recording head 3) comprising a plurality of nozzle rows in which the nozzles are arranged, wherein the group of nozzles includes the partial nozzles. It is characterized by having all the nozzles in the nozzle row (for example, all the nozzles in each nozzle row).
According to this, it is possible to correct the deviation of the liquid discharge characteristic due to the change with time for all the nozzles in the nozzle row from the observation result of the liquid discharge characteristic for some nozzles.

[Sixth aspect]
In the sixth aspect, in any one of the first to fifth aspects, the observation means observes the ejected position (for example, the ink landing position) of the liquid ejected from the partial nozzle, and the correction means is a correction means. It is characterized in that the time when the liquid discharged from the group of nozzles reaches the target position is corrected so as to be changed.
According to this, even if the ejected position of the liquid deviates from the target position due to the change with time, the deviation can be corrected without wasting ink.

[7th aspect]
A seventh aspect is, in any one of the first to sixth aspects, the observing means observes the amount of liquid ejected from the partial nozzles (for example, the amount of ink droplets), and the correction means is a correction means. It is characterized in that the discharge amount of the liquid discharged from the group of nozzles is corrected so as to be changed.
According to this, even if the discharge amount of the liquid deviates from the target amount due to the change with time, the deviation can be corrected without wasting ink.

[8th aspect]
In the eighth aspect, in the sixth or seventh aspect, the observation means includes an image density detecting means (for example, a density sensor) for detecting the image density in a predetermined region by the liquid discharged from the partial nozzle. It is characterized by.
According to this, it is possible to provide a device for discharging a cheaper liquid.

[9th aspect]
In the ninth aspect, in any one of the first to eighth aspects, the partial nozzles are two or more nozzles, and the observation means has the liquid ejection characteristics of the liquid discharged from the two or more nozzles. It is characterized in that it is configured to be movable to each observation position to be observed.
According to this, it is possible to provide a device for discharging a cheaper liquid.

[10th aspect]
The tenth aspect is an inkjet recording device, which comprises an apparatus for ejecting the liquid according to any one of the first to ninth aspects.
According to this aspect, it is possible to provide an inkjet recording device capable of suppressing wasteful consumption of liquid during observation as compared with a conventional device.

[11th aspect]
The eleventh aspect is a method for correcting a liquid ejection characteristic in an apparatus for ejecting liquid from a plurality of nozzles 4 (for example, an inkjet recording apparatus 1), wherein the initial liquid ejection characteristic of the liquid ejected from the plurality of nozzles is nozzleed. The first step (for example, generation of initial error correction information) for generating the first correction information (for example, initial error correction information) for correcting the liquid discharge characteristics of each nozzle based on the observation result for each nozzle. Processing) and the liquid discharge characteristics of the liquid discharged from some of the plurality of nozzles (for example, a specific nozzle) over time are observed, and the part is based on the observation results for the part of the nozzles. A second step (for example, a process of generating a change over time correction information) for generating a second correction information (for example, change over time correction information) for correcting the liquid discharge characteristics of a group of nozzles including the nozzle of Nozzle and another nozzle. It is characterized by having.
According to this aspect, not only the deviation of the liquid discharge characteristic due to the initial error can be corrected, but also the deviation of the liquid discharge characteristic due to the change with time after use can be corrected.

[12th aspect]
In the twelfth aspect, in the eleventh aspect, in the first step, the plurality of nozzles are observed by an observation device (for example, an image pickup device 100) configured separately from the device for discharging the liquid, and the above-mentioned The second step is characterized in that observation of a part of the nozzles is performed by an observation means (for example, an image sensor 60) provided in the device for discharging the liquid.
According to this, the correction step can be carried out by using an expensive observation device, and the correction step can be carried out by using an inexpensive observation device as the device for discharging the liquid.

1: Inkjet recording device 2: Head unit 2C: C recording unit 2K: K recording unit 2M: M recording unit 2Y: Y recording unit 3: Recording head 4: Nozzle 20: Head drive unit 21: Drive waveform correction unit 22: Head Control unit 23: Basic drive waveform generation unit 24: Drive waveform correction information holding unit 40: Control unit 51: Transport drive unit 52: Operation display unit 53: Input / output interface 54: Bus line 60: Image sensors 61A to 61C: Sensor unit 100: Image pickup device 101A, 101B: Image pickup unit 102: Image pickup element 103: Image processing unit 140: Control unit 200: Calculation device 401: Guide member 403: Carriage 404: Liquid discharge head device 405: Main scanning motor 406: Drive pulley 407 : Driven pulley 408: Timing belt 410: Paper 412: Conveyor belt 413: Conveyor roller 414: Tension roller 416: Sub-scanning motor 417: Timing belt 418: Timing pulley 420: Maintenance recovery mechanism 421: Cap member 422: Wiper member 440: Liquid discharge unit 441: Head tank 442: Cover 443: Connector 444: Flow path component 450: Liquid cartridge 451: Cartridge holder 452: Liquid supply unit 456: Tube 493: Main scanning movement mechanism 494: Supply mechanism 495: Conveyance mechanism

Japanese Unexamined Patent Publication No. 2010-167725

Claims (12)

A device that ejects liquid from multiple nozzles.
An observation means for observing the liquid discharge characteristics of the liquid discharged from some of the plurality of nozzles, and
A device for discharging a liquid, which comprises a correction means for correcting the liquid discharge characteristics of a group of nozzles including a part of the nozzles and another nozzle based on the observation result of the observation means. In the device for discharging the liquid according to claim 1,
It has a storage means for storing initial correction information for correcting the liquid discharge characteristics of each nozzle based on the observation result of the initial liquid discharge characteristics of each nozzle.
The correction means is a device for discharging a liquid, which is characterized by correcting the liquid discharge characteristics of the group of nozzles by using the initial correction information. In the device for discharging the liquid according to claim 1 or 2.
The group of nozzles is a device for discharging a liquid, characterized in that all the nozzles are mounted on the device for discharging the liquid. In the device for discharging the liquid according to claim 1 or 2.
The group of nozzles is a device for discharging a liquid, characterized in that the nozzles are all nozzles of a liquid discharge head provided with a part of the nozzles. In the device for discharging the liquid according to claim 1 or 2.
Has a liquid discharge head with multiple nozzle rows in which the nozzles are arranged,
The group of nozzles is a device for ejecting a liquid, characterized in that the nozzles are all nozzles in a nozzle row including the partial nozzles. The device for discharging the liquid according to any one of claims 1 to 5.
The observing means observes the ejected position of the liquid ejected from the part of the nozzles and observes the ejected position.
The correction means is a device for discharging a liquid, which is characterized in that the time when the liquid discharged from the group of nozzles reaches a target position is changed. The device for discharging the liquid according to any one of claims 1 to 6.
The observing means observes the amount of liquid discharged from the part of the nozzles and observes the amount of liquid discharged.
The correction means is a device for discharging a liquid, which is characterized in that the amount of the liquid discharged from the group of nozzles is corrected so as to be changed. In the device for discharging the liquid according to claim 6 or 7.
The observation means is a device for discharging a liquid, which comprises an image density detecting means for detecting an image density in a predetermined region by the liquid discharged from the partial nozzles. The device for discharging the liquid according to any one of claims 1 to 8.
Some of the nozzles are two or more nozzles.
The observation means is a device for discharging a liquid, which is configured to be movable to each observation position for observing the liquid discharge characteristics of the liquid discharged from the two or more nozzles. An inkjet recording apparatus comprising the apparatus for ejecting the liquid according to any one of claims 1 to 9. It is a method of correcting the liquid discharge characteristics in a device that discharges liquid from multiple nozzles.
The first correction information for observing the initial liquid discharge characteristics of the liquid discharged from the plurality of nozzles for each nozzle and correcting the liquid discharge characteristics of each nozzle based on the observation result for each nozzle is generated. One step and
The liquid ejection characteristics of the liquid ejected from a part of the plurality of nozzles over time are observed, and the part of the nozzle and the other nozzles are included based on the observation result for the part of the nozzles. A method for correcting liquid discharge characteristics, which comprises a second step of generating a second correction information for correcting the liquid discharge characteristics of a group of nozzles. In the method for correcting the liquid discharge characteristic according to claim 11,
In the first step, the plurality of nozzles are observed by an observation device configured separately from the device for discharging the liquid.
The second step is a method for correcting liquid discharge characteristics, which comprises observing a part of the nozzles by an observation means provided in the liquid discharge device.

Images