JP6828388B2 - Image forming device, image forming method, and program - Google Patents

Description

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

In recent years, in response to a demand for improved productivity, various companies have released inkjet line printers capable of high-speed printing. In addition, the demand for higher image quality is increasing year by year, and printers of the type with improved recording density are appearing.

Due to these measures, the number of situations where inkjet printers are used in the market is increasing. Along with this, it is often used for various purposes, and various types of recording media have come to be used.

Printing has become common from monochrome to color, and various types have been developed, from four-color types of CMYK (cyan, magenta, yellow, and black) to those with the addition of green, orange, and light-colored inks (for example). See Patent Documents 1 and 2).

The invention described in Patent Document 1 relates to a printer, a recording medium recording a printer driving method, and a printer driving method, and is particularly applied to a line printer having a multi-head configuration, and some nozzles constituting the multi-head have failed. In some cases, the purpose is to prevent a significant deterioration in the quality of the printed result. Specifically, due to a nozzle failure, the drive is switched so that the dot diameter of the nozzle adjacent to the failed nozzle is increased.

There is known a technique for suppressing the generation of white streaks by increasing the amount of droplets from adjacent nozzles when an ink nozzle with poor ejection is detected in an inkjet recording apparatus.
However, when ejection defects occur at the same location in different heads, the amount of droplets is also increased, so that there is a problem that ink overflows and the image quality deteriorates.

Therefore, an object of the present invention is to suppress the occurrence of white streaks and to improve the image quality.

In order to solve the above problems, the invention according to claim 1 comprises a first recording head having a plurality of nozzles for ejecting droplets, a second recording head having a plurality of nozzles for ejecting droplets, and the like. A detection means for detecting the non-ejection nozzle in the first recording head and the non-ejection nozzle in the second recording head, and a control for controlling the amount of droplets to be ejected according to the detection result by the detection means. in the image forming apparatus having a means,,
Wherein if the faulty nozzle is detected in said first recording head, so as to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of said first recording head controlling, if the ejection failure nozzle in the second recording head is detected, control to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of said second recording heads If the landing positions of the droplets discharged from the faulty nozzle of the said first recording head and the the landing positions of the droplets discharged from the faulty nozzle second recording heads are the same, the first The amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the recording head, and the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the second recording head. Is characterized by adjusting so as to reduce.

According to the present invention, it is possible to suppress the occurrence of white streaks and improve the image quality.

It is a side explanatory view explaining the whole structure of the mechanical part of the image forming apparatus which concerns on one Embodiment. It is a plane explanatory view of the mechanical part of the image forming apparatus shown in FIG. It is a conceptual diagram of the line type printer which provided the head which covers the paper width for each color. FIG. 5 is an explanatory cross-sectional view taken along the longitudinal direction of the liquid chamber of the recording head of the image forming apparatus shown in FIG. It is sectional drawing in the short side direction (nozzle arrangement direction) of the liquid chamber of the recording head of the image forming apparatus shown in FIG. This is an example of a functional block diagram of the image forming apparatus shown in FIG. It is a block diagram which shows the hardware configuration example of the image forming apparatus 600 of this embodiment. It is a block diagram which shows the configuration example of the recording head control unit 910, the drive waveform generation circuit 707, and the recording head driver 210. It is explanatory drawing which shows an example of the drive waveform generated and output by the drive waveform generation part of the printing control part of the image forming apparatus shown in FIG. (A) is an explanatory diagram for explaining a small drop selected from the driving waveform, and (b) is an explanatory diagram for explaining a medium drop selected from the driving waveform. (C) is an explanatory diagram for explaining a large drop selected from the drive waveform, and (d) is an explanatory diagram for explaining the fine drive selected from the drive waveform. It is explanatory drawing for demonstrating the drive waveform according to the viscosity of ink. It is a block diagram which shows the structural example of the image processing unit 810 shown in FIG. 7. It is a block explanatory drawing which shows an example of the image formation system which concerns on this invention. It is a block explanatory drawing which shows an example of the image processing apparatus in the image formation system which concerns on this invention. This is an example of a flow chart for detecting nozzle omission. This is an example of a flow chart for nozzle omission correction. (A) is a schematic diagram of a head, (b) is a schematic diagram of dots without nozzle omission correction, and (c) is a schematic diagram of dots at the time of adjacent dot size modulation. (A) is a schematic diagram of a cyan head, (b) is a schematic diagram of a magenta head, and (c) is a schematic diagram of dots at the time of dot size modulation from the cyan head and the magenta head. .. (A) is a schematic diagram of a cyan head, (b) is a schematic diagram of a magenta head, and (c) is a schematic diagram of dots at the time of dot size modulation from the cyan head and the magenta head. .. (A) is a schematic diagram of a cyan head, (b) is a schematic diagram of a magenta head, and (c) is a schematic diagram of dots at the time of adjacent dot size modulation.

<Embodiment>
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, an example of an image forming apparatus that outputs image data generated by the image processing method according to the present invention will be described with reference to FIGS. 1 and 2. Note that FIG. 1 is a side explanatory view illustrating the overall configuration of the mechanical portion of the image forming apparatus according to the embodiment. FIG. 2 is a plan explanatory view of a mechanical portion of the image forming apparatus shown in FIG.

The image forming apparatus slidably holds the carriage 3 in the main scanning direction by the guide rod 1 and the guide rail 2 which are guide members horizontally laid on the left and right side plates (not shown). The main scanning motor 4 moves and scans in the direction indicated by the arrow (main scanning direction) in FIG. 2 via a timing belt 5 stretched between the drive pulley 6A and the driven pulley 6B.

On the carriage 3, for example, four recording head units 7y, 7c, 7m, and 7k including a liquid discharge head that discharges yellow (Y), cyan (C), magenta (M), and black (K) are arranged. ing. The four recording head units 7y, 7c, 7m, and 7k are mounted so that a plurality of ink ejection ports are arranged in a direction intersecting the main scanning direction and the ink droplet ejection direction faces downward. However, when the colors are not distinguished, each recording head unit 7y, 7c, 7m, 7k is called "recording head 7".

In this embodiment, four colored inks are mounted, but other colors can also be mounted, and a treatment liquid for improving fixability and gloss for the purpose of giving gloss can be added. It is also possible to load the liquid.

Examples of the liquid discharge head constituting the recording head 7 include a piezoelectric actuator such as a piezoelectric element and a thermal actuator that utilizes a phase change due to boiling of a liquid film by using an electric heat conversion element such as a heat generating resistor. Further, the liquid discharge head is provided with a shape memory alloy actuator that uses a metal phase change due to a temperature change, an electrostatic actuator that uses an electrostatic force, or the like as a pressure generating means for generating a pressure for discharging droplets. Can be used.

Further, the head configuration is not limited to an independent head for each color, and one or a plurality of liquid ejection heads having a nozzle array composed of a plurality of nozzles for ejecting droplets of a plurality of colors may be used. In the present embodiment, the configuration of the serial printer is as shown in FIG. 2, but the configuration as shown in FIG. 3 may be used.
FIG. 3 is a conceptual diagram of a line-type printer having a head covering the paper width for each color.

Further, the carriage 3 shown in FIG. 2 is equipped with a sub tank 8 of each color for supplying ink of each color to the recording head 7. Ink is replenished and supplied to the sub tank 8 from a main tank (ink cartridge) (not shown) via an ink supply tube 9.

The paper feed unit for feeding the paper 12 loaded on the paper load unit (pressure plate) 11 such as the paper feed cassette 10 is a half-moon roller (paper feed) that separates and feeds the paper 12 from the paper load unit 11 one by one. It is also called a roller.) It is provided with a separation pad 14 facing the 13 and made of a material having a large friction coefficient. The separation pad 14 is urged on the half-moon roller (paper feed roller) 13 side.

Since the transport belt 21 transports the paper 12 fed from the paper feed section on the lower side of the recording head 7, the paper 12 is electrostatically attracted and conveyed. The counter roller 22 sandwiches the paper 12 fed from the paper feed unit via the guide 15 with the transport belt 21 and conveys the paper 12. The transport guide 23 turns the paper 12 fed substantially vertically upward by approximately 90 ° and imitates it on the transport belt 21. The pressing roller 25 is urged toward the transport belt 21 by the pressing member 24. The charging roller 26 is a charging means for charging the surface of the transport belt 21.

Here, the transfer belt 21 is an endless belt, which is hung between the transfer roller 27 and the tension roller 28, and the transfer roller 27 rotates from the sub-scanning motor 31 via the timing belt 32 and the timing roller 33. Will be done. By this rotation, it is configured to orbit in the belt transport direction (sub-scanning direction) of FIG.

A guide member 29 is arranged on the back surface side of the transport belt 21 corresponding to an image forming region formed by the recording head 7. Further, the charging roller 26 is arranged so as to come into contact with the surface layer of the transport belt 21 and rotate in accordance with the rotation of the transport belt 21.
Further, as shown in FIG. 2, a slit disk 34 is attached to the shaft of the transport roller 27, and an encoder sensor 35 for detecting the slit of the slit disk 34 is provided, and these slit disk 34 and the encoder sensor are provided. The rotary encoder 36 is composed of 35.

Further, as a paper ejection unit for ejecting the paper 12 recorded by the recording head 7, a separation claw 51 for separating the paper 12 from the transport belt 21, a paper ejection drive roller 52, and a paper ejection roller 53 are provided. It is provided with a paper ejection tray 54 for stocking the paper to be ejected 12.

In addition, a double-sided paper feed unit is detachably attached to the back. This double-sided paper feed unit takes in the paper 12 returned by the reverse rotation of the transport belt 21, reverses it, and feeds the paper again between the counter roller 22 and the transport belt 21.
Further, as shown in FIG. 2, a maintenance / recovery mechanism 56 for maintaining and recovering the state of the nozzle of the recording head 7 is arranged in the non-printing area on one side of the carriage 3 in the scanning direction.

The maintenance / recovery machine 56 has a cap 57 that caps each nozzle surface of the recording head 7, a wiper blade 58 that wipes the nozzle surface, and a droplet that does not contribute to recording because it discharges thickened ink. It is equipped with an empty discharge receiver 59 or the like that receives droplets.

In the image forming apparatus, the paper 12 is separately fed from the paper feed unit one by one, and the paper 12 fed substantially vertically upward is guided by the guide 15 and sandwiched between the transport belt 21 and the counter roller 22. Will be transported. In the image forming apparatus, the tip is further guided by the transport guide 23 and pressed against the transport belt 21 by the pressing roller 25 to change the transport direction by approximately 90 °.

At this time, an alternating voltage is applied from the AC bias supply unit to the charging roller 26 by a control unit (not shown), and plus and minus are alternately repeated with a predetermined width in the sub-scanning direction which is the circumferential direction of the conveyor belt 21. It is charged with the pattern. When the paper 12 is fed onto the charged transport belt 21, the paper 12 is attracted to the transport belt 21 by electrostatic force, and the paper 12 is transported in the sub-scanning direction by the orbital movement of the transport belt 21.

Therefore, by driving the recording head 7 in response to the image signal while moving the carriage 3 in the outward and return directions, ink droplets are ejected onto the stopped paper 12 to record one line, and the paper 12 is loaded. After transporting the predetermined amount, record the next line. When the recording end signal or the signal that the rear end of the paper 12 reaches the recording area is received, the recording operation is ended and the paper 12 is discharged to the paper output tray 54.

Further, in the case of double-sided printing, the transport belt 21 is rotated in the reverse direction when the recording of the front surface (the surface to be printed first) is completed. By this reverse rotation, the recorded paper 12 is fed into the double-sided paper feed unit 61, the paper 12 is inverted (with the back side facing the printing side), and the paper 12 is supplied again between the counter roller 22 and the transport belt 21. Paper. After performing timing control, transporting the paper onto the transport bell 21 and recording on the back surface in the same manner as described above, the paper is discharged to the paper ejection tray 54.

Further, while waiting for printing (recording), the carriage 3 is moved to the maintenance / recovery mechanism 56 side, the nozzle surface of the recording head 7 is capped by the cap 57, and the nozzle is kept in a wet state, so that ejection failure due to ink drying is performed. To prevent. With the recording head 7 capped by the cap 57, ink is sucked from the nozzles, and a recovery operation is performed to discharge thickened ink and air bubbles. By this recovery operation, wiping is performed with the wiper blade 58 in order to clean and remove the ink adhering to the nozzle surface of the recording head 7. In addition, an empty ejection operation is performed to eject ink that is not related to recording before the start of recording, during recording, or the like. As a result, the stable ejection performance of the recording head 7 is maintained.

Here, 161 is a light emitting element, and 162 is a light receiving element, which irradiates and receives a droplet of ink ejected from a nozzle to detect the presence or absence of nozzle omission and the position of nozzle omission. Since a plurality of methods for detecting nozzle omission are known, they are omitted in the present invention.

Next, an example of the liquid discharge head constituting the recording head 7 will be described with reference to FIGS. 4 and 5. FIG. 4 is a cross-sectional explanatory view of the recording head along the longitudinal direction of the liquid chamber. FIG. 5 is a cross-sectional explanatory view of the recording head in the lateral direction of the liquid chamber (direction in which the nozzles are arranged).

The liquid discharge head is formed with a flow path plate 101, a diaphragm 102, a nozzle plate 103, a nozzle communication passage 105, a liquid chamber (also referred to as a pressure chamber) 106, an ink supply port 109, and the like.

The flow path plate 101 is formed by, for example, anisotropically etching a single crystal silicon substrate. A diaphragm 102 formed by, for example, nickel electroforming, which is joined to the lower surface of the flow path plate 101, and a nozzle plate 103, which is joined to the upper surface of the flow path plate 101, are joined and laminated. To supply ink to the nozzle communication passage 105, which is a flow path through which the nozzle 104 for ejecting droplets (ink droplets) communicates, the liquid chamber 106, which is a pressure generating chamber, and the liquid chamber 106 through the fluid resistance portion (supply path) 107. An ink supply port 109 or the like communicating with the common liquid chamber 108 of the above is formed.

Further, two rows of laminated piezoelectric elements 121 as electromechanical conversion elements, which are pressure generating means (actuator means) for deforming the diaphragm 102 to pressurize the ink in the liquid chamber 106, and the piezoelectric elements 121 It is provided with a base substrate 122 for joining and fixing.

A strut portion 123 is provided between the piezoelectric elements 121. The strut portion 123 is a portion formed at the same time as the piezoelectric element 121 by dividing the piezoelectric element member, but since no driving voltage is applied, it becomes a mere strut.

Further, an FPC cable 126 equipped with a drive circuit (drive IC: Integrated Circuit) (not shown) is connected to the piezoelectric element 121.
The peripheral edge of the diaphragm 102 is joined to the frame member 130. The frame member 130 includes a through portion 131 for accommodating an actuator unit composed of a piezoelectric element 121, a base substrate 122, and the like, a recess serving as a common liquid chamber 108, and ink for supplying ink to the common liquid chamber 108 from the outside. The supply hole 132 is formed. The frame member 130 is formed by injection molding with a thermosetting resin such as an epoxy resin or polyphenylene sulfide.

Here, in the flow path plate 101, for example, a single crystal silicon substrate having a crystal plane orientation (110) is anisotropically etched with an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH) to form a nozzle communication path 105. A recess or a hole that serves as a liquid chamber 106 is formed. However, the present invention is not limited to the single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used.

The diaphragm 102 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition, a metal plate or a joining member between a metal and a resin plate may be used. it can. The piezoelectric element 121 and the support column 123 are adhesively bonded to the diaphragm 102, and the frame member 130 is adhesively bonded.

The nozzle plate 103 forms a nozzle 104 having a diameter of 10 to 30 μm corresponding to each liquid chamber 106, and is adhesively bonded to the flow path plate 101. The nozzle plate 103 has a water-repellent layer formed on the outermost surface of a nozzle-forming member made of a metal member via a required layer.

The piezoelectric element 121 is a laminated piezoelectric element (here, PZT: lead zirconate titanate) in which a piezoelectric material 151 and an internal electrode 152 are alternately laminated. Individual electrodes (also referred to as selective electrodes) 153 and common electrodes 154 are connected to the internal electrodes 152 drawn out to the alternately different end faces of the piezoelectric elements 121.
In this embodiment, the ink in the liquid chamber 106 is pressurized by using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 121, but the liquid chamber is pressurized by using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 121. It is also possible to pressurize the ink inside the 106. Further, the structure may be such that one row of piezoelectric elements 121 is provided on one substrate 122.

In the liquid discharge head head configured in this way, for example, the piezoelectric element 121 contracts by lowering the voltage applied to the piezoelectric element 121 from the reference potential. As the diaphragm 102 descends and the volume of the liquid chamber 106 expands, ink flows into the liquid chamber 106. After that, the voltage applied to the piezoelectric element 121 is increased to extend the piezoelectric element 121 in the stacking direction, and the vibrating plate 102 is deformed in the direction of the nozzle 104 to contract the volume / volume of the liquid chamber 106, thereby causing the inside of the liquid chamber 106. The ink is pressurized. As a result, ink droplets are ejected (jetted) from the nozzle 104.

Then, by returning the voltage applied to the piezoelectric element 121 to the reference potential, the diaphragm 102 is restored to the initial position, the liquid chamber 106 expands and a negative pressure is generated. At this time, the liquid chamber from the common liquid chamber 108 to the liquid chamber. Ink is filled in 106.
Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation for the next droplet ejection is started.

The driving method of this head is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform.
Next, the outline of the control unit of this image forming apparatus will be described with reference to the block diagram of FIG.

Here, FIG. 6 shows an example of a functional block diagram of the image forming apparatus shown in FIG.
The image forming apparatus includes an operating means 71, a display means 72, a paper feeding means 73, a conveying means 74, a first discharging means 75, a second discharging means 76, a detecting means 77, a paper discharging means 78, and a control means 79. The operating means 71 is a device having switches such as a power switch, a numeric keypad, a start key, and a stop key necessary for the user to operate the image forming apparatus, and is realized by an operation panel.

The display means 72 is a member such as a display element and a lamp necessary for the user to operate the image forming apparatus, and is realized by an operation panel.

The paper feeding means 73 is a means for taking out the paper 12 from the paper feeding cassette 10, and is realized by the half-moon roller 13 and the separation pad 14 shown in FIG. The transport means 74 is a means for transporting the paper 12 to the first discharge means 75 and the second discharge means 76, and is realized by various motors 2000 shown in FIG. 7. The first ejection means 75 as the first recording head and the second ejection means 76 as the second recording head are means for ejecting ink as droplets onto the paper 12, and the recording head 7 shown in FIG. Realized by.

The detection means 77 is a detection means for detecting a missing nozzle in the first recording head and the second recording head, and is realized by the light emitting element 161 and the light receiving element 162 shown in FIG. The paper ejection means 78 is a means for ejecting the printed paper 12, and is realized by the paper ejection drive roller 52, the paper ejection roller 53, the separation claw 51, and the paper ejection tray 54 shown in FIG. The control means 79 is a means for controlling the image forming apparatus in an integrated manner, and is realized by the CPU 701, the image processing unit 810, the FPGA 702, the RAM 703, the ROM 704, and the NVRAM 705 shown in FIG.

FIG. 7 is a block diagram showing a hardware configuration example of the image forming apparatus 600 of the present embodiment. The image forming apparatus 600 includes a main control board 700, a head relay board 900, and an image processing board 800.

The main control board 700 includes CPU (Central Processing Unit) 701, FPGA (Field-Programmable Gate Array) 702, RAM (Random Access Memory) 703, ROM (Read Only Memory) 704, NVRAM (Non-Volatile Random Access Memory). 705, motor driver 706, drive waveform generation circuit 707, etc. are mounted.

The CPU 701 controls the entire image forming apparatus 600. For example, the CPU 701 uses the RAM 703 as a work area to execute various control programs stored in the ROM 704, and outputs control commands for controlling various operations in the image forming apparatus 600. At this time, the CPU 701 cooperates with the FPGA 702 to perform various operation controls in the image forming apparatus 600 while communicating with the FPGA 702.

The FPGA 702 is provided with a CPU control unit 711, a memory control unit 712, an I2C control unit 713, a sensor processing unit 714, a motor control unit 715, and a recording head control unit 716.

The CPU control unit 711 has a function of communicating with the CPU 701. The memory control unit 712 has a function of accessing RAM 703 and ROM 704. The I2C control unit 713 has a function of communicating with the NVRAM 705.

The sensor processing unit 714 processes the sensor signals of various sensors 9000. The various sensors 9000 are a general term for sensors that detect various states in the image forming apparatus 600. In addition to the above-mentioned encoder sensor 35, the various sensors 9000 include a paper sensor that detects the passage of the recording paper P, a cover sensor that detects the opening of the cover member, a temperature / humidity sensor that detects the ambient temperature and humidity, and the recording paper P. It includes a paper fixing lever sensor that detects the operating state of the fixing lever, and a remaining amount detection sensor that detects the remaining amount of ink in the cartridge 7.
The analog sensor signal output from the temperature / humidity sensor or the like is converted into a digital signal by an AD converter mounted on the main control board 700 or the like and input to the FPGA 702.

The motor control unit 715 controls various motors 2000. Various motors 2000 are a general term for motors included in the image forming apparatus 600. The various motors 2000 operate a main scanning motor for operating the carriage, a sub-scanning motor for transporting the recording paper P in the sub-scanning direction, a paper feed motor for feeding the recording paper P, and a maintenance mechanism 15. It includes a maintenance motor for making it.

Here, a specific example of control by cooperation between the CPU 701 and the motor control unit 715 of the FPGA 702 will be described by taking the operation control of the main scanning motor 8 as an example.
First, the CPU 701 notifies the motor control unit 715 of the movement speed and the movement distance of the carriage 5 together with the operation start instruction of the main scanning motor 8. Upon receiving this instruction, the motor control unit 715 generates a drive profile based on the movement speed and movement instruction information notified from the CPU 701, and the encoder value supplied from the sensor processing unit 714 (sensor signal of the encoder sensor 35). The PWM command value is calculated and output to the motor driver 706 while comparing with the value obtained by processing). When the motor control unit 715 finishes the predetermined operation, the motor control unit 715 notifies the CPU 701 of the end of the operation.
Although the example in which the motor control unit 715 generates the drive profile has been described here, the CPU 701 may generate the drive profile and instruct the motor control unit 715. The CPU701 also counts the number of prints and the number of scans of the main scanning motor 8.

The recording head control unit 716 passes the head drive data, the discharge synchronization signal LINE, and the discharge timing signal CHANGE stored in the ROM 704 to the drive waveform generation circuit 707, and causes the drive waveform generation circuit 707 to generate a common drive waveform signal Vcom. The common drive waveform signal Vcom generated by the drive waveform generation circuit 707 is input to the recording head driver 210 described later mounted on the head relay board 900.

Next, an example of the print control unit 207 and the head driver 208 will be described with reference to FIG.

FIG. 8 is a block diagram showing a configuration example of the recording head control unit 910, the drive waveform generation circuit 707, and the recording head driver 210.
When the recording head control unit 910 receives the trigger signal Trig that triggers the discharge timing, the recording head control unit 910 outputs the discharge synchronization signal LINE that triggers the generation of the drive waveform to the drive waveform generation circuit 707. Further, the discharge timing signal CHANGE corresponding to the delay amount from the discharge synchronization signal LINE is output to the drive waveform generation circuit 707 (see FIG. 8).
The drive waveform generation circuit 707 generates a common drive waveform Vcom at a timing based on the discharge synchronization signal LINE and the discharge timing signal CHANGE.
Further, the recording head control unit 910 receives the image data SD'after image processing from the image processing unit 810 described later provided on the image processing board 800. Based on this image data SD', the recording head control unit 910 outputs a mask control signal MN for selecting a predetermined waveform of the common drive waveform signal Vcom according to the size of ink droplets ejected from each nozzle of the recording head 7. Generate. The mask control signal MN is a timing signal synchronized with the discharge timing signal CHANGE. Then, the recording head control unit 910 transfers the image data SD', the synchronous clock signal SCK, the latch signal LT instructing the latch of the image data, and the generated mask control signal MN to the recording head driver 210.

As shown in FIG. 8, the recording head driver 210 includes a shift register 211, a latch circuit 212, a gradation decoder 213, a level shifter 214, and an analog switch 215.

The shift register 211 inputs the image data SD'transferred from the recording head control unit 910 and the synchronous clock signal SCK. The latch circuit 212 latches each resist value of the shift register 211 by the latch signal LT transferred from the recording head control unit 910.

The gradation decoder 213 decodes the value (image data SD') latched by the latch circuit 212 and the mask control signal MN, and outputs the result. The level shifter 214 converts the logic level voltage signal of the gradation decoder 213 into a level at which the analog switch 215 can operate.

The analog switch 215 is a switch that is turned on / off by the output of the gradation decoder 213 given via the level shifter 214. The analog switch 215 is provided for each of the above-mentioned nozzles included in the recording head 7, and is connected to an individual electrode 83 of the piezoelectric element 70 corresponding to each nozzle. Further, a common drive waveform signal Vcom from the drive waveform generation circuit 707 is input to the analog switch 215. Further, as described above, the timing of the mask control signal MN is synchronized with the timing of the common drive waveform Vcom. Therefore, by switching the analog switch 215 on / off at an appropriate timing according to the output of the gradation decoder 213 given via the level shifter 214, each nozzle from the drive waveforms constituting the common drive waveform signal Vcom The waveform applied to the piezoelectric element 70 corresponding to is selected. As a result, the size of the ink droplets ejected from the nozzle is controlled.

From the drive waveform generation circuit 707, as shown in FIG. 9, the waveform element that falls from the reference potential Ve and the waveform element that rises from the state after the fall are fair within one print cycle (one drive cycle). A drive signal consisting of the drive pulses P1 to P8 is generated and output.

On the other hand, the drive pulse to be used is selected by the mask signal MN from the recording head control unit 910.

Here, the waveform element in which the potential V of the drive pulse falls from the reference potential Ve is a lead-in waveform element in which the piezoelectric element 121 contracts and the volume of the liquid chamber 106 expands. Further, the corrugated element that rises from the state after falling is a pressurized corrugated element in which the piezoelectric element 121 expands and the volume of the liquid chamber 106 contracts.

FIG. 10 (a) is an explanatory diagram for explaining a small drop selected from the drive waveform, and FIG. 10 (b) shows a medium drop selected from the drive waveform. It is explanatory drawing for this. FIG. 10 (c) is an explanatory diagram for explaining a large drop selected from the drive waveform, and FIG. 10 (d) is an explanatory diagram for explaining the fine drive selected from the drive waveform.
When forming small droplets (small dots) by the mask control signal MN from the recording head control unit 910, the drive pulse P1 is selected as shown in FIG. 10A. When forming a middle drop (middle dot), drive pulses P4 to P6 are selected as shown in FIG. 10 (b). When forming a large drop (large dot), drive pulses P2 to P8 are selected as shown in FIG. 10 (c). In the case of fine drive (vibrating the meniscus without dropping droplets), the fine drive pulse P2 is selected as shown in FIG. 10 (d) and applied to the piezoelectric element 121 of the recording head 7, respectively.

When forming a middle drop, the drive pulse P4 ejects the first drop, the drive pulse P5 ejects the second drop, and the drive pulse P6 ejects the third drop, which are combined during flight and landed as one drop. At this time, assuming that the natural vibration cycle of the liquid chamber 106 is Tc, the interval between the discharge timings of the drive pulses P4 and P5 is preferably 2 Tc ± 0.5 μs.

Since the drive pulses P4 and P5 are composed of simple pulling waveform elements, if the driving pulse P6 is also made of the same simple pulling waveform elements, the ink droplet velocity will become too large, and from the landing position of other droplet types. There is a risk of misalignment.

Therefore, the drive pulse P6 reduces the pull-in voltage (reduces the falling potential) to reduce the pull-in of the meniscus and suppresses the ink drop velocity of the third drop. However, the startup voltage is not reduced in order to obtain the required ink droplet volume.

That is, in the lead-in waveform element of the final drive pulse among the plurality of drive pulses, the pull-in voltage is relatively small, so that the drop ejection velocity due to the final drive pulse is relatively low, and the landing position is set to another drop. It can be matched with the seed as much as possible.

Further, the fine drive pulse P2 is a drive waveform that vibrates the meniscus without ejecting ink droplets in order to prevent the meniscus of the nozzle from drying. In the non-printing area, the fine drive pulse P2 is applied to the recording head 7. Further, by using the drive pulse P2, which is a fine drive waveform, as one of the drive pulses constituting the large droplet, it is possible to achieve shortening (speeding up) of the drive cycle.

Further, by setting the interval between the ejection timings of the fine drive pulse P2 and the drive pulse P3 within the range of the natural vibration period Tc ± 0.5 μs, the volume of ink droplets ejected by the drive pulse P3 can be increased. That is, the drop volume of the drops that can be ejected by the drive pulse P3 is applied by the drive pulse P3 alone by superimposing the expansion of the liquid chamber 106 by the drive pulse P3 on the pressure vibration of the liquid chamber 106 by the vibration cycle generated by the fine drive pulse P2. Can be larger than when

The required drive waveform differs depending on the viscosity of the ink. For this reason, as shown in FIG. 11, the image forming apparatus prepares a drive waveform when the ink viscosity is 5 mPa · s, a drive waveform when the viscosity is 10 mPa · s, and a drive waveform when the viscosity is 20 mPa · s. .. The ink viscosity is determined from the temperature detected by the temperature sensor, and the drive waveform to be used is selected.
FIG. 11 is an explanatory diagram for explaining a drive waveform according to the viscosity of the ink.

That is, when the ink viscosity is low, the voltage of the drive pulse is relatively small, and when the ink viscosity is high, the voltage of the drive pulse is relatively large. The volume can be discharged substantially constant. Further, the drive pulse can vibrate the meniscus without ejecting ink droplets by selecting the peak value according to the ink viscosity.

By using a drive waveform composed of such drive pulses, it is possible to control the time until each of the large, medium and small droplets lands on the paper, and the ejection start time is different for each of the large, medium and small droplets. However, it is possible to land each drop at almost the same position.

FIG. 12 is a functional block diagram showing a configuration example of the image processing unit 810.

The image processing unit 810 performs gradation processing, image conversion processing, and the like on the received image data, and converts the received image data into image data in a format that can be processed by the recording head control unit 716. Then, the image processing unit 810 outputs the converted image data to the recording head control unit 716.

Specifically, the image processing unit 810 includes an interface 41, a gradation processing unit 42, an image conversion unit 43, and an image processing unit RAM 44.

The interface 41 is an input unit for image data, and is a communication interface with the CPU 701 and the FPGA 702. The gradation processing unit 42 performs gradation processing on the received multi-valued image data and converts it into small-value image data. The small value image data is image data having a number of gradations equal to the type of droplets (large droplet, medium droplet, small droplet) ejected by the recording head 7 shown in FIG. Then, the gradation processing unit 42 holds the converted image data on the image processing unit RAM 44 for one band or more. The image data for one band refers to the image data corresponding to the maximum width in the sub-scanning direction that can be recorded by the recording head 7 in one scan in the main scanning direction X.

The image conversion unit 43 converts the image data for one band on the image processing unit RAM 44 in units of images output in one scan (one scan) in the main scanning direction X. This conversion is performed according to the configuration of the recording head 7 according to the information of the printing order and the printing width (= sub-scanning width of image recording per scan) received from the CPU 701 via the interface 41.

The print order and print width may be one-pass printing in which an image is formed by one main scan on a recording medium, and the same nozzle group or different nozzle groups may be used on a plurality of main scans on the same area of the recording medium. Multi-pass printing that forms an image may be used. Further, the heads may be arranged in the main scanning direction, and the same area may be hit by different nozzles. These recording methods can be used in combination as appropriate.

The print width indicates the width in the sub-scanning direction Y of the image recorded by one scan (one scan) of the recording head 7 in the main scanning direction X. In this embodiment, the print width is set by the CPU 701.

The image conversion unit 43 outputs the converted image data SD'to the image recording unit 50 via the interface 41.

The function of the image processing unit 810 may be executed as a hardware function such as FPGA or ASIC, or may be executed by an image processing program stored in the storage device inside the image processing unit 810.

Next, the image forming method according to the present invention for outputting a printed image by the above-mentioned image forming apparatus will be described below with respect to the image processing apparatus and the above-mentioned image forming apparatus in which the program according to the present invention is mounted on a computer.

An example of the image forming system according to the present invention, which is composed of the image processing apparatus according to the present invention and the above-mentioned image forming apparatus, an inkjet printer (inkjet recording apparatus), will be described with reference to FIG.
FIG. 13 is a block explanatory view showing an example of the image forming system according to the present invention.
This printing system (image forming system) is configured by connecting one or a plurality of image processing devices 400 composed of a personal computer (PC) or the like and an image forming device 600 by a predetermined interface or network.

In the image processing apparatus 400, as shown in FIG. 14, the CPU 401 and various ROM 402s and RAM 403s as memory means are connected by a bus line. A storage device 406 using a magnetic storage device such as an HDD, an input device 404 such as a mouse or keyboard, a monitor 405 such as an LCD or CRT, and a storage medium such as an optical disk (not shown) are connected to the bus line via an interface. A storage medium reader for reading is connected. Here, HDD is an abbreviation for Hard Disk Drive, LCD is an abbreviation for Liquid Crystal Display, and CRT is an abbreviation for Cathode Ray Tube.
In addition, a predetermined interface (external I / F) 407 that communicates with a network such as the Internet or an external device such as USB (universal serial bus) is connected.

In the image processing device 400, an image drawing or character recording command from an application or an operating system is temporarily stored in a drawing data memory. The recording command describes, for example, the position, thickness, shape, etc. of the line to be recorded, or the typeface, size, position, etc. of the character to be recorded, and these commands are written in a specific print language. It is described.
The instruction stored in the drawing data memory is interpreted by the rasterizer, and if it is a line recording instruction, it is converted into a recording dot pattern according to a specified position, thickness, and the like. If the command is a character recording command, the outline information of the corresponding character is called from the font outline data stored in the image processing device 400 and converted into a recording dot pattern according to the specified position and size. If the instruction is image data, it is directly converted into a recording dot pattern.

Image processing is performed on these recorded dot patterns and stored in the raster data memory. At this time, the image processing apparatus 400 rasterizes the data of the recording dot pattern with the orthogonal grid as the basic recording position. Image processing includes, for example, color management processing (CMM) for adjusting colors, γ correction processing, halftone processing such as dither method and error diffusion method, background removal processing, and total ink amount regulation processing.

The recording dot pattern stored in the raster data memory is transferred to the inkjet recording device via the interface.

The image processing program is stored in the storage device 406 of the image processing device 400. This image processing program is installed in the storage device 406 by reading it from the storage medium with a storage medium reading device or downloading it from a network such as the Internet.
With this installation, the image processing device 400 is in an operable state for performing the following image processing. Note that this image processing program may operate on a predetermined OS (Operating System). Moreover, it may be a part of a specific application software.

Although this image processing method can be performed on the image forming apparatus side, the inkjet recording apparatus side has a function of generating a dot pattern that is actually recorded by receiving an image drawing or character printing command in the apparatus. Let's take an example of not having it.
That is, the print command from the application software or the like executed by the image processing device 400 serving as the host computer is image-processed by the printer driver according to the present invention incorporated as software in the image processing device 400. After image processing, multi-valued dot pattern data (printed image data) that can be output by the inkjet printer is generated for each color plate, rasterized, transferred to the inkjet printer, and the inkjet printer is printed out. ..

FIG. 15 is a flow of a nozzle omission check performed on the main control board 700 of the control means 79 of the inkjet printer.
First, the detection means 77 in the inkjet printer checks for the presence or absence of nozzle omission for each color plate (step S11). If there is no nozzle omission, the process ends (step S12 / No). If there is a nozzle omission (step S12 / Yes), the main control board 700 notifies the image processing unit 810 of the nozzle omission information (step S13). The nozzle omission information includes the position information of the nozzle with the nozzle omission.

FIG. 16 is an example of a flow chart of nozzle omission correction performed on the image processing board 800 of the control means 79 of the inkjet printer.
The image processing unit 810 converts the multi-valued image data recording head 7 input from the image processing device 400 into image data having the number of gradations ejected, and converts the image data SD'according to the configuration of the recording head 7 into the FPGA 702. This correction flow is executed when the output process is performed.
The image processing unit 810 stores the nozzle omission information notified from the inkjet printer in the image processing unit RAM44.
When the correction flow is started, first, the presence or absence of nozzle omission is checked from the information stored in the image processing unit RAM44 (step S1). If there is no nozzle omission, the flow ends (step S2 / No).
When there is a nozzle omission (step S2 / Yes), the gradation processing unit 42 corrects the dot size of the adjacent dots of the dots corresponding to the nozzle omission in the image for each color plate converted by the image conversion unit 43. .. Since the image conversion unit 43 generates image data according to the configuration of the recording head 7, it is possible for the image conversion unit 43 to specify which dot corresponds to the nozzle omission. Details of dot size modulation will be described later. Dot size modulation is performed for each color plate (step S3).
Next, the gradation processing unit 42 superimposes the images subjected to dot size modulation for each color plate (step S4). As a result of superimposing the images for each color plate, it is confirmed whether or not there is a dot size modulator in the same pixel (step S5), and if there is no dot size modulator in the same pixel (step S5 / No), processing To finish. When the dot size modulation unit is present in the same pixel, the dot size modulation width is reduced to prevent the ink adhesion amount from becoming excessive (step S5 / Yes).

Next, Example 1 of nozzle omission correction will be described below.
First, the normal nozzle omission correction will be described with reference to FIGS. 17A, 17B, and 17C.
17 (a) is a schematic diagram of the head, FIG. 17 (b) is a schematic diagram of dots without nozzle omission correction, and FIG. 17 (c) is a schematic diagram of dots at the time of adjacent dot size modulation.
If the central nozzle of the head does not eject and there is no nozzle omission correction, white streaks will occur because there are no dots in the center, but by modulating the dot diameter adjacent to the nozzle omission to a larger size. It is possible to reduce the visibility of white streaks due to nozzle removal.

The nozzle omission correction when printing the secondary color using FIGS. 18 (a), (b), (c) to 19 (a), (b), and (c) will be described.
FIG. 18 (a) is a schematic diagram of a cyan head, FIG. 18 (b) is a schematic diagram of a magenta head, and FIG. 18 (c) is a diagram of the cyan head and magenta head when the dot size is modulated. It is a dot schematic diagram of. FIG. 19 (a) is a schematic diagram of a cyan head, FIG. 19 (b) is a schematic diagram of a magenta head, and FIG. 19 (c) is a diagram of the cyan head and magenta head when the dot size is modulated. It is a dot schematic diagram of.

Here, the case where cyan and magenta are used is illustrated.
18 (c) and 19 (c) show the case where the central nozzle of the head of both the cyan and magenta heads is non-ejection.

18 (a) to 18 (c) show the nozzle omission correction carried out in FIGS. 17 (a) to 17 (c) for each color plate.
When printing cyan and magenta alone, the visibility of white streaks can be reduced by this nozzle omission correction. However, when printing red with cyan and magenta superimposed, the amount of ink adhered to pixels with larger dot sizes becomes excessive, and if the ink allowance of the recording medium is exceeded, ink may escape to the back surface or transfer due to insufficient drying may occur. Problems will occur.

Therefore, in the present invention, as shown in FIG. 19, when a plurality of colors are driven into the same pixel, the amount of ink adhered is controlled by reducing the modulation width of the dot size.

When the cyan of FIG. 19A is printed by itself, white streaks are visible, but when cyan and magenta are overlapped, the amount of liquid is two drops, so the nozzle missing portion is filled on the recording medium and the white streaks are formed. It is possible to reduce the visibility.
Here, the case of two colors is shown, but for example, when nozzle omission occurs at the same location when four colors are overlapped, the ink adhesion amount is controlled by further reducing the dot size modulation width. Just do it.
Further, although the modulation width of both colors is reduced here, the modulation width of any one color may be reduced as long as there is no problem in color tone or the like.

20 (a) is a schematic diagram of a cyan head, FIG. 20 (b) is a schematic diagram of a magenta head, and FIG. 20 (c) is a schematic diagram of dots at the time of adjacent dot size modulation. ..
FIG. 20C also shows a case where an image is formed by using cyan and magenta, but a case where the driving positions of cyan and magenta do not overlap will be described.
For example, since dots are sparsely generated in the highlight area and the like, it is often seen that even if a plurality of colors are overlapped, they are not driven into the same pixel.

By combining the process of FIG. 19 (c) and the process of FIG. 20 (c), it is possible to effectively perform nozzle omission correction.

In Example 1 described above, the correction flow according to the present invention was carried out by the image processing unit 810, but it may be carried out by the image processing device 400.
In this case, the image processing device 400 stores information on the configuration of the recording head 7 and the recording method such as the printing order and the printing width in some way. For example, the configuration information of the recording head 7 may be stored when the program is installed in the image processing device 400. Further, the information of the recording method may be determined and stored at the stage when the printing is instructed by the user.
The nozzle omission information is transmitted from the inkjet printer to the image processing device 400 after the nozzle omission is detected.

In the above-described embodiment, the serial type printer in which the recording head 7 is mounted on the carriage and moves on the paper has been described, but the present invention is also applied to a line type printer in which the paper in which the position of the recording head 7 is fixed moves. It is possible.

<Program>
The image forming apparatus according to the present invention described above is realized by a program that executes processing on a computer. As an example, the case where the function of the present invention is realized by a program will be described below.

For example
A computer-readable program of an image forming apparatus that includes at least a first recording head and a second recording head.
On the computer
A procedure in which the detection means detects a missing nozzle in the first recording head and the second recording head,
When the control means has the same landing position of the droplet from the defective nozzle of the first recording head and the landing position of the droplet from the defective nozzle of the second recording head, the defective nozzle of the first recording head A procedure for controlling the amount of droplets ejected from an adjacent nozzle and the amount of droplets ejected from an adjacent nozzle of a missing nozzle of the second recording head.
There is a program to execute.

Such a program may be stored on a computer-readable storage medium.

<Storage medium>
Here, examples of the storage medium include a computer-readable storage medium such as a CD-ROM, a flexible disk (FD), and a CD-R, a semiconductor memory such as a flash memory, RAM, ROM, and FeRAM, and an HDD.

CD-ROM is an abbreviation for Compact Disc Read Only Memory. Flexible Disk means Flexible Disk: FD. CD-R is an abbreviation for CD Recordable. FeRAM is an abbreviation for Ferroelectric RAM and means ferroelectric memory.

<Effect>
Based on the above, according to the present embodiment, the amount of droplets ejected from the nozzle adjacent to the defective nozzle of the first recording head and the droplet of droplets ejected from the nozzle adjacent to the defective nozzle of the second recording head. Control the amount. That is, in different heads, it is detected that the nozzles that drip at the same pixel position are missing, and the amount of drops of the adjacent nozzles is controlled. As a result, it is possible to reduce the visibility of white streaks due to nozzle omission and to form a high-quality image on the recording medium by controlling the amount of ink adhered to the recording medium.

It should be noted that the above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be carried out within a range not deviating from the gist thereof. is there. For example, in the above description, the case where the number of recording heads used for correction is two has been described, but the present invention is not limited to this, and the number of recording heads used for correction may be three or more.

1 Guide rod 2 Guide rail 3 Carriage 7 Recording head 8 Sub tank 10 Paper cassette 11 Paper loading section (pressure plate)
12 Paper 13 Half-moon roller (paper feed roller)
14 Separation pad 15 Guide 21 Conveyance belt 22 Counter roller 23 Conveyance guide 24 Pressing member 25 Pressing roller 26 Charging roller 27 Conveying roller 28 Tension roller 29 Guide member 31 Sub-scanning motor 32 Timing belt 33 Timing roller 34 Slit disk 35 Encoder sensor 36 Rotary encoder 41 Interface 42 Gradation processing unit 43 Image conversion unit 44 Image processing unit RAM
51 Separation claw 52 Paper ejection drive roller 53 Paper ejection roller 56 Maintenance / recovery mechanism 57 Cap 101 Flow path plate 102 Diaphragm 103 Nozzle plate 104 Nozzle 105 Nozzle communication passage 106 Liquid chamber (pressure chamber)
108 Common liquid chamber 161 Light emitting element 162 Light receiving element 210 Recording head driver 400 Image processing device 700 Main control board 701 CPU
702 FPGA
703 RAM
704 ROM
705 NVRAM
706 Motor drive 707 Drive waveform generation circuit 711 CPU control unit 712 Memory control unit 713 I2C control unit 714 Sensor processing unit 715 Motor control unit 716 Recording head control unit 800 Image processing board 810 Image processing unit 900 Head relay board 910 Recording head control unit

Japanese Unexamined Patent Publication No. 2002-86767

Claims (5)

A first recording head having a plurality of nozzles for ejecting droplets ,
A second recording head having a plurality of nozzles for ejecting droplets ,
A detection means for detecting a non-ejection nozzle in the first recording head and a non-ejection nozzle in the second recording head ,
Depending on the detection result by said detecting means, possess control means for controlling the drop volume of the droplet discharged, the,
The control means
If the faulty nozzle is detected in the first recording head, it is controlled to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of said first recording head,
If the faulty nozzle is detected in the second recording head, and controlled so as to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of the second recording head,
If the landing positions of the droplets discharged from the faulty nozzle of the said first recording head and the the landing positions of the droplets discharged from the faulty nozzle second recording heads are the same, the first The amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the recording head and the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the second recording head are increased. An image forming apparatus characterized in that it is adjusted to be reduced . The plurality of nozzles of the first recording head and the plurality of nozzles of the second recording head are arranged in the first direction.
The first recording head and the second recording head are movable in a second direction, which is a direction orthogonal to the first direction with respect to the recording medium on which droplets are ejected, or the recording. The medium is movable in the second direction with respect to the first recording head and the first recording head.
The control means
When the droplets are continuously ejected in the second direction, the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the first recording head and the amount of the droplets ejected from the second recording head In adjusting the increase in the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle, the amount of increase from other nozzles is larger than in the case where the droplets are ejected discontinuously in the second direction. The image forming apparatus according to claim 1, wherein the droplets are adjusted to be smaller and smaller . It also has an image processing unit that generates image data for each color.
The plurality of nozzles of the first recording head eject droplets of the first color.
The plurality of nozzles of the second recording head eject droplets of a second color different from the first color.
The control means superimposes the image data for the first color and the image data for the second color to obtain the landing position of the droplets ejected from the non-ejection nozzle of the first recording head and the above. The image forming apparatus according to claim 1 or 2 , wherein it is determined whether or not there is a pixel having the same landing position as the droplet ejected from the non-ejection nozzle of the second recording head . An image forming method in an image forming apparatus including a first recording head, a second recording head, and a detecting means .
A detection step of detecting non-ejection nozzles in a plurality of nozzles that eject droplets of the first recording head and non-ejection nozzles in a plurality of nozzles that eject droplets of the second recording head by the detection means. When,
It has a control step for controlling the amount of droplets to be ejected according to the detection result in the detection step .
In the control step,
If the faulty nozzle is detected in the first recording head, it is controlled to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of said first recording head,
If the faulty nozzle is detected in the second recording head, and controlled so as to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of the second recording head,
If the landing positions of the droplets discharged from the faulty nozzle of the said first recording head and the the landing positions of the droplets discharged from the faulty nozzle second recording heads are the same, the first The amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the recording head and the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the second recording head are increased. An image forming method characterized by adjusting to reduce the number. A computer-readable program of an image forming apparatus including a first recording head, a second recording head, and a detecting means .
On the computer
A detection procedure for detecting non-ejection nozzles in a plurality of nozzles that eject droplets of the first recording head and non-ejection nozzles in a plurality of nozzles that eject droplets of the second recording head by the detection means. When,
In response to said detection result in the detection procedure, a control procedure for controlling the drop volume of the droplet discharged, allowed to run,
In the control procedure,
If the faulty nozzle is detected in the first recording head, it is controlled to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of said first recording head,
If the faulty nozzle is detected in the second recording head, and controlled so as to increase the droplet amount of the droplet to be discharged from a nozzle adjacent to the ejection failure nozzle of the second recording head,
If the landing positions of the droplets discharged from the faulty nozzle of the said first recording head and the the landing positions of the droplets discharged from the faulty nozzle second recording heads are the same, the first The amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the recording head and the amount of droplets ejected from the nozzle adjacent to the non-ejection nozzle of the second recording head are increased. , A program characterized by adjusting to reduce .

Images