JP2023019210A - Liquid discharge device and liquid discharge method - Google Patents

Abstract

To enable a head to discharge liquid stably.SOLUTION: A liquid discharge device according to one embodiment of the present invention comprises: a head that discharges liquid; an output part that outputs, to the head, driving waveform data including data on discharging/driving waveforms for discharging the liquid and data on vibrating/driving waveforms for vibrating the liquid in the head without discharging the liquid; and a changing part that makes second frequencies at which the vibrating/driving waveforms are outputted to the head different from first frequencies, in accordance with the first frequencies at which the driving waveforms are outputted to the head.SELECTED DRAWING: Figure 8

Description

The present invention relates to a liquid ejecting apparatus and a liquid ejecting method.

2. Description of the Related Art Conventionally, among liquid ejecting apparatuses having a head for ejecting liquid, there is known one in which the liquid in the head is vibrated during a period in which no ejection is performed.

As such a liquid ejecting apparatus, a technique for controlling the timing of vibration of the liquid filled in the head during a period in which no ejection is performed is disclosed in order to stabilize the ejection of liquid from the head (for example, See Patent Document 1).

However, in the configuration of Patent Document 1, a first frequency at which a drive waveform for ejecting liquid to the head is output to the head, and a vibration drive waveform for vibrating the liquid in the head without ejecting liquid from the head are output to the head. is equal to the second frequency. Therefore, there is a concern that the vibration of the liquid cannot be controlled with an appropriate frequency, and the liquid ejection from the head cannot be stabilized.

An object of the present invention is to stabilize liquid ejection from a head.

A liquid ejection apparatus according to an aspect of the present invention includes a head that ejects liquid, data of an ejection drive waveform that ejects the liquid, and vibration drive waveform that vibrates the liquid in the head without ejecting the liquid. and a second frequency at which the vibration drive waveform is output to the head according to a first frequency at which the drive waveform is output to the head. and a changing unit for varying the first frequency.

According to the present invention, liquid ejection from the head can be stabilized.

1 is a diagram showing an example of the overall configuration of a printing system according to an embodiment; FIG. 3 is a diagram illustrating a configuration example of an image forming unit according to the embodiment; FIG. 4 is an enlarged view showing nozzles in the head according to the embodiment; FIG. 3 is a cross-sectional view along the nozzle array direction of the head according to the embodiment; FIG. 3 is a cross-sectional view of the head according to the embodiment along a direction perpendicular to the nozzle arrangement direction; FIG. 2 is a block diagram of a hardware configuration example of an image forming apparatus according to an embodiment; FIG. 3 is a block diagram showing a configuration example of a head driver according to the embodiment; FIG. 3 is a block diagram of an example functional configuration of an image processing unit according to the embodiment; FIG. FIG. 5 is a diagram illustrating changes in transport speed of roll paper; FIG. 4 is a diagram for explaining vibration driving in the head; FIG. 5 is a diagram for explaining drive waveform data of the head; 4 is a flowchart of an example of processing by an image processing unit according to the embodiment; FIG. 10 is a diagram illustrating an example of changing mask control signal data by a changing unit; It is a figure which shows the 1st example of the vibration drive waveform before changing a 2nd frequency. It is a figure which shows the 1st example of the vibration drive waveform after 2nd frequency change. FIG. 10 is a diagram showing a second example of a vibration drive waveform before changing the second frequency; FIG. 10 is a diagram showing a second example of the vibration drive waveform after changing the second frequency; It is a figure which shows the transition example of the 2nd frequency which concerns on embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate.

<Overall Configuration Example of Printing System 1>
FIG. 1 is a diagram showing an example of the overall configuration of a printing system 1 according to the first embodiment. The printing system 1 includes an inkjet image forming apparatus 2, which is an example of a liquid ejecting apparatus. The ink ejected by the image forming apparatus 2 is an example of liquid.

As shown in FIG. 1, the printing system 1 includes a loading section 10 that loads the roll paper Md, a preprocessing section 20 that preprocesses the loaded roll paper Md, and a heating unit that heats the preprocessed roll paper Md. and a drying section 30 that is dried by The printing system 1 also includes an image forming unit 40 that forms an image on the surface of the roll paper Md, a post-processing unit 50 that post-processes the roll paper Md on which the image is formed, and a post-processed roll paper Md. and maintenance and recovery sections 90A and 90B.

Roll paper Md is an example of a recording medium. The roll paper Md is, for example, a continuous form paper in which perforations that can be cut are formed at predetermined intervals, or continuous paper such as a continuous form wound in a roll. A page on roll paper is, for example, an area sandwiched by perforations at predetermined intervals.

In the printing system 1 , the roll paper Md is loaded by the loading unit 10 , and the surface of the roll paper Md is preprocessed and dried by the preprocessing unit 20 and the drying unit 30 .

In the printing system 1, the image forming section 40 of the image forming apparatus 2 forms an image on the surface of the roll paper Md that has been preprocessed and dried. The printing system 1 performs post-processing by the post-processing section 50 on the roll paper Md on which the image is formed. After that, the printing system 1 winds the roll paper Md by the unloading unit 60 and then unloads it.

The carry-in section 10 is means for conveying the roll paper Md to the preprocessing section 20 or the like. The carry-in section 10 has a paper feed section 11 and a plurality of transport rollers 12 . The carry-in unit 10 carries in and moves the roll paper Md wound around and held by the paper feed roll of the paper feed unit 11 using the transport rollers 12 and the like, and transports it to the preprocessing unit 20 (platen) and the like.

The preprocessing unit 20 is means for processing the roll paper Md before an image is formed. The pretreatment section 20 pretreats the surface of the roll paper Md carried in by the carry-in section 10 with a pretreatment liquid. The pretreatment is, for example, a treatment of uniformly applying a pretreatment liquid having a function of aggregating ink to the surface of the roll paper Md. The pretreatment liquid is, for example, a treatment liquid containing a water-soluble aliphatic organic acid. A treatment liquid containing a water-soluble aliphatic organic acid is a treatment liquid having a property of aggregating a water-dispersible colorant. Aggregation means that the water-dispersible colorant particles adhere to each other.

The pretreatment unit 20 can adsorb ions on the surface of the water-dispersible colorant by adding an ionic substance such as a water-soluble aliphatic organic acid to the pretreatment liquid. Thereby, the pretreatment unit 20 can neutralize the surface charge of the water-dispersible colorant. In addition, the pretreatment unit 20 can enhance the aggregating action due to the intermolecular force to further agglomerate the water-dispersible colorant.

The pretreatment unit 20 uses a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, and a U comma coating as methods for applying the pretreatment liquid. AKKU coating method, smoothing coating method, micro gravure coating method, reverse roll coating method, four or five roll coating method, dip coating method, curtain coating method, slide coating method, die coating method and the like can be applied.

The drying unit 30 is means for drying the roll paper Md by heating or the like. The drying section 30 includes a pre-processing drying section 31 that dries the roll paper Md that has been pre-processed by the pre-processing section 20, and a post-processing drying section 32 that dries the roll paper Md that has been post-processed by the post-processing section 50. ,including.

The pretreatment drying section 31 has, for example, a heat roller. The pretreatment drying section 31 heats the heat roller to, for example, 50 to 100° C., and brings the surface of the roll paper Md coated with the pretreatment liquid into contact with the heat roller. The pretreatment drying section 31 can heat the surface of the roll paper Md coated with the pretreatment liquid by a heat roller, evaporate the water content of the pretreatment liquid, and dry the roll paper Md. The post-processing drying section 32 has the same configuration as the pre-processing drying section 31 .

The image forming section 40 is means for forming an image on the roll paper Md. The image forming unit 40 forms an image on the surface of the roll paper Md by ejecting ink onto the roll paper Md dried by the drying unit 30 .

The post-processing section 50 is means for processing the roll paper Md on which images have been formed. The post-processing section 50 performs post-processing by applying a post-processing liquid to the surface of the roll paper Md on which an image has been formed by the image forming section 40 . The post-treatment is a process of ejecting and coating the post-treatment liquid in the form of spots on the roll paper Md.

Maintaining and recovering sections 90A and 90B are provided near the image forming section 40 and the post-processing section 50, respectively. The maintenance/recovery units 90A and 90B perform maintenance/recovery operations such as cleaning or maintenance of the nozzles and nozzle surfaces of the heads included in the image forming unit 40 and the post-processing unit 50, respectively.

Image forming section 40 , post-processing section 50 , and maintenance/restoration sections 90 A and 90 B are arranged on housing 74 . The housing 74 has a transport unit 80 .

<Configuration Example of Image Forming Unit 40>
FIG. 2 is a diagram showing an example of the configuration of the image forming section 40, and is a diagram of the image forming section 40 facing the roll paper Md as viewed from the side of the roll paper Md. The image forming section 40 is a full-line type head unit.

The image forming unit 40 sets head modules 40K, 40Ca, 40M, and 40Y for each color in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream in the transport direction Xm of the roll paper Md. I have. However, the arrangement order of the heads in the image forming section 40 is not limited to the order described above, and can be changed as appropriate. Further, the combination of colors is not limited to the above four colors, and may be one color of black (K) or three colors of green (G), red (R) and light cyan (LC). good.

The black (K) head module 40K has four heads 40K-1, 40K-2, 40K-3 and 40K-4 staggered along the width direction substantially orthogonal to the transport direction Xm of the roll paper Md. are placed. By arranging four heads over the entire width direction, the image forming section 40 can form an image over the entire width direction of the roll paper Md without moving the heads in the width direction. In addition, the image forming section 40 can form an image on the entire width of the roll paper Md without omission by arranging the four heads in a zigzag pattern. Since the black (K), cyan (C), magenta (M), and yellow (Y) heads are the same, the black (K) head 40K-1 will be described below as an example.

The post-treatment section 50 also has a head module 50H, in which four treatment liquid ejection heads are arranged in a zigzag pattern, so that the post-treatment liquid can be ejected over the entire area in the width direction. Note that FIG. 2 exemplifies a configuration in which a plurality of heads are arranged in a zigzag pattern, but the configuration is not limited to this. The image forming section 40 may use a plurality of linearly arranged heads or one long head along the width direction to eject ink across the entire width direction.

FIG. 3 is a diagram illustrating nozzles in the head 40K-1. Head 40K-1 has a plurality of nozzles 40N. The nozzles 40N are arranged along the width direction orthogonal to the transport direction Xm to form a nozzle row. Note that the head 40K-1 may include a plurality of nozzle rows arranged along the transport direction Xm.

<Example of internal structure of head 40K-1>
The internal structure of the head 40K-1 will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a cross-sectional view along the nozzle arrangement direction of the head 40K-1. FIG. 5 is a cross-sectional view of the head 40K-1 along a direction orthogonal to the nozzle arrangement direction. In this embodiment, the head 40K-1 is installed so that the nozzle array direction is orthogonal to the transport direction Xm. Each head other than the head 40K-1 included in the image forming section 40 is the same.

In FIG. 4, the head 40K-1 includes a channel plate 41 forming a channel for ejecting ink, a vibration plate 42 joined to the lower surface of the channel plate 41 (inward direction of the head 40K-1), and a channel. A nozzle plate 43 joined to the upper surface of the plate 41 (outward direction of the head 40K-1) and a frame member 44 holding the peripheral edge of the diaphragm 42 are provided. The head 40K-1 also has a pressure generating section 45 for deforming the diaphragm .

In the head 40K-1, a channel plate 41, a vibration plate 42, and a nozzle plate 43 are stacked to form a nozzle communication channel 40R and a liquid chamber 40F, which are channels communicating with the nozzle 40N. In the head 40K-1, further stacking frame members 44 forms an ink inlet 40S for supplying ink to the liquid chamber 40F and a common liquid chamber 40C for supplying ink to the liquid chamber 40F. .

The frame member 44 is formed with an accommodating portion that accommodates the pressure generating portion 45, a concave portion that serves as the common liquid chamber 40C, and an ink supply port 40IN for supplying ink from the outside of the head 40K-1 to the common liquid chamber 40C. .

The pressure generating portion 45 includes a pressure generating element 45P (piezoelectric element) that is an electromechanical conversion element, a base substrate 45B that joins and fixes the pressure generating element 45P, and a pillar portion that is arranged between the adjacent pressure generating elements 45P. A piezoelectric actuator comprising: The pressure generating section 45 also includes an FPC cable 45C and the like for connecting the pressure generating element 45P to the drive circuit.

As shown in FIG. 5, the pressure generating element 45P is a laminated piezoelectric element (PZT) in which piezoelectric materials 45Pp and internal electrodes 45Pe are alternately laminated. The internal electrode 45Pe has a plurality of individual electrodes 45Pei and a plurality of common electrodes 45Pec. The internal electrode 45Pe alternately connects the individual electrode 45Pei or the common electrode 45Pec to the end face of the piezoelectric material 45Pp.

Here, the operation of the head 40K-1 ejecting ink from the nozzles 40N (pull-push operation) will be described.

First, the head 40K-1 shrinks the pressure generating element 45P along the stacking direction by lowering the voltage applied to the pressure generating element 45P from the reference potential. Further, the head 40K-1 bends and deforms the diaphragm 42 by contraction of the pressure generating element 45P. At this time, the head 40K-1 expands the volume of the liquid chamber 40F by flexural deformation of the vibration plate . By this operation, the head 40K-1 causes ink to flow from the common liquid chamber 40C into the liquid chamber 40F.

Next, the head 40K-1 expands the pressure generating element 45P along the stacking direction by increasing the voltage applied to the pressure generating element 45P. Further, the head 40K-1 deforms the vibration plate 42 in the direction of the nozzle 40N by extending the pressure generating element 45P. At this time, the head 40K-1 reduces the volume of the liquid chamber 40F due to the deformation of the vibration plate . By this operation, the head 40K-1 applies pressure to the ink in the liquid chamber 40F and ejects (sprays) the ink from the nozzle 40N.

After that, the head 40K-1 returns the voltage applied to the pressure generating element 45P to the reference potential, and restores the diaphragm 42 to the initial position. At this time, the head 40K-1 decompresses the inside of the liquid chamber 40F by expanding the liquid chamber 40F, and draws ink from the common liquid chamber 40C into the liquid chamber 40F to replenish it. Next, after the vibration of the meniscus surface of the nozzle 40N is damped and stabilized, the head 40K-1 shifts to the operation for ejecting the next ink, and repeats the above operation.

In this way, the head 40K-1 uses the pressure generator 45 to deform the vibration plate 42 to change the volume of the liquid chamber 40F, thereby changing the pressure acting on the ink in the liquid chamber 40F. As a result, the head 40K-1 can eject ink from the nozzles 40N.

The driving method of the head 40K-1 is not limited to pull-push striking. For example, the driving method of the head 40K-1 may be pulling or pushing by controlling the voltage (driving waveform) applied to the pressure generating element 45P.

In the image forming unit 40, the head modules 40K, 40Ca, 40M and 40Y each having a plurality of heads 40-1, 40-2, 40-3 and 40-4 are used to form the roll paper Md once. A single-color or full-color image can be formed on the entire roll paper Md along the width direction by the transport operation.

Here, the printing system 1 does not include any one or more of the pre-processing unit 20, the drying unit 30, the post-processing unit 50, etc., depending on the type of recording medium on which an image is formed. may The recording medium is not limited to the roll paper Md, and may be, for example, cut paper. Any recording medium may be used as long as it is a recordable medium. For example, the recording medium may be plain paper, fine paper, thin paper, thick paper, recording paper, OHP (Overhead Projector) sheet, synthetic resin film, metal thin film, and the like.

The image forming section 40 is not limited to having head modules for four colors of black (K), cyan (C), magenta (M) and yellow (Y). For example, the image forming section 40 may include heads that eject inks of other colors such as green (G), red (R), and light cyan (LC). Further, the image forming section 40 may eject a single color ink such as black (K).

Further, the liquid ejecting apparatus according to the embodiment is not limited to the image forming apparatus. For example, the liquid ejection device may be a device that ejects droplets of ink or the like from a head in a printer, scanner, photocopier, plotter, facsimile machine, or the like.

<Hardware Configuration Example of Image Forming Apparatus 2>
FIG. 6 is a block diagram showing an example of the hardware configuration of the image forming apparatus 2. As shown in FIG. The image forming apparatus 2 has a main control board 100 , a head relay board 200 and an image processing board 300 . The main control board 100 and the image processing board 300 are assumed to be a control section 400 .

The main control board 100 includes a CPU (Central Processing Unit) 101, an FPGA (Field-Programmable Gate Array) 102, a RAM (Random Access Memory) 103, a ROM (Read Only Memory) 104, and an NVRAM (Non-Volatile Random access memory) 105 , a motor driver 106 , and a drive waveform generation circuit 107 .

The CPU 101 controls the entire image forming apparatus 2 . For example, the CPU 101 uses the RAM 103 as a work area, executes various control programs stored in the ROM 104 , and outputs control commands for controlling various operations in the image forming apparatus 2 . At this time, the CPU 101 performs various operation controls in the image forming apparatus 2 in cooperation with the FPGA 102 while communicating with the FPGA 102 .

FPGA 102 has CPU control unit 111 , memory control unit 112 , I2C control unit 113 , sensor processing unit 114 , motor control unit 115 , head control unit 116 , and maintenance/recovery control unit 117 .

A CPU control unit 111 communicates with the CPU 101 . A memory control unit 112 accesses the RAM 103 and the ROM 104 . The I2C control unit 113 communicates with the NVRAM 105 . The sensor processing unit 114 processes sensor signals from various sensors 130 . Various sensors 130 are a general term for sensors that detect various states in the image forming apparatus 2 . The various sensors 130 include a paper position sensor that detects the position of the edge in the width direction of the roll paper Md, a temperature/humidity sensor that detects environmental temperature and humidity, a remaining amount detection sensor that detects the amount of ink remaining in the ink cartridge, and a maintenance/recovery sensor. A position sensor or the like for detecting the position of the hour is included. An analog sensor signal output from a temperature/humidity sensor or the like is converted into a digital signal by an AD (Analog/Digital) converter mounted on the main control board 100 or the like and input to the FPGA 102 .

The motor control unit 115 controls various motors 140 . Various motors 140 are a general term for motors provided in the image forming apparatus 2 . The various motors 140 include a sub-scanning motor for transporting the roll paper Md, a motor for raising and lowering the image forming section 40 and the post-processing section 50, a maintenance motor for operating the maintenance and recovery sections 90A and 90B, and the like.

Motor control unit 115 generates a drive file. Alternatively, the CPU 101 may generate a drive profile and instruct the motor control unit 115 to do so. The CPU 101 also counts the number of images formed.

The head control unit 116 passes the head drive data, the ejection synchronization signal LINE, and the ejection timing signal CHANGE stored in the ROM 104 to the drive waveform generation circuit 107 to cause the drive waveform generation circuit 107 to generate the common drive waveform signal Vcom. A common drive waveform signal Vcom generated by the drive waveform generation circuit 107 is input to the head driver 210 mounted on the head relay board 200 .

The maintenance/recovery control unit 117 controls maintenance motors for operating the maintenance/recovery units 90A and 90B, and communicates the idle time count value with the image processing unit 310 .

The image processing board 300 receives image data Im from an external device such as a PC (Personal Computer), and also receives conveying speed information Ve of the roll paper Md in the printing system 1 . The image processing board 300 executes predetermined processing based on these pieces of information. The functions of the image processing board 300 will be described in detail with reference to FIG. 8 separately.

The head relay board 200 drives the pressure generating elements 45P based on a plurality of signals input from the main control board 100. FIG. The configuration of the head relay board 200 will be described below with reference to FIG.

FIG. 7 is a block diagram showing an example of the configuration of the head driver 210. As shown in FIG. When the head control unit 116 receives the trigger signal Trig that triggers the ejection timing, it outputs the ejection synchronization signal LINE that triggers the generation of the drive waveform to the drive waveform generation circuit 107 . Further, the head control unit 116 outputs an ejection timing signal CHANGE corresponding to the delay amount from the ejection synchronization signal LINE to the drive waveform generation circuit 107 . The drive waveform generation circuit 107 generates the common drive waveform signal Vcom at timing based on the ejection synchronization signal LINE and the ejection timing signal CHANGE. Further, the drive waveform generation circuit 107 acquires waveform data from the ROM 104 whose address is specified.

The head control unit 116 receives image data SD' after image processing from the image processing unit 310 provided on the image processing board 300, and ink droplets ejected from each nozzle of the head 40K-1 based on this image data SD'. A mask control signal MN for selecting a predetermined waveform of the common driving waveform signal Vcom is generated in accordance with the magnitude of . The mask control signal MN is a timing signal synchronized with the ejection timing signal CHANGE. The head controller 116 transfers the image data SD′, the synchronous clock signal SCK, the latch signal LT for instructing latching of the image data, and the generated mask control signal MN to the head driver 210 . The head controller 116 is an example of a latch generator that generates a latch signal with a higher frequency than the trigger signal.

The head driver 210 has 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 receives the image data SD′ transferred from the head controller 116 and the synchronous clock signal SCK. The latch circuit 212 latches each register value of the shift register 211 with a latch signal LT transferred from the head controller 116 .

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. A 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 or off by the output of the gradation decoder 213 given via the level shifter 214 . The analog switch 215 is provided for each pressure generating element (piezoelectric element) 45P associated with the nozzles of the head 40K-1, and is connected to the individual electrode 45Pei of the pressure generating element 45P corresponding to each nozzle. . Further, the common drive waveform signal Vcom from the drive waveform generation circuit 107 is input to the analog switch 215 . Also, the mask control signal MN is synchronized with the common drive waveform signal Vcom.

The head driver 210 switches the analog switch 215 on or off at an appropriate timing according to the output of the gradation decoder 213 given via the level shifter 214, thereby selecting one of the drive waveforms forming the common drive waveform signal Vcom. A waveform to be applied to the pressure generating element 45P corresponding to each nozzle is selected. As a result, the size of ink droplets ejected from the nozzles is controlled.

<Functional Configuration Example of Image Processing Unit 310>
FIG. 8 is a block diagram showing an example of the functional configuration of the image processing section 310. As shown in FIG. The image processing section 310 and the head control section 116 function as a control section of the image forming apparatus 2 .

The image processing unit 310 executes gradation processing, image conversion processing, and the like on the received image data Im, and converts it into image data SD′ in a format that can be processed by the head control unit 116 . The image processing unit 310 outputs the converted image data SD′ to the head control unit 116 .

As shown in FIG. 8 , the image processing section 310 has an input section 311 , a gradation processing section 312 , a determination section 313 , a change section 314 , an image conversion section 315 and an output section 316 .

The input unit 311 is an interface that inputs image data Im from an external device and communicates with the external device, the CPU 101, the FPGA 102, and the like.

The gradation processing unit 312 performs gradation processing on the input multi-valued image data Im and converts it into small-valued image data SD. The small-value image data SD is image data (original image data) with the same number of gradations as the types of droplets ejected by the head 40K-1 (large droplet, medium droplet, small droplet).

The determination unit 313 determines whether or not the first frequency is within a predetermined frequency range according to the first frequency acquired based on the conveying speed information Ve of the roll paper Md in the printing system 1 . In other words, the determination unit 313 determines whether the first frequency is higher than the upper limit frequency in the predetermined frequency range, or whether the first frequency is lower than the lower limit frequency in the predetermined frequency range. Further, when determining that the first frequency is higher than the upper limit frequency, the determination unit 313 determines whether or not the mask control signal data MN′ for selecting the vibration driving are continuous. The determination unit 313 outputs the determination result to the change unit 314 . Here, the mask control signal data MN' is data from which the mask control signal MN is generated.

The first frequency corresponds to the frequency at which the drive waveform is output to head 40K-1. The drive waveform is a waveform including an ejection drive waveform for causing the head 40K-1 to eject ink and a vibration drive waveform for causing the head 40K-1 to vibrate the ink in the head 40K-1.

The second frequency corresponds to the frequency at which the vibration drive waveform is output to the head. When the vibration drive waveform is input, the head 40K-1 does not eject ink, and vibrates the meniscus, which is the air-liquid interface between the air and the ink in the nozzles of the head 40K-1.

The transport speed information Ve is information indicating the transport speed of the roll paper Md by the transport unit 80, information related to the transport speed of the roll paper Md, or the like. The determination unit 313 acquires the conveying speed information Ve from the detection result of a detector such as a rotary encoder provided in the conveying unit 80, for example. The rotary encoder is provided on a transport roller or the like included in the transport unit 80, and outputs rotation angle information of the transport roller as a detection result.

The determining unit 313 can also acquire the conveying speed information Ve via an operation unit or the like that receives an operation input to the printing system 1 by a user of the printing system 1 (hereinafter simply referred to as a user). This point will be described in more detail. The user uses the printing system 1 for image formation while conveying the roll paper Md at a constant conveyance speed, and for image formation while changing the conveyance speed of the roll paper Md as appropriate.

When performing image formation while appropriately changing the transport speed of the roll paper Md, the transport speed may be relatively slow to form images with high resolution, or the transport speed may be reduced to form a large number of images at high speed. For example, it may be relatively fast.

Here, FIG. 9 is a diagram illustrating changes in the transport speed V of the roll paper Md. The horizontal axis of FIG. 9 indicates the printing time, and the vertical axis indicates the conveying speed V of the roll paper Md. FIG. 9 shows changes in the transport speed V as a result of setting or changing the transport speed as appropriate by the user.

A period t1 is a period in which the conveying speed is relatively slow to form an image with high resolution, and a period t2 is a period in which the conveying speed is relatively fast to form a large amount of images at high speed.

On the other hand, in the printing system 1, the image forming conditions may be reset. In this case, if the printing system 1 is completely stopped, no signal is supplied to the heads such as the head 40K-1, and the ink does not move. thicken. If the ink thickens, non-ejection or ejection failure may occur when the operation of the printing system 1 is restarted. In particular, when ink that dries easily is used, ejection defects tend to occur.

In order to return the ejection failure to the original normal state, it is necessary to perform a waste ejection (idle ejection) to discharge the thickened ink and a suction operation to suck out the thickened ink. Ink is wasted due to the increase in Therefore, in the present embodiment, even when the printing system 1 resets the image forming conditions, the printing system 1 is not completely stopped, and the user can perform the resetting work in parallel with the image forming. An image can be formed slowly while conveying the roll paper Md by the conveying speed. A period t3 in FIG. 9 corresponds to the period during which the image is slowly formed.

The user can appropriately set or change the transport speed as shown in FIG. can be obtained.

The printing system 1 determines the first frequency in proportion to the transport speed of the roll paper Md. The determination unit 313 can acquire the first frequency information according to the conveying speed information Ve and determine whether or not the first frequency is within a predetermined frequency range.

Returning to FIG. 8, the description of the functional configuration of the image processing unit 310 is continued.

The changing unit 314 performs processing for changing the second frequency from the first frequency according to the first frequency. Specifically, when the determination unit 313 determines that the first frequency is lower than the lower limit frequency in the predetermined frequency range, the change unit 314 adds vibration corresponding to the latch signal to the predetermined drive waveform data. Add drive waveform data. As a result, the changing unit 314 causes the head 40K-1 to vibrate the ink in the head 40K-1 according to the latch signal LT. As a result, the second frequency is higher than the first frequency. The vibration drive waveform data is data of a vibration drive waveform that vibrates ink in the head 40K-1 without ejecting ink. The driving waveform data is waveform data including ejection driving waveform data for ejecting ink and vibration driving waveform data.

Further, when the determining unit 313 determines that the first frequency is higher than the upper limit frequency in the predetermined frequency range and determines that the mask control signal for selecting the vibration driving is continuous, the changing unit 314 performs image conversion. By changing the mask control signal data MN' for selecting the vibration driving waveform, the unit 315 thins out the number of times the vibration driving waveform data is output. As a result, the second frequency will be lower than the first frequency. The changing unit 314 does not change the second frequency when the first frequency is within the predetermined frequency range. As a result, the second frequency is equal to the first frequency.

The image conversion unit 315 adds the vibration driving information including the information of the second frequency changed by the change unit 314 to the image data SD of the large droplet, the medium droplet, and the small droplet, and converts the image data SD into the image data SD'. Convert. This conversion is performed in accordance with information such as the image forming order obtained from the image data Im via the input unit 311, and in accordance with the configuration of the head 40K-1.

Also, the image conversion unit 315 is an example of a selection unit that selects at least one of the ejection driving waveform data and the vibration driving waveform data. The image conversion unit 315 can select at least one of the ejection drive waveform and the vibration drive waveform by adding the mask control signal data MN' to the image data SD'.

The image conversion unit 315 outputs the converted image data SD′ to the FPGA 102 of the main control board 100 via the output unit 316 . In other words, the output unit 316 can output drive waveform data including ejection drive waveform data and vibration drive waveform data to the head 40K-1 via the main control board 100. FIG.

The functions of the image processing unit 310 may be executed as hardware functions such as FPGA or ASIC, or may be executed by an image processing program stored in a storage device inside the image processing unit 310 . Also, the functions of the image processing unit 310 may be realized by software installed in a computer instead of inside the image forming apparatus 2 .

<Example of vibration drive>
FIG. 10 is a diagram illustrating an example of vibration driving in the head 40K-1. FIG. 10 is a cross-sectional view around the nozzle 40N in the head 40K-1, viewed from a direction orthogonal to the ink ejection direction 81. FIG. FIG. 10 also shows nine states from state 91 to state 99 in nozzle 40N.

In FIG. 10, the ink 90 filled inside the head 40K-1 is exposed to the atmosphere by the nozzles 40N. A meniscus 90a is a gas-liquid interface between the ink 90 and the atmosphere. A negative pressure acting in the direction opposite to the ink ejection direction 81 is applied to the ink 90 in the head 40K-1, so that the meniscus 90a is recessed toward the side opposite to the ink ejection direction 81. to form a meniscus 90a.

In states 91 to 93, if the head 40K-1 is stopped without ejecting, the moisture in the ink 90 evaporates through the nozzles 40N that are open to the atmosphere, and over time the ink 90 near the meniscus 90a is reduced. Viscosity increases (thickens). Due to the increased viscosity of the ink 90, the fluid resistance in the vicinity of the meniscus 90a increases, which may make it impossible to perform targeted ejection.

As shown in states 94 to 96, the image forming apparatus 2 applies pressure to the ink 90 in the head 40K-1 to such an extent that the ink 90 is not ejected, and vibrates the ink 90 in the head 40K-1. conduct. An arrow 90b in FIG. 10 represents the flow of the ink 90 in the head 40K-1 agitated by vibration drive. The image forming apparatus 2 moves the thickened ink 90 in the vicinity of the meniscus 90a to the head 40K-1 by agitation due to vibration drive, thereby suppressing the occurrence of ejection failure.

However, if the frequency (the number of vibration drives per unit time) for driving the ink 90 is too high, the amount of the thickened ink 90 flowing inside the head 40K-1 increases, and the entire ink 90 inside the head 40K-1 increases. As the viscosity increases, the effect of suppressing ejection failure cannot be sufficiently obtained. On the other hand, if the frequency for vibrating the ink 90 is too low, the stirring effect will be insufficient, and the effect of suppressing ejection failure will not be sufficiently obtained.

<Example of drive waveform>
FIG. 11 is a diagram illustrating an example of drive waveform data for driving the head 40K-1. The drive waveform data Da is digital data representing a voltage waveform. The drive waveform data Da is supplied to the head driver 210, converted into an analog voltage signal, and then applied as a drive waveform to the pressure generating element 45P. The pressure generating element 45P applies pressure to the ink 90 in the head 40K-1 according to the driving waveform, and ejects the ink 90 from the nozzle 40N.

The drive waveform data Da includes waveform data for four sections 111a, 111b, 111c and 111d. The mask control signal data MN0', MN1', MN2' and MN3' are signals for invalidating the waveform data for each section in the driving waveform data Da. When the mask control signal data MN0', MN1', MN2' and MN3' are not distinguished, they are collectively referred to as mask control signal data MN'.

The mask control signal data MN0' validates the waveform data of only the section 111b of the drive waveform data Da and invalidates the other sections 111a, 111c, and 111d, so that vibration driving is performed as driving by the head 410K-1. select. The drive waveform data Da to which the mask control signal data MN0' is applied causes the head 40K-1 to vibrate.

The mask control signal data MN1' validates the waveform data of only the section 111d of the drive waveform data Da, and invalidates the other sections 111a, 111b, and 111c. Select dispense. The drive waveform data Da to which the mask control signal data MN1' is applied causes the head 40K-1 to eject droplets.

The mask control signal data MN2' validates the waveform data in the sections 111c and 111d of the drive waveform data Da and invalidates the other sections 111a and 111b. to select. The drive waveform data Da to which the mask control signal data MN2' is applied causes the head 40K-1 to eject medium droplets.

The mask control signal data MN3' selects ejection of large droplets as driving of the head 410K-1 by validating the waveform data of all sections 111a, 111b, 111c and 111d of the drive waveform data Da. The drive waveform data Da to which the mask control signal data MN3' is applied causes the head 40K-1 to eject large droplets.

The image processing section 310 can supply image data SD' including drive waveform data Da and mask control signal data MN' to the head driver 210 via the head control section .

The drive waveform data based on the drive waveform data Da in which only the section 111b is valid corresponds to the vibration drive waveform data. The drive waveform data based on the drive waveform data Da in which the sections other than the section 111b are valid correspond to the ejection drive waveform data. The output unit 316 can output drive waveform data including ejection drive waveform data and vibration drive waveform data to the head 40K-1.

<Example of Processing by Image Processing Unit 310>
FIG. 12 is a flowchart showing an example of processing by the image processing unit 310. As shown in FIG. When the image data Im is input from the external device through the input unit 311, the image processing unit 310 starts the processing of FIG.

First, in step S121, the image processing unit 310 causes the gradation processing unit 312 to perform gradation processing on the multi-valued image data Im input via the input unit 311, and converts it into small-valued image data SD. and outputs the image data SD to the image conversion unit 315 .

Subsequently, in step S<b>122 , the image processing unit 310 causes the determination unit 313 to acquire information about the first frequency from the transport speed information Ve of the roll paper Md.

Subsequently, in step S123, the determination unit 313 of the image processing unit 310 determines whether or not the first frequency is lower than the lower limit frequency.

If it is determined in step S123 that the first frequency is lower than the lower limit frequency (step S123, Yes), in step S124 the image processing unit 310 causes the changing unit 314 to cause the drive waveform data to respond to the latch signal. Add vibration drive waveform data. This causes the head 40K-1 to vibrate the ink in the head 40K-1 according to the latch signal LT. As a result, the second frequency is higher than the first frequency. After that, the image processing unit 310 shifts the process to step S128.

On the other hand, if it is determined in step S123 that the first frequency is not lower than the lower limit frequency (step S123, No), in step S125 the image processing unit 310 determines that the first frequency is Determine whether or not the frequency is higher than the upper limit frequency.

When it is determined in step S125 that the first frequency is not higher than the upper limit frequency (step S125, No), the image processing section 310 proceeds to step S128.

On the other hand, when it is determined in step S125 that the first frequency is higher than the upper limit frequency (step S125, Yes), in step S126, the image processing unit 310 causes the determination unit 313 to perform mask control to select vibration driving. It is determined whether or not the signal data MN' are continuous.

When it is determined in step S126 that the mask control signal data MN' are not continuous (step S126, No), the image processing section 310 proceeds to step S128. On the other hand, if it is determined that the mask control signal data MN' are continuous (step S126, Yes), in step S127, the image processing unit 310 causes the changing unit 314 to cause the image converting unit 315 to select the vibration drive waveform. By changing the mask control signal data MN' for , the number of times the vibration drive waveform is output is thinned out. This makes the second frequency lower than the first frequency.

Subsequently, in step S128, the image processing unit 310 causes the image conversion unit 315 to add the vibration driving information including the second frequency information to the image data SD of the large droplet, the medium droplet, and the small droplet. is converted into image data SD'.

Subsequently, in step S<b>129 , the image processing unit 310 outputs the image data SD′ to the head control unit 116 through the output unit 316 .

In this manner, the image processing section 310 can output the image data SD′ generated based on the image data Im to the head control section 116 .

<Example of Change of Mask Control Signal Data MN′ by Change Unit 314>
FIG. 13 is a diagram illustrating an example of modification of the mask control signal data MN′ by the modification unit 314. In FIG. FIG. 12 shows mask control signal data MN for the image forming apparatus 2 to eject ink 90 onto the roll paper Md transported along the transport direction Xm from one nozzle 40N included in the head 40K-1. " and MN', and image data P(X). Each of the plurality of grids arranged along the transport direction Xm represents each pixel in the image data SD'. Mask control signal data MN″ indicates mask control signal data before change by the change unit 314 , and mask control signal data MN′ indicates mask control signal data after change by the change unit 314 .

In the signal group 121 of the mask control signal data MN'', "0", which is the mask control signal data MN'' for selecting vibration driving, continues twice. The changing unit 314 changes one of two consecutive "0"s to "-1" like the signal group 122 in the mask control signal data MN'. Due to this change, the vibrating driving waveform is not output from the pixels whose mask control signal data MN' is "-1", so the number of times the vibrating driving waveform is output is thinned out.

<Example of operation for changing the second frequency>
The operation of changing the second frequency by the changing unit 314 will be described with reference to FIGS. 14 to 17 . FIG. 14 is a diagram showing a first example of the vibration drive waveform before changing the second frequency. FIG. 15 is a diagram showing a first example of the vibration drive waveform after changing the second frequency. FIG. 16 is a diagram showing a second example of the vibration drive waveform before changing the second frequency. FIG. 17 is a diagram showing a second example of the vibration drive waveform after changing the second frequency.

14 to 17 are timing charts showing three of the trigger signal Trig, the latch signal LT and the drive waveform Da'. In each figure, the signal shown at the top is the trigger signal Trig, the signal shown at the middle is the latch signal LT, and the signal shown at the bottom is the drive waveform Da'. The latch signal LT has a higher frequency than the trigger signal Trig. The drive waveform Da' is an analog signal based on the drive waveform data Da to which the mask control signal data MN' has been applied. Each of period t4, period t5, and period t6 is a period corresponding to one cycle of the first frequency.

In FIGS. 14 and 15, a drive waveform Da' including only the vibration drive waveform is output in response to the trigger signal Trig. Compared with the drive waveform Da' before change shown in FIG. 14, the drive waveform Da' after change shown in FIG. 15 has the vibration drive waveform thinned out in period t5. By thinning out one of the vibration driving waveforms for two cycles, the second frequency becomes half the frequency of the first frequency.

In FIGS. 16 and 17, a driving waveform Da' including both an ejection driving waveform and a vibration driving waveform is displayed according to the trigger signal Trig. A period t7 is a period in which the voltage of the driving waveform Da' is not applied because the period corresponding to the driving waveform Da' is shorter than one cycle corresponding to the first frequency.

While no voltage is applied during period t7 in FIG. 16, voltage 171 is applied during period t7 in FIG. This voltage 171 is applied according to the latch signal LT and corresponds to the vibration drive waveform output during the period t7. Within one cycle corresponding to the first frequency, the voltage 171 is output after a predetermined time has elapsed using the count number of the latch signal LT after the period corresponding to the drive waveform Da' has ended. Since the drive waveform Da′ also includes the vibration drive waveform, two vibration drive waveforms are output within one cycle corresponding to the first frequency by applying the voltage 171 corresponding to the vibration drive waveform. It will be. As a result, the second frequency is twice the frequency of the first frequency.

<Transition example of second frequency>
FIG. 18 is a diagram showing an example of transition of the second frequency. The horizontal axis of FIG. 18 indicates the printing time, and the vertical axis indicates the frequency f. FIG. 18 shows transitions of the first frequency f1 (solid line) and the second frequency f2 (dashed line) in accordance with the change in the conveying speed V, which is the result of setting or changing the conveying speed as appropriate by the user. . The view of FIG. 18 is similar to that of FIG. 9 described above, but the vertical axis is changed to frequency compared to FIG.

The first frequency f1 becomes relatively low during the period t1, becomes relatively high during the period t2, and becomes very low during the period t3 according to the change in the conveying speed V. FIG.

On the other hand, the second frequency f2 is different from the first frequency f1 due to the change processing by the changing unit 314, and is entirely within the predetermined frequency range fth. Specifically, since the first frequency f1 is within the frequency range fth during the period t1, the changing unit 314 does not change the second frequency f2. As a result, the second frequency f2 is equal to the first frequency f1.

In period t2, the first frequency f1 is higher than the upper limit frequency th1 in the frequency range fth, so the changing unit 314 changes the second frequency f2 to be lower than the first frequency f1. As a result, the second frequency f2 is lower than the first frequency f1 and is within the frequency range fth.

In period t3, the first frequency f1 is lower than the lower limit frequency th2 in the frequency range fth, so the changing unit 314 changes the second frequency f2 to be higher than the first frequency f1. As a result, the second frequency f2 is higher than the first frequency f1 and is within the frequency range fth.

Here, the easiness of increasing the viscosity of the ink in the head 40K-1 differs depending on the type of ink, the type of roll paper Md, the method of heating the ink applied to the roll paper Md, and the like. Methods of heating the ink include a method of heating with a heater, a method of heating by blowing hot air, and the like. In this embodiment, the frequency range fth is predetermined according to at least one of the type of ink, the type of roll paper Md, and the method of heating ink applied to roll paper Md. As a result, the frequency of vibration driving can be more optimized according to the easiness of thickening of the ink in the head 40K-1.

<Effects of Image Forming Apparatus 2>
Next, functions and effects of the image forming apparatus 2 will be described.

2. Description of the Related Art In a liquid ejection type image forming apparatus, there is known a technique of vibrating ink in a head in order to prevent the ink in the head from thickening due to drying during a period in which ink is not ejected from the head.

When vibrating the ink in the head, for example, the image forming apparatus provides vibration drive waveform data for vibrating the ink in the drive waveform data for ejecting ink from the head, and vibrates during a period in which ink is not ejected from the head. Ink is vibrated by outputting to the head drive waveform data in which only the drive waveform data is valid.

On the other hand, the liquid ejection type image forming apparatus may change the first frequency for outputting the driving waveform to the head according to the conveying speed of the recording medium. In this case, since the vibration drive waveform is included in the drive waveform, the second frequency for outputting the vibration drive waveform changes equally according to the change in the first frequency. The second frequency has an appropriate frequency range. If the frequency is higher than this range, the vibration becomes excessive and thickens the ink inside the head. The effect may be reduced, and ink ejection from the head may not be stabilized.

The image forming apparatus 2 according to the present embodiment includes a head 40K-1 that ejects ink (liquid), ejection driving waveform data for ejecting ink, and vibration of the ink in the head 40K-1 without ejecting ink. and an output section 316 for outputting to the head 40K-1 drive waveform data including vibration drive waveform data to cause vibration. Further, the image forming apparatus 2 adjusts the second frequency f2 at which the vibration drive waveform is output to the head 40K-1 to the first frequency f1 at which the drive waveform is output to the head 40K-1. It has a changing unit 314 that makes it different.

For example, when the first frequency f1 is higher than the upper limit frequency th1 in the frequency range fth, the changing unit 314 sets the second frequency f2 lower than the first frequency f1 and sets the first frequency f1 to the lower limit frequency in the frequency range fth. If it is lower than th2, the second frequency f2 is made higher than the first frequency f1. As a result, since the second frequency f2 can be kept within the frequency range fth, the image forming apparatus 2 can appropriately suppress the thickening of the ink by vibration driving, and the liquid ejection from the head 40K-1 can be stabilized. can be made

Further, the image forming apparatus 2 applies ink to the roll paper Md by ejecting ink, and the frequency range fth is the type of ink, the type of the roll paper Md, or the type of ink applied to the roll paper Md. is determined in advance according to at least one of As a result, it is possible to further optimize the frequency of the vibration driving according to the easiness of thickening of the ink in the head 40K-1.

The image forming apparatus 2 also includes an image conversion unit 315 (selection unit) that selects at least one of the ejection drive waveform data and the vibration drive waveform data from the drive waveform data Da. When the frequency f1 is higher than the upper limit frequency th1 in the frequency range fth, the number of times the vibration driving waveform is output is changed so as to be thinned out. Thereby, the image forming apparatus 2 can make the second frequency f2 lower than the first frequency f1.

The image forming apparatus 2 also has a head control section 116 (latch generating section) that generates a latch signal LT having a higher frequency than the trigger signal Trig that vibrates the ink in the head 40K-1. When the first frequency f1 is lower than the lower limit frequency th2 in the frequency range fth, the changing unit 314 changes the head 40K-1 to vibrate the ink in the head 40K-1 according to the latch signal LT. . Thereby, the image forming apparatus 2 can make the second frequency f2 higher than the first frequency f1.

In this embodiment, the head 40K-1 has been described as an example, but other heads included in the image forming section 40 can be operated in the same manner as the head 40K-1.

In addition, changes in the transport speed V of the roll paper Md include both intentional changes due to user instructions and the like, and unintended changes due to errors in the components that make up the transport unit 80 and the like. Regardless of the change, the image forming apparatus 2 can change the second frequency f2 according to the first frequency f1.

[Other preferred embodiments]
Although the preferred embodiment has been described in detail above, it is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the claims. can be added.

For example, in the above embodiments, an image forming apparatus equipped with a recording head according to the present invention has been described. can be applied.

For example, in this example, the head 40K-1 included in the image forming means for ejecting ink was described as an example of the head. Morphology can also be applied.

Further, in the above example, an example in which the embodiments are applied to a line-type liquid ejecting apparatus in which the head does not move along the width direction has been described, but a serial-type liquid ejecting apparatus in which the head moves in the width direction via a carriage has been described. Embodiments can also be applied to

In the embodiments, a "device that ejects liquid" is a device that includes a liquid ejection head or a liquid ejection unit, drives the liquid ejection head, and ejects liquid. Devices that eject liquid include not only devices that can eject liquid onto an object to which liquid can adhere, but also devices that eject liquid into air or liquid.

The "liquid ejecting device" can include means for feeding, transporting, and ejecting an object to which liquid can adhere, as well as a pre-processing device, a post-processing device, and the like.

For example, as a "device that ejects liquid", an image forming device that ejects ink to form an image on paper, and powder is formed in layers to form a three-dimensional object (three-dimensional object). There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that ejects a modeling liquid onto a formed powder layer.

Further, the "apparatus for ejecting liquid" is not limited to one that visualizes significant images such as characters and figures with the ejected liquid. For example, it includes those that form patterns that have no meaning per se, and those that form three-dimensional images.

The above-mentioned "substance to which a liquid can adhere" means a substance to which a liquid can adhere at least temporarily, such as a substance to which a liquid adheres and adheres, a substance which adheres and permeates, and the like. Specific examples include media such as recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and test cells. Yes, and unless otherwise specified, includes anything that has liquid on it.

The material of the above-mentioned "thing to which a liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as the liquid can adhere even temporarily.

Also, the "liquid ejection head" is not limited to a pressure generating element to be used. For example, a piezoelectric actuator (which may use a laminated piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a diaphragm and a counter electrode can be used.

Image formation, recording, printing, printing, printing, modeling, and the like in the terms of the embodiments are all synonymous.

Embodiments also include liquid ejection methods. For example, the liquid ejection method is a liquid ejection method using a liquid ejection apparatus, and includes ejection drive waveform data for ejecting liquid from a head and ejecting the liquid from an output unit, data of a vibration drive waveform for vibrating the liquid in the head, and data of a drive waveform including data of a vibration drive waveform for vibrating the liquid in the head; A second frequency at which the vibration drive waveform is output to the head is made different from the first frequency. With this liquid ejection method, the same effects as those of the image forming apparatus 2 described above can be obtained.

Numerals such as ordinal numbers and numbers used in the description of the embodiments are all exemplified to specifically describe the technology of the present invention, and the present invention is not limited to the exemplified numbers. Moreover, the connection relationship between the components is an example for specifically explaining the technology of the present invention, and the connection relationship for realizing the function of the present invention is not limited to this.

Each function of an embodiment can be implemented by one or more processing circuits. Here, the "processing circuit" in this specification means a processor programmed by software to perform each function, such as a processor implemented by an electronic circuit, or a processor designed to perform each function described above. devices such as ASICs (Application Specific Integrated Circuits), DSPs (digital signal processors), FPGAs (field programmable gate arrays) and conventional circuit modules.

1 printing system 2 image forming apparatus (liquid ejecting apparatus)
40 Image forming units 40K, 40Ca, 40M, 40Y Head modules 40K-1, 40K-2, 40K-3, 40K-4 Head 40N Nozzle 45P Pressure generation element 100 Main control board 116 Head control unit (an example of a latch generation unit)
200 head relay board 210 head driver 300 image processing board 310 image processing section 311 input section 312 gradation processing section 313 determination section 314 changing section 315 image conversion section 316 output section Da drive waveform data Da' drive waveform f1 first frequency f2 Two frequencies fth Frequency range th1 Upper limit frequency th2 Lower limit frequency Trig Trigger signal LT Latch signal MN Mask control signal MN' Mask control signal data Im, SD, SD' Image data V Transport speed Ve Transport speed information Md Roll paper (recording medium)
Xm Carrying direction t1, t2, t3, t4, t5, t6, t7 Period

JP 2019-166829 A

Claims (6)

a head for ejecting liquid;
an output unit for outputting to the head drive waveform data including ejection drive waveform data for ejecting the liquid and vibration drive waveform data for vibrating the liquid in the head without ejecting the liquid; ,
a changing unit that varies a second frequency at which the vibration drive waveform is output to the head with respect to the first frequency, according to a first frequency at which the drive waveform is output to the head. . The changing unit makes the second frequency lower than the first frequency when the first frequency is higher than the upper limit frequency in the predetermined frequency range, and sets the first frequency lower than the lower limit frequency in the frequency range. 2. The liquid ejecting apparatus according to claim 1, wherein the second frequency is set higher than the first frequency when the second frequency is also lower than the first frequency. The head applies the liquid to a recording medium by ejecting the liquid,
3. The liquid according to claim 2, wherein the frequency range is predetermined according to at least one of the type of the liquid, the type of the recording medium, and a method of heating the liquid applied to the recording medium. discharge device. a selection unit that selects at least one of the ejection drive waveform data and the vibration drive waveform data from the drive waveform data;
4. The changer according to any one of claims 1 to 3, wherein when the first frequency is higher than an upper limit frequency in a predetermined frequency range, the changer changes the number of times the vibration driving waveform is output so as to be thinned out. 10. A liquid ejection device according to claim 1. a latch generator for generating a latch signal having a higher frequency than a predetermined trigger signal for vibrating the liquid in the head;
2. When the first frequency is lower than a lower limit frequency in a predetermined frequency range, the changing unit changes the head so as to vibrate the liquid in the head according to the latch signal. 5. The liquid ejecting apparatus according to any one of items 1 to 4. A liquid ejection method using a liquid ejection device,
The head ejects the liquid,
An output unit outputs to the head drive waveform data including ejection drive waveform data for ejecting the liquid and vibration drive waveform data for vibrating the liquid in the head without ejecting the liquid. death,
A liquid ejection method in which a changing unit changes a second frequency at which the vibration drive waveform is output to the head according to a first frequency at which the drive waveform is output to the head, with respect to the first frequency.

Images