JP7247679B2 - Liquid ejection device and liquid ejection head drive control method - Google Patents

Description

The present invention relates to a liquid ejection apparatus and a liquid ejection head drive control method.

2. Description of the Related Art Regarding an inkjet type image forming apparatus, there is a fine drive control technique for adjusting the ink viscosity particularly for nozzles that do not eject ink, in order to eliminate local thickening of ink in the vicinity of nozzle holes.

For example, Japanese Patent Application Laid-Open No. 2002-200000 discloses supplying fine drive continuously or intermittently between pages.

In addition, the thickening of ink occurs not only during image formation but also during standing. Reference 2).

However, in Japanese Patent Application Laid-Open No. 2002-200010, if fine drive is operated for an excessively long time during a non-ejection period that exists in the image area, there is a possibility that the fine drive is applied more than necessary, which promotes thickening of the ink. there were. On the other hand, if the micro-driving is too small, the thickening of the ink due to drying cannot be eliminated.

In addition, if the viscosity increases during preliminary ejection, the ejection trajectory during blank ejection may be bent and the nozzle surface may become dirty.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a liquid ejection apparatus capable of adjusting the viscosity of the liquid by optimizing the fine driving before the liquid is ejected.

In order to solve the above problems, in one aspect of the present invention,
a nozzle;
a pressure chamber communicating with the nozzle and containing a liquid;
a pressure generating element that applies pressure to the liquid in the pressure chamber;
a driving waveform generator that outputs a driving waveform to the pressure generating element;
and a control unit that controls the drive waveform generation unit,
The control unit
The input original image data is taken out every predetermined period, and the dot non-forming period from the position immediately before the start of each predetermined period to the dot forming pixel for which liquid is to be ejected next, and from the dot forming pixel to the dot forming pixel in the predetermined period. a dot non-forming period, a counting unit for counting a dot non-forming period from a dot-formed pixel to a predetermined period end position in the predetermined period, and based on the dot non-forming period counted by the counting unit, the nozzle a fine drive waveform that oscillates the meniscus of the fine drive waveform or a strong and fine drive waveform with a greater amount of oscillation than the fine drive waveform is provided to the pressure generating element,
The drive waveform generator generates a drive waveform based on image data including the determined fine drive waveform or the strong and fine drive waveform, and outputs the drive waveform to the pressure generating element. ,I will provide a.

According to one aspect, in the liquid ejection device, it is possible to prevent ink thickening due to fine driving in the image area.

1 is a diagram showing an example of the overall configuration of a printing system according to one embodiment of the present invention; FIG. FIG. 2 is a bottom view and an enlarged view for explaining a case where a line type head is used as an example of the image forming means and the post-treatment liquid discharging means of the image forming apparatus of FIG. 1; FIG. 2 is a cross-sectional view taken in longitudinal and lateral directions of the heads of the image forming means and the post-treatment liquid ejecting means of the image forming apparatus of FIG. 1 is a block diagram showing a hardware configuration example of an image forming apparatus according to an embodiment of the present invention; FIG. FIG. 5 is a block diagram showing a configuration example of a printhead control unit, a driving waveform generation circuit, and a printhead driver in FIG. 4; FIG. 2 is a functional block diagram of an image processing section according to the first embodiment of the present invention; FIG. 5 is a diagram showing an example of selecting a waveform from common drive waveforms using an MN signal; FIG. 2 is a block diagram showing a hardware configuration example of an image forming apparatus according to another embodiment of the present invention; FIG. 10 is a diagram showing differences in waveforms between a fine drive waveform and a strong and fine drive waveform, in which (a) different crest values, (b) different rise and fall speeds, and (c) rise and fall speeds. , a diagram for different retention periods. FIG. 10 is a diagram for explaining input determination of normal fine drive and strong fine drive; An example of the input control flow of the fine driving waveform according to the first embodiment of the present invention. FIG. 7 is a diagram showing an example in which nozzles are finely driven based on print information; FIG. 10 is a diagram showing an example in which fine driving and strong fine driving are performed on nozzles based on print information; FIG. 5 is a functional block diagram of an image processing section according to the second embodiment of the present invention; An example of the input control flow of the fine driving waveform according to the second embodiment of the present invention. FIG. 10 is a diagram showing an example in which fine driving and strong fine driving are performed on nozzles based on printing information and flushing information; 7A and 7B are diagrams for explaining the ejection bending of the preliminary ejection of the comparative example and the fine drive before the preliminary ejection of the present invention; 4A and 4B are explanatory diagrams of the maintenance and recovery operation of the image forming means and the post-treatment liquid means according to the embodiment of the present invention, in which (a) is a diagram during printing on a recording medium, and (b) is a diagram during capping. FIG. 2 is a plan view of image forming means, post-processing means, and maintenance/recovery means according to the embodiment of the present invention; FIG. 11 is a functional block diagram of an image processing unit and a maintenance control unit according to a third embodiment of the present invention; An example of a control flow at startup according to the third embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated with reference to drawings. In each drawing below, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<Overall composition>
First, with reference to FIG. 1, a system including an image forming apparatus which is a liquid ejecting apparatus of the present invention will be described. FIG. 1 is a diagram showing an example of the overall configuration of a printing system 1 according to one embodiment of the invention. The printing system 1 includes an image forming apparatus 2 which is an inkjet device of an inkjet method.

As shown in FIG. 1, the printing system 1 according to the embodiment of the present invention includes an loading unit 10 for loading roll paper (recording medium) Md, a preprocessing unit 20 for preprocessing the loaded roll paper Md, and a drying means 30 for drying the pretreated roll paper Md. The printing system 1 also includes image forming means 40 for forming an image on the surface of the roll paper Md, post-processing means 50 for post-processing the roll paper Md on which the image is formed, and transporting the post-processed roll paper Md. carrying-out means 60 and maintenance/restoration means 90A, 90B.

In the printing system 1 according to the present embodiment, the loading unit 10 loads the recording medium Md, which is roll paper, and the preprocessing unit 20 and the drying unit 30 preprocess and dry the surface of the recording medium Md. In this example, as the recording medium Md, the roll paper Md, which is continuous paper wound in a roll, will be described as an example. The recording medium Md, which is roll paper, is, for example, continuous form paper on which perforations that can be cut are formed at predetermined intervals, or continuous paper such as continuous forms. In addition, a page of roll paper is, for example, an area sandwiched by perforations at predetermined intervals.

Further, the image forming device 2 of the printing system 1 forms an image on the surface of the recording medium Md after pretreatment and drying by the image forming means 40 . Further, the printing system 1 according to the present embodiment uses the post-processing means 50 to post-process the image-formed recording medium Md. After that, the printing system 1 uses the unloading means 60 to wind, eject, and unload the recording medium Md, which is roll paper.

Note that the printing system 1 that can use the present invention may have a configuration that does not include any one or more of the pre-processing means 20 and the like, which will be described later, according to the type of medium on which an image is formed.

Note that the recording medium Md is not limited to roll paper. For example, the recording medium Md may be cut paper.

Furthermore, the recording medium Md may be any medium as long as it is a recordable medium. For example, the recording medium Md may be plain paper, fine paper, thin paper, cardboard, recording paper, OHP (Overhead Projector) sheet, synthetic resin film, metal thin film, and the like.

Note that the embodiment is not limited to the four-color ejection units (head modules) of black (K), cyan (C), magenta (M), and yellow (Y) in the image forming unit 40 . For example, embodiments may have jets corresponding to other colors such as green (G), red (R), light cyan (LC), and the like. Further, embodiments may have jets for black (K) only.

Note that the embodiments are not limited to the form of the image forming apparatus described above. For example, the embodiments can be applied to printers, scanners, photocopiers, plotters, facsimiles, etc., other than the image forming apparatuses described above, in which droplets of ink or the like are ejected from ejection parts such as ejection heads, ink heads, recording heads, and inkjets. A discharge device may be used.

Also, the present invention may be used in an apparatus for forming, printing, copying, printing, or recording an image on the surface of the recording medium Md.

The carry-in means 10 is means for conveying the recording medium Md to the pretreatment means 20 or the like. The carry-in unit 10 has a paper feed unit 11 and a plurality of transport rollers 12 in this embodiment. The carrying-in unit 10 uses a carrying roller 12 or the like to carry in and move the recording medium Md wound around and held by the paper supply roll of the paper supply unit 11, and conveys it to the preprocessing unit 20 (platen) or the like.

The preprocessing means 20 is means for processing the recording medium Md before an image is formed. In this embodiment, the pretreatment unit 20 pretreats the surface of the roll paper Md carried in by the carry-in unit 10 with a pretreatment liquid. The pretreatment is a treatment for uniformly applying a pretreatment liquid having a function of aggregating ink to the surface of the recording medium Md. The pretreatment liquid is, for example, a treatment liquid containing a water-soluble aliphatic organic acid.

Here, the treatment liquid containing the water-soluble aliphatic organic acid is a treatment liquid having a property of aggregating the water-dispersible colorant. Aggregation means that the water-dispersible colorant particles adhere to each other.

Furthermore, the pretreatment means 20 according to the present embodiment 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 means 20 can neutralize the surface charge of the water-dispersible colorant. In addition, the pretreatment means 20 can enhance the aggregating action due to the intermolecular force to further agglomerate the water-dispersible colorant.

The pretreatment means 20 includes pretreatment methods such as blade coating, gravure coating, gravure offset coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U comma coating, 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 used.

The drying unit 30 is a unit that dries the recording medium Md, which is roll paper, by heating or the like. The drying unit 30 includes a preprocessing drying unit 31 that dries the recording medium Md preprocessed by the preprocessing unit 20, and a postprocessing drying unit 32 that dries the recording medium Md postprocessed by the postprocessing unit 50. , has

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

The image forming means 40 is means for forming an image on the roll paper Md. In this embodiment, the image forming means 40 forms an image on the surface of the recording medium Md by ejecting droplets (hereinafter referred to as ink) onto the recording medium Md dried by the drying means 30 . Details of the image forming means 40 will be described later.

The post-processing means 50 is means for processing the recording medium Md after the image has been formed. The post-treatment means 50 post-processes the surface of the recording medium Md on which the image is formed by the image forming means 40 with a post-treatment liquid. The post-treatment is a process of ejecting the post-treatment liquid in the form of spots onto the recording medium Md.

Maintaining and recovering means 90A and 90B are provided in the vicinity of the image forming means 40 and post-processing means 50, respectively. The maintenance/recovery units 90A and 90B perform cleaning, maintenance, and the like, which are maintenance/recovery operations for the nozzles and nozzle surfaces of the heads of the image forming unit 40 and the post-processing unit 50, respectively. Details of the maintenance and recovery means 90A and 90B will be described later with reference to FIGS. 18 and 19. FIG.

Image forming means 40 , post-processing means 50 , and maintenance/recovery means 90 A and 90 B are arranged on housing 74 . Here, the housing 74, which is the main body of the inkjet printer, includes a transport unit 80 having a transport belt 81 (see FIG. 18) and the like.

<Image forming means>
FIG. 2 is a schematic plan view illustrating an example of image forming means according to one embodiment of the present invention.

FIG. 2(a) is a diagram illustrating an example of the overall configuration of an image forming unit according to an embodiment of the present invention. FIG. 2A shows a full-line type recording head as an example.

The image forming means 40 arranges head modules of respective colors in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream in the conveying direction Xm of the recording medium Md which is roll paper. there is Note that the embodiment is not limited to the arrangement order of black (K), cyan (C), magenta (M), and yellow (Y) shown in FIG. For example, the order of black (K), cyan (C), magenta (M) and yellow (Y) may be changed to yellow (Y), magenta (M), cyan (C) and black (K). Also, the combination of colors is not limited to black (K), cyan (C), magenta (M), and yellow (Y). The combination of colors may be, for example, one color, black (K). Also, the color combination may be three colors such as green (G), red (R), and light cyan (LC).

The black (K) head modules 40K, 40C, 40M, and 40Y move the recording heads 40K-1, 40K-2, 40K-3, and 40K-4 in a staggered manner in a direction perpendicular to the conveying direction Xm of the recording medium Md. Deploy. In the head modules 40K, 40C, 40M, and 40Y of each color, the recording heads 40K-1, 40K-2, 40K-3, and 40K-4 are arranged in a zigzag pattern, so that the image forming means 40 has an image forming area , that is, in the direction perpendicular to the conveying direction Xm of the recording medium Md. Since the black (K), cyan (C), magenta (M), and yellow (Y) printheads are similar, the black (K) printhead will be described below as an example.

Also in the post-treatment means 50, the head module 50H has four treatment liquid ejection heads arranged in a staggered arrangement, so that the post-treatment liquid can be ejected over the entire area in the direction orthogonal to the transport direction Xm. can.

Although FIG. 2A shows an example in which a plurality of heads are staggered to form a line, a line may be formed by arranging a plurality of heads in a straight line. I don't mind if you change it. Also, the color scheme is not limited to this.

FIG. 2(b) is a diagram for explaining one of the recording heads, which is a main part of the image forming means according to one embodiment of the present invention.

As shown in FIG. 2B, the print head 40K-1 has a plurality of ejection openings 40N. The ejection ports 40N are arranged in the longitudinal direction to form a nozzle row.

Note that the print head 40K-1 may have a plurality of nozzle rows.

<Head>
Next, the internal structure of the recording head will be described with reference to FIG. In FIG. 3, (a) is a cross-sectional view of the recording head 40K-1 in the longitudinal direction of the liquid chamber, and (b) is a cross-sectional view of the liquid chamber in the lateral direction, which is the SC1 cross section of (a). It is assumed that the head in the post-processing means 50 also has the same configuration as the recording head 40K-1 shown in FIG.

In FIG. 3A, the recording head (40K-1, etc.) of the image forming means 40 has a channel plate 41 that forms a path for ink to be ejected, and a lower surface of the channel plate 41 (inward direction of the recording head). It includes a bonded diaphragm 42, a nozzle surface (nozzle plate) 43 bonded to the upper surface of the flow path plate 41 (outward direction of the recording head), and a frame member 44 that holds the peripheral edge of the diaphragm 42. The recording head also has pressure generating means (actuator means) 45 for deforming the diaphragm 42 .

The recording head according to the present embodiment is formed by laminating a channel plate 41, a vibration plate 42, and a nozzle surface 43, thereby forming a nozzle communication channel 40R, which is a channel communicating with an ejection port (nozzle) 40N, and a liquid chamber. (Pressure chamber) 40F is formed. Further, the recording head forms an ink inlet 40S for supplying ink to the liquid chamber 40F, a common liquid chamber 40C for supplying ink to the liquid chamber 40F, and the like by further stacking the frame member 44. FIG.

Further, in this embodiment, the frame member 44 includes an accommodating portion for accommodating the pressure generating means 45, a concave portion serving as the common liquid chamber 40C, and an ink supply port for supplying ink to the common liquid chamber 40C from the outside of the recording head. 40IN is formed.

In this embodiment, the pressure generating means 45 includes a piezoelectric element 45P that is an electromechanical conversion element, a base substrate 45B that joins and fixes the piezoelectric element 45P, and a pillar portion that is arranged between the adjacent piezoelectric elements 45P. ing. The pressure generating means 45 also includes an FPC cable 45C and the like for connecting the piezoelectric element 45P to a driving circuit (driving IC).

Here, as the piezoelectric element 45P, as shown in FIG. 3B, a laminated piezoelectric element (PZT) in which piezoelectric materials 45Pp and internal electrodes 45Pe are alternately laminated is used. The internal electrode 45Pe has a plurality of individual electrodes 45Pei and a plurality of common electrodes 45Pec. In this embodiment, the internal electrode 45Pe alternately connects the individual electrode 45Pei or the common electrode 45Pec to the end surface of the piezoelectric element 45Pp.

The operation of the recording head ejecting ink from the nozzles 40N (pull-push operation) will be specifically described below.

In the recording head, first, the voltage applied to the piezoelectric element 45P (pressure generating element) is lowered from the reference potential, and the piezoelectric element 45P is contracted in the stacking direction. Further, the recording head bends and deforms the diaphragm 42 by shrinking the piezoelectric element 45P. At this time, the recording head expands (expands) the capacity (volume) of the liquid chamber 40F by bending deformation of the diaphragm 42 . This operation causes ink to flow from the common liquid chamber 40C into the liquid chamber 40F in the print head.

Next, the recording head increases the voltage applied to the piezoelectric element 45P to extend the piezoelectric element 45P in the stacking direction. Also, the recording head deforms the vibration plate 42 in the direction of the nozzle 40N by extending the piezoelectric element 45P. At this time, the recording head reduces (contracts) the capacity (volume) of the liquid chamber 40F by deformation of the diaphragm 42 . This operation causes the print head to apply pressure to the ink in the liquid chamber 40F. Also, the print head ejects (sprays) ink from the ejection openings 40N by pressurizing the ink.

After that, the recording head returns the voltage applied to the piezoelectric element 45P to the reference potential, and returns (restores) the diaphragm 42 to the initial position. At this time, the recording head reduces the pressure inside the liquid chamber 40F by expanding the liquid chamber 40F, and fills (replenishes) the liquid chamber 40F with ink from the common liquid chamber 40C. Next, after the vibration of the meniscus surface of the nozzle 40N is attenuated (stabilized), the recording head shifts to the operation for ejecting the next ink, and repeats the above operation.

In this manner, the recording head deforms (flexurally deforms) the diaphragm 42 using the pressure generating means 45 . Thereby, the print head changes the volume (volume) of the liquid chamber 40F, changes the pressure acting on the ink in the liquid chamber 40F, and as a result, the print head ejects ink from the ejection port 40N.

The method of driving the recording head to which the present invention can be applied is not limited to the above example (pull-push). For example, the recording head may be driven by controlling the voltage (driving waveform) applied to the piezoelectric element 45P to perform pulling or pushing. Further, the pressure generating means 45 may be of a thermal type in which a heating resistor is used to heat the ink in the liquid chamber 40F to generate bubbles, or a vibration plate and an electrode are disposed opposite to each other on the wall surface of the liquid chamber 40F. An electrostatic type that deforms the diaphragm by an electrostatic force generated between the diaphragm and the electrode may be used.

As described above, in the image forming means 40 of the printing system 1 of the present embodiment, the head modules 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40C, 40K, 40K, 40K, 40K, 40K, 40K, 40K, 40K, 40K, 40K, 40K, and Using 40M and 40Y, a black-and-white or full-color image is formed in the entire image forming area by one conveying operation of the recording medium Md (roll paper).

<Control description>
FIG. 4 is a block diagram showing a hardware configuration example of the image forming apparatus 2 of this embodiment. The image forming apparatus 2 includes 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, a drive waveform generation circuit 107, and the like are mounted.

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 .

The FPGA 102 is provided with a CPU control section 111 , a memory control section 112 , an I2C control section 113 , a sensor processing section 114 , a motor control section 115 , a recording head control section 116 and a maintenance/recovery control section 117 .

The CPU control unit 111 has a function of communicating with the CPU 101 . A memory control unit 112 has a function of accessing the RAM 103 and the ROM 104 . The I2C control unit 113 has a function of communicating 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 width direction edge of the recording medium 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 99 for detecting the position of the hour and the like are included. An analog sensor signal output from a temperature/humidity sensor or the like is converted into a digital signal by an AD 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 conveying the recording medium Md, a motor for raising and lowering the image forming means 40 and the post-processing means 50, a maintenance motor for operating the maintenance/recovery means 90A and 90B, and the like.

Motor control unit 115 generates a drive file. Alternatively, the configuration may be such that the CPU 101 generates a drive profile and instructs the motor control section 115 to do so. The CPU 101 also counts the number of printed sheets.

The printhead 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 (drive waveform generation unit) 107 is input to a recording head driver 210 (described later) mounted on the head relay board 200 .

The maintenance/recovery control unit 117 controls maintenance motors for operating the maintenance/recovery means 90A and 90B, and also transmits the idle time count value to the image processing unit 310 . Details of maintenance and recovery will be described with reference to FIGS. 18 to 20. FIG.

FIG. 5 is a block diagram showing a configuration example of the printhead control unit 116, drive waveform generation circuit 107, and printhead driver 210. As shown in FIG.

Upon receiving the trigger signal Trig that triggers the ejection timing, the recording head control unit outputs the ejection synchronization signal LINE that triggers the generation of the drive waveform to the drive waveform generation circuit 107 . Furthermore, the ejection timing signal CHANGE corresponding to the delay amount from the ejection synchronization signal LINE is output to the drive waveform generation circuit 107 . The drive waveform generation circuit 107 generates the common drive waveform Vcom at timing based on the ejection synchronization signal LINE and the ejection timing signal CHANGE.

Further, the recording head control unit 116 receives image data SD′ after image processing from an image processing unit 310 provided on the image processing board 300, which will be described later, and based on this image data SD′, the recording head 40K-1 A mask control signal MN for selecting a predetermined waveform of the common drive waveform signal Vcom is generated according to the size of ink droplets to be ejected from each nozzle. The mask control signal MN is a timing signal synchronized with the ejection timing signal CHANGE. The printhead control unit 116 then 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 printhead driver 210 .

The printhead 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′ and the synchronous clock signal SCK transferred from the recording head control unit 116 . The latch circuit 212 latches each registration value of the shift register 211 with a latch signal LT transferred from the print head control section 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. The level shifter 214 level-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 pressure generating element (piezoelectric element) 45P associated with the above nozzles of the recording head 40K-1, and is connected to the individual electrode 45Pei of the piezoelectric element 45P corresponding to each nozzle. there is Further, the common drive waveform signal Vcom from the drive waveform generation circuit 107 is input to the analog switch 215 . Also, 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 on/off the analog switch 215 at appropriate timing according to the output of the gradation decoder 213 given via the level shifter 214, each nozzle is selected from the drive waveforms forming the common drive waveform signal Vcom. A waveform to be applied to the piezoelectric element 45P corresponding to is selected. As a result, the size of ink droplets ejected from the nozzles is controlled.

<Image processing unit>
FIG. 6 is a functional block diagram showing a configuration example of the image processing unit 310 according to the first embodiment. The image processing unit 310 and the printhead control unit 116 function as a control unit of the liquid ejection device.

The image processing unit 310 performs gradation processing, image conversion processing, and the like on the received image data, and converts it into image data in a format that can be processed by the recording head control unit 716 . The image processing unit 310 then outputs the converted image data to the printhead control unit 716 .

Specifically, the image processing unit 310 includes an interface 311, a gradation processing unit 312, a gradation data storage unit 313, a pre-data reading unit 314, a fine drive determination unit 315, and a fine drive instruction signal generation unit 316. , and an image conversion unit 317 .

An interface 311 is an input unit for image data, and is a communication interface with a higher-level device that transmits image data, the CPU 101 and the FPGA 102 .

The gradation processing unit 312 performs gradation processing on the received multi-valued image data and converts it into small-valued image data. The small-value image data is image data (original image data) with the same number of gradations as the types of droplets ejected by the recording head 40K-1 (large droplet, medium droplet, small droplet). The gradation processing unit 312 is configured by, for example, a RAM, and stores the converted image data for one band or more in the gradation data storage unit 313 .

The image data Dn for one band includes, for example, at least the previous data (for example, 10 dots ahead) for which the previous data is read. Alternatively, in the case of a serial image forming apparatus, it refers to image data corresponding to the maximum width in the sub-scanning direction that can be printed by the recording head in one scan in the main scanning direction X, for example.

The pre-data reading unit 314 is a counting unit that counts a dot non-formation period from a predetermined position in the input original image data to a dot formation pixel (print pattern), which is the next pixel to eject liquid. do. Specifically, the pre-data reading unit 314 retrieves data for each predetermined period, and determines the dot non-formation period from the position immediately before the start of each predetermined period to the next dot-formed pixel, and the dot-formed pixel to dot-formed pixel in the predetermined period. The non-formation period and the dot non-formation period from the dot-formed pixel in the predetermined period to the end position of the predetermined period are counted. At this time, the line synchronization signal LS, which serves as a reference for printing, is used as a reference. This operation pre-reads the pattern several lines before the print dot.

Based on the number of pixels counted by the previous data reading unit, the fine drive determination unit 315 inputs to the piezoelectric element 45P a fine drive waveform for swinging the meniscus of the nozzle or a strong/fine drive waveform with a larger swing amount than the fine drive waveform. to decide whether

The fine drive instruction signal generation unit 316 instructs the image conversion unit 317 to perform fine drive or strong/fine drive.

The image conversion unit 317 converts the image data for one band on the gradation data storage unit 313 into the image data SD of large droplets, medium droplets, and small droplets for each image to be output. is added to convert to image data SD'.

This conversion is performed in accordance with the information about the printing order obtained from the image data via the interface 311 and in accordance with the configuration of the recording head 40K-1.

The image converter 317 outputs the converted image data SD′ to the FPGA 102 of the main control board 100 via the interface 311 .

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 performed by software installed in a computer instead of inside the image forming apparatus.

FIG. 7 shows an example of waveforms for generating fine drive waveforms and strong/fine drive waveforms based on the common drive waveform.

The common drive waveform Vcom shown in FIG. 7 is generated by the drive waveform generation circuit 107 shown in FIG. waveform.

The analog switch 215 is turned on in the recording head driver 210 according to the results of the waveform selection signals (MN signals) MN0, MN1 and MN2. While the analog switch 215 is on, waveform elements such as a required liquid ejection waveform, a fine drive waveform, or a strong and fine drive waveform that constitute the common drive waveform are selected and applied to the piezoelectric element 45P of the recording head 40K-1. be done.

Although FIG. 7 simplifies the illustration, it is assumed that the liquid ejection waveforms include, for example, three or more types of waveforms, namely, a large droplet, a medium droplet, and a small droplet.

FIG. 8 is a block diagram showing a hardware configuration example of an image forming apparatus according to another embodiment of the invention.

In the configuration shown in FIG. 5, the drive waveform generation circuit 107 is provided on the main control board 100, but in the present embodiment, the drive waveform generation circuit 217 is provided inside the printhead driver 210A and associated with the nozzles. The same number as the plurality of piezoelectric elements 45P provided are provided. Further, the printhead driver 210A is provided with a driver control section 216 that controls the driving waveform generation circuit 217. FIG.

In this configuration, the drive waveform generation circuit 217 is provided in association with each of the piezoelectric elements 45Pa to 45Px. Then, the drive waveform generation circuits 217a to 217x generate drive waveforms suitable for droplet size, fine drive, and strong drive to be applied to the piezoelectric elements 45Pa to Px, respectively.

FIG. 9 is a diagram showing the difference in waveform between the fine drive waveform and the strong and fine drive waveform. In FIG. 9, (a) shows different wave height values, (b) shows different rising and falling speeds, and (c) shows different rising and falling speeds and holding periods. These waveforms may be of any type, but there are two types of fine drive waveforms, a fine drive waveform and a strong fine drive waveform (hereinafter also referred to as a strong fine drive waveform), which have different meniscus vibration energies. generated.

When the crest values are different, as shown in FIG. 9A, the crest value of the strong/fine drive waveform is made stronger than that of the normal fine drive. By making the peak value Vpp1 of the strong/fine drive waveform higher than the peak value Vpp2 of the fine drive waveform, the fluctuation of the meniscus of the nozzle is increased even if the other rising, falling, and holding periods are the same.

When the start-up and fall speeds shown in FIG. to As a result, even if the holding period is the same, the fluctuation of the meniscus of the nozzle is increased. At this time, the crest value Vpp1 of the strong and weak drive waveform may be increased.

FIG. 9(c) shows the case where the rising and falling speeds and holding periods are different. In this example, resonance is utilized by changing the rising, falling, and holding periods. In this example, in the strong and weak drive waveform, the rise and fall are gentle, and the energy is accordingly small, but the energy is increased because the holding period Vh2 is long. In this example, stronger agitation can be achieved by utilizing resonance with the natural vibration period of the meniscus of the nozzle. At this time, the peak value Vpp1 of the strong and weak drive waveform may be increased.

<Fine drive control>
Hereinafter, setting determination between normal fine drive and strong fine drive will be described using FIGS. 10 to 13. FIG.

First, as a premise, in the present invention, two types of fine driving with different energies are prepared as shown in FIG.

When the non-printing portion (image non-formation period, dot non-formation period) continues for a long time, the strong and weak drive waveform is used so as to thin out more. Since the inside of the nozzle is strongly agitated by the strong and weak drive, thickening of the ink can be suppressed for a long time with one fine drive.

However, since strong and weak driving causes strong stirring, ejection is adversely affected if there is a pixel to be ejected immediately after it. Therefore, a static period, which is a period during which strong and weak driving is not performed, is always required.

Therefore, when there are not many non-printing portions and the printing portions continue intermittently, there is no need to stir to that extent, so the normal fine driving waveform is used during the dot non-forming period to eject the liquid immediately after. Reduce the impact on pixels.

10A and 10B are diagrams for explaining input determination of normal fine drive and strong fine drive. FIG. 10 will be described in order from the left.

(1): If there is a printing section 1 pix (pixel) after the current position, fine driving is not performed.

(2): If there is a printing section 2 pix after the current position, fine drive is performed at the current position, and fine drive is not performed for the next pixel.

(3): If there is a print section 3 pix after the current position, fine driving is performed at the current position and not performed thereafter. That is, fine driving is performed every 1 pix. This is because normal fine driving does not affect the image quality even if thinned to 1/2 of the maximum driving frequency.

In this case, fine driving is performed immediately before printing, but normal fine driving is unlikely to affect ejection, so there is no problem.

(4), (5): Fine driving is performed every 1 pix in the same way when the printing unit is 4 pix or 5 pix ahead from the current position.

(6): If the print area is 6 pix or more from the current position, select strong/fine drive.

In this example, the determination threshold for fine drive is set to 2 pix, and the determination threshold for strong/fine drive is set to 5 pix, but other values may be set.

FIG. 11 is an example of the input control flow of the fine driving waveform of the present invention. Note that the determination threshold for strong/fine drive (eg, 5 pix) is also referred to as a first count number, and the determination threshold for fine drive (eg, 2 pix) is also referred to as a second count number.

In S101, the gradation processing unit 312 of the image processing unit 310 receives multilevel image data.

In S102, the previous data reading unit 314 reads data 10 pix ahead (predetermined period) from the current position. This data is small-valued image data obtained by dividing the multi-valued image data into gradations for liquid ejection, and is referred to as original image data.

Then, in S103, it is determined whether or not there is a print pattern, which is dot formation pixels for which liquid is to be ejected, within a first count number (for example, 5 pix) from the current position.

If Yes in S103, that is, if the print pattern exists within 5 pix, the flow proceeds to normal fine drive flow of S104.

If No in S103, that is, if the print pattern does not exceed 5 pix, the use of strong and weak drive is selected in S105. Specifically, when the dot non-formation period in the original image data exceeds a predetermined first count number (5 pix), the fine drive determination unit 315 moves the fine drive determination unit 315 to the position immediately before the start of the predetermined period, which is the current position. Decide to give a waveform.

At this time, a period in which the number of dot forming pixels (printing pixels, printing portion, printing pattern) included in the original image data is equal to or less than the immediately preceding first count number is set as a period during which strong/weak driving is not performed.

On the other hand, when proceeding to the normal fine drive flow in S104, it is determined in S106 whether there is a print pattern one pixel ahead.

If Yes in S106, that is, if there is a print pattern one pixel ahead, fine driving is not input in S107. Specifically, when the dot non-formation period in the original image data is less than the second count number (2 pix), the fine drive determination unit 315 determines to give neither the fine drive waveform nor the strong and fine drive waveform. do.

If No in S106, it is determined in S108 whether or not there is a printing section 2 pix ahead.

If Yes in S108, that is, if there is a print pattern 1 pix ahead, in S109, fine driving is input once. Specifically, when the dot non-formation period in the original image data is equal to or less than the first count number (5 pix) and the second count number (2 pix), the fine drive determination unit 315 determines that the current position is It is decided to apply the fine driving waveform once at a position immediately before the start of the predetermined period.

If No in S108, it is determined in S110 whether there is a printing section 3 pix ahead or 4 pix ahead.

If Yes in S110, that is, if there is a print pattern 3 pix ahead or 4 pix ahead, fine drive is input twice in S111.

If No in S110, that is, if there is a print pattern 5 pix ahead, fine drive is input three times in S112. Specifically, when the dot non-formation period in the original image data is equal to or less than the first count number (5 pix) and exceeds the second count number (2 pix), the fine drive determination unit 315 A fine drive waveform is applied to a position immediately before the start of a predetermined period, and fine drive is performed every third predetermined number of pixels (1 pix), which is smaller by one than the second count number, during the subsequent dot non-formation period. to give a fine drive waveform.

Although this example shows an example in which the number of fine drive waveforms is thinned every pixel, thinning may be performed by lowering the drive frequency of the fine drive waveform.

Then, when fine driving is performed every third predetermined number (1 pix) of pixels, fine driving is performed even during a period of less than the immediately preceding second count number (2 pix) of the dot formation pixels included in the original image data. ( For example, 2nd time 3pix ahead, 3rd time 5pix ahead).

In S113, it is determined whether 10 pix is the end of the image.

In the case of No in S113, that is, in the case where the original image data continues after 10 pix determined this time, the process returns to before S102 and repeats the flow.

When the above determination is completed for all the original image data, printing is completed in S114.

FIG. 12 is a diagram showing a specific example in which the nozzles are finely driven based on print information. FIG. 12(a) is a specific example in which uniform control is performed on the nozzle rows in the comparative example, and FIG. 12(b) is a specific example in which fine drive control is performed for each nozzle in the present invention.

In FIG. 12, gray portions indicate fine driving, and black portions indicate printed pixels.

In the prior art of FIG. 12(a), all nozzles in the nozzle row are uniformly controlled, so fine driving is performed even for nozzles that are not originally required.

In the present invention, since fine drive is controlled for each nozzle, the minimum required fine drive is performed for each nozzle to maintain image quality. FIG. 12 shows an example in which the second count value, which is the determination threshold for normal fine driving, is set to 3 pix.

In the example of FIG. 12, since the predetermined period of reading is 6 pix, there is no dot non-formation period exceeding 5 pix. .

FIG. 13 shows an example in which the nozzles are finely and finely driven based on the print information.
Note that in FIG. 13, the first count value, which is the determination threshold for the strong and weak drive waveform, is 5 pix, the second count value, which is the determination threshold for the fine drive waveform, is 2 pix, which is one smaller than the second count number. Assume that the third predetermined number, which is the interval, is 1 pix.

10 to 12, the first position as the current position within the predetermined period (10 pix) read out has been described, but the same determination is made immediately after the dot formation pixel within the predetermined period. .

More specifically, the pre-data reading unit 314 retrieves input original image data for each predetermined period, and the fine drive determination unit reads the dot from the position immediately before the start of each predetermined period to the dot formation pixel for which liquid is to be ejected next. The non-formation period, the dot non-formation period from the dot formation pixel to the dot formation pixel in the predetermined period, and the dot non-formation period from the dot formation pixel to the predetermined period end position in the predetermined period are counted.

Based on the counted dot non-formation period, the fine drive determination unit 315 determines whether to apply the fine drive waveform or the strong/fine drive waveform to each of the plurality of piezoelectric elements 45Pa to 45Px.

In FIG. 13, fine drive selection is performed based on each non-printing portion (dot non-forming period) with the original image data 10 pix ahead from the current position as a predetermined period.

For example, since nozzles N1, N3, N4, N5, N8, and N9 do not have a printing portion (dot formation pixel) within 5 pix from the current position, strong and weak driving that is stronger than usual is input at the current position.

In addition, when a non-printing portion continues for 6 pix or more immediately after ejection, such as nozzles N2 and N7, after the dot formation pixel, a stronger and weaker drive waveform than usual is input.

By inputting strong and fine driving, it is possible to reduce the number of times of fine driving. At this time, with the function to read the image data up to 10 pix ahead, if the print part is within 5 pix ahead, stop the strong and weak drive and stabilize it to reduce the influence of the print part after that. .

The reason why it is not performed within 5 pix before the printing unit is that if ejection is performed immediately after the strong and fine drive, the vibration caused by the fine drive will adversely affect the next ejection. It is also known that the image quality can be maintained even if fine driving is not performed for 10 pix or more after strong and fine driving.

Therefore, considering the influence on the next 10 lines of the predetermined period following the read 10 lines of the predetermined period, the 5 lines immediately before the end position of the predetermined period (the period equal to or less than the first count number) are shown in FIG. During the drive waveform non-input period, no strong drive is input.

Also, if the non-printing area from the current position to the dot formation pixel is less than 6 pix, like nozzles N2, N6, and N7, a normal fine drive waveform is input to the current position, and then every 1 pix. Fine drive is performed by thinning out.

Then, if the non-printing area between the dot-forming pixels is less than 6 pix and 2 pix or more, input a normal fine drive waveform like nozzle N1, and then every 1 pix. Fine drive is performed by thinning out.

Similarly, if the non-printing portion is less than 6 pix and 2 pix or more between the dot formation pixel and the predetermined period end position (10 lines), nozzles N3, N5, N6, N8, N9 are normally fine drive waveform is input, and then fine drive is performed by thinning out every 1 pix.

Although not shown in FIG. 13, when the non-printing portion is less than 2 pix, neither fine drive nor strong drive is input.

As described above, in the present invention, the type and interval of the driving waveform are adjusted for each nozzle in the blank area within the image area. can prevent thickening of ink due to fine driving while appropriately performing fine driving within an image area.

In the above-described first embodiment, an example in which fine driving is performed in association with image data being printed has been described. However, for example, idle ejection (flushing), which is ejection of liquid that does not contribute to image formation, may be performed in a page boundary area other than an image formation area even during printing. It is preferable to perform fine driving immediately before flushing during printing.

Therefore, a second embodiment will be described in which fine driving is performed for both ink ejection for image formation based on image data and blank ink ejection for flushing during printing.

<Second embodiment>
Fine drive control according to the second embodiment will be described below with reference to FIGS. 14 to 16. FIG. FIG. 14 is a functional block diagram of an image processing section according to the second embodiment of the present invention.

The image processing section 310A of the present embodiment includes a print hollow ejection setting section 318 and an upper image conversion section 319 in addition to the constituent elements of the image processing section 310 shown in FIG.

The hollow print ejection setting unit 318 sets the head 40K-1 to a predetermined position on the recording medium Md, for example, at a predetermined inter-page timing on the recording medium Md. A blank discharge instruction is output a predetermined time before the discharge. The idle discharge instruction also includes a preset number of times of idle discharge.

Alternatively, the print blank ejection setting unit 318 determines the timing at which the page is interrupted based on the image data, and issues a blank ejection instruction a predetermined time before the head 40K-1 reaches a predetermined position on the recording medium Md. may be output.

The high-level image conversion unit 319 adds blank ejection data (blank ejection pattern) to original image data instructing image formation, and outputs the result as image data Dn.

FIG. 15 is an example of the input control flow of the fine drive waveform according to the second embodiment of the present invention. The idle discharge of this embodiment is performed at the top of the page immediately after the page boundary. Therefore, this flow is carried out when there is a page boundary and the blank discharge instruction is included at the beginning of the next page.

In S201, image data from the current position to 10 pix ahead is read.

In S202, it is determined whether or not the end of the image area within the page (the end of the image forming area before blank discharge) exists within 10 pixels.

If there is no end of the image area within the page (No in S202), in S203, the normal printing operation including application of fine drive and strong/fine drive shown in S101 to S111 of FIG. 11 is performed.

In S202, if the end of the in-page image area exists within 10 pix, it is checked whether the end of the in-page image area is the end of the entire image data (S204).

In the case of the end of the entire image data (Yes in S204), in S205, normal printing operation including application of fine drive and strong/fine drive shown in S101 to S111 of FIG. 11 is performed, and then the flow ends (END). .

On the other hand, if it is the end of the pixel area within the page in S202 (Yes) and if it is not the end of the entire image data in S204 (No), then in S206 the dot formation pixels (printing portion, print pattern) are not shown in the drawing. 11, the normal printing operation including application of fine drive and strong/fine drive is performed.

In S207, a driving waveform is applied at the timing of the printing unit to eject ink.

Then, if the print portion is not at the end of the in-page image area in S208 (No), the strong and weak drive waveform is applied to the pixels of the non-print portion (dot non-formation period) immediately after the output of the print portion (S209). .

If the print portion exists at the end of the image area within the page (Yes in S208), the fine drive waveform is applied to the non-print portion immediately after the output of the print portion, and then the fine drive waveform is applied to every other portion ( S210).

In S211, the image data of the next 10 pix are read. Then, it is checked whether or not there is an idle discharge pattern at the beginning of the read period (S212).

If there is an idle discharge pattern at the beginning of the read period (Yes in S212), the process proceeds to S221.

If there is no idle discharge pattern at the beginning of the current read period (No in S212), it is checked whether the strong and weak drive was applied during the previous read period (S213).

If the strong/fine drive was applied during the previous reading period (Yes in S213), the fine drive waveform is applied every other time when 10 pixels are reached after the application of the strong/fine drive waveform (S214).

If the strong/fine drive was not applied during the previous read period (No in S213), the fine drive waveform is changed to 1 so that the application of every other pulse continues from the fine drive applied during the previous read period. It is applied every other time (S215).

If a blank discharge pattern exists within 10 pix read in S211 (Yes in S216), the process proceeds to step S221.

If no blank discharge pattern exists within the 10 pix read in S211 (No in S216), the process proceeds to S217, and the next 10 pix of image data is read again.

Then, if there is an idle discharge pattern at the beginning of the next reading period (Yes in S218), the process proceeds to S221.

If there is no idle discharge pattern at the beginning of the next reading period (No in S218), in S219, the fine drive waveform is applied to every other nozzle from the previous reading period.

Then, it is checked whether or not there is an idle discharge pattern within the 10 pixels read in S217, and if it exists (Yes in S220), the process proceeds to S221.

On the other hand, if no blank ejection pattern exists in the 10 pix read in S217 (No in S220), the process returns to S217, the image data is read again, and S217 to S220 are repeated until the blank ejection pattern appears.

For example, when the margin is set large on the recording medium, the boundary of the page is not reached even after 10 pixels have passed after the end of the image area within the page. In this case, until the arrival of the next page, during the second and subsequent reading periods, while continuing fine driving every other page in steps S217 to S220, idle discharge is on standby in the margin period.

When the page boundary is reached and the application timing of the blank ejection pattern is reached in S212, S216, S218, or S220, blank ejection is performed at the top position of the next page in S221.

After performing the blank ejection between pages in S221, fine driving and fine driving are not performed during the reading period during which the blank ejection is performed.

Then, the idle discharge control between pages is finished, and the process returns to S201, the image data after the next 10 pix is read, and fine driving and strong/fine driving are appropriately applied as normal printing according to the image data.

In addition, if the margin on the top side of the page on which the blank ejection is performed is large, the printing part may not exist within the reading period of 10 pix next to the blank ejection, but even in that case, the ink will be Since the ink is sufficiently refreshed, it is not necessary to apply fine drive or strong/fine drive while the printing unit is on standby after executing the blank discharge.

Here, an example of fine drive and strong fine drive when the control of FIG. 15 is performed will be described with reference to FIG. FIG. 16 is a diagram showing an example in which fine driving and strong fine driving are performed on nozzles based on printing information and flushing information.

In the present embodiment, in FIG. 16, similar to FIG. 13, fine drive selection is performed based on each non-printing portion (dot non-forming period) with the original image data 10 pix ahead from the current position as a predetermined period. . In FIG. 16, since the 10th dot from the bottom is the same as in FIG. 13, the 11th dot and subsequent dots will be described.

For example, the nozzles N1 and N4 eject at the second current position of the 10th dot, and after that, there is no printing portion (dot formation pixel) until the end of the image within the page, so at the position next to the second current position , to input a stronger dynamic drive than usual.

Here, it is assumed that the image quality can be maintained without executing the fine drive for at least 10 pix for the nozzles to which the fine drive was applied during the previous predetermined period.

For example, in N7, although the print section after the strong and fine drive is 9 pix away, the effect of the strong and fine drive still continues within 10 pix. of ink is ejected.

On the other hand, in N2, since the print section after the strong/fine drive is 11 pix away, the effect of the strong/fine drive is terminated, and the fine drive is applied at the 10th pix from the application of the strong/fine drive immediately before the print section.

Also, if the non-printing area between the dot formation pixels is less than 6 pix and 2 pix or more, input a normal fine drive waveform like nozzle N6, and then every 1 pix. Fine drive is performed by thinning out.

As indicated by the nozzle N3, when the non-printing portion of the dot formation pixels and the dot formation pixels is less than 2 pix, neither the fine drive nor the strong and fine drive is input.

Then, when the last dot-forming pixel for that nozzle exists before the end of the in-page image area, just after the dot, such as nozzles N3, N5, N7, N8, and N9, stronger than usual, Enter the strong and weak drive waveform.

In addition, like N2 and N6, when there is a dot forming pixel in the nozzle at the end of the image area in the page, the normal fine drive waveform is input immediately after the dot, and then fine drive is performed by thinning out every 1 pix. to implement.

In consideration of the effect on flushing, the period after the end of the in-page image area is a read period of 10 pix including the end of the in-page image area. As an input period, strong and weak driving is not input.

Note that FIG. 16 shows an example in which the margin is narrow and the page boundary exists within 10 pix immediately following the 10 pix including the end of the in-page image area. After the end of the image area, the page boundary is not reached even after 10 pix minutes have passed. In that case, until the idle discharge pattern is reached in the next and subsequent reading periods, in the second and subsequent reading periods (10 pix), fine driving of each nozzle in the previous cycle continues. Continue every other fine drive.

In this example, during the non-printing period before the blank discharge, the application state of the fine drive and the strong fine drive in the previous period is taken into consideration, and the fine drive is applied to every other nozzle. As described above, during the non-printing period before the blank discharge, fine driving may be applied to all the nozzles at the same timing.

Further, in this example, in the non-printing period before the blank discharge, the fine drive is applied every other time in the same manner as in the non-printing period during the normal printing. The fine drive application interval may be different between the non-printing period during the period.

As described above, in the second embodiment of the present invention, the type and interval of the drive waveform are adjusted for each nozzle in the margin within the image area and immediately before flushing. (Liquid ejection device, droplet ejection device) can prevent thickening of ink due to fine driving while appropriately performing fine driving within an image area.

Here, in the above-described first and second embodiments, in order to eliminate ink thickening around nozzles during printing, prior to ejection for image formation and ejection for flushing onto a recording medium, Although an example of controlling the fine driving has been described, ink thickening occurs around the nozzles even when the nozzles are covered with caps during non-printing periods. Therefore, in the startup period in which the printing operation is resumed from the idle state, idle ejection and fine driving for eliminating ink thickening will be described in the following third embodiment.

<Third Embodiment>
Fine drive control according to the third embodiment of the present invention will be described below with reference to FIGS. 17 to 21. FIG.

17A and 17B are diagrams for explaining ejection bending in preliminary ejection in a comparative example and fine driving before preliminary ejection in the present invention. FIG. 17(a) shows the comparative example, and FIG. 17(b) shows the state of the present invention.

In a standby state that is not a printing period, even if the nozzles are covered with caps, the ink around the nozzles thickens. Therefore, as shown in FIG. If the liquid is suddenly discharged, the discharge bending occurs. When ejection bending occurs, there is a risk that the nozzle surface 43 (see FIG. 3A) will be stained, or that the ink will land on the transport path outside the recording medium Md. may adversely affect

Therefore, in the present invention, in order to eliminate the thickening of the ink, fine driving is inserted before the ejection for image formation is started in the startup period. Then, by performing idle ejection (preliminary ejection) after fine driving is completed, abnormal ejection at the start of ejection is prevented.

As preliminary ejection, FIG. 17 illustrates an example in which the cap is removed and idle ejection (line flushing) is performed on the blank area of the recording medium Md, which is roll paper. Pre-discharge may be performed.

(Maintenance and recovery department)
Here, the configuration of the maintenance/restoration section including the cap will be described with reference to FIGS. 18 and 19. FIG. FIG. 18 is an explanatory diagram of maintenance and recovery operations of the image forming means and the post-processing means according to the embodiment of the present invention. In FIG. 18, (a) is a diagram during printing on a recording medium, and (b) is a diagram during capping.

In FIG. 18, an image forming means (generic term for multi-color head modules) 40 and a post-treatment means (post-treatment liquid output section, head) 50 are arranged to face a conveying belt 81 as a conveying section. The transport belt 81 transports the recording medium Md in the direction of the arrow Xm. Maintenance means (maintenance means) 90A and 90B are provided upstream (right side in FIG. 18(a)) and downstream (left side in FIG. 18(a)) in the conveying direction of the recording medium Md from the image forming means and the post-processing section. It is The maintenance/restoration means 90A and 90B perform maintenance/restoration of the image forming means 40 and the post-processing means 50, respectively, which are line type heads.

The head modules of the image forming means 40 and the post-processing means 50 are vertically movable. A head module including heads 40K-1, 40C-1, 40M-1, and 40Y-1 for each color, which are image forming means, is installed on a carriage 46, and a head 50 for ejecting post-treatment liquid. -1 etc. are installed on the carriage 56 .

By moving up and down, the carriages 46 and 56 move between a position near the transport unit 80 shown in FIG. 18(b), which is a position separated from the conveying unit 80, is movable. This separated position is a maintenance position in which both the image forming means 40 and the post-processing means 50 are maintained by the maintenance/recovery means 90A and 90B, and is a standby position to wait until the next operation and a recovery position to perform maintenance. .

For this vertical movement, the carriages 46 and 56 are supported by carriage position moving means 47 and 57, for example. By moving the carriage position moving means 47, 57, the positions of the carriages 46, 56 move up and down with respect to the housing 74 of the printer engine 72E provided with the transport belt 81. FIG. Although the carriage position moving means 47 and 57 are indicated by arrows in FIG. 18A, a moving mechanism combining rails and rollers may be used as the carriage position moving means 47 and 57, or an arm or the like may be used. can be lifted.

In the transport unit 80 , the transport belt 81 is looped between a drive roller 83 and a driven roller 82 that are rotated by a motor, and the recording medium Md is supported by a support member 84 on the transport belt 81 . Transported by orbital movement. Here, the support member 84 may be provided with suction means or electrostatic attraction means in order to attract the paper while it is being conveyed.

Further, the maintenance and recovery means 90A includes an engaging portion 91A and a cleaning unit 95A. The maintenance and recovery means 90B includes an engaging portion 91B and a cleaning unit 95B.

The engaging portion 91A is a facing region that faces the heads of the head modules 40K, 40C, 40M, and 40Y as the image forming means at the separated position (dotted line portion in FIG. 18A) when maintenance is performed. , and selectively engage heads 40K-1, 40C-1, 40M-1, 40Y-1, and the like. When maintenance is performed, the engaging portion 91B reciprocates and reciprocates to a region facing the head 50-1 as a post-processing process portion at the separated position and engages with the head 50-1.

The maintenance and recovery means 90A and 90B are the same except for the number of caps 92K-1 and the like engaged with the head 40K-1 in the cap portion 92 and the liquid (ink color/post-treatment liquid) to be received. , the same configuration will be described by taking the head 40-1 and the cap 92-1 for ejecting ink as image forming means as an example, and the symbols at the end of words indicating colors will be omitted.

The engaging portion 91 has a cap portion 92 , a wiper 93 , and a fixing member 94 that fixes the cap portion 92 and the wiper 93 . The cap portion 92B is engaged with the head 40-1 at the spaced position to seal and cap the nozzle 40N (see FIG. 2(b)) of the head 40-1. During maintenance, the head 40-1 performs so-called idle ejection in which ink is ejected while the caps 92-1 of the cap portion 92 are engaged. It functions as an empty ejection receiver that receives ink that has been discharged. The wiper 93 cleans (wipes) the head 40-1 by wiping ink flowing out from the head 40-1 at the separated position.

The cleaning unit 95 cleans the cap portion 92, the wiper 93, etc. in a state in which the engaging portion 91 has returned to the home position after the reciprocating movement of the engaging portion 91 during maintenance. The cleaning of the engagement portion 91 by the cleaning unit 95 may be performed periodically such as after a predetermined number of images are formed.

The maintenance/recovery means 90 also sucks the ink inside the head 40-1 in a state where each cap 92-1 of the cap portion 92 is engaged with the head 40-1 at the spaced position, and the ink is drawn outside the head 40-1. A pump 96 is provided as a suction means for causing the liquid to flow out into the water. The maintenance/recovery means 90 further includes a discharge path for connecting the cap portion 92 and the pump 96 to discharge the ink to the outside of the head 40-1, and a liquid (ink/afterflow) connected to the discharge path that flows out of the head 40-1. and a liquid reservoir for respectively storing a processing liquid).

FIG. 19 is a plan view of the image forming section 40, post-processing section 50, and maintenance/recovery section 90 according to the embodiment of the present invention. As shown in FIG. 19, the maintenance/recovery means 90A includes cap portions 92K, 92C, and 92M corresponding to each head 40-1 of each head module as the image forming means 40 in the direction perpendicular to the recording medium conveying direction. , and 92Y, respectively. The cap portion 92B of the maintenance and recovery means 90B includes the same number of caps 92B-1, 92B-2, 92B-3 and 92B-4 as the maintenance and recovery heads 50-1, 50-2, 50-3 and 50-4. there is

Further, the maintenance/recovery means 90 has a moving means for moving the engaging portion 91 . As moving means for the engaging portion 91, reciprocating means (belt 97, pulley 98) for reciprocating the engaging portion 91 to each head of the head modules 40 and 50, and engaging portion 91 supporting the reciprocating means. and a vertical movement means (base portion 75) for vertically driving the cap portion 92 integrally therewith.

The reciprocating means has a fixed member 94 integrated with the engaging portion 91, an endless belt 97 partially fixed to the fixed member 94, and two pulleys 98 around which the belt 97 is wound. .

The reciprocating means also has a position sensor 99 (a position sensor 99 ( 99K, 99C, 99M, 99Y and 99B). The reciprocating means also has a support stand that supports the engaging portion 91 from below so as to be reciprocable as described above, and a motor or the like as driving means for rotating the pulley 98 .

On the other hand, there is provided a base portion 75 on which a support portion including a belt 97 is placed as vertical movement means, and which is arranged and fixed upward from the upper surface of the housing 74 with the paper moving space interposed therebetween. The base portions 75A and 75B are connected to, for example, a shaft as a drive shaft with which the lower surface portion is screwed, and a plurality of gears fixed to the other end of the shaft and rotating integrally with the shaft. It is connected to a stepping motor that rotates the gear.

Therefore, by driving the motor as the reciprocating means to rotate the pulley 98 and move the belt 97 in a circular motion, the engaging portion 91 can be reciprocated. At this time, by driving the motor so that one of the position sensors 99 detects the fixing member 94, the cap portions 92K, 92C, 92M, and 92Y or 92B are placed at the separated positions, and the head modules 40K, 40C, 40M are moved. , and 40Y or a position facing 50 or a home position.

In a state where the cap portions 92K, 92C, 92M, 92Y and 92B are positioned by the position sensor 99 at any of 40K, 40C, 40M, or 40Y or at a position facing 50, the stepping motor is rotated by a predetermined amount, that is, By driving with a predetermined number of pulses, the base portions 75A and 75B are moved upward. As a result, the engaging portions 91A and 91B are moved upward by a predetermined amount, and any of the head modules 40K, 40C, 40M and 40Y occupying the spaced position where the cap portions 92K, 92C, 92M and 92Y or 92B face each other. or 50. A combination of a sensor for detecting the position of the cap portion 92 in the vertical direction and a motor may be used instead of the stepping motor.

When performing the maintenance and recovery operation using such a configuration, as shown in FIG. , stops and engages just below each head in the spaced apart position.

In the present invention, as the maintenance recovery operation, the nozzle surfaces 43 including the nozzles 40N and 50N of the heads 40-1 and 50-1 of the image forming means 40 and the post-processing means 50 are each capped 92-1 of the discharge cap portion 92. , 92B-1, and pumps 96A, 96B suck the ink and post-treatment liquid from the nozzles 40N, 50N through the cap portion 92. As shown in FIG.

After the nozzle suction as a maintenance recovery operation is completed and the engaging portions 91A and 91B return to their home positions, the image forming means 40 and the post-processing means 50 also move downward again, and the conveying unit 80 moves downward. It returns to the printing position (position shown in FIG. 18(a)) and becomes ready for printing.

18 and 19, the heads 40-1 of the head modules 40K, 40C, 40M, and 40Y of the image forming means and the heads 50-1 of the post-processing means are independent from each other. It is mounted on carriages 46 and 56 . This makes it possible to perform maintenance on the image forming means and the post-processing means at different times.

However, the image forming means 40 and the post-processing means 50 may be integrated and mounted on the same carriage. In this configuration, the maintenance and recovery means 90A and 90B are also integrated, so the moving mechanism is simplified and the cap portions 92A and 92B are also simplified. In this case, the integrated engaging portion 91 collectively caps the plurality of heads of the head modules 40K, 40C, 40M and 40Y and the plurality of heads of the post-processing means 50 for maintenance and recovery. Therefore, the maintenance and recovery section can be collectively arranged upstream or downstream of the image forming section 40 or the post-processing section 50 in the sheet conveying direction.

<Image processing of the third embodiment>
FIG. 20 is a functional block diagram of an image processing section 310B and a maintenance/restoration control section 117B according to the third embodiment of the present invention.

An image processing unit 310B of the present embodiment includes, in addition to the constituent elements of the image processing unit 310A of the second embodiment, an idle discharge instruction unit 321 at startup, a fine drive determination unit 322 at startup, and a fine drive condition correlation storage unit 323 at startup. It has

Further, the maintenance/recovery control section 117B has an idle time counting section 171 . Detection information from the position sensor 99 is input to the maintenance/recovery control unit 117B.

The standing time counting unit 171 is set to the position where the position sensor 99 faces each head of the head modules 40K, 40C, 40M, and 40Y or 50 where the cap units 92K, 92C, 92M, and 92Y or 92B are at the separated positions. During a certain period, assuming that the device is in the capped state, the idle time is counted.

Upon receiving a print instruction, the boot-time blank ejection instruction unit 321 instructs blank ejection (preliminary ejection) to be performed before ejection for image formation. Depending on the configuration of the cap and the like, the idle ejection at the time of activation may be performed by landing the ink droplets on the recording medium Md after releasing the engagement between the cap and the nozzles (after uncapping), or Ink droplets may be ejected into the cap while the cap and nozzle remain engaged.

The start-up slight drive condition correlation storage unit 323 divides the idle time into levels and stores the drive condition in correlation with the idle time. Table 1 below is an example of a correlation table stored in the start-up fine drive condition correlation storage unit 323 .

なお、表１は例として放置時間を３段階にレベル分けした例を示しているが、放置時間に応じて、より細分化して設定してもよい。

Although Table 1 shows an example in which the standing time is divided into three levels, the standing time may be subdivided and set according to the standing time.

The start-up fine drive determination unit 322 calls fine drive conditions associated with the counted idle time, and executes fine drive under the corresponding fine drive conditions immediately before blank ejection (preliminary ejection) at startup. , set.

Then, the fine drive instruction signal generation unit 316B generates and outputs a fine drive instruction signal at startup for the set number of times in the set type of fine drive (fine drive or strong fine drive) at the time of startup. . Further, when fine driving at startup is performed a plurality of times (for example, 500 times and 1000 times shown in Table 1), instructions are given to perform the fine driving at predetermined intervals according to the driving frequency.

Before starting, the image conversion unit 317B adds starting fine drive data (starting fine drive instruction signal) to the blank ejection data input as the image data Dn, and outputs the result as image data Dn'.

<Startup control flow>
Next, the startup control flow of the third embodiment, which is realized using the control configuration of FIG. 20, will be described using FIG. FIG. 21 is an example of a control flow at startup according to the third embodiment of the present invention.

First, in S301, a print instruction is input.

In S302, the print instruction in S301 is used as a trigger to set the blank ejection timing, which is the preliminary ejection.

In S<b>303 , the start-up slight drive determining unit 322 calls the cap idle time from the idle time counting unit 171 . When the idle time is called, the idle time counting unit 171 resets the count value.

In S304, the start-up fine drive determination unit 322 refers to the correlation table stored in the start-up fine drive condition correlation storage unit 323, and determines the fine drive waveform type and the fine drive count associated with the idle time. set. For example, as shown in Table 1 above, the longer the standing time is, the greater the number of times of fine driving is set. When the standing time is long, strong and fine drive is selected as the type of fine drive waveform.

In S305, the cap engagement state is released (uncapping), the maintenance mechanism is moved, and the head unit is moved (FIG. 18(b)→FIG. 18(a)).

In S306, just before the blank ejection timing set in S302, fine driving is performed with the type of fine driving waveform and the number of times of fine driving set in S304.

In S307, preliminary ejection (preliminary ejection) is performed on the recording medium Md.

At S308, printing is started. This printing operation continues until printing ends in S309. During printing, as shown in FIGS. 11 and 15, it is preferable to perform fine driving based on the original image data and idle discharge (flushing data).

When printing is completed in S309 (Yes), the head unit is moved in S310, the maintenance mechanism is moved, and the nozzle surface of the head unit and the cap are engaged (FIG. 18(a)→FIG. 18(b)).

When the position sensor 99 detects engagement between the nozzle surface and the head unit in S311, the idle time counting section 171 starts counting in S312.

Then, the idle time is continued to be counted until the printing instruction is notified in S312, and the flow ends.

As described above, in the present embodiment, by optimizing the fine drive according to the standing time and inserting it between uncap and the start of ejection, the viscosity of the ink around the nozzle is adjusted, and the preliminary It is possible to prevent ejection abnormalities such as ejection bending at the time of ejection.

In this flow of FIG. 12, an example is shown in which the ink for blank ejection is removed from the cap and preliminarily ejected onto the recording medium at startup. may In that case, the operations of releasing the cap engagement state (uncapping) in S305, moving the maintenance mechanism, and moving the head unit are performed after application of fine drive in S306 and blank ejection in S307. In this way, even when preliminary ejection is performed in the cap instead of on the recording medium at startup, the viscosity of the ink around the nozzles is adjusted by inserting a fine drive that is optimized according to the idle time. As a result, it is possible to prevent ejection abnormalities such as ejection bending at the time of preliminary ejection.

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 recording head 40K-1 included in the image forming means for ejecting ink has been described as an example of the liquid ejection head. Fine drive control of the liquid ejection head of the invention may be implemented.

Further, in the above example, an example in which the liquid ejection apparatus of the present invention is applied to an image forming apparatus using a line-type liquid ejection head that ejects liquid over the entire area in the direction orthogonal to the transport direction has been described. In a serial type image forming apparatus that moves in a direction orthogonal to the transport direction, the fine drive control of the liquid ejection device and the liquid ejection head of the present invention may be applied.

In the present application, 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.

Further, the terms used in the present application, such as image formation, recording, printing, printing, printing, modeling, etc., are synonymous.

1 printing system 2 image forming apparatus (liquid ejection apparatus)
40K, 40M, 40C, 40Y Head module (image forming means)
40K-1, 40K-2, 40K-3, 40K-4 recording head (liquid discharge head)
40F liquid chamber (pressure chamber)
40N Nozzle 43 Nozzle surface 45P (45Pa to 45Px) Piezoelectric element (pressure generating element)
50 post-processing means 90 (90A, 90B) maintenance and recovery means 92 (92K, 92C, 92M and 92Y, 92B) cap portion 92-1 (92K-1, 92K-1, 92K-1, 92K-1), 92B -1 cap 99 position sensor 107 drive waveform generation circuit (drive waveform generation unit)
116 recording head control unit (control unit)
117 maintenance and recovery control unit 171 idle time counting unit 217 drive waveform generation circuit (driving waveform generation unit)
310 image processing unit (control unit)
314 Preceding data reading unit (counting means)
315 Fine drive determination unit 316 Fine drive instruction signal generation unit 317, 317A, 317B Image conversion unit 318 Print hollow ejection setting unit 319 Higher-level image conversion unit 321 Blank ejection instruction unit at startup 322 Fine drive determination unit at startup 323 Fine drive condition at startup Correlation storage unit 171 Leaving time counting unit Md Recording medium (roll paper)

JP 2009-154512 A JP 2016-041473 A

Claims (12)

a nozzle;
a pressure chamber communicating with the nozzle and containing a liquid;
a pressure generating element that applies pressure to the liquid in the pressure chamber;
a driving waveform generator that outputs a driving waveform to the pressure generating element;
and a control unit that controls the drive waveform generation unit,
The control unit
The input original image data is taken out every predetermined period, and the dot non-forming period from the position immediately before the start of each predetermined period to the dot forming pixel for which liquid is to be ejected next, and from the dot forming pixel to the dot forming pixel in the predetermined period. a dot non-forming period, a counting unit for counting a dot non-forming period from a dot-formed pixel to a predetermined period end position in the predetermined period, and based on the dot non-forming period counted by the counting unit, the nozzle a fine drive waveform that oscillates the meniscus of the fine drive waveform or a strong and fine drive waveform with a greater amount of oscillation than the fine drive waveform is provided to the pressure generating element,
The drive waveform generator generates a drive waveform based on image data including the determined fine drive waveform or the strong and fine drive waveform, and outputs the drive waveform to the pressure generating element. . In the original image data, when the dot non-formation period exceeds a predetermined first count number, the fine drive determination unit determines the strong drive position immediately before the start of the predetermined period or immediately after the dot formation pixel. Deciding to give a fine drive waveform,
The period of the first count number or less immediately before the pixel for ejecting the liquid included in the original image data and the period of the first count number or less immediately before the end position of the predetermined period are the strong and weak driving. decide not to give a waveform
2. The liquid ejecting apparatus according to claim 1, wherein: When the dot non-formation period in the original image data is a first count number or less and is a second count number, the fine drive determination unit determines a position immediately before the start of the predetermined period or the dot 2. The liquid ejecting apparatus according to claim 1, wherein the fine drive waveform is determined to be applied immediately after forming pixels. When the dot non-formation period in the original image data is equal to or less than a first count number and exceeds a second count number, the fine drive determination unit determines a position immediately before the start of the predetermined period, or The fine drive waveform is applied immediately after the dot formation pixel, and the fine drive is performed at intervals of a predetermined number smaller than the second count number by one in the subsequent dot non-formation period. Deciding to give the waveform,
When the fine drive is performed at intervals of the predetermined number , the fine drive waveform is applied even during a period less than the second count number immediately before the dot forming pixels included in the original image data.
2. The liquid ejecting apparatus according to claim 1, wherein: The fine drive determining unit determines to apply neither the fine drive waveform nor the strong/fine drive waveform when the dot non-formation period in the original image data is less than a second count number. The liquid ejecting apparatus according to claim 1, characterized by: The input original image data includes not only image forming data for forming an image, but also idle ejection data for idle ejection of liquid that does not contribute to image formation to areas other than the image forming area of the recording medium,
When the original image data to be input is taken out for each predetermined period, the fine drive determination section determines the dot non-formation period counted by the counting section up to the end of the image forming area before the blank ejection data. , determining whether or not to apply to the pressure generating element a fine drive waveform that oscillates the meniscus of the nozzle, or a strong and fine drive waveform that oscillates more than the fine drive waveform. Liquid ejection device. The control unit includes an image conversion unit that adds data of the determined fine drive waveform or the strong/fine drive waveform to the input original image data, and converts the data into the image data. Item 7. The liquid ejection device according to any one of Items 1 to 6. comprising a plurality of nozzles and a plurality of pressure generating elements associated with the plurality of nozzles;
The counting unit extracts the input original image data for each of the plurality of nozzles for each predetermined period, and performs a dot non-formation period from a position immediately before the start of each predetermined period to the next dot formation pixel, and Counting a dot non-formation period from a dot-formed pixel to a pixel for ejecting liquid, and a dot non-formed period from the dot-formed pixel to a predetermined period end position in the predetermined period,
The fine drive determining unit determines whether to apply the fine drive waveform or the strong/fine drive waveform to each of the plurality of pressure generating elements based on the dot non-formation period counted by the counting unit. decide and
The drive waveform generation unit generates a drive waveform based on the image data including the determined fine drive waveform or the strong and fine drive waveform, and outputs the drive waveform to each of the plurality of pressure generation elements. The liquid ejecting apparatus according to any one of claims 1 to 7, characterized by: a plurality of nozzles, a plurality of pressure generating elements associated with the plurality of nozzles, and a plurality of drive waveform generators associated with the plurality of pressure generating elements,
The counting unit extracts the input original image data for each of the plurality of nozzles for each predetermined period, and performs a dot non-formation period from a position immediately before the start of each predetermined period to the next dot formation pixel, and Counting a dot non-formation period from a dot-formed pixel to a dot-formed pixel and a dot non-formed period from a dot-formed pixel to a predetermined period end position in the predetermined period,
The fine drive determination unit determines whether to apply the fine drive waveform or the strong/fine drive waveform to each of the plurality of pressure generating elements based on the dot non-formation period counted by the counting unit. death,
Each drive waveform generation unit of the plurality of drive waveform generation units generates a drive waveform generated based on the image data including the determined fine drive waveform or the strong and fine drive waveform, and converts the drive waveform to each associated pressure. 8. The liquid ejecting apparatus according to claim 1, outputting to a generating element. a liquid ejection head comprising a nozzle, a pressure chamber that communicates with the nozzle and stores liquid, and a pressure generating element that applies pressure to the liquid in the pressure chamber;
a cap member for capping the nozzles of the liquid ejection head;
a driving waveform generator that outputs a driving waveform to the pressure generating element;
and a control unit that controls the drive waveform generation unit,
The control unit
a start-up blank discharge instructing unit for instructing blank discharge at the start of the discharge operation;
a start-up fine drive determining unit configured to perform fine drive immediately before idle discharge at start-up ,
The start-up fine drive determination unit provides a fine drive waveform for swinging the meniscus of the nozzle or a swing amount larger than the fine drive waveform, according to the time from the start of capping of the liquid ejection head to the instruction to start printing. applying at least one of the strong and weak driving waveforms to the pressure generating element
A liquid ejection device characterized by: 11. The liquid ejecting apparatus according to claim 10, wherein the start-up fine drive determining unit sets the number of fine drive applications according to the time from the start of capping to the instruction to start printing. A drive control method for a liquid ejection head comprising a nozzle, a pressure chamber communicating with the nozzle and containing liquid, and a pressure generating element applying pressure to the liquid in the pressure chamber, comprising:
The input original image data is taken out every predetermined period, and the dot non-forming period from the position immediately before the start of each predetermined period to the dot forming pixel for which liquid is to be ejected next, and from the dot forming pixel to the dot forming pixel in the predetermined period. and counting the dot non-formation period from the dot-formed pixel to the predetermined period end position in the predetermined period;
Based on the counted dot non-formation period, it is determined whether or not to apply to the pressure generating element a fine drive waveform for swinging the meniscus of the nozzle or a strong and fine drive waveform with a larger swing amount than the fine drive waveform. a step;
and generating a drive waveform based on image data including the determined fine drive waveform or the strong and fine drive waveform, and outputting the drive waveform to the pressure generating element. Method.

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