Patent Grant
9931849
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2016-005547, filed Jan. 14, 2016 and Japanese Patent Application No. 2016-234477, filed Dec. 1, 2016. The contents of which are incorporated herein by reference in their entirety.
1. Field of the Invention
The present invention relates to a liquid ejection apparatus, an inkjet system, and a flushing method.
2. Description of the Related Art
An inkjet recording apparatus, which is known as one type of liquid ejection apparatus, is an apparatus configured to eject ink as recording liquid onto a recording medium from nozzles of a recording head to form an image on the recording medium. In this type of apparatus, some nozzles may less frequently eject ink depending on image data. The nozzles with low ejection frequency cause a phenomenon that ink remains in the nozzle part to be thickened and abnormality occurs in ink ejection to cause non-ejection of ink and abnormal landing of ink. In order to avoid such a phenomenon, processing called “flushing” for discharging thickened ink is performed. Flushing is classified into line flushing for performing flushing between printing pages and star flushing for performing flushing during a printing page.
As technology for performing such flushing operation, for example, a technique described in Japanese Unexamined Patent Application Publication No. 2015-058556 (Patent Literature 1) is publicly known. In an inkjet recording apparatus disclosed in Patent Literature 1, flushing operation with ink is controlled on the basis of conveyance speed. This inkjet recording apparatus is configured to change at least one of the ejection amount of ink, the ejection speed of ink, ejection liquid droplets of ink, the amplitude of a waveform of a signal for controlling the ejection of ink, the number of inputs of the waveform, the type of the waveform, or the pulse width of the waveform.
In the case where line flushing or star flushing is performed alone, however, it is difficult to maintain print quality under certain conditions. Line flushing is a method of discharging thickened ink with as small an ink consumption amount as possible, and needs to be performed in as small a region as possible in the conveyance direction. Thus, when an image forming region in the conveyance direction is large, the discharged amount of ink needs to be increased and the thickened ink cannot be discharged for a certain period of time, with the result that abnormal landing of ink occurs at the end of the image forming region.
Star flushing is a method of ejecting ink sparsely in an image forming region irrespective of the image forming region, to discharge thickened ink. Star flushing enables a larger amount of thickened ink to be discharged by increasing the ejection amount of ink. When the ejection amount of ink is increased, however, scumming becomes conspicuous and a printed image becomes dirty. In particular, scumming is more conspicuous on a sheet such as coated paper. If the number of ink droplets necessary to discharge thickened ink is ejected, the printed image deteriorates more depending on the type of sheet.
In other words, line flushing involving ejecting ink between printing pages has a problem in that when an image forming region of a page in the conveyance direction is large, a printed image deteriorates at the end of the image forming region. Star flushing involving ejecting ink in an image forming region has a problem in that when the ejection amount of ink is increased, dirt becomes conspicuous to deteriorate printing quality.
According to one aspect of the present invention, a liquid ejection apparatus includes a plurality of nozzles and a control unit. The plurality of nozzles are configured to eject liquid onto a conveyed object conveyed by a conveyance unit, based on input image data. The control unit is configured to control a number of droplets in first flushing for ejecting the liquid outside a region corresponding to the image data and a number of droplets in second flushing for ejecting the liquid inside the region corresponding to the image data in addition to ejection based on the image data. The control unit is configured to control the number of droplets in the first flushing and the number of droplets in the second flushing based on at least a length of the image data in a direction in which the conveyed object is conveyed.
The accompanying drawings are intended to depict exemplary embodiments of the present invention and should not be interpreted to limit the scope thereof. Identical or similar reference numerals designate identical or similar components throughout the various drawings.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
In describing preferred embodiments illustrated in the drawings, specific terminology may be employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that have the same function, operate in a similar manner, and achieve a similar result.
An embodiment of the present invention will be described in detail below with reference to the drawings.
An embodiment has an object to suppress quality degradation of an image formed by ejecting liquid.
It is an object of an embodiment to secure image quality by appropriately combining line flushing (first flushing) and star flushing (second flushing) on the basis of an image forming region of a recording medium in a conveyance direction thereof and conveyance speed of the recording medium. A description is given of a flushing method in which a flushing operation according to the present invention is used to reduce scumming in an image forming region to a certain level or less and reduce the amount of waste ink to suppress the occurrence of abnormal landing. Embodiments of the present invention are described in detail below with reference to the accompanying drawings.
An image forming apparatus according to the present embodiment is an inkjet recording apparatus for inkjet printing as an example of liquid ejection apparatuses. The inkjet recording apparatus according to the present embodiment includes ejection units of four colors of black (K), cyan (C), magenta (M), and yellow (Y). In the following description, each color of the four-color ejection units is represented by symbol in brackets.
In the present embodiment, a medium is continuous paper wound into a roll (hereinafter referred to as “rolled paper Md”). For example, the rolled paper Md is long paper wound into a roll. Long paper may have perforations formed at predetermined intervals. The present embodiment can be applied to not only rolled paper but also Z-fold paper, which is stacked on paper feeding means while being folded at predetermined locations.
The carry-in unit 10 includes a paper feeding unit 11 and a plurality of carry-in-side conveyance rollers 12, and conveys the rolled paper Md to the image forming unit 40 side. The carry-in unit 10 uses the carry-in-side conveyance rollers 12 to convey the rolled paper Md to the image forming unit 40 side while winding the rolled paper Md around a paper feeding roll in the paper feeding unit 11.
The image forming unit 40 forms an image on the rolled paper Md. The image forming unit 40 ejects liquid or liquid droplets (hereinafter referred to as “ink”) on the rolled paper Md conveyed from the carry-in unit 10 to form an image on the front surface of the rolled paper Md. Details of the image forming unit 40 are described later.
The posttreatment unit 50 executes posttreatment for ejecting and depositing posttreatment liquid in a spot pattern on the front surface of the rolled paper Md having the image formed thereon by the image forming unit 40. The drying unit 30 dries the rolled paper Md post-treated by the posttreatment unit 50 by heating, for example.
The discharge unit 60 discharges the rolled paper Md having the image formed thereon. The discharge unit 60 includes a storage unit 61 and a plurality of discharge-side conveyance rollers 62. The discharge unit 60 stores therein the rolled paper Md such that the rolled paper Md having the image formed thereon is wound around a storage roll in the storage unit 61 using the discharge-side conveyance rollers 62. Thus, the carry-in unit 10 and the discharge unit 60 function as conveyance units configured to convey the rolled paper Md, which is a conveyed object.
If a large pressure acts on the rolled paper Md when the rolled paper Md is wound around the storage roll in the storage unit 61, another drying unit configured to further dry the rolled paper Md immediately before the rolled paper Md is wound may be provided in order to prevent another image from being transferred on the back surface of the rolled paper Md. As illustrated in
Specifically, the image forming apparatus 100 is configured such that an image is formed on the front surface of the rolled paper Md carried in by the carry-in unit 10 and the posttreatment unit 50 executes posttreatment on the rolled paper Md having the image formed thereon. The drying unit 30 dries the post-treated rolled paper Md, and the discharge unit 60 winds the rolled paper Md, so that the rolled paper Md is ready to be discharged from the image forming apparatus 100.
As illustrated in
A first ejection head 40K-1, a second ejection head 40K-2, a third ejection head 40K-3, and a fourth ejection head 40K-4 are arranged in the ejection head 40K for black (K) in a staggered pattern in the direction orthogonal to the conveyance direction Xm of the rolled paper Md.
The staggered arrangement of the first ejection head 40K-1, the second ejection head 40K-2, the third ejection head 40K-3, and the fourth ejection head 40K-4 enables the image forming unit 40 to form an image in the entire image forming region in the width direction, that is, in the direction orthogonal to the conveyance direction Xm of the rolled paper Md.
The respective ejection heads for K, C, M, and Y have the same configuration, and hence the ejection head 40K for black (K) is taken as an example to omit the description of the ejection heads 40C, 40M, and 40Y.
For example, the diaphragm 42 is formed of a metal plate processed by nickel electroforming (such as electroforming and electrocasting). The diaphragm 42 may be a metal plate formed of a material other than nickel or a member obtained by bonding metal and a resin plate. The diaphragm 42 is bonded onto the bottom surface of the flow path plate 41, that is, in the inward direction of the ejection head 40K. The diaphragm 42 is applied with force from the pressure generation unit to be deformed.
The nozzle plate 43 is formed of, for example, a monocrystalline silicon substrate. The nozzle plate 43 is processed by anisotropic etching similarly to the flow path plate 41. The nozzle plate 43 may be obtained by forming a water-repellent layer on an external surface configured by a metal member through a necessary layer. The nozzle plate 43 is bonded onto the top surface of the flow path plate 41, that is, in the outward direction of the ejection head 40K.
The nozzle plate 43 includes a plurality of nozzles 40N configured to eject ink droplets. Specifically, the nozzles 40N having a diameter of 10 μm to 30 μm are formed in the nozzle plate 43 correspondingly to each liquid chamber 40F.
The frame member 44 is formed of a thermosetting resin such as an epoxy resin or polyphenylenesulfide (PPS). Another resin having similar characteristics may be used for the material of the frame member 44. The frame member 44 includes a housing portion configured to store the pressure generation unit therein, a recessed portion serving as a common liquid chamber 40CR, and an ink supply port 40IN configured to supply ink to the common liquid chamber 40CR from outside the ejection head. The frame member 44 is processed by injection molding. The frame member 44 holds a peripheral part of the diaphragm 42.
The pressure generation unit includes a piezoelectric element 45P, a base substrate 45B that bonds and fixes the piezoelectric element 45P, and a pillar portion disposed in a gap between adjacent piezoelectric elements 45P. The pressure generation unit is connected with a flexible printed circuit (FPC) cable 45C that connects the piezoelectric element 45P to a drive circuit. As the piezoelectric element 45P, for example, a laminated piezoelectric element (PZT) obtained by alternately laminating piezoelectric materials and internal electrodes is used. The internal electrode includes a plurality of individual electrodes and a plurality of common electrodes. The individual electrodes and the common electrodes are alternately connected to the end surface of the piezoelectric element.
The piezoelectric direction of the piezoelectric element 45P is, for example, a d33 direction in which the length of a crystalline body of the piezoelectric element 45P is increased when an electric field parallel to the polarization direction is applied to the crystalline body. The pressure generation unit pressurizes or depressurizes ink inside the liquid chamber 40F in the d33 direction of the piezoelectric element 45P using the piezoelectric effect. The piezoelectric direction of the piezoelectric element 45P may be set such that ink inside the liquid chamber 40F is pressurized or depressurized in a d31 direction. The pressure generation unit may have piezoelectric elements arranged in a row for each nozzle 40N serving as an ink ejection port.
The pillar portion may be formed at the same time as the piezoelectric element 45P serving as a piezoelectric element member by dividing the piezoelectric element 45P. Specifically, the ejection head 40K may use the piezoelectric element member as the pillar portion by applying no voltage to the piezoelectric element 45P.
Pull ejection or push ejection, which is an operation of the ejection head 40K for ejecting ink from the nozzles 40N, is specifically described.
A print control unit 72Cc in a printer controller 72c illustrated in
Next, the print control unit 72Cc increases the voltage applied to the piezoelectric element 45P to elongate the piezoelectric element 45P in the lamination direction thereof so that the diaphragm 42 is deformed in the direction of the nozzles 40N due to the elongation of the piezoelectric element 45P. The deformed diaphragm 42 reduces the volume of the liquid chamber 40F. Accordingly, the ink in the liquid chamber 40F is applied with pressure, and the ink is ejected from the nozzles 40N due to the pressurization of the ink.
Thereafter, the print control unit 72Cc executes a restore operation for returning the voltage applied to the piezoelectric element 45P to the reference potential so that the diaphragm 42 is returned to its original position. In the ejection head 40K, the liquid chamber 40F is depressurized due to the expansion of the liquid chamber 40F, and the liquid chamber 40F is filled with ink from the common liquid chamber 40CR. Subsequently, the vibration of meniscus in the nozzles 40N attenuates, and then the operation shifts to the next ink ejection operation. The ejection operation is repeated in this manner.
The method of driving the ejection head 40K is not limited to the pull ejection or push ejection. Pull ejection or push ejection may also be performed by controlling a voltage applied to the piezoelectric element 45P (hereinafter referred to as “drive waveform”).
The print control unit 72Cc can control the force or pressure of the piezoelectric element 45P to be applied to ink, thereby controlling flushing operation and fine driving for discharging thickened ink. Flushing is classified into preprinting flushing performed immediately before printing, line flushing in which ink is ejected on the rolled paper Md all at once upon the finish of each page during printing, and star flushing in which ink is ejected in an image forming region in an unnoticeable manner.
“Page” as used in the present embodiment indicates a unit of a group of image data. For example, “page” is a unit that is cut by processing after printing.
Specifically, line flushing is processing of ejecting ink at a location not to be used for a user as a printed object. For another example, line flushing is processing of ejecting ink in the range outside input image data. In contrast, star flushing is processing of ejecting ink in an unnoticeable manner in addition to ejecting on the basis of image data within the range corresponding to input image data.
Fine driving is, for example, an operation of applying a pressure to the liquid chamber 40F by the piezoelectric element 45P to vibrate ink inside the liquid chamber 40F, thereby preventing the viscosity of ink on the surface of the meniscus from being increased due to the evaporation and drying of the ink from the surface of the meniscus. The fine driving is controlled by the pulse amplitude, period, and width and the number of pulses. The print control unit 72Cc stirs ink in such a range that the ink is not ejected from the ejection head 40K. For the fine driving, an upper limit may be set for the pulse amplitude, period, or width, the number of pulses, or the number of pulses per unit time.
The pressure generation unit according to the present embodiment is not limited to the piezoelectric element 45P. Publicly known technology, such as a thermal method or an electrostatic method, can be employed. The thermal method is a method in which a heat generating resistor is used to heat ink in the liquid chamber 40F and generate air bubbles. The electrostatic method is a method in which a diaphragm and an electrode are arranged on wall surfaces of the liquid chamber 40F so as to be opposed to each other, and the diaphragm is deformed by electrostatic force generated between the diaphragm and the electrode.
The image forming apparatus 100 according to the present embodiment uses the ejection heads 40K, 40C, 40M, and 40Y described above to perform the operation of conveying the rolled paper Md, thereby being capable of forming a full-color image or a monochrome image in the entire image forming region.
As illustrated in
As illustrated in
The higher-level device 71 performs RIP processing as described above on the basis of print job data, such as job data and print data, output from a host device.
Specifically, the higher-level device 71 generates image data for printing (hereinafter referred to as “print image data”) such as bitmap data corresponding to each color of CMYK on the basis of the print job data. The print image data may include data related to the ejection of posttreatment liquid to be ejected by the posttreatment unit 50 (hereinafter referred to as “posttreatment-related image data”).
The higher-level device 71 generates, on the basis of the print job data, information from the host device, and others, data for controlling the print operation (hereinafter referred to as “control information data”). The control information data includes data related to print conditions such as print form, print type, paper feeding/ejection information, print side order, print sheet size, data size of print image data, resolution, paper type information, gradation, color information, and number of pages to be printed. The control information data may further include data related to the ejection of posttreatment liquid to be ejected by the posttreatment unit 50 (hereinafter referred to as “posttreatment-related control data”).
The CPU 71a controls the overall operation of the higher-level device 71. The CPU 71a controls the operation of the higher-level device 71 using a computer program stored in the ROM 71b or the HDD 71d. The ROM 71b, the RAM 71c, and the HDD 71d store data or computer programs therein. A control program for controlling the CPU 71a is stored in the ROM 71b or the HDD 71d. The RAM 71c is used as a work memory configured to expand the computer program used by the CPU 71a or intermediate data.
The external I/F 71e is used for communication between the image forming apparatus 100 and an external device such as the host device. For example, the external I/F 71e is used for communication compatible with the Transmission Control Protocol/Internet Protocol (TCP/IP). The control information I/F 71f is used for communication of the control information data. For example, the control information I/F 71f is Peripheral Component Interconnect Bus Express (PCI Express). The control information I/F 71f may be PCI or Industry Standard Architecture (ISA).
The image data I/F 71g is used for communication of the print image data. For example, the image data I/F 71g is PCI Express. The image data I/F 71g may be PCI or ISA. In the present embodiment, the image data I/F 71g has a plurality of channels corresponding to respective colors of print image data.
The higher-level device 71 receives print job data transmitted from an external device such as the host device with the external I/F 71e under control of the CPU 71a, and stores the print job data in the HDD 71d. The CPU 71a generates bitmap data for each color of CMYK on the basis of the stored print job data, and stores the generated bitmap data for each color in the RAM 71c. For example, the higher-level device 71 performs, as RIP processing, processing of rendering a page description language (PDL) to generate bitmap data for each color of CMYK and writing the bitmap data on the RAM 71c.
Specifically, the higher-level device 71 executes the processing of:
The printer device 72 sets the conditions for flushing operation on the basis of the types of recording medium and ink, the recording resolution, the conveyance speed, the image sheet length, or temperature and humidity. In regard to the method of setting the conditions for the flushing operation, for example, a condition table as illustrated in
The printer device 72 is configured such that the conditions for flushing operation are extracted on the basis of the types of recording medium and ink, the recording resolution, the conveyance speed, the image sheet length, or the temperature and humidity and configured such that a condition table as illustrated in
The image formation period for one printing may be extremely long depending on users. Thus, constrains may be provided for the flushing operation, and the flushing operation may be automatically set within this range. The flushing operation as used herein means flushing with a combination of star flushing and line flushing. Flushing conditions mean control conditions for the flushing operation.
The printer controller 72c includes a CPU 72Cp and a print control unit 72Cc, and the CPU 72Cp and the print control unit 72Cc are connected to each other via a bus 72Cb so as to transmit and receive information therebetween. The bus 72Cb is connected to the control line 70LC via a communication I/F. The CPU 72Cp controls the overall operation of the printer device 72 using a control program stored in the ROM in the printer device 72.
The print control unit 72Cc transmits and receives information such as commands, parameters, and data to and from the printer engine 72E on the basis of the control information data transmitted from the higher-level device 71. The print control unit 72Cc controls the printer engine 72E by transmitting and receiving information to and from the printer engine 72E.
The printer controller 72c controls the printer engine 72E. The printer controller 72c transmits and receives control information data to and from the higher-level device 71 via the control line 70LC. The printer controller 72c transmits and receives control information data to and from the printer engine 72E described later via a control line 72LC.
The printer controller 72c writes printing conditions included in the transmitted/received control information data in a register of the print control unit 72Cc, and stores the printing conditions in the register. The printer controller 72c controls the printer engine 72E on the basis of the control information data, and executes printing in accordance with the print job data and the control information data.
The printer engine 72E includes a conveyance control unit 72Ec, an image output unit 72Ei, a posttreatment liquid output unit 72Ep, a drying-after-posttreatment control unit 72pb, and a plurality of data management units 72EC, 72EM, 72EY, 72EK, and 72EP. The conveyance control unit 72Ec controls conveyance speed of the rolled paper Md. The image output unit 72Ei receives print image data from the data management units 72EC, 72EM, 72EY, and 72EK, and performs image formation output for forming an image on the rolled paper Md.
The printer engine 72E converts bitmap data input from the higher-level device 71 into less-valued data corresponding to the image formation output on the basis of an instruction from the printer controller 72c, and divides the resultant data for each of the ejection head 40C, the ejection head 40M, the ejection head 40Y, and the ejection head 40K. For example, the printer engine 72E converts input 256-bit bitmap data into quadrature values of large droplet, medium droplet, small droplet, and fine driving, and divides the resultant data into data for the corresponding ejection head 40C, ejection head 40M, ejection head 40Y, and ejection head 40K.
The printer engine 72E is connected with a plurality of data lines TOLD-Y, TOLD-C, TOLD-M, TOLD-K, and TOLD-P, and receives print image data from the higher-level device 71. The posttreatment liquid output unit 72Ep receives posttreatment-related data from the data management unit 72EP, and performs posttreatment.
The printer engine 72E includes, as indicated by the broken line, a pretreatment liquid application control unit 72Ef1, a drying-after-pretreatment control unit 72Ef2, or a drying-before-winding control unit 72Ef3, for example. The pretreatment liquid application control unit 72Ef1 and the drying-after-pretreatment control unit 72Ef2 are necessary when a pretreatment liquid application unit and an after-pretreatment drying unit are placed between the carry-in unit 10 and the image forming unit 40 or when a before-winding drying unit configured to dry the rolled paper Md immediately before the rolled paper Md is wound by the discharge unit 60 is placed.
With the configuration described above, the printer engine 72E has the functions of:
Next, the flushing operation according to the present embodiment is described in detail with reference to the accompanying drawings.
Control of the flushing operation can be automatically set from various kinds of printing conditions as described later, but the flushing operation can be manually selected as well. For the manual selection, an access is made to the printer controller 72c from an input device. In the following description related to
When flushing operation is automatically controlled or when the range that can be manually selected is limited, the table illustrated in
For example, when the recording medium in the image forming apparatus 100 is plain paper and ink that is less volatile is used, a mask table Tn2 illustrated in
In this case, the respective mask tables are combined to obtain a mask table Tn2+T1n as illustrated in
In
In contrast, even when the selectable flushing operations are presented, there may be a plurality of options as illustrated in
In the case of discharging thickened ink when ink that is more volatile is used in the image forming apparatus 100, the thickened ink remains to cause abnormal landing of ink at the end of the image forming region unless line flushing is performed with a larger number of droplets. Similarly to line flushing, star flushing also needs to be performed with a larger number of droplets in order to reduce the residual of thickened ink.
In contrast, in the case of discharging thickened ink when ink that is less volatile is used in the image forming apparatus 100, ink is wastefully consumed unless line flushing is performed with a smaller number of droplets. Star flushing needs to be performed with a smaller number of droplets so that scumming is less conspicuous on coated paper.
If star flushing has an output of droplets smaller than small droplets or star flushing has an output of droplets larger than large droplets, the printer engine 72E adds data on values corresponding to star flushing and line flushing to obtain 6-value data. The number of values is an example, and is not limited to four and six.
Thus, after the selectable flushing operations are determined, a flushing operation that can reduce the waste ink amount most among the selectable flushing operations is fed back to execute a job. Control of feeding back temperature and humidity conditions measured at S1113 may be replaced with adjustment of a temperature/humidity mask table to a selected mask to select flushing conditions.
The printer controller 72c controls the piezoelectric element 45P to control the ejection of ink, the flushing, and the fine driving. The piezoelectric element 45P is controlled to be driven by a drive waveform as a control signal.
The operation is described for each of four values, that is, large droplet ejection of ejecting ink in a large amount from the ejection head 40K, medium droplet ejection of ejecting ink in an amount smaller than of large droplets and larger than of small droplets, small droplet ejection of ejecting ink in a small amount, and fine driving. Specifically, in the present embodiment, for example, the drive waveform (a) is masked to form four kinds of waveforms for large droplets, medium droplets, small droplets, and fine driving. In the fine driving, ink is not ejected because the fine driving is the operation of stirring ink in the range where ink is not ejected from the ejection head 40K as described above.
As illustrated at (f) in
The amplitude value of the waveform input to the piezoelectric element 45P during the fine driving (fine driving peak value) has conditions suitable for the non-ejection period. For example, when the non-ejection period is long, the amplitude value of the waveform input to the piezoelectric element 45P is reduced in order to reduce the amount of flushing droplets. In contrast, when the non-ejection period is shorter, the amplitude value of the waveform input to the piezoelectric element 45P can be increased to reduce the amount of flushing droplets.
For example, when star flushing is selected as main flushing means, ink is ejected during printing. In this case, the non-ejection period is shorter than when star flushing is not performed. It is therefore sufficient if the amplitude value of the waveform input to the piezoelectric element 45P is reduced to execute fine driving.
In contrast, when line flushing is selected as main flushing means, the non-ejection period is longer than the case of star flushing. It is therefore desired to increase the amplitude value of the waveform input to the piezoelectric element 45P to execute fine driving. When the non-ejection period is equal to or more than a given period of time, control may be performed to increase the amplitude value of the waveform input to the piezoelectric element 45P only immediately before the ejection to execute fine driving.
As the suitable conditions, for example, the relation between the amplitude value of the waveform input to the piezoelectric element 45P in the fine driving and the non-ejection period may be measured in advance by a real machine and converted into a table, and the printer controller 72c may select a suitable amplitude value from the table on the basis of the non-ejection period. For another example, when the relation between the amplitude value of the waveform input to the piezoelectric element 45P in the fine driving and the non-ejection period is definite, the printer controller 72c may select suitable conditions on the basis of the relation.
The printer controller 72c may calculate the amplitude value of the waveform input to the piezoelectric element 45P on the basis of the non-ejection period using a mathematical expression serving as a characteristic graph indicated by a table of the relation between the amplitude value of the waveform input to the piezoelectric element 45P in the fine driving and the non-ejection period, which is a value measured in advance by an actual machine. A plurality of mathematical expressions may be used.
The ejection speed of ink is controlled by the pulse width of the waveform illustrated at (e) in
For example, the number of ejection droplets of ink is controlled by the input number of waveforms illustrated at (e) in
For example, the pressure to be applied to ink by the fine driving is controlled by the amplitude of the waveform illustrated at (f) in
A fine driving cycle, which is a cycle during which the fine driving is executed, is controlled by a cycle during which the first use waveform P1 is input. Examples of the control of the fine driving cycle include setting the cycle to 20 kHz from 40 kHz. The control of the fine driving cycle is not limited to the control by the cycle during which the first use waveform P1 is input, and the fine driving cycle may be controlled by another means. The cycle may be controlled by the count of the fine driving per unit time. For example, the count of the fine driving is controlled by the input number of waveforms illustrated at (f) in
The image forming apparatus 100 can control the flushing operation suited to the conveyance speed, thus discharging thickened ink and reducing the phenomenon of non-ejection caused by thickened ink or abnormal landing of ink.
It is desired that the flushing operation be controlled by the control of ejection speed among the control of ejection amount of ink, the control of ejection speed, and the control of the number of ejection droplets. For example, in the case of line flushing, the force of discharging ink in the flushing operation can be enhanced by increasing the ejection speed, and hence ink with high viscosity can be discharged.
In the case of a line head, flushing is performed such that the ejection amount of ink becomes a given amount or the range where ink is ejected falls within a given range, and it is therefore desired to perform flushing with the ejection amount of droplets based on the conveyance speed. Flushing, which is performed with the amount of droplets based on the conveyance speed, has sufficient flushing strength and can reduce the phenomenon of non-ejection caused by thickened ink or abnormal landing of ink.
Next, the flow of control of the flushing operation executed by the control unit 70 according to the present embodiment is described with reference to
Next, the printer controller 72c sets data on a recording medium to be used, that is, the rolled paper Md (S1102). The data on the rolled paper Md is information on the thickness of the rolled paper Md, the type of recording medium, such as plain paper, inkjet paper, and ordinary coated paper, or physical properties or characteristics of the recording medium. Examples of the physical properties of the recording medium include the size, the medium material physical properties, and the thickness and weight of the medium.
When the setting of the print data and the data on the rolled paper Md is finished, the printer controller 72c sets the type of ink to be used (S1103), and sets the recording resolution (S1104). The printer controller 72c automatically selects a print waveform on the basis of the recording resolution, and determines the ejection amount of recording liquid (ink) per droplet on the basis of the print waveform. When the setting of the recording resolution has already been included in the image data received at S1101, the printer controller 72c sets the print waveform on the basis of the image data received at S1101.
Next, the printer controller 72c sets a tone curve and an ink limit (S1105). The printer controller 72c sets conveyance speed (S1106), and next sets the image sheet length, that is, information on recording in an image forming region in the conveyance direction Xm (image forming region recording information) (S1107). The image sheet length can be freely set irrespective of the image size. The information set at S1102 to S1107 is transmitted to the higher-level device 71 from the printer controller 72c.
The higher-level device 71 converts the print data into image data on the basis of the conditions set at S1102 to S1107, and transfers the converted image data to the printer device 72 (S1108). The printer controller 72c calculates a non-ejection period, which is the period during which ink is not ejected from the nozzles 40N, in accordance with the image data, the conveyance speed, and the image sheet length received from the higher-level device 71 (S1109). In this case, the printer device 72 calculates a non-ejection period of a nozzle 40N that is the longest non-ejection period among non-ejection periods of the nozzles 40N.
Next, the printer controller 72c selects a combination of the flushing means on the basis of the information set by the user. In other words, the printer controller 72c can receive an input of the number of star flushing droplets and an input of the number of line flushing droplets. The printer controller 72c can further receive setting of automatic selection of the flushing conditions. The printer controller 72c generates information on the conditions based on the selection by the user (S1110).
The non-ejection period in the present embodiment indicates the period during which the image forming unit 40 does not perform flushing or eject ink. The image forming apparatus 100 forms an image on the rolled paper Md. In this case, the printer controller 72c determines a non-printing region where no printing in accordance with the generated image data and the image sheet length, and divides the length of the non-printing region in the conveyance direction Xm by the conveyance speed to calculate the non-ejection period.
The printer controller 72c calculates the non-ejection period on the basis of the conveyance speed, the image sheet length, and the image data as described above. The printer controller 72c may calculate an interval between places where line flushing can be performed on the basis of the image sheet length, and may divide the interval by the conveyance speed to calculate the non-ejection period. For example, some image forming apparatuses 100 may be frequently input with image data for which nozzles 40N that are never used to eject ink during printing are set. In such apparatuses, by determining the non-ejection period on the basis of the interval between places where line flushing can be performed, the non-ejection period can be determined more easily and reliably.
The printer controller 72c selects drying conditions for the image forming apparatus 100 (S1111). Next, the conveyance control unit 72Ec starts to carry in the rolled paper Md (S1112).
The printer device 72 includes a temperature sensor and a humidity sensor configured to measure environmental temperature and humidity respectively in the vicinity of the ejection head. The printer controller 72c controls the temperature sensor to measure environmental temperature around the ejection head, and controls the humidity sensor to measure humidity around the ejection head (S1113).
Next, the printer controller 72c selects a mask table for each of non-ejection time and printing condition on the basis of the information set at S1101 to S1113 (S1114). In this case, the printer controller 72c determines the non-ejection period [second] as described above on the basis of the input image data and the conveyance speed of the rolled paper Md. The printer controller 72c specifies a mask table Txy on the basis of the non-ejection period and the printing conditions (such as the type and thickness of the recording medium, the drying unit 30, the type of ink, and the recording resolution). When the fixed number of droplets is manually input by a user at S1110, the processing from S1114 to S1116 is not executed, and an image is formed with the input number of flushing droplets without any further processing.
Mask tables T11 to Tnn each have a table with ◯ and x as illustrated on the left side in
For example, a mask table Tn2 illustrated in
When the table illustrated in
Next, the printer controller 72c selects the number of flushing droplets from printing conditions on the basis of the flushing operation information selected at S1110 (S1115).
The printer controller 72c receives the temperature information and the humidity information to set each number of flushing droplets in real time during printing, and reflects the set numbers of flushing droplets to a print job executed at S1117 (S1116).
Next, the printer controller 72c transmits the determined number of line flushing droplets and the determined number of star flushing droplets to the printer engine 72E. The printer engine 72E arranges data for star flushing such that star flushing is irregularly formed on an image of bitmap data received from the higher-level device 71, and arranges data for line flushing. Thereafter, the image output unit 72Ei outputs data obtained by combining the data for star flushing and the data for line flushing (S1117).
The printer controller 72c controls the sensors to measure temperature information and humidity information when the print job is executed. The printer controller 72c executes control of feeding the measurement result back to the processing executed at S1113. The printer controller 72c discharges the formed image (S1118), and finishes the job. In the present processing, the printer controller 72c need not execute real-time detection with masking the real-time detection when it takes processing time to change the flushing conditions in real time at S1113.
A larger amplitude of the waveform input to the piezoelectric element 45P results in a larger stirring effect of ink obtained by fine driving and can reduce the amount of star flushing. To increase the amount of star flushing, it is therefore sufficient if the amplitude of the waveform input to the piezoelectric element 45P is reduced, thereby reducing the stirring effect of ink obtained by fine driving.
However, when the amplitude of the waveform input to the piezoelectric element 45P is increased to execute large fine driving, the amount of ink to be brought into contact with the air is increased, and as a result, the viscosity of ink is increased. Line flushing can suppress the increase in viscosity of ink. Thus, when the number of line flushing droplets is set such that ink with increased viscosity can be ejected, the printer controller 72c can perform control of increasing the fine driving and reduce the number of star flushing droplets.
Thus, in the processing at S1115, the printer controller 72c may select each number of flushing droplets and the amplitude of fine driving from the printing conditions on the basis of the information on the flushing operation selected at S1110. In this case, the printer controller 72c selects the amplitude of the waveform input to the piezoelectric element 45P in order to perform fine driving on the basis of the number of line flushing droplets indicated by the mask table selected at S1114.
In the processing at S1116, the printer controller 72c may set each number of flushing droplets and the amplitude of fine driving in real time even during printing, and may reflect the set information to a print job executed at S1117. The processing thereafter is the same as in the steps in the flow described above with reference to
The image forming apparatus 100 according to the present embodiment may use production printing as a printing system. Production printing involves efficient job management, printing data management, and others. Production printing is a manufacturing system capable of performing image formation such as printing or printing characters on a massive amount of media or printed objects in a short period of time. Specifically, the image forming apparatus 100 according to the present embodiment performs RIP processing for controlling printing operation such as bitmap data and printing processing based on the bitmap data controlled by the RIP processing with different devices.
The control unit 70 according to the present embodiment builds a workflow system configured to manage the creation of print data and the distribution of printed objects. Specifically, the control unit 70 in the image forming apparatus 100 according to the present embodiment can separate a device configured to perform RIP processing requiring processing time and a device configured to perform printing processing from each other to increase the speed of printing. The processing executed by the printer controller 72c in the present invention may be executed by the higher-level device 71. In this case, the present invention may be embodied as an inkjet system including the higher-level device 71 as a control device and the printer device 72.
The image forming apparatus 100 according to the present invention exemplifies an inkjet recording apparatus as a liquid ejection apparatus in the present embodiment. The inkjet recording apparatus is an apparatus configured to drive a liquid ejection head to eject liquid. The liquid ejection apparatus is an apparatus including a liquid ejection head or a liquid ejection unit and configured to drive the liquid ejection head to eject liquid. The liquid ejection apparatus includes not only an apparatus that is capable of ejecting liquid on an object to which liquid can adhere but also an apparatus configured to eject liquid in the air or liquid.
The liquid ejection apparatus in the present embodiment is a recording apparatus (printer) configured to eject liquid from liquid ejection heads as in the image forming apparatus 100 to form an image on a recording medium, but is not limited to the one configured such that a significant image such as characters and figures is visualized by ejected liquid. Examples of the liquid ejection apparatus include a liquid ejection apparatus configured to form patterns that are meaningless themselves and a liquid ejection apparatus configured to form three-dimensional images.
The above-mentioned objects to which liquid can adhere means objects to which liquid can adhere at least temporarily, such as an object to which liquid adheres for fastness and an object to which liquid adheres for permeation. Specific examples thereof include recording media such as sheets, recording paper, recording sheets, films, and cloths, electronic components such as electronic substrates and piezoelectric elements (piezoelectric members), and media such as granular layers (powder layers), organ models, and test cells, and all kinds of objects to which liquid adhere are encompassed unless otherwise limited. The material to which liquid can adhere may be any material to which liquid can adhere at least temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramics.
According to an embodiment, the quality degradation of an image formed by ejecting liquid can be suppressed.
The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, at least one element of different illustrative and exemplary embodiments herein may be combined with each other or substituted for each other within the scope of this disclosure and appended claims. Further, features of components of the embodiments, such as the number, the position, and the shape are not limited the embodiments and thus may be preferably set. It is therefore to be understood that within the scope of the appended claims, the disclosure of the present invention may be practiced otherwise than as specifically described herein.
The method steps, processes, or operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance or clearly identified through the context. It is also to be understood that additional or alternative steps may be employed.
Further, any of the above-described apparatus, devices or units can be implemented as a hardware apparatus, such as a special-purpose circuit or device, or as a hardware/software combination, such as a processor executing a software program.
Further, as described above, any one of the above-described and other methods of the present invention may be embodied in the form of a computer program stored in any kind of storage medium. Examples of storage mediums include, but are not limited to, flexible disk, hard disk, optical discs, magneto-optical discs, magnetic tapes, nonvolatile memory, semiconductor memory, read-only-memory (ROM), etc.
Alternatively, any one of the above-described and other methods of the present invention may be implemented by an application specific integrated circuit (ASIC), a digital signal processor (DSP) or a field programmable gate array (FPGA), prepared by interconnecting an appropriate network of conventional component circuits or by a combination thereof with one or more conventional general purpose microprocessors or signal processors programmed accordingly.
Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), digital signal processor (DSP), field programmable gate array (FPGA) and conventional circuit components arranged to perform the recited functions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-005547 | Jan 2016 | JP | national |
| 2016-234477 | Dec 2016 | JP | national |
| Number | Name | Date | Kind |
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| 20100245919 | Kanzaki | Sep 2010 | A1 |
| 20120075377 | Kyotani | Mar 2012 | A1 |
| 20130063507 | Sasaki | Mar 2013 | A1 |
| 20150116400 | Sasaki | Apr 2015 | A1 |
| Number | Date | Country |
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| 2015-058556 | Mar 2015 | JP |
| 2015-058557 | Mar 2015 | JP |
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| Extended European Search Report for Corresponding European Application No. 17151185.0 dated Sep. 27, 2017. |
| Number | Date | Country | |
|---|---|---|---|
| 20170203570 A1 | Jul 2017 | US |
