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    • 专利摘要:
    METHOD FOR EJECTING LIQUID DROPS. A liquid jet includes a fundamental period of jet rupture. An impression period is defined as N times the fundamental jet break period, where N is an integer greater than 1. Input image data is provided, presenting M levels per input image pixel, including a non-printing level where M is an integer and 2 (less than) M (less than or equal) N + 1. A charging device waveform, independent of the input image data, is repeated during printing periods and includes both print and non-print drop voltage states. A drop-forming device waveform, with a period equal to the printing period, is selected in response to the input image data to form, from the jet drops, presenting a volume corresponding to a level of input image pixel. The devices are synchronized to produce a charge to mass of print droplet mass and a charge to mass of non-print droplet dropping from the jet.
    公开号:BR112014031129B1
    申请号:R112014031129-3
    申请日:2013-06-11
    公开日:2021-01-26
    发明作者:Hrishikesh V. Panchawagh；Michael A. Marcus；Shashishekar P. Adiga
    申请人:Eastman Kodak Company；
    IPC主号:
    专利说明:

    FIELD OF THE INVENTION
    [001] This invention relates in general to the field of digitally controlled printing systems and, in particular to continuous printing systems in which a liquid flow divides into drops, some of which are deflected. BACKGROUND OF THE INVENTION
    [002] Inkjet printing has become recognized as a prominent competitor in the area of digitally controlled electronic printing, due, for example, to its non-impact, low noise characteristics, its use on plain paper and the fact that avoid toner transfer and fixing. Inkjet printing mechanisms can be categorized by technology as on-demand drip inkjet (DOD) or continuous inkjet (CIJ).
    [003] The first technology, inkjet printing by “iqVgjcogpVq uqd fgocpfc”, rtqxê iqVcu fg VkpVc swg korceVco uqdtg woc recording surface using a pressurizing actuator, for example, a thermal, piezoelectric or electrostatic actuator. A commonly practiced on-demand drip technology uses thermal actuation to eject ink droplets from a nozzle. A heater, located at or near the nozzle, heats the ink sufficiently to boil, forming a vapor bubble that creates enough internal pressure to eject a drop of ink. This form of inkjet is commonly called “jcVq fg VkpVc Vfitoieq * VIJ +”
    [004] The second technology commonly referred to as jcVq fg VkpVc printing “eqpVipwq” (EIJ). wuc woc fopVg fg VkpVc rtguuwtkzcfc rcta produce a continuous liquid jet ink flow, forcing the ink under pressure through a nozzle. The flow of ink is disturbed in such a way that the liquid jet is divided into drops of ink in a predictable manner. Printing occurs through the selective deflection of any of the droplets and captures drops of ink that are not intended to reach the media. Various approaches to selectively deflect droplets have been developed, including electrostatic deflection, air deflection and thermal deflection mechanisms.
    [005] In a first electrostatic deflection approach based on CIJ, the liquid jet flow is disturbed in some way, causing it to divide into uniformly sized droplets at a nominally constant distance, the extent of rupture, from the nozzle . A charge electrode structure is positioned at the point of constant rupture, in order to induce an amount of electrical charge in the drop, depending on the data, at the moment of rupture. The charged droplets are then directed through a region of fixed electrostatic field, causing each droplet to be deflected proportionally to its charge. The load levels established at the breaking point thus cause the drops to move to a specific location on a recording medium or to a trough for collection and recirculation. This approach is disclosed by R. Sweet in Patent W0U0 "Pq0" 507; 80497. "Eqpegfkfc" go "49" fg "Lwnjq" fg "3; 93." Uyggv "Ò497" c "ugiwkt" Q "crctgnjq" EKL " fkxwnicfq "rqt" Uyggv "Ò497" single-jet eqpukuvka, that is, a single-drop generation liquid chamber and a single nozzle structure. A disclosure of a CIJ printhead version using this approach was also done by Sweet et al., US Patent No. 3,373,439 eqpegfkfc go 34 fg Oct> q fg 1%: UyggV Ò659 c ugiwkt. communicates with a row (an arrangement) of drop-emitting nozzles, each with its own charge electrode This approach requires that each nozzle has its own charge electrode, with each of the individual electrodes being provided with an electrical waveform which depends on the image data to be printed. This requirement for individually addressable charge electrodes places limits on the space fundamental nozzle and therefore in the resolution of the printing system.
    [006] In conventional CIJ printers, there is a variation in the charge on the print droplets, caused by electrostatic fields dependent on image data, from neighboring charged droplets, in the vicinity of the jet rupture and electrostatic fields from adjacent electrodes associated with neighboring jets. These input-dependent image variations are referred to as electrostatic interference. Katerberg described a method for reducing interference interactions from neighboring charged droplets by providing a droplet guard between adjacent printing droplets for the same jet, in U.S. Patent No. 4,613,871. However, electrostatic interference from neighboring electrodes limits the minimum spacing between adjacent electrodes and therefore the resolution of the printed image. So, the requirement for individually addressable charge electrodes on traditional electrostatic CIJ printers places limits on fundamental nozzle spacing and therefore on the resolution of the printing system. A number of alternative methods have been disclosed to overcome the limitation on nozzle spacing by using an individually addressable nozzle array in a nozzle array and one or more common charge electrodes at constant potentials. This is achieved by controlling the extent of jet rupture in the method described by Vago et al., In U.S. Patent No. 6,273,559 and by B. Barbet and P. Henon in U.S. Patent No. 7,192,121. T. Yamada described a printing method using a constant potential charge electrode, based on the drop volume, in U.S. Patent No. 4,068,241. B. Barbet in U.S. Patent No. 7,712,879 disclosed an electrostatic charging and deflection mechanism based on the extent of rupture and droplet size using charge electrodes common to constant potentials.
    [007] A well-known problem with any type of inkjet printer, be it drip on demand or continuous inkjet, relates to the accuracy of point positioning. As is well known in the inkjet printing technique, one or more drops are generally desired to be placed within pixel areas (pixels) on the receiver, the pixel areas corresponding, for example, to pixels of information comprising digital images . In general, these pixel areas comprise a general or hypothetical arrangement of squares or rectangles on the receiver, and impression drops are intended to be placed at desired locations within each pixel, for example, in the center of each pixel area, for layouts. of simple printing or, alternatively, in multiple precise locations within each of the pixel areas to obtain halftones. If the drop placement is incorrect and / or its placement cannot be controlled to obtain the desired placement within each pixel area, image artifacts can occur, particularly if similar types of deviations from the desired locations are repeated in adjacent pixel areas .
    [008] High-speed, high-quality inkjet printing requires carefully spaced drops, of relatively small volumes, to be directed precisely to the receiving medium. Since ink droplets are usually charged, there are drip interactions between adjacent droplets, from adjacent nozzles on a CIJ printer. These interactions can adversely affect drop placement and print quality. In electrostatic-based CIJ printing systems using high density nozzle arrangements, a significant source of drop placement error on a receiver is due to electrostatic interactions between adjacent charged print drops.
    [009] As the drops travel from the printhead to the receiving medium (launch distance) through an electrostatic deflection zone, the relative spacing between the drops varies progressively, depending on the configuration of the print drops. When carefully spaced print drops from adjacent nozzles are similarly charged while traveling through the air, electrostatic interactions will cause the spacing of these adjacent print drops to increase as the print drops travel towards the receiving medium. This results in printing errors that are observed as a spread of the intended printed liquid configuration in an outward direction and are called tapering errors or errors of drop placement on the cross track. Since tapering errors increase with increasing launch distance, the launch distance is required to be as short as possible, which negatively affects the print margins defined as the separation between print drops and gutter drops.
    [0010] In inkjet printing, it is sometimes desirable to use a halftone technique to improve the ability to produce various levels of gradation for medium shade shades. Halftone is the reprographic technique that simulates images through the use of dots, varying in size, shape or spacing. For example, black and white continuous-tone photographs contain millions of shades of gray. When printed, these shades of gray are converted to a black dot setting that simulates the continuous tones of the original image. Lighter shades of gray consist of few or less distant black dots spaced apart. Darker remains of gray contain more black or larger dots, spaced closer together. US Patent No. 7,637,585 by M. Serra et al. Describes an inkjet printer with a drip half tone print on demand that forms differently sized dots on the medium, depositing different configurations of adjacent droplets that amalgamate in the droplets differently sized.
    [0011] On CIJ printers, it has been difficult to print simultaneously with different sized drops, in order to produce a multi-tone image. As such, there is an ongoing need to provide a high resolution continuous inkjet printing system that can produce different sized droplets on a recording medium, using a single nozzle arrangement from all nozzle orifices in the same size. There is also a need to provide such a printing system with an electrostatic deflection mechanism to deflect selected print drops using an individually addressable nozzle arrangement and a common charge electrode, in order to provide a simplified design, improved print image quality and an improved print margin. SUMMARY
    [0012] According to one aspect of the present invention, a method of ejecting drops of liquid includes providing liquid under sufficient pressure to eject a jet of liquid through a nozzle of a liquid chamber, with the liquid jet including a fundamental period of rupture of the liquid jet. A drop formation device is associated with the liquid jet. An impression period is defined as N times the fundamental liquid jet burst period, where N is an integer greater than 1. Input image data is provided, showing M levels per input image pixel, including one level and not print where M is an integer and 2 <M ~ N + 1. A charging device is provided and includes a charge electrode associated with the liquid jet and a source of variable electrical potential between the charge electrode and the liquid jet. The variable electrical potential source provides a waveform for the charge electrode. The waveform is repeated at least once during each printing period. The waveform includes one or more states of print drop voltage and one or more states of non-print drop voltage. The waveform is independent of the input image data.
    [0013] The liquid jet is modulated using the drop forming device to selectively cause portions of the liquid jet to burst in a sequence of impression drops and non-impression drops traveling along an initial path, providing several waveforms to the drop forming device. Each of the different waveforms has a period equal to the printing period. Each waveform is selected in response to the input image data, to form an impression drop having a volume that corresponds to the level of the input image pixel. For example, a waveform can be selected to control the timing of the jet burst and the formation of droplets of printing droplets and non-printing droplets during the printing period in response to input image data. The charging device and the droplet forming device are synchronized to produce a charge-to-mass ratio of print droplets, on printing droplets, as they drop from the liquid stream and to produce a charge-to-mass ratio of non-printing droplets on non-printing droplets as they burst from the liquid stream. The charge ratio for print droplet mass and charge ratio for non-print droplet mass, being different when compared with each other. At least one of the impression drops and the non-impression drops is made to deviate from the initial path using a deflection device. BRIEF DESCRIPTION OF THE DRAWINGS
    [0014] In the detailed description of the example of embodiments of the invention presented below, reference is made to the accompanying drawings, in which:
    [0015] Figure 1 is a simplified schematic block diagram of a typical continuous inkjet system, according to the present invention;
    [0016] Figure 2 shows an image of a liquid jet being ejected from a drop generator and its subsequent rupture in drops in its fundamental period v presenting a drop spacing n;
    [0017] Figure 3A shows an example of 4 pixel by 4 pixel input image data (Figure 3A) and the corresponding input pixel levels (Figure 3B);
    [0018] Figure 3B shows input pixel levels corresponding to the 4 pixel by 4 pixel input image data shown in Figure 3A;
    [0019] Figure 4A shows the printing drops traveling through the air for the 4 by 4 pixel configuration shown in Figure 3A;
    [0020] Figure 4B shows printing drops of the 4 by 4 pixel configuration shown in Figure 3A, being printed on a recording medium;
    [0021] Figure 5 shows the burst timing of printing drops of various sizes and non-printing drops, along with the state of the charge electrode voltage waveform as a function of time, shown in fundamental drop periods. ;
    [0022] Figure 6 shows typical drop-forming waveforms as a function of time, used to generate burst timing events shown in Figure 5;
    [0023] Figures 7A-7E show a sectional point of view through a liquid jet of an embodiment of a continuous liquid ejection system according to this invention, with Figure 7A showing a non-printing condition; Figure 7B showing a 1X size droplet print; Figure 7C showing the printing of drops of size 2X; Figure 7D showing 3X size droplet printing and Figure 7E showing 4X size droplet printing;
    [0024] Figures 8A-8C show examples of printing drops of various sizes on a recording medium with Figure 8A showing drops 1X and 3X; Figure 8B showing 1X and 2X drops; and Figure 8C showing 2X and 3X drops; and
    [0025] Figure 9 shows a block diagram of a variable size drop printing method, according to an example of an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION
    [0026] The present description will be directed in particular to elements being part of or cooperating more directly with apparatus according to the present invention. It is to be understood that elements not shown or described specifically can take various forms well known to those skilled in the art. In the following description and drawings, identical reference numerals were used, where possible, to designate identical elements.
    [0027] Examples of embodiments of the present invention are illustrated schematically and not to scale, for clarity. One skilled in the art will be able to readily determine the specific size and interconnections of the elements of the exemplary embodiments of the present invention.
    [0028] As described here, examples of embodiments of the present invention provide a printhead or printhead components typically used in inkjet printing systems. In such systems, the liquid is an ink to print on a recording medium. However, other applications are emerging, which use inkjet printheads to emit liquids (other than inks) that need to be finely measured and deposited with high spatial resolution. As such, as described here, or Vgtoqu “níswkfq” g “VkpVc” refer to any material that can be ejected by the printhead or printhead components described below.
    [0029] Continuous inkjet drop generators (CIJ) are based on the physics of an unforced fluid jet, first analyzed in two fkogpuõgu rqt H0T0U0 * Nqtf + Tc {ngkij, “KpuVcdükV {qh jgVu”, Rtqeo Nqpfq Math. Soc. 10 (4), published in 1878. Lord Rayleigh's analysis showed that liquid under pressure, P, will flow through an orifice, the nozzle, forming a liquid jet of dj diameter, moving at a speed vj. The diameter of the jet dj is approximately equal to the effective diameter of the nozzle dn and the speed of the jet is proportional to the square root of the pressure of the reservoir P. Rayleigh's analysis showed that the jet will break naturally in drops of varying sizes, based on the waves surface that have wavelengths n longer than rdj, that is, n> rdj. Rayleigh's analysis also showed that particular surface wavelengths will become dominant if dcuVcpVg starts at a large magnitude. fguVg oqfq "stimulating" q jcVq c rtqfwzkt iqVcu fg Vcocnhq úpkeq. Continuous ink jet (CIJ) generators typically employ a periodic physical process, woc cuuko ehcocfc "rertwtdc>" q "qw" euVkown q gfekVq fg guVcdgngegt woc qpfc fg uwrgtfíekg dominant, particular, over the jet. Stimulation results in the jet bursting in single-dimensional drops synchronized with the fundamental frequency of the disturbance. It has been shown that the maximum efficiency of the jet burst occurs at a frequency optimal Fopt which results in the shortest break time. At the optimal Fopt frequency (optimal Rayleigh frequency) the wavelength n of the disturbance is approximately equal to 4.5dj. The frequency at which the wavelength of the disturbance n is equal rdj is called the Rayleigh, FR cutoff frequency, since disturbances of the liquid jet at frequencies higher than the cutoff frequency will not actually cause a drop to be formed.
    [0030] The droplet flow that results from applying Rayleigh stimulation will be referred to here as creating a droplet flow of predetermined volume. Although in CIJ systems of the prior art the drops of interest for printing or depositing a standardized layer were invariably unitary in volume, it will be explained that, for current inventions, the stimulation signal can be manipulated to produce drops of predetermined multiples of the xqnwog wpkVátkOo Fcí. c htcug “flwzou fg iqVcu fg xqnwogu rtgfgVgtmipcfou” be inclusive of droplet streams that are fractionated into droplets, all of which have a size or fractional streams in droplets of different planned volumes.
    [0031] In a CIJ system, a few drops, usually called “ucVfilkVgu”, owkVq ogpqtgu go xqlwog swg q xqlwog wpkvátkq rtgfgVgtokpcfq, can be formed as flow collars in a thin fluid ligament. Such satellites may not be fully predictable or may not always merge with another drop in a predictable manner, thereby slightly altering the volume of drops intended for printing or patterning. The presence of small, unpredictable satellite droplets is, however, of no consequence for the present invention and is not considered to avoid the fact that droplet sizes were predetermined by the synchronization energy signals used in the present invention. Drops of predetermined volume each have an associated portion of the drop-forming waveform responsible for creating the drop. Satellite drops do not have a portion fkuVkpVc fc fotoc fg qpfc tgurqpuáxgl rqt uwc etkc> «qo GpV« o. c htcug “xqlwog rtgfgVgtokpcfq” eqpfotog wucfc rctc fguetgxgt c rtgugpVg kpxgp> «q. fgxgtkc be understood to understand that some small variation in the drop volume in relation to a planned target value may occur due to the formation of an unpredictable satellite drop.
    [0032] A continuous inkjet printing system 10 is illustrated in Figure 1 and Figure 2 shows an image of a liquid jet 43 being ejected from a single drop generator from a printhead 12 and its subsequent rupture in droplets 35 and 36 in their fundamental period v presenting an adjacent droplet spacing The continuous inkjet printing system 10 includes an ink reservoir 11 that continuously pumps ink into a printhead 12, also called a liquid ejector or drop generator, to create a continuous flow of ink drops. The continuous inkjet printing system 10 receives scanned image processing data from an image source 13 such as a digitizer, computer or digital camera or other digital data source that provides raster image data, image data from outline in the form of a page description language or other forms of digital image data. The image data from the image source 13 is periodically sent to an image processor 16. The image processor 16 processes the image data and includes a memory for storing image data. Image processor 16 is typically a raster image processor (RIP), which converts received image data into print data, a bitmap of pixels for printing. The print data is sent to a pacing controller 18 that generates pacing waveforms 55; configurations of time-varying electrical stimulation pulses to cause a flow of droplets to form the output of each of the nozzles on the printhead 12, as will be described. These stimulation pulses are applied at an appropriate time and at a frequency appropriate to the stimulation device (s) 59 associated with each of the nozzles 50 with appropriate amplitudes, work cycles and timings to cause drops 35 and 36 are broken from the continuous stream 43. The printhead 12 and deflection mechanism 14 work cooperatively to determine whether ink droplets are printed on a recording medium 19 in the appropriate position designated by the data in the image memory, or deflected and recycled through the ink recycling unit 15. The recording medium 19 is also called a receiver and is commonly composed of paper, polymer or some other porous substrate. The ink in the ink recycling unit 15 is directed back to the ink reservoir 11. The ink is distributed under pressure to the rear surface of the printhead 12 through an ink channel that includes a chamber or plenum formed on a typically constructed substrate. of silicon. Alternatively, the chamber could be formed in a single piece to which the silicon substrate is attached. The ink preferably flows from the chamber through slits and / or holes deposited through the silicon substrate of the printhead 12 to its front surface, where several nozzles and stimulation devices are located. The paint pressure suitable for optimal operation will depend on a number of factors, including the geometry and thermal properties of the nozzles and the thermal and dynamic properties of the paint fluids. Constant ink pressure can be achieved by applying pressure to the ink reservoir 11, under the control of the ink pressure regulator 20.
    [0033] The RIP or other type of processor 16 converts the image data to a pixel-mapped image page image, for printing. Image data can include raw image data, additional image data generated from image processing algorithms to improve the quality of printed images, and data from drop placement corrections, which can be generated from many sources , for example, from measurements of direction errors of each nozzle in the printhead 12, as is well known to those skilled in the art of printhead characterization and image processing. Information about the image processor 16 can then be considered to represent a general source of droplet ejection data, such as desired locations of ink droplets to be printed and identification of those droplets to be collected for recycling.
    [0034] During printing, the recording medium 19 is moved relative to the printhead 12 by means of several transport rollers 22 which are electronically controlled by the media transport controller 21. A logic controller 17, preferably based on a microprocessor and properly programmed as it is well known, it provides control signals for cooperation of the media transport controller 21 with the ink pressure regulator 20 and pacing controller 18. The pacing controller 18 comprises one or more waveform sources of stimulation 56 that generate gout waveforms in response to impression data and provide or apply the stimulation waveforms 55, also called stimulation waveforms, to the stimulation device (s) 59, also called gout forming device (s) 59 associated with each nozzle 50 or liquid jet 43. In response to the energy pulses of the applied stimulation waveforms , the drop forming device 59 disturbs the continuous liquid flow 43, also called a liquid jet 43, to cause individual liquid drops to burst from the liquid flow. The droplets burst from the liquid jet 43 at a BL distance from the nozzle plate. The information in the image processor 16 can then be said to represent a general source of droplet data, such as desired locations of ink droplets to be printed and identification of those droplets to be collected for recycling.
    [0035] It can be verified that different mechanical configurations for control of receiver transport can be used. For example, in the case of a page width printhead, it is convenient to move the recording medium 19 after a stationary printhead 12. On the other hand, in the case of a scan-type printing system, it is more convenient to move a printhead along an axis (that is, a main scan direction) and to move the recording medium along an orthogonal axis. (ie, a sub sweep direction) in relative sweep motion.
    [0036] Drop formation pulses are provided by the pacing controller 18 which can generally be referred to as a drop controller and are typically voltage pulses sent to the printhead 12 via electrical connectors, as is well known in the art signal transmission. However, other types of pulses, such as optical pulses, can also be sent to the printhead 12, to cause printing and non-printing drops to form on particular nozzles, as is well known in inkjet printing techniques. . Once formed, drops of impression travel through the air to a recording medium and subsequently fall on a particular pixel area of the recording medium or are collected by a pickup, as will be described.
    [0037] Referring to Figure 2, the printing system has associated with it a printhead that is operable to produce, from an arrangement of nozzles 50, all of the same diameter, an arrangement of liquid jets 43. Associated each liquid jet 43 is a drop forming device 59 and a drop forming waveform source 56 that provides a stimulation waveform 55, also called a drop forming waveform, to the forming transducer of gout. The drop forming device 59, commonly called a drop forming transducer or a drop stimulation transducer, can be of any type suitable for creating a disturbance in the liquid stream, such as a thermal device, a piezoelectric device, an actuator MEMS, an electro-hydrodynamic device, an optical device, an electro-restrictive device, and combinations thereof. Depending on the type of transducer used, the transducer can be located inside or adjacent to the liquid chamber that supplies the liquid to the nozzles, to act on the liquid in the liquid chamber, to be located inside or immediately around the nozzles to act on the liquid as it passes through the nozzle, or located adjacent to the liquid jet to act on the liquid jet after it has passed through the nozzle. The droplet waveform source 56 provides a droplet waveform source having a fundamental frequency fo and a fundamental period of vo = 1 / fo for the droplet transducer, which produces a modulation with a length n wave in the liquid jet. The modulation grows in amplitude to cause portions of the liquid jet to burst into drops. Through the action of the drop forming device, a sequence of drops is produced at a fundamental frequency fq with a fundamental period of vq = 1 / fq. Typically, the fundamental frequency fq for a printhead is chosen to be approximately equal to the optimal Rayleigh frequency Fqpt.
    [0038] In Figure 2, a liquid jet 43 breaks into droplets with a regular period at the break location 32, which is a BL distance from the nozzle 50. The distance between a pair of successive droplets 35 and 36 is essentially the same as wavelength n of the liquid jet. The pair of successive droplets 35 and 36 that break from the liquid stream forms a so-called droplet pair 34, each droplet pair having a first droplet and a second droplet. Then, the frequency of formation of the drop pair 34, commonly called the frequency of the drop pair fp is given by fp = fq / 2 and the period of the corresponding drop pair is vp = 2vo. Usually, the drop stimulation frequency of the simulation transducers for the entire array of nozzles 50 on a printhead is the same for all nozzles on the printhead 12.
    [0039] Also shown in Figure 2 is a charge device 83 comprising charge electrode 44 and charge voltage source 51. Charge voltage source 51 provides a source for varying the electrical potential between the charge electrode and the jet. liquid. The source for varying the electrical potential provides a charge electrode 97 waveform for the charge electrode, which controls the voltage signal applied to the charge electrode. The charge electrode waveform repeats at least once during each printing period (see definition below), and the waveform includes one or more print drop voltage states and one or more print drop voltage states. not impression. The waveform of the charge electrode is also independent of the input image data. The charge electrode 44 is associated with the liquid jet and is positioned adjacent to the breaking point 32 of the liquid jet 43. When a non-zero voltage is applied to the charge electrode 44, an electric field is produced between the charge electrode and the jet electrically grounded liquid. The capacitive coupling between the charge electrode and the electrically grounded liquid jet induces a liquid charge at the end of the electrically conductive liquid jet. (The liquid jet is grounded by contacting the liquid chamber of the grounded drop generator). If the end portion of the liquid jet breaks to form a drop while there is a liquid charge at the end of the liquid jet, the charge from that end portion of the liquid jet is captured in the newly formed drop. When the voltage level at the charge electrode is modified, the charge induced in the liquid jet varies due to the capacitive coupling between the charge electrode and the liquid jet. Hence, the charge on the newly formed drops can be controlled by varying the electrical potential at the charge electrode.
    [0040] In order to print a multi-tone image using the present invention, the input image data needs to be converted to a multi-level image corresponding to the number of levels that must be printed. Using 2-bit encoding allows three different print and non-print drop sizes with 00 corresponding to white, 01 corresponding to a first gray, 10 corresponding to a second gray and 11 corresponding to black. Using 3-bit encoding allows 7 different print and non-print drop sizes with 000 corresponding to white and 001 - 110 corresponding to 6 different gray densities and 111 corresponding to black. In general, all the different levels do not need to be used, since the generation of larger drops reduces the maximum printing speed. Printing a drop of N times the fundamental impression drop volume requires a time interval of N times the fundamental impression drop period to generate a drop of that size. In the practice of this invention, a printing period of time N is provided for the fundamental period of the ruptured liquid jet, where N is an integer greater than 1.
    [0041] When practicing the invention, input image data is provided showing M levels per pixel of input image where M is an integer and 2> M ~ N + 1. One of the M levels is a non-printing level or a white level. The M levels result in different shades of light and dark or multi-tones when printed on the recording medium. Figure 3A shows an example of 4 pixel by 4 pixel input image data using a total of 5 levels, including non-printing (white) (decimal 0), 3 levels of gray (decimal 1, 2 and 3) and black (decimal 4). Figure 3B shows the corresponding input pixel levels shown in decimal notation. In order to create a 5-level image, 3-bit encoding is required. Usually, decimal 0 white would correspond to binary 000 and decimal 4 or binary 100 in 3-bit coding would correspond to black.
    [0042] Figure 4A shows the impression drops traveling through the air after the non-impression drops are deflected and captured by a collector for the 4 pixel by 4 pixel configuration shown in Figure 3, assuming that the background of the image is generated first . The direction of flow of the liquid jet is indicated by arrows 26. The different sized print drops being 1X, 2X, 3X and 4X are shown as 35, 37, 30 and 31, respectively. F 4B shows the resulting printed drop configuration on the recording media produced by the drops traveling in the air in Figure 4A, from the input image data in Figure 3. In Figure 4B, the pixel outlines are represented by shaded lines 62. Unprinted pixels or white pixels are represented by 53. The printed drop 1X is represented by 46, the printed drop 2X is represented by 45, the printed drop 3X is represented by 42 and the printed drop 4X is represented by 49. As measured As N increases, the size of the printed drops increases, resulting in an increased average print density when viewed by an observer.
    [0043] The dynamics of droplet formation, of droplets formed from a flow of liquid being released from an ink jet nozzle, can be varied by changing the waveforms applied to the respective droplet transducer associated with a hole particular nozzle. Modifying at least one of the amplitude, duty cycle or timing relative to other pulses in the waveform or in a sequence of waveforms, can alter the dynamics of drop formation from a particular nozzle orifice. In order to practice this invention, it is desirable that the drops formed of several volumes, broken at approximately the same distance BL from the nozzle arrangement. The droplet waveform and burst timing waveforms to form droplets of various volumes ranging from 1-4 times the fundamental droplet volume are described in Figures 5 and 6.
    [0044] Figure 5 shows an example of a timing diagram showing the burst timing of printing drops and non-printing drops of various sizes, together with the waveform state and charge electrode voltage with a function of time measured in fundamental gout formation periods for a single printing period that lasts for 4 fundamental gout formation periods. The charge electrode waveform 97 shown is a 2-state waveform having a non-printing drop voltage state 96, also called a drop collection voltage state 96, and a print drop voltage state. 95 which is shown to be repeated twice during a printing period. Each state of tension is shown active for a period of fundamental gout formation. The drop rupture timing for the various print drop size waveforms that are shown in Figure 6, is also shown in Figure 5. Print drops are formed when they break adjacent to the charge electrode, when the charge electrode charge is in the 95 droplet voltage state, which produces a charge to droplet mass ratio in the droplets. Non-printing droplets, also called collecting droplets, are formed when they break adjacent to the charge electrode, when the charging electrode is in the non-printing droplet voltage state 96 which produces a charge to non-printing droplet mass ratio. in the non-printing drops. The charge ratio for print droplet mass is different from the charge ratio for non-print droplet mass. The print droplet voltage state does not need to be at the earth potential and it is sometimes advantageous that it is at a non-zero DC level. If there is an appropriate DC bias during the burst of print drops, the charge on the print drops can be reduced to near zero charge. In one embodiment, the DC bias is adjusted or selected in such a way that the charge of the 1X print droplets is approximately zero charge, while the print droplets of the other sizes may differ slightly from zero charge. The selection of the 1X drop is made as the drop to have zero charge, as it has the lowest mass and is therefore more susceptible to drop-by-drop electrostatic interactions and other printing drops. To further reduce possible electrostatic drop-by-drop interactions, a phase shift can be applied between the drop-forming waveforms applied to adjacent nozzles. For example, the droplet waveforms applied to the droplet devices associated with the odd numbered nozzles can be delayed by / printing period or equivalent to twice the droplet period, in relation to waveforms. drop formation applied to the drop forming devices associated with the even numbered nozzles. In this way, the spacing between print drops from adjacent nozzles can be increased, reducing the electrostatic forces between lightly charged print drops.
    [0045] Another way to reduce load-to-mass variations in printing drops of different volumes, includes using a non-printing drop of a predetermined size, which precedes printing drops. For example, in a 4X period, 1X, 2X and 3X print drops are preceded by a 1X non-print drop. This reduces the effect of drop-dependent electrical fields in the jet burst area and helps to increase the consistency of the charge-to-mass ratio in the print droplets.
    [0046] The rupture timing of the droplets formed when using the non-printing droplet waveform is shown as black diamonds; the rupture timing of droplets formed using the 1X print droplet waveform is shown as black triangles; the burst timing of droplets formed using the 2X print droplet waveform is shown as black circles; the burst rupture timing formed using the 3X print drop waveform is shown as black squares and the burst rupture timing formed using the 4X print drop waveform is shown as crosses. The relative sizes of the symbols used to indicate rupture events correlate with the sizes of the droplets that break. Note that all the print drops shown in Figure 5 break during the second fundamental time period, during the printing period. In general, a constant phase delay is applied between the pulse timing applied to the drop formation transducers and the charge electrode waveform, in order to properly synchronize the timing or rupture events, in such a way that drops print sizes of the desired sizes break during the charge state of the charge voltage waveform print drop and non-print drops break during the charge state waveform non-print charge state.
    [0047] Figure 6 shows an example of droplet waveforms with a time function, used to generate the burst timing events in Figure 5. The droplet waveform to be printed is based on the input image data. The nonprint drop waveform 70 consists of a pair of 2X 92 drop formation pulses, occurring during the first and third fundamental periods of the print period. The 1X 71 droplet waveform consists of a pair of 1X 91 droplet pulses occurring during the first and second fundamental periods and a 2X 92 droplet pulse occurring during the third fundamental period of the printing period. The 2X 72 print droplet waveform consists of a 1X 91 droplet pulse during the first fundamental period, a 2X 92 droplet pulse during the second fundamental period and a 1X 91 droplet pulse during the third key period of the printing period. The 3X 73 droplet waveform consists of a 1X 91 droplet pulse during the first fundamental period and a 3X 89 droplet pulse during the second fundamental period of the printing period. The 4X 74 print drop waveform consists of a 4X 90 drop formation pulse during the second fundamental period of the print period. The waveforms 71-74 shown in Figure 6 produce print drops of X times the fundamental volume, in response to an X level of input image pixel data, where 1 ~ X ~ N. Other sets of timing diagrams they could also be used to provide printing drops of varying sizes. In all cases, when the input image data level is 0, the waveforms are modulated to cause portions of the liquid stream to burst into one or more non-printing drops. In the various drop forming waveforms 70, 71, 72, 73 and 74 shown in Figure 6, the total energy applied to the drop forming transducer over the printing period is the same.
    [0048] Figures 7A-E show a sectional view in section through a single liquid jet of an embodiment of the continuous liquid ejection system according to this invention, while not printing in A, while printing drops 1X in B , while printing 2X drops in C, while printing 3X drops in D, and while printing 4X drops in E, using a print period of four fundamental duration periods and the drop and timing waveforms shown in Figures 5 and 6. In In various embodiments of the invention, the continuous liquid ejection system 40 includes a printhead 12 comprising a liquid chamber 24 in fluid communication with an arrangement of one or more nozzles 50, for emitting liquid jets 43. Liquid is supplied under a enough pressure to eject jets of liquid through the nozzles of the liquid chamber. Liquid jets have a fundamental period of liquid jet rupture. A stimulation transducer 59 is associated with each liquid jet. In the embodiments shown, stimulation transducer 59 is formed on the wall around nozzle 50. Separate stimulation transducers 59 can be integrated into each of the nozzles, in different nozzles. The stimulation transducer 59 is actuated by a drop-forming waveform source 56 that provides periodic stimulation of the liquid jet 43 in the form of stimulation waveforms 55 shown in Figure 6 as 70, 71, 72 and 73 that are dependent on the input image data.
    [0049] The energy and timing of the stimulation waveforms applied to the liquid jets is controlled in such a way that all droplets burst from the adjacent continuous liquid flow 43, at the same distance 32 from the nozzle outlet. As the drops of various sizes burst from the liquid jets 43, they travel along an initial path 87, as shown in Figure 2. Through Figure 7A-E, drops are indicated with circles of various sizes, to indicate the relative size of the drops. Print drops are shown without any charge and non-print drops are shown as having a negative sign. Numerals 35, 37, 30 and 31 represent 1X, 2X, 3X and 4X printing drops, respectively, and numerals 36 and 38 represent 1X and 2X non-printing drops, respectively.
    [0050] A deflection mechanism 14 is required to deflect non-printing drops. The deflection mechanism includes the charge device 83 consisting of the charge electrode 44, the charge voltage source 51 and the charge electrode waveform 97, the collector 47 featuring the collector face 52 and the optional deflection electrode 66 with its deflection electrode voltage source 67. Charge electrode 44 is common to all nozzles among the various nozzles of the printhead 12. The pulse charge voltage source 51 provides a time-varying electrical potential (shape charge electrode waveform 97) between charge electrode 44 and liquid jet 43, which is usually grounded. The charge electrode waveform is repeated at least once during each printing period, the waveform includes one or more print drop voltage states and one or more non-print drop voltage states and the shape charge electrode waveform is independent of the input image data. In the examples shown in Figure 7, the waveform of the charge electrode is repeated twice during a printing cycle, which is of 4 fundamental periods of duration, and presents a state of print drop voltage and a state of voltage drop. non-impression drop, as shown in Figure 5. When a voltage potential is applied to the charge electrode 44 located on one side of the liquid stream adjacent to the breaking point, the charge electrode 44 attracts the charged end of the jet, prior to rupture of a drop, and also attracts the charged drops 36 and 38, after their rupture from the liquid jet. This mechanism fg fgflgz «q fok fguetkVq go L0C0 McVgtdgti. “Ftor ejctikpi cpf fgflgeVkqp wukpi a rlanct ejctig platg”. 6vj KpVgmcVkqpan Eopitguu qp Advances in Non-Impact Printing Technologies. Collector 47 also makes up a portion of deflection device 14. As described in US Patent No. 3,656,171 to J.Robertson, charged drops passing in front of a conductive collector face cause surface charges on the conductive collector face 52 are redistributed in such a way that the charged drops are attracted to the collector face 52. In the embodiments shown in Figures 7A-7E, drops 36 and 38 are highly negatively charged and deflected in the direction and captured by the collector 47, and recycled while the print drops 35, 37, 30 and 31 have a relatively low charge and are found to be relatively undeflected. In practice, the print droplets can be slightly deflected away from the collector and can reach the recording medium 19. For proper operation of the printhead 12 shown in Figures 7A-7E, the collector 47 and / or the bottom plate of the collector 57 are grounded to allow the charge on the intercepted drops to be dissipated as the ink flows into the collector face 52 and enters the ink return channel 58. the collector face 52 of the collector 47 makes an angle s with respect to the liquid jet shaft 87 shown in Figure 2. Charged droplets 36 and 38 are attracted to the collector face 52 of the collector 47 grounded and intersect the collector face 52 at the charged drop collector contact location 27, to form a film ink 48 traveling to the collector face 47. The bottom of the collector face has a curved surface of radius R, around which ink can flow from the collector face 52 into the ink return channel 58. The return channel 58 ink is formed between the fu of the collector body and the collector bottom plate 57 for capturing and recirculating the ink in the ink film 48. If a positive voltage potential difference exists, from the charge electrode 44 to the liquid jet 43 at the time of burst a drop, breaking adjacent to the electrode, a negative charge will be induced in the forming drop, which will be retained after the drop rupture from the liquid jet.
    [0051] Figure 7A shows a non-printing mode, which uses the non-printing droplet waveform 70 shown in Figure 6, which causes the droplets to burst from the liquid jet 43 with the burst timing shown. by the black diamonds in Figure 5, in relation to the charge electrode waveform. Only 2X 38 negatively charged droplets rupture and are attracted and captured by the collector 47 and recirculated. These 2X non-printing droplets 38 follow the trajectory of the non-printing droplet or path shown by the dashed line 39. If used, the optional deflection electrode 66 would be supplied with a negative DC voltage by the deflection electrode voltage source 67.
    [0052] Figure 7B shows a 1X drop printing mode that uses the 1X 71 drop drop waveform shown in Figure 6 that causes the drops to burst from the liquid jet 43 with the burst timing shown by the black triangles in Figure 5. In this case, a single 1X drop is printed on each pixel as 1X drops printed 46 on the recording medium 19 which is moving at a speed vm. The 1X 35 print drops are relatively undeflected as they travel in the air towards the recording medium 19 and follow the trajectory or path of the print drop shown by the dashed line 34. Both 1X 36 non-print drops and non-print drops 2X prints are attracted and captured by collector 47 and recirculated as they travel along the non-print 39 drop path. The 1X drops printed sub fill the pixel area, as shown in Figure 4B, as indicated by the non-overlapping drops on recording medium 19 in Figure 7B.
    [0053] Figure 7C shows a 2X drop print mode that uses the 2X 72 print drop waveform shown in Figure 6, which causes the drops to burst from liquid jet 43 with burst timing shown by the black circles in Figure 5. In this case, a single 2X drop is printed on each pixel as 2X drops printed 45 on the recording medium 19, which is moving at vm speed. The 2X 37 print drops are relatively deflected as they travel through the air towards the recording medium 19 and follow the trajectory of the print drop 34 shown. The unprinted 1X 36 drops are attracted and captured by the collector 47 and recirculated as they travel along the non-print 39 drop path. The 2X printed drops 45 are larger than the 1X 46 printed drops but still sub fill the pixel, as shown in Figure 4B, as indicated by the non-overlapping drops on the recording medium 19 in Figure 7B.
    [0054] Figure 7D shows a 3X droplet printing mode that uses the 3X 73 droplet waveform shown in Figure 6, which causes the droplets to burst from liquid jet 43 with burst timing shown by the black squares in Figure 5. In this case, a 3X drop is printed on each pixel as 3X drops printed 42 on the recording medium 19, which is moving at vm speed. The 3X 30 print drops are relatively undeflected as they travel in the air towards the recording medium 19 and follow along the print drop path 34. The 1X 36 unprinted drops are attracted and captured by the collector 47 and recirculated as they travel along the non-printing 39 drop path. 3X printed drops 42 are larger than 2X 45 printed drops and the ends between adjacent drops formed from the same nozzle 50 touch the contours between drops. As shown in Figure 4B, the printed 3x drops still sub fill the pixel area.
    [0055] Figure 7E shows a 4X droplet printing mode that uses the 4X 74 droplet forming waveform shown in Figure 6, which causes the droplets to burst from the liquid jet 43 with the time delay. rupture shown by the crosses in Figure 5. In this case, a 4X drop is printed on each pixel as 4X drops printed 49 on the recording medium 19, which is moving at vm speed. The 4X print droplets 31 are relatively undeflected as they travel in the air towards the recording medium 19 and follow along the print droplet path 34. In this case, none of the droplets that break from the liquid stream 43 they are attracted and captured by the collector 47 and recirculated. The 4X printed drops 31 are larger than the 3X 42 printed drops.
    [0056] Examples of printing drops of various simultaneous dimensions on a recording medium using the drop forming waveforms shown in Figure 6, are shown in Figure 8. In each AC section of Figure 8, a sequence of drops and printed by an arrangement of nozzles. The droplets are printed well spaced apart to allow the size of the individual droplets to be seen. In section A, the drop stimulation waveforms alternating between 1X print drop waveform and 3X print drop waveform, separated by various non-print drop waveforms, are applied to the forming device droplet to print 1X 46 droplets and 3X 42 droplets. In section B, the droplet stimulation waveforms alternated between 1X droplet waveform and 2X droplet waveform, separated by different shapes print drop waveform, were applied to the drop forming device to print 1X 46 drops and 2X 45 drops. In section C, the drop stimulation waveforms alternated between the 2X print drop waveform and the 3X printing drop wave, separated by different print drop waveforms, were applied to the drop forming device to print 2X 45 drops and 3X 42 drops. It is observed that the 1X 46 printed drops are smaller in diameter than the impr drops these 2X 45, which are smaller in diameter than the 3X 42 printing drops.
    [0057] Figure 9 shows a block diagram outlining the steps required to practice the printing method according to various embodiments of the invention. Referring to Figure 9, the printing method begins with step 150. In the support structure 150, pressurized liquid is provided under a pressure that is sufficient to eject a liquid jet through a nozzle or a linear arrangement of nozzles. Step 150 is followed by step 155.
    [0058] In step 155, multiple droplet size input image data is provided. An impression period defined as N times the fundamental period of the liquid jet burst is selected where N is an integer greater than 1. The input image data has M levels per input image pixel including a non-print level where M is an integer and 2 <M ~ N + 1. Step 155 is followed by step 160.
    [0059] In step 160, the liquid jets are selectively modulated to cause portions of the liquid jets to break into one or more drops of various sizes, traveling along a path dependent on the input image data. The liquid jet is modulated using a droplet forming device that selectively causes portions of the liquid jet to burst in streaks of impression droplets and non-impression droplets traveling along an initial path, providing several waveforms to the drop formation device. Each of the various waveforms has a period equal to the printing period, and each waveform is selected in response to the input image data, to form a print drop having a volume that corresponds to the pixel level of the image. Prohibited. Step 160 is followed by step 165.
    [0060] In step 165, a charging device is provided. The charging device includes a charging electrode and a time-varying source of electrical potential. The charge electrode is common and associated with each of the liquid jets. The time-varying electrical potential source applies a charge electrode waveform between the charge electrode and the liquid jets. The charge electrode waveform is repeated at least once during each printing period and includes one or more print drop voltage states and one or more non-print drop voltage states. The waveform of the charge electrode is independent of the input image data applied to the nozzle drop forming devices. Step 165 is followed by step 170.
    [0061] In step 170, the charging device and the droplet forming device are synchronized, such that the print droplet voltage state is active when printing droplets of various sizes break from the nozzles and the non-printing droplet tension state is active when non-printing droplets of various sizes burst from the liquid. This produces a charge to mass ratio of printing droplets in printing droplets of various sizes as they burst from the liquid jet and produces a charge to mass ratio of unprinted droplets in the various unprinted droplets. sizes, as they break from the liquid jet, the charge ratio for non-print droplet mass is different from the charge ratio for non-print droplet mass. Step 170 is followed by step 175.
    [0062] In step 175, non-printing drops are printing drops that are forced to travel along different trajectories, using a deflection mechanism. The deflection mechanism includes an electrostatic deflection device that causes non-printing droplets of various sizes to travel along a trajectory of non-printing droplets and causes printing droplets of various sizes to travel along a trajectory. distinct drop pattern, the print drop path and the non-print drop path are different. Then, at least one of the impression drops and the non-impression drops deviate from the initial path, using the deflection device. Step 175 is followed by step 180.
    [0063] In step 180, drops traveling along one and only one of the first trajectory and the second trajectory, are intercepted by a collector for recycling. These drops are non-printing drops and the drops traveling along the other path in addition to the drops that are intercepted by the collector, are allowed to contact the recording medium and be printed.
    [0064] Generally, this invention can be practiced to create printing drops of 1-100 pl, with nozzle diameters in the range of 5-50 om, depending on the resolution requirements of the printed image. The jet speed is preferably in the range of 10-30 m / s. The fundamental drop generation frequency is preferably in the range 50-1000 kHz. The specific selection of this drop size, drop speed, nozzle size and drop generation frequency parameters is dependent on the printing application.
    [0065] The invention also allows droplets to be selected for printing or non-printing, without the need for a separate charge electrode to be used for each liquid jet in a liquid jet arrangement as found in deflection-based inkjet printers conventional electrostatic. Instead, a single common charge electrode is used to charge drops from the liquid jets, in an arrangement. This eliminates the need to critically align each charge electrode with the nozzles. The interference of charging drops from a liquid jet by means of a charge electrode associated with a different liquid jet is not a problem. Since charging interference is not an issue, there is no need to minimize the distance between charge electrodes and liquid jets, as is required for traditional drop charge systems. The common charge electrode also offers improved charge efficiency and deflection, thus allowing for a greater separation distance between the jets and the electrode. Distances between the charge electrode and the jet shaft in the range of 25-300 om are usable. The elimination of the individual charge electrode for each liquid jet also allows for higher nozzle densities than in the traditional electrostatic deflection continuous inkjet system, which requires separate charge electrodes for each nozzle. The nozzle arrangement density can be in the range of approximately 30 nozzles per centimeter to approximately 472 nozzles per centimeter.
    [0066] In the realizations of the various figures, the impression drops were relatively uncharged and relatively undeflected, while the non-impression drops were charged and deflected to reach the collector. In other embodiments, the print drops can be loaded and deflected and the non-printed drops can be relatively unloaded and relatively non-deflected, with the collector positioned to intercept the path of the non-deflected non-printing drops.
    [0067] The examples of embodiments discussed above with reference to Figures 1-9 are described using a particular combination of a drop charge structure, drop deflection structure, drop collection structure and drop forming device. It should be understood that there are many known configurations of drop charge structures, drop deflection structures, drop collection structures and drop forming devices, including some in which a single structure performs multiple functions (such as a structure electrode that serves both charge drops and deflects them) and various combinations of these structures can be used. PART LIST 10 Continuous Inkjet Printing System 11 Ink Reservoir 12 Printhead or Liquid Ejector 13 Image Source 14 Deflection Mechanism 15 Ink Recycling Unit 16 Image Processor 17 Logic Controller 18 Stimulation Controller 19 Recording Medium 20 Ink Pressure Regulator 21 22 24 26 27 30 31 32 34 35 36 37 38 39 40 42 43 44 45 46 47 48 49 50 51 52 53 54 55 Media Transport Controller Transport Rollers Liquid Chamber Direction Liquid Jet Flow Rate Load Drop Collector Contact Location 3X Print Drop 4X Drop Drop Print Drop Path 1X Non-Print Drop 1X Non-Print Drop 2X Non-Print Drop 2X Non-Drop Drop 2X Drop Path Continuous Liquid Ejection System Printed Drop 3X Liquid Jet Charge Electrode Printed Drop 2X Printed Drop 1X Collector Ink Film Printed Drop 4X Nozzle Voltage Source Load Collector Face Pixels of White Speed Modulation Source Drop Stimulation Waveform 56 57 58 59 62 65 66 67 70 71 72 73 74 83 87 90 91 92 95 96 97 150 155 160 165 170 175 180 185 Source Drop Formation Waveform Collector Bottom Plate Ink Return Channel Drop Formation Device Pixel Contours Arrow Deflection Electrode Deflection Electrode Voltage Source Non-Printing Drop Waveform Impression 1X Impression Drop Waveform 2X Impression Drop Waveform 3X Impression Drop Waveform 4X Loading Device Central Jet Spindle Drop Formation Pulse 4X Drop Formation Pulse 1X Drop Formation Pulse 2X Drop Print Drop Voltage State Non-Print Drop Voltage Status Charge Electrode Waveform Pressurized Liquid Supply Step Supply Stage Input Data Data Modular Stage Liquid Jet Supply Stage Load Synchronization Step Step of Merging Pairs of Drops Step of Deflecting Selected Drops Step of Intercepting Selected Drops
    权利要求:
    Claims (10)
    [0001]
    1. Method for ejecting drops of liquid, characterized by the fact that it comprises: providing liquid under sufficient pressure to eject a liquid jet (43) through a nozzle (50) of a liquid chamber (24), the liquid jet (43) including a fundamental period of liquid jet rupture; providing a drop forming device (59) associated with the liquid jet (43); provide an impression period defined as N times the fundamental period of rupture of the liquid jet (43), where N is an integer greater than 1; provide input image data having M levels per input image pixel, including a non-printing level where M is an integer and 2 <M <N + 1; providing a charging device (83) including: charging electrode (44) associated with the liquid jet (43); and variable electric potential source (51) between the charge electrode (44) and liquid jet (43), the variable electric potential source (51) providing a waveform (97) to the charge electrode (44), the waveform repeating at least once during each printing period, the waveform (97) including one or more states of print drop voltage and one or more states of non-print drop voltage, the form of wave being independent of the input image data; modulate the liquid jet (43) using the drop forming device (59) to selectively cause portions of the liquid jet (43) to burst in a sequence of print drops and non-print drops traveling over a initial path, providing several waveforms to the drop forming device (59), each of the various waveforms presenting a period equal to the printing period, each waveform being selected in response to the input image data, for forming a printing drop having a volume that corresponds to the level of the input image pixel; synchronize the charge device (83) and the drop forming device (59) to produce a charge to mass ratio of print droplet over print droplets as they stop from the liquid jet (43) and to produce a charge ratio for non-printing droplet mass on non-printing droplets as they burst from the liquid jet, the charge ratio for impression droplet mass being different from the charge ratio for droplet mass of not printing; and causing at least one of the impression drops and non-impression drops to deviate from the initial path, using a deflection device (14).
    [0002]
    2. Method according to claim 1, characterized by the fact that modulating the liquid jet (43) includes causing portions of the liquid jet to interrupt in one or more non-printing drops, when the input image data level is 0 and cause portions of the liquid jet (43) to break into print drops of different volumes for each of the pixel level input image data 1 to M.
    [0003]
    3. Method according to claim 1, characterized by the fact that the volume of the impression droplet is equal to X times a fundamental droplet volume, the fundamental droplet volume corresponding to the fundamental period of the ruptured liquid jet in response to data from input image pixel level X, where 1 <X <N.
    [0004]
    4. Method according to claim 1, characterized in that the nozzle (50) is one of several nozzles, the charging electrode (44) of the charging device (83) comprising an electrode that is common and associated with each one of the liquid jets ejected from the nozzles between the different nozzles, where the different nozzles are all the same size.
    [0005]
    5. Method according to claim 1, characterized in that the deflection device (14) additionally comprises at least one deflection electrode (67) to deflect charged drops, the at least one deflection electrode (67) being in contact with electrical communication with one of a source of electrical potential and the earth.
    [0006]
    6. Method according to claim 1, characterized by the fact that the deflection device (14) additionally comprises a deflection electrode (67) in electrical communication with a source of electrical potential that creates a drop deflection field to deflect charged drops.
    [0007]
    Method according to claim 1, characterized by the fact that the print droplet voltage state (95) includes a non-zero DC level.
    [0008]
    8. Method according to claim 1, characterized by the fact that the various waveforms provided to the drop forming device (59) are selected from a set of at least M waveforms, where the various shapes of waveforms each include a distinct sequence of pulses.
    [0009]
    9. Method according to claim 1, characterized by the fact that the various waveforms provided to the drop forming device (59) are selected from a set of at least M waveforms, where a total energy applied the drop formation transducer over the printing period is the same for each of the various waveforms.
    [0010]
    Method according to claim 4, characterized in that the different nozzles (50) are arranged in two or more groups, such that the printing drops from the adjacent nozzles are not aligned.
    类似技术:
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    同族专利:
    公开号 | 公开日
    BR112014031129A2|2017-06-27|
    EP2864121A1|2015-04-29|
    US8641175B2|2014-02-04|
    CN104395086B|2016-03-16|
    JP2015523929A|2015-08-20|
    EP2864121B1|2016-07-20|
    WO2013191959A1|2013-12-27|
    CN104395086A|2015-03-04|
    US20130342597A1|2013-12-26|
    IN2014DN09144A|2015-05-22|
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    法律状态:
    2018-12-04| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2020-02-11| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-12-01| B09A| Decision: intention to grant|
    2021-01-26| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 11/06/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US13/530,171|US8641175B2|2012-06-22|2012-06-22|Variable drop volume continuous liquid jet printing|
    US13/530,171|2012-06-22|
    PCT/US2013/045120|WO2013191959A1|2012-06-22|2013-06-11|Variable drop volume continuous liquid jet printing|
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