CN103547455B - Liquid jetting using droplet charge and mass - Google Patents

Abstract

A continuous liquid ejection system includes a liquid chamber in fluid communication with a nozzle. The liquid chamber contains a liquid that is subjected to a pressure sufficient to eject a jet of liquid through the nozzle. The droplet forming device is associated with a liquid jet. The drop formation device is actuatable to produce a modulation in the liquid jet to selectively cause portions of the liquid jet to break off into one or more drop pairs traveling along a path. Each drop pair is equally separated by drop pair period. Each drop pair includes a first drop and a second drop. The drop formation device can also be actuated to produce a modulation in the liquid jet to selectively cause portions of the liquid jet to break off into one or more third drops traveling along the path that are equally separated by the same drop pair period. The third droplet is larger than the first and second droplets. The charging device includes a charging electrode associated with the liquid jet, and a source of varying electrical potential between the charging electrode and the liquid jet. The source of varying potential provides a waveform comprising a period equal to a drop pair period forming a drop pair or a third drop. The waveform also includes a first distinct voltage state and a second distinct voltage state. The charging device is synchronized with the drop formation device to produce a first charge-to-mass ratio on a first drop of the drop pair, a second charge-to-mass ratio on a second drop of the drop pair, and a third charge-to-mass ratio on a third drop. The third charge-to-mass ratio is substantially the same as the first charge-to-mass ratio. The deflection device causes a first drop of the drop pair having a first charge-to-mass ratio to travel along a first path, and causes a second drop of the drop pair having a second charge-to-mass ratio to travel along a second path, and causes a third drop having a third charge-to-mass ratio to travel along a third path. The third path is substantially the same as the first path.

Description

Liquid jetting using droplet charge and mass

technical field

The present invention relates generally to the field of digitally controlled printing systems and, more particularly, to continuous printing systems in which a liquid stream is divided into drops, some of which are electrostatically deflected.

Background technique

Inkjet printing has been recognized as the most prominent choice in the field of digitally controlled electronic printing, for example due to its non-impact, low-noise properties, its use of plain paper, and its avoidance of toner transfer and fixation. Inkjet printing mechanisms can be classified by technology as drop-on-demand inkjet (DOD) or continuous inkjet (CIJ).

The first technique, "drop-on-demand" inkjet printing, provides ink droplets that strike the recording surface using pressurized actuators (thermal, piezoelectric, etc.). One common drop-on-demand technology uses thermal actuation to eject ink drops from nozzles. A heater located on or near the nozzle heats the ink sufficiently to boil to form a bubble that creates sufficient internal pressure to eject a droplet. This form of inkjet is generally referred to as "thermal inkjet (TIJ)".

The second technique, generally referred to as "continuous" inkjet (CIJ) printing, uses a pressurized ink supply to produce a continuous stream of liquid jet ink by forcing the ink under pressure through a nozzle. The ink stream is perturbed in such a way that the liquid jet breaks up into drops in a predictable manner. Printing occurs by selectively deflecting and capturing unwanted ink droplets. Various methods have been developed for selectively deflecting droplets, including the use of electrostatic deflection, air deflection, and thermal deflection mechanisms.

In the first CIJ method based on electrostatic deflection, the liquid jet is disturbed in such a way that it breaks into uniformly sized droplets at a nominally constant distance (break-off length) from the nozzle. At the nominally constant cut-off point a charging electrode structure is arranged to induce a data-dependent amount of charge on the droplet at the moment of cut-off. The charged droplets are then directed through a region of fixed electrostatic field such that each droplet is deflected proportionally to its charge. Thus, the charge level established at the truncation point causes the droplet to travel to a specific location or channel of the recording medium, commonly known as a catcher, for collection and recirculation. This approach is disclosed in U.S. Patent No. 3,596,275 to R. Sweet, issued July 27, 1971 (hereinafter Sweet '275). The CIJ device disclosed by Sweet '275 consists of a single jet, ie a single droplet generating liquid chamber and a single nozzle structure. A multi-jet CIJ printhead version utilizing this approach is also disclosed in US Patent No. 3,373,437 to Sweet et al., issued March 12, 1968 (hereinafter Sweet '437). Sweet '437 discloses a CIJ printhead having a common drop generator chamber in communication with a row (array) of drop emitting nozzles, each drop emitting nozzle having its own charging electrode. This approach requires each nozzle to have its own charging electrode, each of which is supplied with an electrical waveform dependent on the image data to be printed. This requirement for individually addressable charge electrodes places a limit on the basic nozzle spacing, thereby limiting the resolution of the printing system.

A second electrostatic deflection based CIJ method is disclosed in US Patent No. 6,273,559 to Vago et al., issued August 14, 2001 (hereinafter Vago '559). Vago '559 discloses a binary CIJ technique in which a conductive ink is pressurized and discharged through a calibrated nozzle and the resulting liquid jet is interrupted at two different time intervals. Periodic excitation pulses are used at the nozzle to generate droplets to be printed or not to be printed. Each drop to be printed is established with a relatively strong periodic energization pulse, and the periodic energization pulse causes the inkjet streams forming the drop to be printed to be separated by a relatively short cutoff length. Each non-printing drop is established with a relatively weak periodic excitation pulse, and the periodic excitation pulse causes the drop to be separated by a relatively long cut-off length. Two sets of closely spaced electrodes applying different DC potentials are arranged downstream of the nozzle adjacent to the two truncation positions. Droplets with truncated lengths provide different charge levels. Droplets of longer intercept length are selectively deflected from their path by a deflection device due to their charge and are deflected by the deflection device towards the catcher surface where the droplets are collected into the gutter and returned to the Ink bank for reuse. Vago '559 also requires that the difference in cut-off length between the relatively short cut-off length and the relatively long cut-off length be less than the wavelength (λ), which is the distance between successive drops or dots of ink in a liquid jet . This requires two stimulus levels (printing and non-printing stimulus levels). Restricting the truncation length position difference to be smaller than λ constrains that the excitation amplitude difference must use a small amount. For a printhead with only a single jet, it is very easy to adjust the position of the electrodes, the voltage on the charging electrodes, and the print and non-print excitation amplitudes to produce the desired spacing between printing and non-printing small droplets. However, in printheads with nozzle arrays, component tolerances can make this adjustment very difficult. The need to have high electric field gradients in the small droplet cut-off region makes the droplet selection system sensitive to slight differences in charging electrode flatness, electrode thickness, and electrode-to-jet distance. Different jet distances will lead to different electric field strengths and electric field gradients in the small droplet cut-off region for different liquid jets in the array. Additionally, droplet generators and associated actuation devices may not be perfectly consistent along an array of nozzles, and different actuation amplitudes may be required from nozzle to nozzle to produce a particular cutoff length. These problems are exacerbated by the ink's drifting properties over time and thermal expansion, which can cause the charging electrodes to shift and bend with temperature. In these systems, additional control complexity is required to adjust the print and non-print excitation amplitudes on a nozzle-by-nozzle basis to ensure the desired separation between printing and non-printing of small droplets. In US Patent No. 7,192,121 issued March 20, 2007, B. Barbet and P. Henon also disclosed the use of different truncation lengths to control printing.

Electrostatic charging and deflection mechanisms based on cutoff length and droplet size are disclosed in US Patent No. 7,712,879 to B. Barbet, issued May 11, 2010. A separate common charging electrode is used to charge the small droplet and the large droplet respectively according to the diameter of the droplet, wherein a DC low voltage is applied to the upper part of the common charging electrode and a DC high voltage is applied to the lower part.

In U.S. Patent No. 4,068,241 to T. Yamada, issued January 10, 1978 (hereinafter referred to as Yamada '241), an inkjet recording apparatus that alternately produces large and small droplets is disclosed. In the cut-off region of the liquid jet, all droplets are charged with a DC electrostatic field. Yamada '241 also varies the excitation droplet amplitude for small droplets that do not need to be recorded so that they will collide and combine with larger droplets. The large droplet and the large droplet combined with the small droplet are collected by the gutter and not printed, while the deflected small droplet is printed. One of the disadvantages of this approach is that deflected droplets are printed, which can lead to drop placement errors. This method is very sensitive to small changes in excitation amplitude as well as small changes in ink properties. Additionally, since smaller droplets need to be much smaller than larger droplets to establish a different charge state on each droplet, higher nozzle diameter nozzles are required to produce print droplets of the desired size. This limits the density of nozzle spacing that can be used in this approach and severely limits the ability to print high-resolution images.

Accordingly, there continues to be a need to provide a continuous printing system that electrostatically deflects selected drops, can accommodate different drop intercept lengths, has a simplified design, and produces improved print quality.

Contents of the invention

It is an object of the present invention to establish high resolution, high quality printing by using mass charging and electrostatic deflection for CMOS-MEMS printheads while maintaining or improving drop placement accuracy and minimizing printed droplets The difference in droplet volume, thereby overcoming at least one of the above-mentioned disadvantages.

The present invention provides image data dependent control of droplet formation via truncation of each liquid jet and charging electrodes with time varying potentials (called charging electrode waveforms) independent of image data. Drop formation is controlled using a drop formation waveform provided to the drop formation device to create a drop pair comprising a first drop and a second drop, or to create a third drop. The third droplet is larger (in size or volume) than the first droplet and the second droplet in the droplet pair. synchronizing the charge electrode waveform and the drop formation waveform to alternately charge the first droplet of the drop pair to a first charge-to-mass ratio and the second droplet of the drop pair to a second charge-to-mass ratio, Or charge the larger third droplet to a third charge-to-mass ratio state.

The present invention helps provide system robustness by allowing greater tolerance for differences in off-time between jets in long nozzle arrays. In addition, at least every other droplet is collected by the catcher, which helps to ensure that the liquid remains on the catcher, which reduces the possibility of liquid splashing during operation. The present invention reduces the complexity of the control of the signals sent to the actuation devices associated with the nozzles in the nozzle array. This helps reduce the complexity of the charge electrode structure and increases the spacing between the charge electrode structure and the nozzle.

According to one aspect of the present invention, a continuous liquid injection system is provided. The system includes a liquid chamber in fluid communication with the nozzle. The liquid chamber contains a liquid which is subjected to a pressure sufficient to eject a jet of liquid through the nozzle. A drop forming device is associated with the liquid jet. The drop forming device is actuatable to create a modulation in the liquid jet to selectively cause portions of the liquid jet to break off into one or more pairs of droplets traveling along a path. Each droplet pair is evenly separated by droplet pair period. Each drop pair includes a first drop and a second drop. The drop forming device may also be actuatable to create a modulation in the liquid jet to selectively cause portions of the liquid jet to break off into one or more third droplets traveling along said path, said third droplets Split evenly by the same droplet pair period. The third droplet is larger than the first droplet and the second droplet. The charging device includes a charging electrode associated with the liquid jet, and a source of varying electrical potential between the charging electrode and the liquid jet. The source of varying potential provides a waveform comprising a period equal to the period of the drop pair forming the drop pair or the third drop. The waveform also includes a first distinct voltage state and a second distinct voltage state. The charging device is synchronized with the drop forming device to produce a first charge-to-mass ratio on a first droplet of the pair, a second charge-to-mass ratio on a second droplet of the pair, and a third charge-to-mass ratio on a second droplet of the pair A third charge-to-mass ratio occurs on the droplet. The third charge-to-mass ratio is substantially the same as the first charge-to-mass ratio. a deflection device causes a first droplet of the droplet pair having a first charge-to-mass ratio to follow a first path and a second droplet of the droplet pair having a second charge-to-mass ratio to follow a second path, and A third droplet having a third charge to mass ratio is caused to travel along a third path. The third path is basically the same as the first path.

Description of drawings

In the following detailed description of the preferred embodiments of the invention, reference is made to the accompanying drawings, in which:

Figure 1 is a simplified schematic block diagram of an exemplary continuous inkjet system according to the present invention;

Figure 2 shows an image of a liquid jet ejected from a droplet generator and its subsequent truncation into droplets with fundamental periods;

Figure 3 is a simplified schematic block diagram of a nozzle and associated jet excitation device according to one embodiment of the present invention;

Figure 4A shows a cross-sectional view of a liquid jet through a first embodiment of a continuous liquid ejection system in accordance with the present invention and operating under full printing conditions;

Figure 4B shows a cross-sectional view of a liquid jet through a first embodiment of a continuous liquid ejection system in accordance with the present invention and operating under non-printing conditions;

Figure 4C shows a cross-sectional view of a liquid jet through a first embodiment of a continuous liquid ejection system according to the present invention and illustrates general printing conditions;

Figure 5A shows a cross-sectional view of a liquid jet through an alternate embodiment of a continuous liquid ejection system in accordance with the present invention and operating under full printing conditions;

Figure 5B shows a cross-sectional view of a liquid jet through an alternative embodiment of a continuous liquid ejection system in accordance with the present invention and operating under non-printing conditions;

Figure 5C shows a cross-sectional view of a liquid jet through a first embodiment of a continuous liquid ejection system in accordance with the present invention and operating under typical printing conditions;

Figure 6A shows a cross-sectional view of a liquid jet through a second alternative embodiment of a continuous liquid ejection system in accordance with the present invention and operating under full printing conditions;

Figure 6B shows a cross-sectional view of a liquid jet through a second alternative embodiment of a continuous liquid ejection system in accordance with the present invention and operating under non-printing conditions;

Figure 7 shows images of a liquid jet ejected from a droplet generator and its subsequent truncating into droplets generated at half the fundamental frequency; A shows a droplet pair that is truncated as a single droplet and remains grouped together, B C shows droplet pairs truncated as single droplets, separated and then recombined, and C shows droplets truncated individually with similar truncation moments and then recombined into single droplets;

Figure 8 shows a front view of droplets produced from a jet stream producing successive pairs of droplets in a time-lapse sequence from a to h, in accordance with the continuous liquid ejection system of the present invention;

Figure 9 shows a front view of several adjacent liquid jets of the continuous liquid ejection system of the present invention;

FIG. 10 shows a first exemplary embodiment of a timing diagram illustrating drop formation pulses, charge electrode waveforms, and break-off moments of a drop;

FIG. 11 shows a second exemplary embodiment of a timing diagram illustrating drop formation pulses, charging electrode waveforms, and moment of break-off of a drop; and

12 is a block diagram of a droplet ejection method according to an embodiment of the present invention.

Detailed ways

The description will be directed in particular to elements forming part of, or cooperating more directly with, a device according to the invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. In the following description and drawings, the same reference numerals have been used, where possible, to refer to the same elements.

Exemplary embodiments of the present invention are shown schematically and not to scale for the sake of clarity. Those of ordinary skill in the art will readily be able to determine the specific dimensions and interrelationships of the elements of the exemplary embodiments of the invention.

As described herein, exemplary embodiments of the present invention provide a printhead or printhead assembly commonly used in inkjet printing systems. In these systems, the liquid is the ink used to print on the recording medium. However, other applications are emerging that use inkjet printheads to emit (in addition to ink) liquids that require fine measurement and deposition with high spatial resolution. Thus, as used herein, the terms "liquid" and "ink" refer to any substance that may be ejected by a printhead or printhead assembly as described below.

Continuous inkjet (CIJ) droplet generators rely on the physics of unconstrained liquid jets, as described in the 1878 article "Instability of jets" by FRS (Lord) Rayleigh (Proc .London Math.Soc.10(4)), the first two-dimensional analysis of the physics of this unconstrained liquid jet. Lord Rayleigh's analysis shows that the liquid, under pressure P, will flow out of the orifice, the nozzle, forming a liquid jet with diameter _dj and moving at velocity _vj . The jet diameter _dj is approximately equal to the effective nozzle diameter dn and the jet velocity is proportional to the square root of the liquid reservoir pressure P. Rayleigh's analysis shows that the jet will naturally break up into droplets of various sizes based on surface waves having a wavelength λ greater than _πdj , ie, _λ≥πdj . Rayleigh's analysis also showed that if a specific surface wavelength is launched with a sufficiently large amplitude, that specific surface wavelength will become dominant, thereby "stimulating" the jet to produce a single-sized droplet. Continuous inkjet (CIJ) drop generators employ a periodic physical process (so-called "perturbation" or "excitation") that has the effect of establishing a specific dominant surface wave on the jet. The excitation causes the jet to break up into single-sized droplets synchronously with the fundamental frequency of the disturbance. It has been shown that the maximum efficiency of jet cut-off occurs at an optimum frequency F _opt which _results in the shortest cut-off time. At the optimum frequency F _opt , the perturbation wavelength λ is approximately equal to 4.5d _j . The frequency at which the perturbation wavelength λ is equal to _πdj is called the _Rayleigh cut-off frequency FR because perturbations of the liquid jet at frequencies higher than this cut-off frequency will not become large enough to cause droplets to form.

The flow of droplets produced by applying Rayleigh excitation is referred to herein as creating a flow of droplets of predetermined volume. Although in prior art CIJ systems the droplets of interest used for printing or patterned layer deposition invariably have a uniform volume, it will be explained that for the present invention the excitation signal can be manipulated to produce a predetermined volume of uniform volume. Droplets of multiple volumes. Thus, the phrase "a stream of droplets of a predetermined volume" includes a stream of droplets that is truncated into droplets of one size or a stream of droplets that is truncated into droplets of a planned different volume.

In a CIJ system, droplets commonly referred to as "satellites" can form as necks of liquid flowing down into thin ribbons, and these "satellites" are much smaller than a predetermined unit volume. These satellites may not be completely predictable, or may not always mix with additional droplets in a predictable manner, slightly changing the volume of droplets required to be used for printing or mapping. However, the presence of unpredictable satellite droplets is not critical to the present invention and is not considered to eliminate the fact that the droplet size has been predetermined by the synchronization energy signal used by the present invention. Accordingly, the term "predetermined volume" as used to describe the present invention should be understood to mean that some small variations in droplet volume from the planned target value may occur due to the formation of unpredictable satellite droplets.

The exemplary embodiments discussed below with reference to FIGS. 1-12 are described using specific combinations of components, such as droplet charging structures, droplet deflection structures, droplet capture structures, droplet formation devices, and droplet velocity adjustments. A specific combination of devices. It should be understood that these components are interchangeable and other combinations of these components are within the scope of the invention.

A continuous inkjet printing system 10 as shown in FIG. 1 includes an ink reservoir 11 that continuously pumps ink into a printhead 12 (also called a liquid ejector) to create a continuous stream of ink droplets. The printing system 10 receives digitized image processing data from an image source 13 such as a scanner, computer, or digital camera, or other digital data source that provides raster image data, outline image data in the form of a page description language, or other form of digital image data. Image data from image source 13 is periodically sent to image processor 16 . The image processor 16 processes image data and includes memory for storing image data. Image processor 16 is typically a raster image processor (RIP). The image data stored in the image memory of the image processor 16 (also referred to as print data) in the image processor 16 is periodically sent to the drive controller 18, which, as will be described below, generates A time-varying pattern of electrical energization pulses is applied such that a stream of droplets is formed at the opening of each nozzle of the printhead 12 . These excitation pulses are applied to the excitation device(s) associated with each nozzle at the appropriate time and at the appropriate frequency. The printhead 12 and deflection mechanism 14 cooperate to determine whether the droplet is printed on the recording medium 19 at the proper location specified by the data in the image memory, or is deflected and recovered via the ink recovery unit 15 . Ink in the ink recovery unit 15 is led back to the ink reservoir 11 . Ink is dispensed under pressure to the rear surface of printhead 12 through ink channels comprising cavities or filled spaces formed in a substrate, typically composed of silicon. Alternatively, the cavity may be formed in a manifold piece to which the silicon substrate is attached. Ink preferably flows from the chamber through slits and/or holes etched through the silicon substrate of the printhead 12 to the front surface of the printhead 12 where a plurality of nozzles and actuation devices are located. Ink pressure for optimal operation will depend on several factors including the geometry and thermal properties of the nozzle as well as the thermal and fluid dynamic properties of the ink. A constant ink pressure is achieved by applying pressure to the ink reservoir 11 under the control of the ink pressure regulator 20 .

A well-known problem with any type of inkjet printer, whether drop-on-demand or continuous, is related to the accuracy of dot positioning. As is known in the art of inkjet printing, it is generally desirable to place one or more droplets on a receiver within pixel areas (pixels), eg corresponding to pixels containing information of a digital image. In general, these pixel areas consist of a real or hypothetical array of squares or rectangles on the receiver, and it is desired to place a printer droplet at a desired location within each pixel, e.g., for a simple printing scheme, at each The center of the pixel area, or alternatively, multiple precise locations within each pixel area to achieve half-toning. Image artifacts can occur if droplet landing is inaccurate and/or droplet landing cannot be controlled to achieve the desired landing within each pixel area, if repeating distances from desired position on adjacent pixel areas This is especially true for similar types of deviations. A RIP or other type of processor 16 converts the image data into image-mapped image page images for printing. During printing, recording medium 19 is moved relative to printhead 12 using a plurality of transport rollers 22 that are electronically controlled by a media transport controller 21 . A logic controller 17 (preferably microprocessor based and suitably programmed in a known manner) provides control signals for cooperating transport controller 21 with ink pressure regulator 20 and actuation controller 18 . Actuation controller 18 includes a drop controller that provides drop formation pulses for ejecting individual ink drops from printhead 12 to A drive signal for the recording medium 19. The image data may include raw image data, additional image data generated from image processing algorithms to enhance the quality of the printed image, and data from drop point correction, which may be generated from a number of sources, Generated, for example, by measuring the operational error of each nozzle in printhead 12, well known to those skilled in the art of printhead characterization and image processing. Thus, it can be said that the information in the image processor 16 represents a general source of data for droplet ejection, such as the desired location of ink droplets to be printed and the identification of those droplets to be collected for recycling.

It should be appreciated that different mechanical configurations for receiver transmission control may be used. For example, in the case of pagewide printheads, it is convenient to move the recording medium 19 past a stationary printhead 12 . On the other hand, in the case of scanning-type printing systems, it is more convenient to move the printhead along one axis (i.e., the main scanning direction) and the recording medium along an orthogonal axis (i.e., the sub-scanning direction) in a relative raster motion. .

The drop formation pulses are provided by an actuation controller 18, which may generally be referred to as a drop controller, and as is known in the art of signal transmission, the drop formation pulses are typically voltages sent to the printhead 12 via an electrical connector. pulse. However, other types of pulses, such as optical pulses, may also be sent to the printhead 12 to cause printing and non-printing drops to form at particular nozzles, as is known in the art of inkjet printing. As will be described below, the print droplets, once formed, travel through space to the recording medium, and then hit specific pixel regions of the recording medium or are collected by a catcher.

Referring to FIG. 2 , the printing system has associated therewith a printhead operable to generate an array of liquid jets 43 from an array of nozzles 50 . Associated with each liquid jet 43 is a drop forming device 89 . The drop formation apparatus comprises a drop formation transducer 59 and a drop formation waveform source 56 providing a waveform 55 (also referred to as a drop formation waveform) to the drop formation transducer. The droplet forming transducers (commonly called actuation transducers) can be of any type suitable for creating a disturbance on a liquid jet, such as thermal devices, piezoelectric devices, MEMS actuators, electrohydrodynamic devices, optical devices, electrical Scalable devices or combinations thereof. FIG. 3 shows an example of a thermal drop formation transducer 59 consisting of a resistive load driven by a voltage provided by excitation waveform source 56 . Depending on the type of transducer used, the transducer may be located in or near the liquid chamber supplying the nozzle to act on the liquid in the liquid chamber, or in or immediately around the nozzle to act upon the liquid passing through the nozzle. The nozzle acts on the liquid, or is positioned adjacent to the liquid jet to act on the liquid jet after it passes through the nozzle. The droplet forming waveform source provides a waveform to the droplet forming transducer, the waveform has a fundamental frequency f ₀ , and the corresponding fundamental period is T ₀ =1/f ₀ , and the droplet forming transducer operates at a wavelength λ to modulate. The fundamental frequency f ₀ is usually close to F _opt and is always smaller than FR _. The modulation amplitude is increased so that portions of the liquid jet are broken into droplets. Through the action of the drop forming device, a sequence of droplets can be generated at a fundamental frequency f ₀ with a fundamental period T ₀ =1/f ₀ . In FIG. 2 , the liquid jet 43 is broken into droplets with a uniform period at the break-off position 32 , which is the distance BL from the nozzle 50 . The distance between a pair of consecutive droplets 35 and 36 generated at the fundamental frequency is substantially equal to the wavelength λ of the disturbance on the liquid jet. This sequence of droplets broken off from the liquid jet forms a sequence of drop pairs 34 each having a first drop 36 and a second drop 35 . Thus, the formation frequency of drop pairs 34 (commonly referred to as drop pair frequency f _p ) is given by f _p =f ₀ /2 and the corresponding drop pair period is T _p =2T ₀ .

The generation of droplets is associated with the energy provided by the droplet forming device operating at a fundamental frequency _{f 0} which generates droplets having substantially the same volume separated by a distance λ. It will be appreciated that although the first and second droplets have substantially the same volume in the embodiment shown in FIG. First and second droplet pairs are generated. For example, the volume ratio of the first droplet to the second droplet can vary between about 4:3 and about 3:4. The activation of the liquid jet 43 in FIG. 2 is independently controlled by the drop formation transducer associated with the liquid jet or nozzle 50 . In one embodiment, drop formation transducer 59 includes one or more resistive elements adjacent to nozzle 50 . In this embodiment, liquid jet excitation is achieved by sending arbitrarily shaped periodic current pulses provided by a drop formation waveform source through resistive elements surrounding each opening of the drop generator .

The formation of droplets from a liquid stream ejected from an inkjet nozzle can be controlled by a waveform in which the amplitude, duty cycle, or timing of other pulses in the waveform or sequence of waveforms applied to each dropforming transducer At least one of is associated with a particular nozzle opening. The drop formation pulses of the drop formation waveform can be controlled such that two consecutive fundamental wavelength long portions of the jet form two consecutive droplets or form a single larger droplet. Larger droplets will be generated at half the fundamental frequency and have an average spacing between adjacent large droplets of 2λ.

FIG. 2 also shows a charging device 83 comprising a charging electrode 44 and a charging voltage source 51 . The charge voltage source 51 provides a charge electrode waveform 97 that controls the voltage amplitude and duty cycle of the charge electrode voltage output over time. The charging electrode 44 associated with the liquid jet is located near the break-off point 32 of the liquid jet 43 . If a non-zero voltage is applied to the charging electrode 44, an electric field is created between the charging electrode and the electrically grounded liquid jet. Capacitive coupling between the charging electrode and the electrically grounded liquid jet induces a net charge at the end of the conductive liquid jet. (The liquid jet is grounded by contact with the liquid chamber of a grounded drop generator.) If the terminal portion of the liquid jet intercepts to form a droplet while there is a net charge on the tip of the liquid jet, the liquid jet's The charge from the terminal portion is then trapped in the newly formed droplet.

The voltage on the charge electrode 44 is controlled by the charge pulse source 51 which provides a binary waveform 97 operating at a frequency equal to fp _{= f0} /2 (which is half the fundamental frequency) The drop pair frequency, or equivalently, operates on the drop pair period T _p =2T ₀ (which is twice the fundamental period). Thus, the charging pulse voltage source 51 provides a varying electrical potential 97 between the charging electrode 44 and the liquid jet 43 . In FIG. 2, the charge electrode waveform 97 includes a first and a second differentiated voltage state, each voltage state being active for a time interval equal to a fundamental period. The waveform provided to the charging electrodes is independent of, or not responsive to, the image data to be printed. The charging device 83 is synchronized with the drop formation device such that a fixed phase relationship is maintained between the charge electrode waveform generated by the charge pulse voltage source 51 and the clock of the drop formation waveform source. As a result, the truncation phase of droplets from the liquid stream produced by the droplet formation waveform is phase locked to the charging electrode waveform. As indicated in Figure 10, there may be a phase shift (represented by delay 93) between the charge electrode waveform and the drop formation waveform. The phase shift is set such that for each drop pair produced, a first drop is cut off from the jet when the charge electrode is in a first voltage state and a drop is cut off from the jet when the charge electrode is in a second voltage state The second droplet of the drop pair, the first voltage state produces a first charge-to-mass ratio state on the first droplet 36, and the second voltage state produces a second charge state on the second droplet 35 of the droplet pair. quality ratio status. Droplet pairs generated from portions of the jet having a length of two consecutive fundamental wavelengths are in response to appropriate droplet formation waveforms 55 supplied to excitation transducer 59 .

As noted above, other drop formation waveforms may be used to form large droplets 49 from portions of the jet that are two consecutive fundamental wavelengths long. By using an appropriate drop formation waveform, the portion of the jet that is cut off to form large droplets 49 can be made to cut off from the jet when the charge electrode is in the first voltage state (see FIG. 4B ). Similar formed large droplets 49 are generated with off-times separated in time according to droplet pair frequency and with off-times synchronized with the first voltage state of the charge electrode. Thus, the time interval between the formation of successive large droplets 49 is substantially equal to the time interval between the formation of successive pairs of droplets 34 . Large droplet 49 has a mass approximately equal to the sum of the masses of droplets 35 and 36 and is charged to approximately equal to droplet 35 when intercepted, compared to first droplet 36 which intercepts in the corresponding voltage state of the charge electrode. and twice the charge on 36. Thus, the charge-to-mass ratio on the large droplet 49 intercepted at the first voltage state of the charge electrode is substantially equal to the charge-to-mass ratio of the first droplet 36 of the droplet pair. Since the charge-to-mass ratio on large droplets 49 is substantially equal to the charge-to-mass ratio of droplets 36, the drop deflection electric field will cause charged large droplets 49 to deflect substantially the same amount as they deflect corresponding smaller droplets. The waveforms used to form large and small droplets and the phases of drop break-off with the charge electrode waveform are discussed in more detail later.

Figures 4A-6B illustrate various embodiments of the invention in which drop pairs 35 and 36 or a single large drop 49 are intercepted from liquid jet 43 during each drop pair cycle. Figures 4A, 5A and 6A illustrate various embodiments in an all-print mode, where a continuous sequence of drop pairs is generated at a fundamental frequency twice the drop pair frequency, and every other drop is printed. Figures 4B, 5B and 6B illustrate various embodiments in a non-printing mode in which a continuous sequence of larger droplets 49 having a mass approximately equal to the sum of the masses of droplets 35 and 36 is generated at the drop pair frequency and No droplets are printed. Figures 4C and 5C illustrate a normal printing mode in which during a drop pair cycle both drop pairs and larger drops are produced and one drop of each formed drop pair is printed. Therefore, an arbitrary dot pattern can be printed on the recording medium 19 by controlling the jet cutoff to form a droplet pair 34 or a large droplet 49 for each pixel. Typically, the drop pair frequency of the drop actuation transducers for the entire array of nozzles 50 in the printhead is the same for all nozzles in the printhead 12 .

In various embodiments of the invention, the first drop 36 of the drop pair has a first charge state and travels along a first path, and the second drop 35 of the drop pair has a second charge state and travels along a second path. path travel. A catcher is arranged to intercept the first path, and the catcher does not intercept the second path, so that a first droplet 36 traveling along the first path is caught by the catcher, while a second droplet 35 traveling along the second path Not caught by the catcher. The terms "first droplet" and "second droplet" and the terms "first voltage state" and "second voltage state" are not intended to indicate a chronological order in which droplets or voltage states are established. In Figures 6A and 6B, the first charge state is shown as possessing a negative charge. In an alternate embodiment, the first and second waveform states are configured such that the first droplet is positively charged rather than negatively charged. In the embodiment of FIG. 5, the first state of charge corresponds to an uncharged droplet state and the second state of charge corresponds to a second droplet that is charged. The second state of charge is shown as possessing a negative charge. In an alternate embodiment, the second state of charge may correspond to a positive charge.

A drop forming device 89 is associated with the liquid jet 43 . As shown in FIG. 3 , the droplet forming device consists of an excitation transducer 59 and an excitation waveform source 56 . An excitation waveform source 56 provides an excitation waveform 55 to an excitation transducer 59 which creates a disturbance in the liquid jet 43 flowing through the nozzle 50 . The amplitude, duration and timing of the energy pulses of the excitation waveform 55 determine the droplet formation, including the moment of break-off or phase. The time interval between the truncation of consecutive droplets determines the droplet size. Data from the excitation controller 18 (shown in FIG. 1 ) is sent to the excitation waveform source 56 where the data is converted into a time-varying pattern of voltage pulses such that droplets are formed at the opening of the nozzle 50 flow. The droplet-specific excitation waveform 55 provided to the excitation transducer 59 by the excitation waveform source 56 determines the moment of break-off of successive droplets as well as the size of the droplet. The drop firing waveform is varied in response to print or image data provided by image processor 16 to firing controller 18 . Thus, the timing of the energy pulses from the excitation waveform applied to the excitation transducers depends on the print or image data. When the print data stream calls for a drop to be printed on a pixel, the waveform provided to the excitation transducer is one that will produce pairs of drops equally spaced in time at the fundamental frequency, one of which will be printed . When the print data stream requires a sequence of pixels to be printed, the sequence of waveforms supplied to the drive transducers produces a sequence of drop pairs, and the same drop in each drop pair will be printed. When the print data calls for a non-print drop, the waveform provided to the fire transducer is one that will produce a large drop, and when the print data calls for a sequence of non-print drops, the waveform provided to the fire transducer is a waveform that will produce a large drop. Waveform of a droplet sequence. None of these large droplets will be printed. In some embodiments, the sequence of waveforms created based on the print data stream includes a sequence of waveforms selected from a set of predetermined waveforms. The set of predetermined waveforms includes one or more waveforms for creating drop pairs in which the droplets in the drop pairs do not mix and one or more waveforms for creating large droplets. It has been found that the droplet formation pulse of the droplet formation waveform can be tuned to form a single larger droplet through several different modes; as shown in Figure 7A, the part of the jet that is two consecutive fundamental wavelengths long can be truncated A unit formed into a single larger droplet that stays together; as shown in Figure 7B, portions of the jet having two consecutive fundamental wavelength lengths can be truncated together as a single larger droplet that The droplet then splits into two droplets, which are then remixed together; or, as shown in Figure 7C, a portion of the jet having two consecutive fundamental wavelength lengths can be truncated into two separate droplets, the two The individual droplets are then mixed into larger droplets. The waveform such that the portion of the jet having two consecutive fundamental wavelengths long is truncated into two separate droplets and the two separate droplets are subsequently mixed into one larger droplet as shown in FIG. 7C can be further adjusted to The truncation phases of two separated droplets are brought close to each other. Thus, two droplets mixing to form a larger droplet can be cut off from the jet when the charging electrode is in the first voltage state. As a result, the two droplets that mix to form a large droplet are similarly charged to the first state of charge. The mixing of these droplets produces a large droplet 49 having a mass equal to the sum of the masses of the constituent droplets and a charge equal to the sum of the charges of the constituent droplets. The combined large droplet formed from constituent droplets with nearly simultaneous droplet truncation has a third charge-to-mass ratio. The third charge-to-mass ratio state is similar to the first charge-to-mass ratio state. It is also possible that when the drop formation waveform is adjusted or selected such that the cut-off phase of the two drops of a drop pair is cut off when the charge electrode is in the first voltage state, the two drops will Will not mix. These droplets will each have approximately the same charge-to-mass ratio as the first droplet.

Consider a macrodroplet 49 formed from a portion of the jet having two consecutive fundamental wavelengths long and truncated into a unit to form a single macrodroplet when the charge electrode is in a first voltage state. The charge induced on the cut-off portion of the liquid jet is related to the surface area of the portion and to the electric field strength at the surface of the portion. When the surface area of the portion truncated to form a large droplet is approximately twice the surface area of the portion truncated to form a first droplet, and the electric field provided by the charging electrode is compatible with that provided by the charging electrode to the first droplet in the droplet pair When the electric field is similar, the charge induced on the large droplet upon break-off is about twice that of the first droplet in the droplet pair. Since the macrodroplet has a mass approximately equal to approximately twice the mass of the first droplet in the pair, the mass formed by portions of the jet that are two consecutive fundamental wavelengths long, truncated together into a single macrodroplet The charge-to-mass ratio of the large droplet is approximately equal to the charge-to-mass ratio state of the first charge-to-mass ratio state. The charge-to-mass ratio of large droplets formed from portions of the jet that are two consecutive fundamental wavelengths long does not depend on whether the large droplet truncates into two droplets that subsequently merge or never separate.

4A-6B illustrate various embodiments of the continuous liquid ejection system 40 described in detail herein, as well as certain various embodiments of the charging device 83 and deflection mechanism 14 included in the continuous liquid ejection system 40 . The continuous liquid jetting system 40 embodiment includes components described with reference to the continuous ink jetting system shown in FIG. 1 . The continuous liquid ejection system 40 embodiment includes a liquid ejector or printhead 12 that includes a liquid chamber 24 in fluid communication with a nozzle 50 or array of nozzles. (In these figures, the array of nozzles will extend both in and out of the plane of the drawing.) Liquid chamber 24 contains liquid under pressure sufficient to continuously eject liquid jets 43 through nozzles 50 . Each liquid jet has a drop forming device 89 associated therewith. The drop formation device 89 includes a drop formation device transducer 59 and a drop formation waveform source 56 which provides an excitation waveform 55 operable to produce a modulation in the liquid jet such that The continuous fundamental wavelength long portion of the liquid jet is broken up into a series of drop pairs comprising the first droplet 36 and the second droplet 35 following the initial path or a series of larger droplets 49 following the same initial path . The waveform provided by waveform source 56 is adjusted or selected such that drop pairs 35 and 36 or larger drop 49 are generated during each drop pair cycle. The continuous liquid ejection system also includes a charging device 83 comprising a charging electrode 44 or 45 associated with the array of liquid jets and a source of varying electrical potential 51 between the charging electrode and the liquid jets. The source of varying potential 51 applies a charge electrode waveform 97 having a period equal to the drop pair period to the charge electrode. The waveform includes a first distinct voltage state and a second distinct voltage state. As described with reference to FIG. 2, the charging electrode 44 is arranged so as to be adjacent to the location where the liquid jet breaks off in the nozzle array. The charging device is synchronized with the drop forming device so that the first voltage state is active when the first droplet 36 of the droplet pair intercepts adjacent to the electrode and the second voltage state is active when the second droplet 35 of the droplet pair Active when adjacent electrodes are truncated. As a result of the electric fields generated by the charging electrodes in the first and second voltage states, a first charge-to-mass ratio state is created on the first droplet of each droplet pair and a second charge-to-mass ratio state is created on the second droplet. Two charge-to-mass ratio states. The charging device is also synchronized with the drop forming device so that only the first voltage state is active when a large drop 49 or temporally closely separated droplets 49a and 49b are intercepted adjacent to the charging electrode 44, said droplets 49a and 49b Closely truncated in time and subsequently combined into a single large droplet 49 . Thus, a third charge-to-mass state is created on the large droplet 49 . The third charge-to-mass ratio state is similar to the first charge-to-mass ratio state.

In the embodiment shown in FIGS. 4A-4C , charge electrode 44 is part of deflection device 14 . The electrically biased charging electrode 44, located on the side of the liquid jet adjacent the break-off point, not only attracts a charge to the end of the jet before the drop breaks off, but also attracts the charged liquid after the drop breaks off from the liquid jet. drop. This deflection mechanism has been described in J.A. Katerberg's paper "Dropcharging and deflection using a planar charge plate" (4th International Conference on Advances in Non-Impact Printing Technologies). The catcher 47 also forms part of the deflection device 14 . As described in U.S. Pat. No. 3,656,171, a charged droplet passing in front of the conductive catcher surface causes a surface charge on the conductive catcher surface 52 such that the charged droplet attaches to the catcher. way on the surface 52 to redistribute.

To selectively print the droplets onto the substrate, a catcher is used to intercept the droplets traveling along the first and third paths. 4A-4C and 6A-6B illustrate embodiments in which the catcher intercepts droplets traveling along the first and third paths, while allowing droplets traveling along the second path to contact the substrate and be printed. In these embodiments, the first and third charge states are charged more strongly than the second charge state. Figures 5A-5C illustrate an embodiment in which a catcher intercepts droplets traveling along the first and third paths, while allowing droplets traveling along the first path to contact the substrate and be printed. In this embodiment, the second state of charge is charged more strongly than the first and third states of charge.

4A-4C show cross-sectional views of the main components of a continuous liquid ejection system and show different printing modes of the first embodiment of the present invention. The continuous liquid ejection system includes a printhead 12 that includes a liquid chamber 24 in fluid communication with an array of one or more nozzles 50 for emitting a stream 43 of liquid. Each liquid jet is associated with an excitation transducer 59 . In the illustrated embodiment, the excitation transducer 59 is formed in the wall around the nozzle 50 . A separate excitation transducer 59 may be integrated with each of the plurality of nozzles. The excitation transducer 59 is actuated by a drop formation waveform source 56 which provides periodic excitation of the liquid jet 43 .

A grounded catch 47 is located below the charge electrode 44 . The purpose of the catcher 47 is to intercept or collect the charged droplets so that the droplets do not touch and are printed on the print medium or substrate 19 . For proper operation of the printhead 12 shown in FIG. 4A and subsequent figures, the catcher 47 and/or catcher base plate 57 are grounded to allow the intercepted ink to flow below the catcher surface 52 and into the ink return channel 58. The charge on the droplet dissipates. The catcher surface 52 of the catcher 47 has an angle Θ with respect to the liquid jet axis 87 shown in FIG. 2 . As shown in FIG. 4A , the charged droplet 36 attaches to the catcher surface 52 of the grounded catcher 47 . Droplet 36 intercepts catcher surface 52 at charged droplet catcher contact point 26 to form ink film 48 that travels below the surface of catcher 47 . The bottom of the catcher has a curved surface of radius R and includes a bottom catcher plate 57 and an ink recovery channel 58 above the bottom catcher plate 57 for capturing and recycling ink in the ink film 48 . If there is a positive voltage potential difference from the electrode 44 to the liquid jet 43 at the break-off time of the drop adjacent to the electrode break-off, a negative charge will be induced on the formed droplet which will be removed after the drop is broken off from the liquid jet. reserve. If there were no voltage potential difference from the electrode 44 to the liquid jet 43 at the time of drop interception, it would be expected that no charge would be induced on the formed droplet that would remain after the droplet is intercepted from the liquid jet. However, due to the capacitive coupling of the second droplet 35 intercepted from the liquid jet to the charged first droplet 36, a small charge is induced on the second droplet even when the charging electrode is at 0V in the second state of charge. charge.

To simplify the understanding of the invention, FIGS. 4A-4C are plotted for the case where the second state of charge is close to zero charge, such that the presence of little or no second droplet 35 in the droplet pair is dictated by the direction of the second path 37. deflection shown. For ease of understanding, the second path 37 is drawn to correspond to the liquid jet axis 87 shown in FIG. 2 . In fact, there may be a small charge on the droplets along the second path, in which case the path 37 will deviate from the liquid jet axis 87 . The first droplet 36 of the droplet pair is in a highly charged state such that the first droplet 36 is deflected as it travels along the first path 38 . Thus, the invention allows printing one print drop per drop pair period with a drop pair frequency f _p =f ₀ /2 or a drop pair period T _p =2T ₀ . We define this as the small droplet printing mode, in contrast to the large droplet printing mode, which achieves the printing of one droplet in a droplet pair formed at the fundamental frequency _f0 , The fundamental frequency f ₀ can be adjusted to the optimum frequency for jet cutoff, in the large droplet printing mode, where large combined droplets are used for printing.

As mentioned above, a small charge is induced on the second droplet even when the charge electrode is at 0V in the second state of charge. Therefore, the second droplet will experience a small deflection. In some embodiments, the charge induced in the second drop row by the charge of the first droplet is neutralized by changing the second voltage state of the charge electrode waveform. Instead of using 0V in the second voltage state, a small offset from 0V is used. The offset voltage is selected so that the charge induced during the second voltage state on the droplet intercepted adjacent to the charge electrode is of the same magnitude and of opposite polarity as the charge induced on the intercepted droplet by the previous droplet. The result is substantially charge-free droplets that experience substantially no deflection due to electrostatic forces. The amount of DC offset depends on the specific configuration of the system (including, for example, whether one charging electrode or two charging electrodes are used in the system) or the geometry of the system (including, for example, the relative Location). Typically, the range from the second voltage state to the first voltage state is between 33% and 10%. For example, in some applications, when the first voltage state includes 200 volts, the second voltage state includes a DC offset of 50 volts (25% of the first voltage state).

The consecutive droplets 36 and 35 are considered to be a droplet pair, wherein the first droplet 36 of the droplet pair is charged to the first charge-to-mass ratio state by the charging electrode, and the second droplet 35 of the droplet pair is charged to the first charge-to-mass ratio state by the charging electrode. The second charge-to-mass ratio state. Figure 4A shows a full print condition where long sequences of drop pairs are formed. Due to the different charge-to-mass ratios on these two droplets, they experience different amounts of deflection caused by deflection device 14, which includes grounded trench 47 and charging device 83, which includes electrodes 44, a charging voltage source 51 and charging electrode waveform 97. Charge electrode waveform 97 is independent of print data and has a repetition frequency of half the fundamental frequency of drop formation of drops 35 and 36 . The first drop 36 is deflected to follow the first path 38, while the second drop 35 follows the second path 37 to strike the recording medium 19, thereby depositing the printed ink drop 46 while the recording medium 19 is moving at a velocity _v to the recording medium.

4A shows a cross-sectional view through a liquid jet 43 of a first embodiment of a continuous inkjet system according to the present invention, and shows a sequence of drop pairs under full printing conditions, wherein the second of each drop pair The droplets 35 are charged to the second charge-to-mass ratio state by the charging electrode 44 and are not attracted to the catcher 47, but are printed on the recording medium 19 as a sequence of print droplets 46, the first drop 36 of the drop pair The charged electrode 44 is charged to the first charge-to-mass ratio state and is attracted to the catcher 47 without being printed. To generate droplets as shown in FIG. 4A , successive droplets are established with a fundamental period by excitation of the drop formation waveform source 56 with a fundamental period T ₀ using the excitation waveform 55 . As a result, the first and second droplets in a droplet pair do not mix, but are separated by a distance λ. A suitable waveform to apply to the electrode 44 would be a square wave with approximately 50% duty cycle, with a period equal to the drop pair period T _p =2T ₀ , and with a positive voltage in the high state and ground in the low state.

Figure 4B shows a non-printing condition in which a long sequence of large droplets 49 is formed at half the fundamental frequency. The large droplet 49 breaks off near the electrode while the high voltage is in the first voltage state, after breaking off the large droplet 49 has a net charge approximately equal to twice the charge on the first droplet 36 . The net charge on the large droplet corresponds to the third charge-to-mass ratio state. The deflection device acts on the large droplet 49 having the third charge-to-mass ratio state such that the large droplet travels along the third path 39 . Since the large droplets 49 have a similar charge-to-mass ratio as the charged first droplet 36 , they experience a similar magnitude of deflection as the first droplet 36 . As a result, the large droplet 49 travels along a third path 39 similar to the first path 37 and is intercepted by the catcher surface 52 at the charged droplet catcher contact point 27 to form ink that travels below the surface of the catcher 47 Film 48. The catcher contact point 26 for the first droplet 36 is similar in height to the catcher contact point 27 for the large droplet 49 . Therefore, as shown in FIG. 4B , in the drop pair sequence under non-printing conditions, all drop pairs are combined and pooled, and no drops 46 are printed on the recording medium 19 .

FIG. 4C shows a normal printing sequence in which drop pairs 35 and 36 are created along with some larger drops 49 . Droplets 35 are printed onto the moving recording medium 19 as printing ink drops 46, while charged droplets 36 and larger charged droplets 49 are pooled without being printed. As described with reference to the discussion of FIG. 1 , the pattern of printed ink drops 46 will correspond to the image data from image source 13 .

5A-5C illustrate an alternative embodiment of a continuous inkjet system according to the present invention. A cross-section through the liquid jet is shown, where the large drop 49 and the undeflected first drop 36 are pooled, while the deflected second drop 35 is printed. Figure 5A shows the drop pair sequence under full printing condition, Figure 5B shows the drop pair sequence under non-printing condition, and Figure 5C shows the normal printing condition, where some drops are printed. In FIG. 5B , large droplet 49 is shown near the break-off point as two separate droplets 49a and 49b, which may break off together, then separate, and recombine into a single large droplet 49. . It is also possible for droplets 49a and 49b to each truncate into two droplets at approximately the same time, and subsequently mix into a single large droplet. In this embodiment, the first voltage state corresponds to a low or zero voltage state, so that the first charge state on the first droplet of the droplet pair is relative to the second charge state on the second droplet of the droplet pair. The state of charge is uncharged.

FIG. 7 shows images of droplets intercepted from the jet stream 43 at half the fundamental frequency to generate large droplets 49 using different excitation waveforms applied to the droplet forming transducer. As shown in A, B, and C of Figure 7, changing the excitation waveform applied to the drop formation transducer changes the drop formation dynamics. A shows a pair of droplets that break off as a single droplet 49 and remains combined, B shows a pair of droplets that break off as a single droplet 49, split into droplets 49a and 49b, and then recombine, and C shows Droplets 49 a and 49 b are produced which individually break off at nearly the same break time and subsequently combine into a single droplet 49 . Once the large droplets are fully formed, the average distance between them is 2λ. All droplets are intercepted from the jet at the interception plane shown as BOL in FIG. 7 .

In the embodiment shown in FIGS. 5A-5C, the charge electrode 44 includes a first portion 44a and a second portion 44b on opposite sides of the liquid jet, between which the liquid jet is interrupted. Typically, the first portion 44a and the second portion 44b of the charge electrode 44 are either separate distinct electrodes, or separate parts of the same device. As discussed in FIGS. 4A-4C , the charge voltage source 51 delivers the repeating charge electrode waveform 97 at the drop pair frequency of drop formation such that the first drop 36 of a sequential drop pair is charged by the charge electrode 44 to The first charge state, and the second droplet 35 of the droplet pair is charged to the second charge state by the charge electrode 44 . The charging pulse source 51 biases the left and right portions of the charging electrodes to the same potential. Adding a second charge electrode portion 44b biased to the same potential on the opposite side of the liquid jet from the first portion 44a creates a region between the charge electrode portions 44a and 44b with about the center of the jet almost left and right. Symmetrical electric field. As a result, the charging of droplets intercepted from the liquid jet between the electrodes is very insensitive to small changes in the lateral position of the jet. The near symmetry of the electric field about the liquid jet allows the droplets to be charged without exerting significant lateral deflection forces on the droplets near the cut-off point. In this embodiment, deflection mechanism 14 includes a pair of deflection electrodes 53 and 63 located below charging electrodes 44a and 44b and below the mixing point where droplets 49a and 49b mix into a single large droplet 49 . The potential between these two electrodes creates an electric field between the electrodes that deflects the negatively charged droplet to the left. The strength of the droplet-deflecting electric field depends on the separation between these two electrodes and the voltage across them. In this embodiment, deflection electrode 53 is positively biased and deflection electrode 63 is negatively biased. By biasing the two electrodes with opposite polarity relative to the grounded liquid jet, their contribution to the charge of the droplets intercepted from the liquid jet can be minimized.

In the embodiment shown in Figures 5A-5C, a knife-edge catcher 67 has been used to intercept non-printing drop trajectories. The catcher 67 includes the groove portion 30 and is located below the pair of deflection electrodes 53 and 63 . The catcher 67 and gutter portion 30 are oriented such that the catcher intercepts droplets traveling along the second path 37 for a single uncharged droplet (as shown in FIG. 5A ), and also intercepts large droplets 49 traveling along the third path 39 (as shown in FIG. 5B ), but individual charging droplets 36 traveling along the first path 38 are not intercepted. Preferably, the catcher is arranged such that droplets hitting the catcher hit the sloped surface of the groove portion 30 to minimize splashing upon impact. Charged droplets 36 having a first charge-to-mass ratio traveling along a first path 38 are printed on the recording medium 19 .

For the purposes of the following discussion, we assume that the charging pulse source 51 delivers a square wave waveform with approximately a 50% duty cycle at half the fundamental frequency of drop formation. With a positive potential on the electrode 44, the droplet 36 develops a negative charge on it when it breaks off from the grounded jet 43. When little or no voltage is present on electrode 44 during formation of droplet 35, droplet 35 will induce little or no charge on droplet 35 when intercepted from grounded jet 43. A positive potential is placed on the deflection electrode 53 , which will attract negatively charged droplets towards the plane of the deflection electrode 53 . Placing a negative potential on deflection electrode 63 will repel negatively charged droplets 36 away from deflection electrode 63 , which will tend to assist deflection of droplet 36 towards deflection electrode 53 . The field generated on the deflection electrodes by the applied voltage will provide sufficient force to the droplets 36 so that they can be deflected sufficiently to avoid the gutter portion 30 and be printed on the recording medium 19 . For the configuration shown in Figures 5A-5C to work properly, the phase of the binary waveform 97 must be approximately 180 degrees out of phase with respect to the phase of the binary waveform 97 utilized in the configuration shown in Figures 4A-4C. For the configuration of Figures 5A-5C, drop 35 and large drop 49 are uncharged and print drop 36 is charged, whereas in the configuration shown in Figures 4A-4C, drop 36 and large drop 49 are charged to print Droplet 35 is not charged.

FIG. 5C shows a normal printing sequence in which drop pairs 35 and 36 are created along with some larger drops 49 . Charged droplets 36 are printed as print ink droplets 46 on the moving recording medium 19, and uncharged droplets 36 and uncharged large droplets 49 are pooled without being printed. The pattern of printed ink drops 46 will correspond to the image data from image source 13 described with reference to the discussion of FIG. 1 . In the embodiment shown in Figure 5C, an air chamber 61 is formed between the charge electrode and the geometric nozzle plate. Air supplied to the air chamber by an air source (not shown) surrounds the liquid as the liquid jet and droplet stream pass between the first and second portions 44a and 44b, respectively, of the charging electrodes (as indicated by arrow 65). Jet stream and droplet stream. This air flow, moving roughly parallel to the initial drop trajectory, helps to reduce the air drag effect on the drop that can produce drop point errors.

6A-6B show cross-sectional views through a liquid jet of a second alternative embodiment of a continuous inkjet system according to the present invention with an integrated electrode and gutter design. Figure 6A shows the drop pair sequence under full printing conditions, and Figure 6B shows the drop pair sequence under non-printing conditions. All components shown to the right of jet stream 43 are optional. Insulator 68 and optional insulator 68a are respectively attached to the upper surface of charging electrode 45 and optional second charging electrode portion 45a, and act as spacers to ensure that charging electrode 45 and optional charging electrode 45a are positioned with respect to the liquid spray. The cut-off locations 32 of the flow 43 are adjacent. There may be a gap 66 between the top of the insulator 68 and the exit plane of the nozzle 50 . The edges of charging electrodes 45 and 45a facing jet 43 are angled in FIGS. 6A and 6B to maximize the strength of the electric field at the cut-off region, which will induce more charge on charging droplet 46 . An insulating spacer 69 is also attached to the lower surface of the charging electrode 45 . An optional insulating spacer 71 is attached to the lower surface of the optional charging electrode 45a. The lower region of the insulator 68 has an insulating adhesive 64 near the upper surface of the charging electrode 45 facing the liquid jet 43 . Similarly, the lower region of the optional insulator 68a has an insulating adhesive 64a facing the liquid jet 43 near the upper surface of the charging electrode 45a. The insulating spacer 69 also has an insulating adhesive 62 attached to the side facing the inkjet droplet and the lower surface of the electrode 45 . The optional insulating spacer 71 also has an insulating adhesive 62a attached to the side facing the inkjet droplet and the lower surface of the electrode 45 . The purpose of the insulating adhesives 64, 64a, 62 and 62a is to prevent the liquid from forming a continuous film on the surface of the insulator and to keep the liquid away from the electrodes 45 to eliminate the possibility of electrical shorts. As shown in FIGS. 6A and 6B , the grounded trench 47 is attached to the lower surface of the insulating spacer 69 and the insulating adhesive 64 . Attached to the lower surface of the optional insulating spacer 71 is a grounded conductor 70 . Another optional insulator 72 is attached to the lower surface of the grounded conductor 70 . An optional deflection electrode 74 facing the upper region of trench 47 is attached to the lower surface of insulator 72 . An optional insulator 73 is attached to the lower surface of the deflection electrode 74 . Grounded conductor 75 is located adjacent to the bottom region of trench 47 and is attached to the lower surface of insulator 73 . The grounded conductor 70 acts as a barrier between the electrode 45a and the deflection electrode 74 to isolate the droplet charging region near the droplet intercept point from the droplet deflection field in front of the catcher. This helps to ensure that the droplets are not charged by the electric field generated by the deflection electrodes when they are intercepted from the jet. The purpose of the grounded conductor 75 is to shield the droplet impact area of the catcher from the electric field generated by the deflection electrodes. The presence of these fields in the droplet impingement region can assist in the generation of mist and spray from the groove 47 surface. Deflection electrode 74 operates in the same manner as deflection electrode 63 shown in Figures 5A-5C.

Figure 8 shows a front view of a stream of droplets produced from a single jet, producing successive pairs of droplets, in a time-lapse sequence from a to h, of a continuous inkjet system according to the invention. Figure 8a shows a sequence of non-printing large droplets 49 (droplets 49a and 49b at break-off points) produced by breaking off from the liquid jet 43 at the break-off location 32 adjacent to the charging electrode 44, and intercept the gutter at the charged large drop gutter contact point 27 , forming an ink film 48 that flows below the surface of the catcher 47 . The film of ink that flows below the catcher surface flows around a radius (shown as R in FIG. 4A ) at the bottom of the catcher surface and flows into the ink recovery channel 58 between the catcher 47 and the catcher floor 57, the ink recovery unit of the printer. 15 Collect ink from the ink recovery channel 58. The ink recovery channel 58 is maintained under vacuum to assist in the recovery of the ink film 48a into the ink recovery unit of the printer. In this mode of operation, charged large droplets 49 are all pooled but not printed. Figure 8b shows the generation of the next drop pair following the sequence of non-print drops to produce the first print drop. The first (lower) drop 36 of the drop pair is charged, while the second (higher) drop 35 is not charged. Uncharged droplets are printed, while charged droplets are pooled and captured by catcher 47 . Figures 8c-8h show that successive pairs of print drops are generated. The diagonal dashed line 81 is called a drop time-lapse sequence indicator, which indicates the position of the same drop in successive views. The last non-printing drop pair formed in Figure 8a is shown intercepting the catcher at the charged combined drop gutter contact point 27 in Figure 8c. The first charged drop 36 of the first print drop pair formed in Figure 8b is shown intercepting the catcher at the charged drop gutter contact point 26 in Figure 8d. The contact point 26 on the catcher for a single drop is similar in position to the contact point for a large drop 27 because the charge to mass ratio for the non-print drop 36 and the large non-print drop 49 is about the same. The uncharged print drops 35 of the first print drop pair formed in FIG. 8 b are shown reaching the recording medium 19 and being printed as print drops 46 in FIG. 8 h .

Figure 9 shows a front view of the array 9 of adjacent liquid jets 43 of the printhead 12 of the continuous inkjet system of the present invention during printing. The individual nozzles exhibit different printing and non-printing sequences that would occur during normal printing operations. Charge electrode 44 and catcher 47 are common to the jets emitted from all nozzles in the printhead's linear array of nozzles. A charging electrode 44 is associated with each liquid jet from an array of nozzles which, as required for proper operation of the invention, are placed adjacent to the cut-off location 32 of the respective jet. As the charged droplets 36 and charged macrodrops 49 are intercepted to the catcher and the uncharged drops 35 are printed, a continuous film of ink 48 is formed across the surface of the catcher. When the path 38 of the charged droplet 36 and the path 39 of the charged large droplet 49 are substantially the same, all collected droplets intercept the catcher at substantially the same height. This is required to establish a stable and uniform ink film on the catcher surface and to achieve high accuracy of drop placement. The ink film 48 on the gutters is collected in the channel between the catcher 47 and the common catcher floor 57 and sent to the ink recovery unit of the printer.

Figure 10 shows a timing diagram showing the droplet formation pulse (droplet excitation waveform), the charge electrode waveform, and the break-off moment of the droplet, according to an embodiment of the present invention. Upper panel A of FIG. 10 shows the droplet excitation waveform (heater voltage waveform 55 ) as a function of time for a single nozzle in a linear array of nozzles. The lower part B of Figure 10 shows the common charge electrode voltage waveform as a function of time, and the moment of break-off of the droplet resulting from each droplet excitation waveform shown in part A of each figure. The time axes of both parts of FIG. 10 are shown in terms of drop pair periods (numbered from 1 to 5) which are equal to twice the fundamental period of drop formation for drops 36 and 35 . The view shown in Figure 10 shows a pair of drops formed during drop pair cycle number 2, in which one of the drops is printed while the other drop is pooled (not printed), and In drop pair cycle numbers 1, 3, 4, 5, only unprinted large drops were formed and pooled. The drop formation waveform in the second drop pair cycle includes the portion of the waveform that causes the formation of the first drop, a portion that includes the print drop formation pulse 98, and another portion of the waveform that includes the non-print drop formation pulse 99 and resulting in the formation of a second droplet. Part B of FIG. 10 shows the charging voltage V, generally referred to as the charging electrode waveform 97 provided by the charging voltage source 51 to the charging electrode (44 or 45), and the moment at which the droplet interception event occurs, as a function of time. . The charge electrode waveform 97 is shown as a dashed line and is shown as a 50% duty cycle square wave from a high positive voltage state to a low voltage state with a period equal to the drop pair period which is Twice the fundamental period of drop formation so that a drop pair of two drops or a large drop 49 can be created during one drop charging waveform cycle. The drop charging waveform for each drop pair time interval includes a first voltage state 96 and a second voltage state 95 . The first voltage state corresponds to a high positive voltage and the second voltage state corresponds to a low voltage around 0 volts. In part B, the moment at which each droplet breaks off from the liquid jet is marked as a diamond. Arrows have been drawn from the drop formation pulses occurring during each drop pair time interval as shown in part A of FIG. 10 to the respective cut-off moments in part B for each of the individual drops. Delay time 93 shows the time delay between the start of the first drop formation heater voltage pulse and the start of each charging waveform cycle in each drop pair time interval. The timing of the start phase of the charge electrode waveform 97 is adjusted to appropriately differentiate the difference in charge level between drops to be printed and drops that will not be printed. The timing shown in Figure 10 is suitable for the embodiment shown in Figures 4 and 6, where the first drop 36 and the large drop 49 of the drop pair are charged droplets and the second drop 35 of the drop pair is uncharged. drop. Varying the delay time 93 by half the drop pair period will produce a charged second drop 35 and an uncharged first drop 36 and large drop 49, which is suitable for the embodiment shown in FIG. Therefore, a delay time 93 is used to synchronize the drop formation device with the electrode charging voltage source in order to maintain a fixed phase relationship between the charge electrode waveform and the drop formation waveform source clock.

FIG. 10 shows a configuration in which the macrodroplet is completely truncated as a single macrodroplet 49 . Each non-print drop pair period 1 , 3 , 4 , 5 includes a large drop formation pulse 94 for creating a large drop 49 . Drop pair cycle 2 has print drop formation pulses 98 and non-print drop formation pulses 99 . The pulse width of the large droplet formation pulse 94 can be adjusted to change the break-off time of the large droplet 49 such that they break off during the high voltage charge state 96 . During drop pair period 2 , drop formation pulse 98 causes first drop 36 to break off during high voltage state 95 . The drop formation pulse 99 causes the second drop 35 to break off during the subsequent low voltage state 96 . Droplets 36 and 49 that break off during high voltage state 95 are charged by the electric field generated by the charging electrodes, while droplet 35 is not charged by the charging electrodes.

Figure 10 shows an embodiment of printing low or uncharged droplets. For embodiments where charged drops will be printed and uncharged drops will be captured, by adjusting the start of the first drop formation heater voltage pulse and the duration of the charging waveform period in each drop pair time interval The delay time 93 between start points phase shifts the starting phase of the charge electrode waveform 97 . As an example, adding one fundamental period of the droplet to delay time 93 will cause large droplet 49 and droplet 36 to be in a low charge state when breaking off, while droplet 35 will be in a high charge state for printing.

In the embodiments described above, the first droplet 36 and the second droplet 35 in the droplet pair 34 have substantially the same volume. The formation of drop pairs 34 or large drops 49 occurs in a drop pair period T _p =2T ₀ . This enables efficient drop formation and the ability to print at top speeds. In other embodiments, the volumes of the first drop and the second drop in a drop pair may be different, and the drop pair period T _p that forms the drop pair 34 or the large drop 49 is greater than 2T ₀ , where T ₀ Defines the period of the smaller of the two droplets in a droplet pair. As an example, the first and second drops of a drop pair may have a volume ratio of 4/3 or 3/2, which corresponds to a drop pair period _Tp of 7T ₀ /3 or 5T ₀ /3. The smallest droplet size is determined by the Rayleigh cutoff frequency FR _. In these embodiments, the period of the charge electrode waveform will be equal to the period of the drop pair forming drop pair 34 or large drop 49 .

Figure 11 shows an embodiment where the first and second droplets of a droplet pair have the same volume. As shown in Figure 10, the time axis is labeled by droplet pair cycles or periods. Each non-printing drop period includes a first drop forming pulse 91 and a second drop forming pulse 92 . The time between the first and second drop formation pulses 91 and 92 in a drop pair cycle is less than the time between the second drop formation pulse and the first drop formation pulse in a subsequent drop pair cycle. As a result, the first droplet of the pair is larger than the second droplet of the pair. The non-uniform timing between the first and second drop formation pulses may create a velocity difference between the first and second drops of the drop pair. With such a velocity difference, the first and second droplets of a droplet pair can mix to form a large droplet 49 without the use of velocity modulation pulses. During the first voltage state 95 of the charge electrode waveform 97, the droplets forming the large droplet 49 break off close to each other in time (similar to that shown in Figure 7C). A different drop formation waveform consisting of pulses 101 , 102 and 103 is used to create print drops in the second drop pair cycle. The waveforms for the second drop pair cycle are selected to cause the first droplet 36 to truncate during the first voltage state 95 of the charge electrode waveform 97 and the second droplet 35 to truncate during the second voltage state 96, and prevent the droplet 35 and 36 mixed. In some embodiments, the timing of waveform pulses 101 and 102 may be the same as waveform pulses 91 and 92 . Pulse 103 delays the break-off of the second drop of the drop pair and prevents mixing of the drops of the second drop pair cycle, thereby allowing the second drop of the drop pair to be printed.

Similarly, in the preceding embodiments, a charge electrode waveform with two voltage states was used, with each state active for half of the total cycle. In other embodiments, other charge electrode waveforms having a period equal to the drop pair period used to form drop pairs 34 or large drops 49 may be used. Figure 11 shows an example where the waveform 97 has two charge states that are active for different time periods during the drop pair cycle.

In general, depending on the resolution requirements of the image being printed, the present invention can be implemented for creating print droplets in the range of 1-100 pl with nozzle diameters in the range of 5-50 μm. The jet velocity is preferably in the range of 10-30 m/s. The base droplet generation frequency is preferably in the range of 50-1000 kHz.

The present invention allows for the selection of droplets for printing or non-printing without the need for a separate charging electrode for each liquid jet in an array of liquid jets as in conventional electrostatic deflection based inkjet printers. In contrast, a single common charging electrode is used to charge droplets from a liquid jet in an array. This eliminates the need to strictly align each charging electrode with the nozzle. Crosstalk charging of droplets from one liquid jet with charging electrodes associated with different liquid jets is no longer a problem. Since crosstalk charging is not an issue, there is no need to minimize the distance between the charging electrode and the liquid jet as required by conventional droplet charging systems. The common charging electrode also provides improved charging and deflection efficiency, allowing greater separation distances between the jet and the electrodes. A distance between the charging electrode and the jet axis may be used in the range of 25-300 μm. The elimination of separate charge electrodes for each liquid jet also allows for higher nozzle densities than conventional electrostatic deflection continuous inkjet systems, which require separate charge electrodes for each nozzle. Nozzle array densities may range from 75 nozzles per inch (npi) to 1200 npi.

Referring to FIG. 12 , a method of ejecting liquid droplets begins at step 150 . At step 150, liquid is provided at a pressure sufficient to eject a jet of liquid through a nozzle of the liquid chamber. Step 150 is followed by step 155 .

At step 155, the liquid jet is conditioned by providing a drop forming waveform to the drop forming device such that portions of the liquid jet break off into a series of droplets. The adjustment selectively causes portions of the liquid jet to break off into pairs of droplets traveling along a path, including a first droplet and a second droplet. Each droplet pair is evenly separated in time according to the droplet pair period. This adjustment selectively causes other portions of the liquid jet to be intercepted into one or more third droplets traveling along said path, the third droplets being equally separated by the same droplet pair period, the third droplets being shorter than the first The first droplet and the second droplet are large. The selection of whether to form a drop pair of first and second drops or to form a large drop is based on the print data. Step 155 is followed by step 160 .

At step 160, a charging device is provided. The charging device includes charging electrodes and a source of varying potential. A charging electrode is associated with the liquid jet. The source of varying electrical potential varies the electrical potential between the charging electrode and the liquid jet by providing a waveform to the charging electrode. The waveform includes a period equal to the period of the drop pair forming the drop pair or the third drop, a first differential voltage state and a second differential voltage state. The waveform to the charging electrodes does not depend on the print data. Step 160 is followed by step 165 .

At step 165, the charging device and drop forming device are synchronized to produce a first charge-to-mass ratio on a first droplet, a second charge-to-mass ratio on a second droplet, and a second charge-to-mass ratio on a third droplet. Three charge-to-mass ratios, the third charge-to-mass ratio is substantially the same as one of the first charge-to-mass ratio and the second charge-to-mass ratio. Step 165 is followed by step 170 .

At step 170, a deflection device is used to cause a first droplet having a first charge-to-mass ratio to follow a first path, a second droplet having a second charge-to-mass ratio to follow a second path, and having a third charge-to-mass ratio The third drop travels along a third path; the third path being substantially the same as one of the first path and the second path. Step 170 is followed by step 175 .

At step 175, a catcher is used to intercept droplets traveling along one of the first path or the second path. The catcher is also used to intercept droplets traveling along the third path.

Note that the waveform provided to the drop formation device in step 155 is dependent on the image data, whereas the waveform provided to the charge electrode in step 160 is independent of the image data.

parts list

10 Continuous Inkjet Printing System

11 ink bank

12 print heads or liquid injectors

13 image sources

14 Deflection mechanism

15 Ink recovery unit

16 image processor

17 logic controller

18 Excitation controller

19 Recording media

20 Ink pressure regulator

21 Media Transport Controller

22 Transport rollers

24 liquid chamber

26 Charging Droplet Groove Contacts

27 Charging Combination Droplet Groove Contacts

30 Groove

31 droplet mixing position

32 Truncation position

34 droplet pairs

2nd droplet of 35 droplet pair

1st droplet of 36 droplet pairs

37 Second Path

38 First Path

39 Third Path

40 Continuous Liquid Injection System

42 Droplet Forming Device Transformer

43 Liquid Jet

44 charging electrode

44a Second charging electrode

45 charging electrode

45a Second charging electrode

46 ink drops

47 catcher

48 ink film

49 Large Droplets

50 nozzles

51 Charging voltage source

52 catch surface

53 deflection electrode

54 Third Alternative Path

55 excitation waveform

56 excitation waveform source

57 Trapper Base Plate

58 Ink return channel

59 excitation converter

60 incentive devices

61 air chamber

62 insulating adhesive

62a Second insulating adhesive

63 deflection electrodes

64 insulating adhesive

64a Second insulating adhesive

65 Arrow indicating direction of air flow

66 Gap

67 catcher

68 insulators

68a insulator

69 insulators

70 Ground conductor

71 Insulators

72 Insulators

73 Insulators

74 deflection electrodes

75 Ground conductor

81 Droplet Time Lapse Sequence Indicator

83 Charging equipment

87 liquid jet central axis

89 droplet forming equipment

91 First droplet formation pulse

92 Second droplet formation pulse

93 Phase delay time

94 large droplet formation pulse

95 First voltage state

96 Second voltage state

97 Charging electrode waveform

98 print droplet forming pulse

99 Non-printing droplet formation pulses

101 Print the first pulse of the droplet formation waveform

102 Print the second pulse of drop formation waveform

103 The third pulse of the print droplet formation waveform

150 Steps for supplying pressurized liquid through nozzles

155 Procedure for Conditioning a Liquid Jet Using a Droplet Formation Device

160 Steps to provide charging equipment

165 Steps for synchronizing charging device and droplet forming device

170 Steps to Deflect Droplets

175 Steps for Intercepting Selected Droplets

Claims (42)

1. a continuous liquid spraying system, comprising:

The fluid chamber be communicated with fluid nozzle, this fluid chamber comprises liquid, and liquid is subject to being enough to the pressure by described nozzle atomizing of liquids jet flow;

The droplet-shaped forming apparatus be associated with described liquid jet, this droplet-shaped forming apparatus can operate and regulate for producing in described liquid jet, one or more drops pair of advancing along a path are blocked into optionally to cause the part of described liquid jet, each drop separates the cycle fifty-fifty to by drop, each drop is to comprising the first drop and the second drop, described droplet-shaped forming apparatus also can operate and regulate for producing in described liquid jet, one or more 3rd drops of advancing along described path are blocked into optionally to cause the part of described liquid jet, described 3rd drop separates the cycle fifty-fifty by identical drop, and described 3rd drop than described first drop and described second drop large,

Charging equipment, comprising:

The charging electrode be associated with described liquid jet; And

Change potential source between described charging electrode and described liquid jet, described change potential source provides waveform, this waveform comprise with formed described drop to or the drop of described 3rd drop to equal cycle in cycle, described waveform comprises the first difference voltage status and the second difference voltage status, described charging equipment is synchronous with described droplet-shaped forming apparatus, to produce the first charge-mass ratio on described first drop of described drop centering, described second drop of described drop centering produces the second charge-mass ratio, and on described 3rd drop, produce the 3rd charge-mass ratio, described 3rd charge-mass ratio is substantially identical with described first charge-mass ratio, and

Deflecting apparatus, this deflecting apparatus causes described first drop with described first charge-mass ratio of described drop centering to be advanced along the first path, and cause described second drop with described second charge-mass ratio of described drop centering to be advanced along the second path, and described 3rd drop with described 3rd charge-mass ratio is caused to be advanced along the 3rd path.

2. the system as claimed in claim 1, also comprises:

Grabber, this grabber is arranged to tackle the drop of advancing along described 3rd path and also tackles the drop of advancing along described first path.

3. the system as claimed in claim 1, wherein said 3rd path is substantially identical with described first path.

4. the system as claimed in claim 1, wherein said liquid comprises the ink for printing at recording medium.

5. the system as claimed in claim 1, described nozzle is one in nozzle array, and the described charging electrode of described charging equipment is shared by each described liquid jet sprayed from the nozzle in described nozzle array and is associated with each described liquid jet.

6. the system as claimed in claim 1, wherein said first drop has substantially identical volume with described second drop.

7. the system as claimed in claim 1, wherein said 3rd drop has the volume substantially equal with the volume sum of described first drop and described second drop.

8. the system as claimed in claim 1, wherein said droplet-shaped forming apparatus also comprises:

Converter is formed with a drop be associated in described fluid chamber, described nozzle and described liquid jet; And

Drop forms sources of waveforms, and it forms converter to described drop provides drop to form waveform.

9. system as claimed in claim 8, wherein said drop formation converter is one in following equipment: hot equipment, piezoelectric device, MEMS actuator, electric hydrodynamic force equipment, light device, electrostrictive device, and their combination.

10. system as claimed in claim 8, be wherein provided to described drop that described drop forms converter formed waveform can regulates liquid jet flow block in phase place, liquid drop speed and droplet size at least one.

11. systems as claimed in claim 8, the print data that the described drop formation waveform response being wherein provided to described drop formation converter provides in excitation controller.

12. systems as claimed in claim 8, wherein said drop forms waveform and comprises the Part I of described first drop setting up described drop centering and set up the Part II of described second drop of described drop centering.

13. the system as claimed in claim 1, one in wherein said first drop and described second drop is not charged relative to another electric charge be associated in described first drop and described second drop.

14. the system as claimed in claim 1, the described change potential source wherein between described charging electrode and described liquid jet is not in response to the print data provided by excitation controller.

15. the system as claimed in claim 1, described change potential source wherein between described charging electrode and described liquid jet produces following waveform, and wherein said first difference voltage status and described second difference voltage status are movable for equaling the time interval of described drop to the half in cycle separately.

16. the system as claimed in claim 1, wherein said charging electrode is placed in adjacent with the disconnect position of described liquid jet.

17. the system as claimed in claim 1, wherein said deflecting apparatus also comprises at least one deflecting electrode for deflecting charged droplets, an electrical communication at least one deflecting electrode described and a potential source and ground.

18. the system as claimed in claim 1, wherein said charging equipment comprises charging electrode, and this charging electrode comprises the Part I of the first side being positioned at described liquid jet and is positioned at the Part II of the second side of described liquid jet.

19. the system as claimed in claim 1, wherein said deflecting apparatus also comprises the deflecting electrode with potential source electrical communication, and it sets up drop deflection field to deflect charged droplets.

20. the system as claimed in claim 1, wherein said first drop and described second drop separated fifty-fifty by the basic cycle, and drop is the twice of basic cycle to the cycle.

21. the system as claimed in claim 1, wherein said second difference voltage status comprises DC skew.

The method of 22. 1 kinds of atomizing of liquids drops, comprising:

There is provided liquid, this liquid is subject to the pressure of the nozzle atomizing of liquids jet flow be enough to by fluid chamber;

Use the droplet-shaped forming apparatus be associated with described liquid jet to regulate described liquid jet, one or more drops pair of advancing along a path are blocked into optionally to cause the part of described liquid jet, each drop separates the cycle fifty-fifty to by drop, and each drop is to comprising the first drop and the second drop;

Use described droplet-shaped forming apparatus to regulate described liquid jet, one or more 3rd drops of advancing along described path are blocked into optionally to cause the part of described liquid jet, described 3rd drop separates the cycle fifty-fifty by identical drop, described 3rd drop than described first drop and described second drop large;

Charging equipment is provided, comprises:

The charging electrode be associated with described liquid jet; And

Change potential source between described charging electrode and described liquid jet, described change potential source provides waveform, this waveform comprise with formed drop to or the drop of the 3rd drop to equal cycle in cycle, described waveform comprises the first difference voltage status and the second difference voltage status;

Make described charging equipment synchronous with described droplet-shaped forming apparatus, to produce the first charge-mass ratio on described first drop of described drop centering, described second drop of described drop centering produces the second charge-mass ratio, and produce the 3rd charge-mass ratio on described 3rd drop, described 3rd charge-mass ratio is substantially identical with described first charge-mass ratio; And

Use deflecting apparatus, described first drop with described first charge-mass ratio of described drop centering is caused to be advanced along the first path, cause described second drop with described second charge-mass ratio of described drop centering to be advanced along the second path, and cause described 3rd drop with described 3rd charge-mass ratio to be advanced along the 3rd path.

23. methods as claimed in claim 22, also comprise:

Grabber is used to tackle the drop of advancing along described first path and described 3rd path.

24. methods as claimed in claim 22, wherein said 3rd path is substantially identical with in described second path with described first path.

25. methods as claimed in claim 22, wherein said liquid comprises the ink for printing on the recording medium.

26. methods as claimed in claim 22, described nozzle is one in nozzle array, and each described liquid jet that the described charging electrode of described charging equipment comprises by spraying from the nozzle in described nozzle array shares and the electrode be associated with each described liquid jet.

27. methods as claimed in claim 22, wherein said first drop has substantially identical volume with described second drop.

28. methods as claimed in claim 22, wherein said 3rd drop has the volume substantially equal with the volume sum of described first drop and described second drop.

29. methods as claimed in claim 22, wherein said droplet-shaped forming apparatus also comprises:

Converter is formed with a drop be associated in described fluid chamber, described nozzle and described liquid jet; And

Drop forms sources of waveforms, and it forms converter to described drop provides drop to form waveform.

30. methods as claimed in claim 29, wherein said drop formation converter is one in following equipment: hot equipment, piezoelectric device, MEMS actuator, electric hydrodynamic force equipment, light device, electrostrictive device, and their combination.

31. methods as claimed in claim 29, be wherein provided to described drop that described drop forms converter formed waveform can regulates liquid jet flow block in phase place, liquid drop speed and droplet size at least one.

32. methods as claimed in claim 29, the print data that the described drop formation waveform response being wherein provided to described drop formation converter provides in excitation controller.

33. methods as claimed in claim 29, wherein said drop forms waveform and comprises the Part I of described first drop setting up described drop centering and set up the Part II of described second drop of described drop centering.

34. methods as claimed in claim 22, one in wherein said first drop and described second drop is not charged relative to another electric charge be associated in described first drop and described second drop.

35. methods as claimed in claim 22, the described change potential source wherein between described charging electrode and described liquid jet is not in response to the print data provided by excitation controller.

36. methods as claimed in claim 22, described change potential source wherein between described charging electrode and described liquid jet produces following waveform, and wherein said first difference voltage status and described second difference voltage status are movable for equaling the time interval of described drop to the half in cycle separately.

37. methods as claimed in claim 22, wherein said charging electrode is placed in adjacent with the disconnect position of described liquid jet.

38. methods as claimed in claim 22, wherein said deflecting apparatus also comprises at least one deflecting electrode for deflecting charged droplets, an electrical communication at least one deflecting electrode described and a potential source and ground.

39. methods as claimed in claim 22, wherein said charging equipment comprises charging electrode, and this charging electrode comprises the Part I of the first side being positioned at described liquid jet and is positioned at the Part II of the second side of described liquid jet.

40. methods as claimed in claim 22, wherein said deflecting apparatus also comprises the deflecting electrode with potential source electrical communication, and it sets up drop deflection field to deflect charged droplets.

41. methods as claimed in claim 22, wherein said first drop and described second drop separate fifty-fifty by the half of described drop to the cycle.

42. methods as claimed in claim 22, wherein said second difference voltage status comprises DC skew.