KR19990063801A - Single Pass Inkjet Printer - Google Patents

Abstract

In particular in the embodiments described herein, the single pass inkjet printer includes a plurality of ink jetting modules 54 arranged in adjacent rows extending across the surface of the object being moved relative to the printer. The module 54 is mounted and coupled to a manifold 84 mounted to the support frame 82. Ink passes through the opening 98 of the frame to the manifold, which distributes the ink to a corresponding opening 66 in the manifold that is connected back to the array of ink pressure chambers and the ink supply. As a result, the ink can be continuously circulated through the entirety of the ink ejection module and can maintain suspension in the suspension of the suspended ink. The ink supply is removably connected to the printhead through a quick coupling, and a filter is provided at the inlet of the ink supply and the printhead to prevent contamination of the ink in the printhead. Another filter 86 designed to filter particles blocking the orifice in the orifice plate is located between the ink injection module 54 and the orifice plate 90. In an embodiment, the twelve ink spray modules 54 are arranged to supply approximately 275 dots per centimeter resolution across a 5.6 inch (14.2 cm) image width, and in another embodiment, 48 Inkjet modules 54 are arranged to supply 600 dots per cm resolution across 10 and 1/4 inch image widths.

Description

Single pass inkjet printer

In many cases an image is printed in a single pass on a continuously moving object, substrate or web, such as a package carried on a conveyor, i.e. without the need to repeat or return the print head to the object. It is desirable to. In general, however, for ink jet printers in rows extending across the width of the substrate, the spacing of the ink jet orifices does not produce an image with sufficient acceptable resolution. In many cases, moreover, it is desirable to be able to change the color of the ink used for printing without replacing the print head, but conventional printers generally do not print different colored inks from the same printer head.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer, and more particularly to an inkjet printer configured to be able to print an image in a single pass when an object moves adjacent to the printer.

1 is a schematic block diagram showing an arrangement of a representative embodiment of a single pass inkjet printer according to the present invention;

2 is a schematic exploded perspective view showing a representative arrangement of the ink jetting module used in the printer of the present invention;

3 is an exploded perspective view showing a representative arrangement of the inkjet printer head used in the printer of the present invention;

4 is a perspective view showing the assembled relationship of the components of FIG. 3;

5 is a schematic cross-sectional view showing the arrangement of the print head shown in FIG. 4 in the printer of the present invention;

6 is a schematic plan view showing another exemplary embodiment of the present invention; And

FIG. 7 is a schematic exploded perspective view of the embodiment shown in the direction of the arrow in the VII-VII line shown in FIG.

It is therefore an object of the present invention to provide a single pass inkjet printer that overcomes the disadvantages of the prior art.

Another object of the present invention is to provide a single pass inkjet printer having the ability to print inks of different colors while using the same printer head.

It is another object of the present invention to provide a single pass ink jet printer which provides a high resolution image.

The above and still further objects of the present invention are directed to a printer head having a plurality of ink jetting modules extending transversely in a web moving direction with respect to the ink jet head, and orifices in orifice plates arranged in an offset relationship with respect to each other in the web moving direction. It is obtained by providing an inkjet printer having a print head having one or more arrays of orifices extending across the total width of the printed image in order to be formed on the object in communicating modules. In order to print a relatively wide image, preferably 10 inches (25.4 cm) or more satisfactory resolution, several sets of ink jetting modules are provided and the ends of adjacent modules in the direction transverse to the width of the web The images created on the web are superimposed to supply ink to orifices corresponding to adjacent image areas. Ink is supplied to each part of the module through a passage in the manifold plate sandwiched between the module and the orifice plate and supported by the support frame. Preferably each module also has an outlet passage and the manifold also has a return passage so that the ink circulates continuously throughout the module even when the ink is not used for printing to maintain the suspension of the pigment in the colored ink. Make it possible.

In order to ensure a uniform drop size for all ambient temperatures, a heater is provided in the support frame to maintain the ink at a predetermined temperature regardless of the change in the ambient temperature. If hot melted ink is to be used, the heater is controlled to maintain the temperature above the melting point of the ink.

To enable replacement or exchange of ink supply, the printhead also includes a quick coupling and a separation filter is provided between the quick coupling and the printhead on the inlet side to prevent contamination of the ink in the head. In particular, with embodiments having a resolution of about 275 dots / inch (108 dots / cm) and a print width of about 5.6 inches (14.2 cm), each of the twelve ink spray modules supplying 128 orifices may have a neighboring ink spray module. Two adjacent rows extending in parallel in the direction of web movement with the ends of the modules in one row extending between the ends of the modules in the other row to communicate with the orifices corresponding to adjacent burn zones in the orifice plate. .

In another embodiment with approximately 600 dots / inch resolution across a 10 and 1/4 inch (26.0 cm) printer width, 48 modules are provided for each module, web supplying 128 orifices. Aligned in four spaced apart columns across the width.

In the exemplary arrangement schematically illustrated in FIG. 1, the printhead 10 is disposed adjacent to a platen 12 on which a substrate 14, such as a paper web, is supported. In operation, the paper web 14 is continuously moved in a direction perpendicular to the drawing, and the print head 10 is printed via the wire 16 at the control unit 18 as shown in FIG. In response to the signal, ink droplets are ejected along the adjacent path 20 from the orifice of the orifice plate. Ink droplets are ejected against the paper in time for the movement of the paper 14 to form an image that extends substantially over the entire width of the paper in a single pass. In this way the need for scanning the printhead across the width of the substrate is eliminated and the image is a single scanning movement between the substrate and the printhead (ie, web 14 movement relative to the printhead 2). Can be printed.

Instead of attaching to the web 14 supported on the platen 12, the surface to which the ink droplets are attached becomes the surface of the object, such as a package, carried by the kenveyer past the printhead 10.

In order to supply a selectable color to the printhead, the ink supply line 22 is another filter 28 which is part of the printhead 10 via a disposable filter 24 and a quick coupling 26. Is connected to. It circulates through the printhead from the ink supply line 22 by a pump 30 which draws ink from the replaceable ink bottle 32, through the stainer 34, which is the method described below. At the discharge end of the printhead 10, another quick coupling 36 is connected to a return conduit 38 connected to a J-tube unit having an exhaust opening open to the atmosphere through a filter 42.

An ink stand pipe drain 44 is connected from the J-tube unit 40 to the replaceable ink bottle 32 evacuated to the atmosphere through the filter 46. To prevent ink from seeping out of the orifice in the orifice plate, as shown in FIG. 1, the ink reservoir discharge line 44 at the selected distance 50 down the ink spray orifice in the orifice plate at the bottom of the printhead. By placing the J-tube unit 40 to have the height 48 of the ink at the connected J-tube outlet 49, some back pressure is maintained at the printhead orifice. The J-tube unit 40 includes a valve 41 between the inlet from the return conduit 38 and the filter 42 which is normally closed but open when discharging bubbles from the ink reservoir discharge line 44 and inlet. And another valve 43 between the opening 38 which normally opens but closes when pressure is applied to the ink in the printer head to push the orifice in the orifice plate 52. As described below below, the orifice plate 52 in the printhead 10 is in the embodiment of the form shown in FIGS. 636 or 1536 orifice for the embodiment described below with respect to FIGS. Preference is given to a single plate formed of 6144 orifices for the orifice plates used.

The failure of a single orifice in an orifice plate with foreign material can cause the printer head to be unusable by dropping enough burns, and quick disconnect couplings for ink supply provide an opportunity for contaminants to enter the system. A filtering arrangement is provided to prevent contamination of the ink supplied to the orifices in the print head. For this purpose, both the replaceable ink bottle 32 and the J-tube unit 40 evacuated to the atmosphere are micron filters to prevent contamination such as air entering the components during operation of the system. It has an exhaust port covered with the filters 42 and 46. In addition, a replaceable filter 24, which is preferably a 5-10 micron cartridge type filter, is contained within the line 22 in the quick coupling 26, and preferably a filter that is a 10-micron Nucleopore filter ( 28) filters incoming contaminants when the quick coupling is disconnected and reconnected.

In the exploded view of Fig. 2, there is shown an arrangement of a representative ink jetting module for use in a printhead. The manufacture and assembly of such ink spray modules is described in US patent application Ser. No. 08 / 406,297 to Moynihan et al., Which is incorporated herein by reference, the contents of which are also incorporated herein by reference. 2, the illustrated ink jetting module 54 comprises a carbon pressure chamber plate 56 formed on the opposite side with an array 58 which is a closely spaced groove forming an ink pressure chamber and corresponding to the converter plate. Surrounded by a piezoelectric transducer plate 60 having an electrode array 62 positioned relative to the pressure chamber in the array 58 to selectively deflect the portion to be refracted, such arrays respond to appropriate electrical signals. To change the volume of the corresponding pressure chamber.

The pressure chamber plate 56 also has, in an embodiment, a transaxially extending opening 64 receiving ink at one end from an inner passage 66 connected from the lower end surface 68 of the plate 56. After supplying the ink to the pressure chamber, the ink is discharged to the opposite end through the inner passage 70 toward the opening in the lower end 68 of the plate.

1.5 mm to extract melted air from the ink as it passes through the transversely extending opening 64. A degassing 72 consisting of tubular structure 74 consisting of an air permeable, ink impermeable material, such as protruding polytetrafluoroethylene having an inner diameter and 0.1 mm thickness, is provided at the end of the pressure chamber plate 56. It passes through the opening 76 and extends through the transversely extending opening 64. The plug 78 closes the protruding end of the tubular structural member 74 and the opposite end passes through the axial opening 64 to a level below that which forms bubbles inside the pressure chamber during operation of the ink spray system. To reduce the volume of air dissolved in the ink, it is connected to a vacuum source 80 which supplies a sufficient back pressure, such as 0.7 atmospheres. In order to prevent the tube 72 from colliding in response to the supply of back pressure, an osmotic support, such as an osmotic carbon rod or a helical line having a diameter substantially equal to the inner diameter of the tube, is inserted into the tube.

To form the printhead 10, a plurality of ink spray modules 54 are mounted to the manifold sandwich structure 84 in the support frame 82. As shown in FIGS. 3 and 4, the manifold sandwich structure 84 is composed of a fixed plate 85, a filter layer 86, a manifold plate 88 and an orifice plate 90. Orifice plate 90 is a linear array of orifices 91 arranged in two groups with end orifices in adjacent arrays that are spaced from each other in the direction of the array at equal intervals, such as orifices in the array. Have arrays. In addition, the orifices in successive arrays in each group are offset by the same distance as the orifice spacing in each array divided by the number of one less arrays in each group. In this way the resolution of the resulting image along the length direction of the array is equal to the number of orifices per unit length of each array multiplied by the number of arrays in the group.

The filter layer 86 in the manifold assembly 84 is provided to prevent any orifice-clogging solid material from the orifices 91 extending in the orifice plate 90 but the size of the orifice in the plate 90. Smaller particles of solids are provided to pass through the filter. The filter layer is disclosed, for example, in the publication 08 / 231,102 (April 22, 1994) of Moonihan et al., Which is incorporated by reference in the specification for "filter arrangement for ink jet heads", for example. In the form of For example, if the orifice 91 has a diameter of about 50 μm, the size of the opening in the filter layer 86 is about 25 to 30 μm.

The reinforcement plate 85 is for reinforcing and electrically insulating the manifold sandwich structure 84 and may be made of, for example, ceramic alumina material. The reinforcement plate 85 and the filter layer 86 are provided with a plurality of holes 92 so as to align with the ink inlets and the ink outlets 66 and 70 in each of the ink injection modules 54, and the module is further provided with a manifold plate ( The screw hole 94 is formed by the screw 95 for fixing the 88 to the support frame 82. On the other hand, the orifice plate 90 is adhesively bonded to the manifold plate.

The manifold plate is of the type described in the above-mentioned patent application 08 / 406,297 to Mohinian et al., Which is received through the inlet opening 98 on the edge of the support frame 82 and which has the opening of the filter layer 86 and the reinforcing plate ( A dispensing passage 96 for appropriately distributing ink passing through the ink 100 to the ink inlet opening 66 of the ink ejection module 54 is provided. The ink discharged from the ink discharge opening 70 in the module to the manifold plate is transferred to the support frame 82 through the filter layer and the opening 102 of the reinforcement plate by the corresponding return passage 101 in the manifold plate 88. It is carried to the discharge opening 104 at the edge. The discharge opening 104 of the support frame is connected to the return lead via the quick coupling 36 shown in FIG.

For convenience in forming the required passageway, the manifold plate 88 is preferably made of carbon, as described in the aforementioned US application 08 / 406,297, and the support frame 82 is made of aluminum It can be rigid. The support flame 82 is equipped with two holes 106 to receive heating elements arranged to maintain the manifold assembly 84 at a constant temperature above ambient temperature.

For simplicity of illustration, FIG. 4 shows a printhead assembled by mounting the four ink jetting modules 54 shown in FIG. 3 to the support frame 82. However, the cross sectional view of FIG. 5 shows all twelve ink spray modules 54 mounted on the support frame 82. These consist of two groups of modules arranged laterally so that adjacent ends of the modules overlap one another. Each inkjet module forms 128 jets at intervals of 0.022 inches (0.56 mm), with a resolution of about 275 dots per inch (108 dots / cm) in the direction across the web and a maximum image width of about 5.6 (14.2 cm) inches To be provided.

In addition, since the print head itself does not contain an ink container, there is a minimum amount of ink in the print head. Thus, when the ink supply is removed from the print head and another ink supply with a different type of ink is used, the discharge conduit 38 is connected to the waste ink container until the new ink passes through the print head, so that the remaining ink in the print head remains. Ink is expelled quickly and properly before connecting the new ink supplier to the printhead. As shown in FIG. 5, the print head 10 is supported by the head mounting portion 108 adjacent to the web 14 arranged at close intervals with the platen 12, such that the web 14 is driven by the driving roller 110. By successively passing through the orifice plate 88 by means of ink droplets from the orifice plate 88 are sprayed onto the printing paper along the corresponding passage 20. A head interface plate 112 is connected to the ink injection module 54 so as to receive an ink injection operation signal transmitted along the conductive line 16 from the control device 18 and to supply it to the module 54 in a timely manner. ) Forms an image thereon as it passes the printhead.

As shown in FIG. 5, heater 114 is mounted in the support frame opening. In this embodiment, this is particularly used for inks that are liquid at room temperature, and the heater 114 is always at a constant temperature in the printhead at a level slightly above the maximum ambient temperature so that the viscosity of the ink, and hence the size of the droplets, remains constant. It is preferred to be controlled to maintain.

In the other embodiment shown in Figures 6 and 7, the printhead 120 has 48 modules 54 arranged in the same manner as described for the first embodiment above, with the difference being the orifices in each row. Are arranged at intervals of about 0.020 inches (0.51 mm) so that a group of four modules each consisting of 12 modules are stacked on the side across the width of the printing paper 121 to produce a print image of about 10 and ¼ inches (26.0 cm). To form a width. In this embodiment, as shown in FIG. 7, the replaceable ink container 122 is mounted to the support frame 124 on which the module 54 is mounted by attaching to the printhead. Therefore, the relative motion and vibration between the ink container and the print head are minimized to prevent pressure fluctuations that may affect the injection and image quality. In this case, the ink container 122 is sealed from the atmosphere and connected to the negative pressure generator by a connecting conduit to maintain the desired negative pressure of about 3 to 5 inches (7.6 to 12.7 cm) water gauge on the orifice plate. As in the embodiment of Figs. 2 to 5, each ink injection module 54 is connected to the control device 180 via the interface plate 128 and the conductive line 16 to receive the operation signal of the piezoelectric conversion electrode therefrom, In order to use the hot melted ink, the ink container 122, the support frame 124 and the module 54 are schematically shown in the printhead heater of the type described above with reference to FIG. The container heater 129 as described above is maintained at a temperature above the ink melting point.

In some ink injection systems, it is possible to use liquid inks that can be cured by exposure to ultraviolet or other radiation. In the case, the printer includes a radiation generator 132 for curing the ink supplied to the web 14 in the printhead 10.

In response to an operation signal from the control device, the ink droplets are plated 12 spaced apart along the passage 20 from the orifice plate in the manifold assembly 84 at small intervals of about 0.02 to 0.03 inches (0.51 to 0.76 mm). It is sprayed toward the web 14 driven by the drive roll 110 along. With this arrangement, a resolution of about 600 dots per inch (263 dots per centimeter) can be obtained for an image width of about 10 and ¼ inch (26.0 cm), and the resolution in the direction of web movement is determined by the speed of the web and the ink injection module. It is adjusted to be substantially the same by the supply speed of the operation signal for. Preferably, the spacing 134 between adjacent modules 54 in each module group is about 0.32 to 0.4 inches (0.8 to 1.0 cm) so that the total width of the modules arranged in the direction of movement of the web is about 3.5 to 4.4 inches (8.9 to 11.2 cm).

In a high resolution ink ejection system, the position and volume error of the ink drops degrade the image quality. As mentioned above, by installing a heater to maintain a constant and uniform ink temperature, the volumetric error of droplets is reduced to an acceptable level. Ink drop position errors result in arranging the orifices on the orifice plate with an accuracy of about 0.0001 inch (2.5 μm), keeping the orifice plate and web 14 as small as possible, and the movement of web 14 This can be minimized by ensuring that they are aligned exactly with the axis.

If desired, two or more printheads 10 may be installed successively along the travel path of web 14 to obtain a multicolor image. In this case, the corresponding pixel orifices in the orifice plate of the printhead must be exactly aligned, and the movement of the web 14 must be maintained accurately in the passage adjacent to the continuous printhead. Instead of the web 14 being propelled by the drive roll 110 across the platen 12, ink droplets from the print head are directed against the surface of the article, such as a package or container, carried by the conveyor in the same direction as the web. It will be appreciated that it can be injected.

Although the invention has been described with reference to specific embodiments, those skilled in the art will readily be able to make numerous variations. Therefore, all such modifications are within the scope of the present invention.

Claims (14)

A driving device for transferring an object having an image printing surface in a selected direction, an inkjet printer head which is disposed at close intervals with respect to the object, and sprays ink droplets onto the image printing surface, and an ink supply supplying ink to the printer head In an inkjet printer, wherein the printhead, Support frame with mounting holes, An orifice plate for forming one or more rows of orifices in a direction crossing the width of the image printing surface at right angles to the moving direction of the image printing surface and attaching to the support frame; A manifold plate having a plurality of orifice connecting passages communicating with the orifices of the orifice plate and an ink inflow passage for delivering ink from the ink inlet; A plurality of ink pressure chambers are formed and combined with the orifices of the orifice plate and the corresponding transducers so that they are installed in the mounting frame of the support frame in a direction crossing the width of the image printing, while the end portion of the ink of the manifold plate is formed. And a plurality of ink ejection modules adapted to be in communication with the inflow path such that ink flowing through the inflow path is supplied to the orifice of the orifice plate through the orifice connection path. According to claim 1, Quick couplings connecting the ink supply to the printhead; And And a filter between the quick coupling and the printhead to filter out contaminants introduced during replacement of the ink supply. The method of claim 2, A return conduit for returning ink from the printhead to the ink supply; And And another quick coupling for connecting said return conduit to said printhead. The method of claim 3, And a replaceable filter in the ink supply line connected to the quick coupling. The method of claim 1, The ink supply in a single pass inkjet printer is Ink magnetic field machine; And And a pump for circulating ink from said ink reservoir to said printhead. The method of claim 1, A filter layer between the orifice plate and the ink spray module and sufficiently large to prevent openings through the orifice in the orifice plate, but large enough to block the openings, but the particles are small enough to pass through the orifice in the orifice plate so that the opening is not large enough to prevent clogging. Single pass inkjet printer comprising a. The method of claim 1, An elongated opening in each ink injection module for supplying a passage through which ink enters the ink pressure chamber; And And a degassing tube in said elongated passageway and made of an air permeable, ink impermeable material and connected to a pressure source under atmospheric pressure. The method of claim 1, Each inkjet module in a single pass inkjet printer, An ink inflow passage; An ink distribution passage for receiving ink from the ink inflow passage and distributing ink to the ink pressure chamber in the module; And An ink discharge passage for receiving ink from an end of the ink distribution passage; The manifold plate, An ink supply passage for supplying ink to the ink receiving passage in the ink injection module; And And an ink return passage for receiving ink from the discharge passage in the ink injection module and communicating with the discharge line from the print head. The method of claim 1, The modules in each group include twelve ink spray modules in two groups of six modules overlapping the ends of the modules in the other group, Each ink injection module, A carbon plate having an array of ink pressure chambers on each side of the carbon plate; And And a piezoelectric transducer mounted on each side of the carbon plate and having an electrode for the operating portion of the transducer corresponding to the adjacent ink pressure chamber in the carbon plate. The method of claim 9, The orifice plate comprising a plurality of orifice rows arranged in groups, the orifices in each row of orifices in the orifice plate spaced about 0.02 inch (0.57 mm), supplied by a continuous orifice in the direction of web movement Supplying a resolution of approximately 275 dots per inch (108 dots per centimeter) in the direction across the width of the web, including the rows within each group that are offset to provide uniform spacing between the image pixels. Single pass inkjet printer. The method of claim 1, 48 ink spray modules in four groups of twelve modules each overlapping an end of the module in an adjacent group, Each ink injection module, A carbon plate having an array of ink pressure chambers on each side of the carbon plate; And And a piezoelectric transducer mounted on each side of the carbon plate and having an electrode for the operating portion of the transducer corresponding to the adjacent ink jet pressure chamber in the carbon plate. The method of claim 11, A plurality of orifice rows arranged in groups, offset to provide uniform spacing between the orifices in each column spaced about 0.02 inches (0.57 mm), the image pixels supplied by the orifices continuous in the web moving direction And a resolution of about 600 dots per inch (236 dots per centimeter) in a direction across the width of the web, including the rows within each group. The method of claim 1, And a heater in said printhead for maintaining ink at a substantially constant temperature. The method of claim 1, And a radiation source for protecting an ink image that is fixed to an image receiving substrate after the substrate has moved past the printhead.