Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/17—Ink jet characterised by ink handling
  • B41J2/175—Ink supply systems ; Circuit parts therefor
  • B41J2/17596—Ink pumps, ink valves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/015—Ink jet characterised by the jet generation process
  • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
  • B41J2002/041—Electromagnetic transducer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
  • B41J2202/01—Embodiments of or processes related to ink-jet heads
  • B41J2202/05—Heads having a valve

Definitions

• the present invention relates to a printhead structure, and especially a printhead structure valve arrangement, for use in an image forming apparatus, such as an liquid-jet printer, in which a computer generated image information is converted into an image pattern formed of selectively discharged ink droplets deposited on an information carrier.
• An image forming apparatus such as for example a liquid-jet printer of a kind which is disclosed in US patent No 4,826,135, generally include one or several printhead structures in which a plurality of valve units are used to feed a print liquid to an outlet aperture through which liquid droplets are selectively ejected toward an information carrier to form an image configuration.
• the printhead structure is generally movable across the entire width of the information carrier to perform line by line scan printing in consecutive transversal lines. During each print sequence, one or several printhead structures in which a plurality of valve units are used to feed a print liquid to an outlet aperture through which liquid droplets are selectively ejected toward an information carrier to form an image configuration.
• the printhead structure is generally movable across the entire width of the information carrier to perform line by line scan printing in consecutive transversal lines. During each print sequence, one or several printhead structures in which a plurality of valve units are used to feed a print liquid to an outlet aperture through which liquid droplets are selectively ejected toward an information carrier to form
• the outlet apertures are disposed in a predetermined pattern corresponding to pixel locations in the image configuration to be recorded on the information carrier.
• An object of the invention is to provide a printhead structure of a liquid jet printer which overcomes the previously mentioned drawbacks.
• Another object of the invention is to define a printhead structure which can attain a high resolution and/or high printing speed.
• Still another object of the invention is to define a method of increasing the controllability of a liquid ink valve unit.
• a liquid ink valve unit including a movable elongated valve body is made to increase its maximum controllable frequency by creating a free movement of the valve body. This is attained according to the invention by counteracting undesirable pressure changes across the valve body, especially during movement of the valve body.
• a liquid ink transport is created between a first cavity at a first end section of the valve body and a second cavity at the second end section of the valve body.
• a liquid ink valve unit of a printhead structure of a liquid ink image forming apparatus in which an image information is converted into an image pattern on an information carrier.
• the image pattern is formed by selectively discharging print liquid through liquid ink outlets of a liquid deposition part of the printhead structure with coordinated movement of the printhead structure in a first direction across the information carrier, thereby creating a scanline from each outlet.
• the printhead structure can suitably include at least two valve units.
• the liquid deposition part is arranged in conjunction with the valve units.
• Each of the valve units includes a movable elongated valve body which by a first end section of the valve body and its movement regulates print liquid through a liquid discharge opening of each corresponding valve unit.
• the moveable valve body further comprises a second end section located along the valve body at an opposite end to the first end section. Further at least a part of a body of the moveable valve body is guided by guidance means at least during a part of the movement.
• the liquid ink valve unit comprises means which counteract undesirable pressure changes between a first cavity at the first end section and a second cavity at the second end section of the movable valve body, this in addition to any pressure equalizing which might occur by liquid ink transport between the guidance means and the part of the body of the movable valve body guided by the guidance means.
• the undesirable pressure change counteracting means comprises a liquid ink transport coupling that couples the first cavity with the second cavity.
• the transport coupling can pass by a hollowed, such as tapered, upper limit adjustment screw, and/or through one or more through holes in an upper limit adjustment screw.
• the transport coupling can pass through one or more through holes in the valve body, or pass by the valve body.
• the valve body is suitably hollowed, suitably ground, milled or manufactured such, in at least one place along the body, i.e.
• the guidance means only providing guidance at other places than at the at least one hollowed place along the body of the valve body, or the guidance means can be hollowed in at least one place along the body of the valve body, the guidance means only providing guidance at other places than at the at least one hollowed place.
• valve unit comprises a seal, which seals the first cavity from the second cavity between the guidance means and the body of the valve body guided by the guidance means.
• the seal can be integrated with the guidance means, and/or integrated with the moveable valve body.
• the undesirable pressure change counteracting means comprises a liquid ink transport coupling that couples the second cavity with a third cavity, the third cavity being separate from the first cavity.
• the third cavity can suitably be comprised of a closed vessel, of a closed flexible vessel, or of an open vessel.
• the valve unit can comprise a seal, which seals the first cavity from the second cavity between the guidance means and the body of the valve body guided by the guidance means.
• the seal can be integrated with the guidance means, and/or integrated with moveable valve body.
• the third cavity can be arranged to at least be partly filled with liquid ink, and/or at least partly be filled with a gas, and/or at least partly be filled with a liquid.
• the undesirable pressure change counteracting means comprises a flexible seal in direct association to the second cavity. In some embodiments the undesirable pressure change counteracting means comprises a moveable seal in direct association to the second cavity.
• a pressure pulse can be applied at the third cavity for actively at least assisting moving the valve body to a valve unit closed state and/or a valve unit open state.
• the valve body movement is at least in one direction effected by an electromagnetic coil.
• the electromagnetic coil can be at least in part around at least a part of the valve body, or be around first part of a magnetic circuit of which circuit the valve body forms a separate second part. The electromagnetic coil when actuated moves the valve body so that the liquid ink valve unit opens, and/or so that the liquid ink valve unit closes.
• a liquid ink image forming apparatus in which image information is converted into an image pattern on an information carrier.
• the image pattern is formed by selectively discharging print liquid through liquid ink outlets of a liquid deposition part of a printhead structure of a print unit with coordinated movement of the print unit in a first direction across the information carrier.
• the information carrier and the print unit are coordinatedly moved in relation to each other in a second direction, which second direction is perpendicular to the first direction.
• the print unit comprises at least one printhead structure comprising at least one liquid ink valve unit according to any above described embodiment.
• the liquid ink image forming apparatus comprises a control unit, which control unit controls the valve units of a printhead structure.
• the liquid ink image forming apparatus can suitably, but not limited to, be arranged to print with up to either four or six different liquid ink colors.
• the print unit can suitably either comprise one or two printhead structures for each different liquid ink color.
• the aforementioned objects are also achieved according to the invention by a method of increasing the maximum control frequency of a liquid ink valve unit of a printhead structure of a liquid ink image forming apparatus in which an image information is converted into an image pattern on an information carrier.
• the image pattern is formed by selectively discharging print liquid through liquid ink outlets of a liquid deposition part of the printhead structure with coordinated movement of the printhead structure in a first direction across the information carrier, thereby creating a scanline from each outlet.
• the printhead structure can suitably include at least two valve units and the liquid deposition part is arranged in conjunction with the valve units.
• Each of the valve units includes a movable elongated valve body which by a first end section of the valve body and its movement regulates print liquid through a liquid discharge opening of each corresponding valve unit. Each discharge opening is associated with a corresponding liquid ink outlet.
• the moveable valve body further comprises a second end section located along the valve body at an opposite end to the first end section. And at least a part of a body of the moveable valve body is guided by guidance means at least during a part of the movement.
• the method comprises the step of counteracting undesirable pressure changes between a first cavity at the first end section and a second cavity at the second end section of the movable valve body, this in addition to any pressure equalizing which might occur by liquid ink transport between the guidance means and the part of the body of the movable valve body guided by the guidance means.
• the present invention relates to a printhead structure for use in an image forming apparatus such as a liquid-jet printer in which a computer-generated image information is converted into an image pattern formed of selectively discharged liquid droplets deposited on an information carrier, said printhead structure including a plurality of valve units and a liquid deposition unit arranged in conjunction with said valve units, each of said valve units including a movable valve body having a piston with a stop made of essentially inflexible material, a cavity surrounding said piston and stop for holding print liquid, a liquid discharge opening, and a flexible valve seat extending around said liquid discharge opening.
• the printhead structure further includes a liquid deposition part or unit which includes a plurality of channels, each of which extends from a corresponding liquid discharge opening to an outlet aperture arranged in a predetermined position with respect to said information carrier, all of said channels having at least substantially a same length and at least substantially a same cross-section so as to ensure a uniform liquid deposition regardless of variations of the liquid viscosity or other factors.
• a liquid deposition part or unit which includes a plurality of channels, each of which extends from a corresponding liquid discharge opening to an outlet aperture arranged in a predetermined position with respect to said information carrier, all of said channels having at least substantially a same length and at least substantially a same cross-section so as to ensure a uniform liquid deposition regardless of variations of the liquid viscosity or other factors.
• valve unit of a printhead structure By providing a valve unit of a printhead structure according to the invention a plurality of advantages over prior art printhead structures are obtained.
• Primary purposes of the invention are to provide a printhead structure which is able to print with a higher resolution and/or with a higher speed by enabling an increased valve unit control frequency which is achieved by inhibiting or at least minimizing unvoluntary pressure changes between the two ends of the valve body.
• Fig. 1 shows a schematic section view across a valve arrangement suitably included in a printhead structure to which the invention is suitably applied
• Fig. 2A-D shows liquid ink flow around the opposite end to the stop portion end of the valve body
• Fig. 3 shows a liquid ink valve arrangement with liquid ink pressure change dampening at the top of the piston/valve body, according to a basic embodiment of the invention
• Fig. 4A-B shows dif erent embodiments of the invention applied to a liquid ink valve arrangement with an adjustment screw
• Fig. 5 shows a further embodiment according to the invention with a modified valve body
• Fig. 6A-C shows different embodiments of valve bodies according to the invention
• Fig. 7A-C shows different alternative embodiments of liquid ink pressure change dampening according to the invention
• Fig. 8A-C shows different alternative cavity separator embodiments according to the invention
• Fig. 9A-C shows different integrated membrane embodiments according to the invention.
• Fig. 10 shows a two piston valve arrangement embodiment according to the invention
• Fig. 11 shows a liquid ink valve arrangement according to the invention with a displaced electromagnetic coil according to the invention.
• the present invention relates to a printhead structure for use in an image forming apparatus, such as a liquid ink printer, in which a computer generated image information is converted into an image pattern formed of selectively discharged ink deposited on an information carrier, such as for example a sheet of textile material.
• the image pattern is formed of transversal image lines each of which comprise a predetermined number of similarly spaced image pixels.
• the information carrier is caused to move stepwise in a first, longitudinal direction relative to the printhead, such that each step corresponds to a whole number of image pixels.
• the printhead is caused to move across the width of the information carrier in a second, transversal direction in order to achieve line by line scan printing.
• an image forming apparatus of the kind described in the invention is used to record large-size color images on textile material, each color image being composed of four different color pigments such as, conventionally, cyan, yellow, magenta and black.
• each color image is composed of six different color pigments, such as light cyan, cyan, yellow, light magenta, magenta, and black.
• one or several printheads of the kind described in the present invention are utilized for each color pigment, the total number of printheads included in the apparatus being consequently a whole multiple of the number of pigments used.
• a printhead structure in accordance with the present invention includes generally a plurality of valve units, comprising a liquid ink deposition part or arranged in conjunction with a liquid deposition unit.
• a valve unit in accordance with the present invention is schematically illustrated in figure 1 and is constructed for controlling the feed of a liquid ink, which is fed 101 to a cavity 119 under pressure, to the liquid deposition part or unit 107 and out through a liquid ink outlet 109.
• the valve unit comprises generally a movable valve body 110 having an elongated shape, a substantially cylindrical cavity surrounding the movable valve body and an electromagnetic element 112, used for controlling the movement 113, 115 of the valve body 110 in such a manner that the valve body 110 is bidirectionally movable along its axis, as indicated by the valve open direction arrow 113 and valve close direction arrow 115.
• the electromagnetic element 112 has a fixed portion which forms part of the valve unit, and a movable portion which forms part of the valve body 110.
• the cavity 119 has a front part which forms a liquid container for holding a print liquid.
• a liquid discharge opening 118 is arranged on the front surface of the liquid container.
• the liquid discharge opening 118 suitably has a circular shape.
• the valve body 110 includes a piston part which is provided with a stop 117 made of essentially inflexible material, which stop 117 is caused to move away from or toward the liquid discharge opening 118 so as to permit or restrict a liquid discharge through the opening.
• the stop When caused to move toward the opening, the stop is brought in contact with a valve seat 105 to inhibit liquid flowing through the discharge opening 118 and out through the liquid ink outlet 109.
• a part of the piston is surrounded by one or more springs 114 which exert a force 115 such that the stop 117 is forced towards the valve seat.
• the stop 117 is caused to move away from the valve seat and discharge opening 118 by means of activating the electromagnet element 112 which then causes a force 113 on the valve body 110 overwinning the spring force 115.
• valve units are usually mounted within the same liquid cavity 119, said cavity then having one discharge opening 118 for each valve unit.
• a printhead structure commonly traverses an image receiving surface such as a two meter wide textile material.
• An image receiving surface is moved stepvise underneath the printhead structure in a direction which is perpendicular to the transverse movement of the printhead structure.
• the printhead structure is usually moved by means of some transversal printhead structure movement arrangement across the image receiving surface. The movement arrangement will sweep the liquid ink outlets across the image receiving surface between a first end stop and a second end stop. The end stops define the printable width.
• the printhead structure with its liquid ink outlets will print along scan lines, which are spaced apart a same distance as the liquid ink outlets are spaced apart, during each travel across the image receiving surface between the end stops.
• it can either only print during one transversal direction or during both transversal directions.
• Some printers will only print with a resulting pitch equal to the scan line interdistance, i.e. between each print run, the image receiving surface moves, corresponding to the number of discharge openings, for example eight or sixteen.
• the printhead structure prints lines in between already printed scan lines to thereby attain a pitch in the longitudinal direction which is smaller than the scan line interdistance.
• scan lines and scan line interdistance is what and where a printer and thus a printhead structure prints during travel of the printhead structure in one direction.
• an improved printing speed and/or a higher resolution/quality is attained by improving the control of the valve unit.
• this is accomplished by a valve body which is easier to move during closure and opening of the valve unit, thereby enabling a valve unit with a faster response time resulting in a higher attainable liquid ink deposition frequency.
• a higher liquid ink deposition frequency is necessary since for a given liquid ink deposition frequency a higher resolution results in a slower printing speed and a higher printing speed will result in a lower attainable resolution/quality.
• the movement of the valve body is at least in part determined by flow of liquid ink to and from a cavity/space at the opposite end to the stop end of the valve body, during opening and closure of the valve.
• Figure 2A-D which shows liquid ink flow around the opposite end to the stop portion end of the valve body during different stages of valve operation.
• the opposite end to the stop portion end of the valve body will be referenced to as the top end of the valve body, no orientational restrictions intended.
• Figure 2A shows the top end 223 of the valve body 210 in a state when the valve is closed. A large cavity 220 is thus formed between the top end 223 of the valve body 210 and the encasement 221.
• valve body 210 moves 213 to thereby diminish the cavity 222.
• the cavity 220 is filled with, usually liquid ink, has to move/flow 224 somewhere else.
• the flow will have to pass the small clearances 229 between the valve body 210 and any valve body supports 216, in some embodiments walls of the encasement 221 provide the support.
• the walls of the encasement 221 will be as close to the valve body 210 as possible, in most cases acting also as support for the valve body, due to a desire to have a very small gap to the electromagnetic coil and a small valve arrangement to be able to fit several side by side.
• valve is fully open.
• the cavity 225 is or is almost diminished completely.
• valve unit closes its outlet, this is shown in Figure 2D.
• the valve body 210 moves 215 to increase the cavity 228 again.
• an under-pressure is created at the top end 223 of the valve body 210 which will create a flow 226 of liquid ink to fill up the cavity 228 and a counter force on the valve body 210 in dependence on the rate of flow.
• the cavity 220, 225 accordingly changes volume by the cross sectional area of the valve body times the movement 213, 215 made by the valve body 210.
• This volume of, in most cases, liquid ink has to be transported 224, 226 back and forth along the sides of the valve body 210, during closure and opening of the valve. This in turn creates a counter force to the desired force on the valve body 210 which counter force opposes any positional changes the valve body 210 is controlled to make.
• each valve unit is so arranged as to minimize the counter forces on the valve body during its transitions between closed and open valve unit states. This is accomplished according to the invention by diminishing a pressure change on the top end of the valve body during these transitions.
• FIG. 3 shows a liquid ink valve unit with liquid ink pressure change dampening means according to one basic embodiment of the invention.
• a liquid ink valve unit typically comprises a liquid ink inlet 301 , a liquid ink outlet 309, and a movable 332 valve body/piston 310 with a stop portion 317 in a liquid ink cavity/reservoir 319.
• the liquid ink pressure change dampening means 331 is in this embodiment a connection means, such as a tube, connecting a cavity/space 320 at an end of the piston/valve body 310 opposite to stop portion end 317, with the liquid ink cavity 319 to allow an unrestricted flow 330 of liquid ink to and from the cavity/space 320 during valve opening/closing.
• valve body 310 By allowing a more unrestricted flow 330 to and from the cavity 320 at the top end of the valve body 310, the valve body 310 can move 332 freely without any unnecessary counter force during transitions.
• Figure 4 shows different embodiments of the invention applied to liquid ink valve units with adjustment screws.
• Figure 4A shows an upper end of a valve unit having an adjustment screw comprising a tapered part 442 and an upper part 441.
• the tapered part 442 of the adjustment screw allows a fairly unrestricted flow 443 of liquid ink past the adjustment screw from the cavity 420 above the valve body 410, to, for example, the reservoir of the valve unit.
• Figure 4B shows an embodiment where a adjustment screw 445 is provided with one of more holes 446 to the cavity 420.
• the hole or holes 446 provide a fairly unrestricted flow 447 of liquid ink to and from the cavity 420 above the valve body 410 with, for example, the reservoir of the valve unit.
• FIG. 5 shows a further embodiment according to the invention where the liquid ink pressure change dampening means is a modified valve body 510.
• the valve body 510 is provided with one or more holes/perforations 550 between the cavity 520 and the reservoir 519. The importance with this modification is that a flow 552 can be led past any bottlenecks. This modification also has the benefit of diminishing the cross sectional area of the valve body 510.
• Figure 6 shows further different embodiments of liquid ink pressure change dampening means as modified valve bodies according to the invention. All of these valve bodies and encasements which are modified according to the invention provide the advantage of lowering the valve body cross sectional area within an available encasement cross sectional area. This will increase the available cross sectional area for flow of liquid ink past the valve body.
• Figure 6A shows a plane view of a first example of a modified valve body 660 according to the invention.
• the valve body 660 support 616 is in this example unmodified.
• the encasement of the valve body can either be at the inner or outer circumference of the support 616, i.e.
• the modified valve body 660 comprises one or more groves along the length of the valve body to thereby create one or more passages 667 past any flow restrictions 629.
• the one or more grooves can be provided along the whole length of the valve body, but are at least provided past any bottlenecks, such as unmodified supports.
• valve body can assume many different shapes according to the invention, as can be seen in Figure 6B which shows another modified valve body 662.
• This valve body 662 is only supported in two smaller areas, suitably at least three points/areas spread out in the circumference are used, thereby providing a large area 668 for flow of liquid ink from the cavity to the reservoir, past any restrictive areas 629.
• Figure 6C illustrates an embodiment where the valve body 610 is not modified, but rather the support/encapsulation 665 is modified to create free flow passages 669 as well as support with narrow passages 629.
• This embodiment can for example be combined with the embodiments of Figure 6A, i.e. a modified valve body with a suitably modified support/encasement.
• Figures 7A, 7B, and 7C show three alternative methods according to the invention of allowing liquid ink flow in order to diminish a counter force on the valve body 710 during transitions.
• Figure 7A shows a method of allowing an open vessel 771 function as a reservoir for the cavity 720. This method is less suitable if the pressure the liquid ink is fed into the valve unit is high.
• Figure 7B shows an example of using an expandable tank 773 into which liquid ink can be fed into and received from.
• Figure 7C shows a method of using a closed vessel 775, suitably filled, at least in part, with a compressible medium, such as gas.
• FIG. 8B, and 8C show different embodiments according to the invention of separating the liquid ink from another medium that is used to absorb the displacement of the valve body during transitions.
• Figure 8A shows a first basic version of a valve unit with a liquid ink inlet 801 feeding liquid ink into a reservoir 819 being separated from a cavity 820 at the other end of the valve body 810.
• the liquid ink is kept from the cavity 820 by means of one or more seals 880 having a combined function as supports.
• the cavity 820 can then be filled with any suitable liquid and gas and for example be combined with a vessel/tank according to any one of Figures 7A to 7C.
• the cavity 820 is filled with air, then suitably this embodiment is combined with an open vessel according to Figure 7A.
• Figure 8B shows a version where the seal 882 is attached to the valve body, in contrast to the version according to Figure 8A where the seal 880 is not attached to the valve body 810.
• Figure 8C shows another embodiment where a movable plate/disc comprises a seal 886 which divides the cavity in two.
• the primary cavity 820 preferably being filled with the liquid ink, and a secondary cavity 821 which can be filled with a suitable medium of a liquid or gaseous form.
• the secondary cavity can be filled with air which is suitably either coupled to an open vessel ( Figure 7A) or a closed vessel ( Figure 7C).
• the plate 885 is suitably easily movable and being subjected to a pressure from the secondary cavity 821 which is preferably at least approximately the same as a pressure of the primary cavity 820 during states of rest, i.e. not during transitionary states.
• FIG. 9A shows the valve unit in a closed state with a flexible membrane 987 in a rest position dividing a primary cavity 920 from a secondary cavity. Factors such as how long the valve body 910 is in the different rest states and the tension of the flexible membrane 987, will determine if and how long it will take before the flexible membrane 987 reaches its rest position, and it is assumed in Figure 9A that the flexible membrane 987 has reached its rest position.
• Figure 9B shows the upper end of a valve unit during a transitional state, the valve body 910 is opening the valve and flexing the flexible membrane 988.
• the pressure difference of the two cavities 920, 921 , and the rate of liquid ink escapement from the primary cavity 920 will determine how quickly it will reach a rest position.
• the open time is so short in relation to other influencing factors that the flexible membrane does not reach its rest position during valve open states.
• Figure 9C shows an alternative embodiment of a valve unit with a flexible membrane 989. In this embodiment the valve body 910 relies on an adjustment screw 911 , and the flexible membrane 989 is thus place in the side of the encasement.
• FIG. 10 shows a two piston valve embodiment according to the invention.
• the valve body 1010 is not necessarily of the same size as the closure piston 1090, especially if there is one closure piston 1090 for several valve units/valve bodies.
• FIG. 10 there is a movable valve body 1010 with a stop portion 1017 for regulating liquid ink through a discharge opening 1018.
• a cavity 1020 which is coupled to the closure piston 1090 allowing a flow 1052.
• liquid ink couples the valve body with the closure piston, but in other embodiments, a combination with, for example, the embodiments of any one of Figures 8A to 9C, would allow coupling to and action of the closure piston 1090 to be made by another medium, such as another, or the same, liquid or a gas.
• a primary electromagnetic coil or coils 1012 will move 1013 the valve body 1010 to open the valve unit and also at the same time push 1052 liquid ink towards the closure piston 1090.
• the closure piston 1090 will preferably comprise rest springs or other means to ensure that it is in a known position when it is needed to close the valve unit or units.
• closure piston electromagnetic coil or coils 1092 are activated to thus move 1093 the closure piston 1090 to create a pressure pulse which is coupled 1052 to the valve body 1010 in such a way that the valve body 1010 moves and closes the valve.
• closure piston electromagnetic coil or coils 1092 are activated to thus move 1093 the closure piston 1090 to create a pressure pulse which is coupled 1052 to the valve body 1010 in such a way that the valve body 1010 moves and closes the valve.
• valve unit becomes smaller at the discharge opening 1018 where space is very scarce, and less force is required to open the valve, thus requireing smaller electromagnetic coils and drive electronics. Less force to open the valve is required since the valve body does not have to move against any spring force which is trying to keep the valve closed.
• Figure 11 shows a liquid ink valve unit with a displaced electromagnetic coil 1199 according to the invention, i.e the electromagnetic coil does not coil around, i.e. surround, the movable valve body 1110, but around a magnetic core, which forms a first part of a magnetic circuit of which the movable valve body 1110 is a second and separate part.
• the space consuming electromagnetic coil 1199 is not around the valve body where space is very scarce, particularly if the valve unit is apart of a printhead structure with several valve units.
• Figure 11 further shows an embodiment of the invention where seals 1182 separate the liquid ink cavity from the cavity 1120 at the end of the valve body opposite to the stop portion 1117 end, thus enabling flow 1152 of a gas or liquid to/from the cavity 1120.
• control unit The control functions and monitoring of a liquid ink printer according to the invention can be handled by a control unit.
• the described control unit is merely one example of an embodiment. All the different parts of a control unit can be separated into physically distinct features as depicted, or be integrated to a higher or lower degree.
• a user commonly a user computer or scanner, is connected to an I/O interface of the control unit.
• the I/O interface in turn is connected to the other parts of the control unit by means of a data/control bus.
• the data/control bus allows communication between the different parts of the control unit.
• a control unit will further suitably comprise some kind of processing means, in this example a CPU, which will receive its intructions from a program memory and use a scratchpad memory for calculations and storage of data.
• Control and monitoring of various mechanical and electro-mechanical components of the printer is usually done by means of an I/O interface with inputs from the printer itself or buttons, and outputs to motors and/or lamps.
• the liquid ink printer receiving image data to be printed either directly or after appropriate processing is suitably stored in one or more bitmaps, where each bitmap will control a plurality of liquid ink valves, as previously described.
• a typical liquid ink printer according to the invention will comprise six different colors, but may, depending on the specific embodiment comprise more or less colors.
• the basic principle of the invention is to provide a valve unit whith a valve body with freer movement. This is attained according to the invention by removing the restrictions of transport of whatever, such as liquid ink, is at the opposite end of the valve body to the end which controls the liquid ink outlet. This ensures a rapid movement of the valve body, thus increasing its maximum complete movement frequency.
• FIGURE 1 a valve unit of a printhead structure to which the invention is suitably applied
• FIGURE 2 liquid ink flow around the opposite end to the stop portion end of the valve body, which is referenced to as the top end of the valve body, 210 movable valve body, piston,
• FIGURE 3 a liquid ink valve unit with liquid ink pressure change dampening at the top of the piston/valve body, according to a basic embodiment of the invention, 301 liquid ink inlet, 309 liquid ink outlet,
• FIGURE 4 different embodiments of the invention applied to a liquid ink valve unit with an adjustment screw, 410 movable valve body, piston,
• FIGURE 5 a further embodiment according to the invention with a modified valve body, 510 movable valve body, piston,
• FIGURE 6 different embodiments of valve bodies according to the invention, 610 unmodified movable valve body/piston,
• FIGURE 7 different alternative embodiments of liquid ink pressure change dampening according to the invention, 710 movable valve body, piston,
• FIGURE 8 different alternative cavity separator embodiments according to the invention
• FIGURE 10 a two piston valve embodiment according to the invention, 1010 movable valve body, piston,
• FIGURE 11 a liquid ink valve unit according to the invention with a displaced electromagnetic coil according to the invention, 1110 movable valve body, piston,

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• Ink Jet (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)
• Multiple-Way Valves (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

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Family Applications (1)

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• 2001
  • 2001-12-13 SE SE0104209A patent/SE521081C2/sv not_active IP Right Cessation
• 2002
  • 2002-12-12 AU AU2002358378A patent/AU2002358378A1/en not_active Abandoned
  • 2002-12-12 EP EP02792141A patent/EP1453681A1/de not_active Withdrawn
  • 2002-12-12 WO PCT/SE2002/002314 patent/WO2003053700A1/en not_active Application Discontinuation

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