EP1201432A1 - Appareil et méthode pour améliorer la qualité d'impression - Google Patents

Appareil et méthode pour améliorer la qualité d'impression Download PDF

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Publication number
EP1201432A1
EP1201432A1 EP00123724A EP00123724A EP1201432A1 EP 1201432 A1 EP1201432 A1 EP 1201432A1 EP 00123724 A EP00123724 A EP 00123724A EP 00123724 A EP00123724 A EP 00123724A EP 1201432 A1 EP1201432 A1 EP 1201432A1
Authority
EP
European Patent Office
Prior art keywords
printhead
print media
carriage
printing device
ink drops
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00123724A
Other languages
German (de)
English (en)
Inventor
Xavier Gros
Josep Miquel Canal
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HP Inc
Original Assignee
Hewlett Packard Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hewlett Packard Co filed Critical Hewlett Packard Co
Priority to EP00123724A priority Critical patent/EP1201432A1/fr
Publication of EP1201432A1 publication Critical patent/EP1201432A1/fr
Withdrawn legal-status Critical Current

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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
    • B41J2/015—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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04503—Control methods or devices therefor, e.g. driver circuits, control circuits aiming at compensating carriage speed
    • 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
    • B41J19/00—Character- or line-spacing mechanisms
    • B41J19/14—Character- or line-spacing mechanisms with means for effecting line or character spacing in either direction
    • B41J19/142—Character- or line-spacing mechanisms with means for effecting line or character spacing in either direction with a reciprocating print head printing in both directions across the paper width
    • 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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04505—Control methods or devices therefor, e.g. driver circuits, control circuits aiming at correcting alignment
    • 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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04526—Control methods or devices therefor, e.g. driver circuits, control circuits controlling trajectory
    • 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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04556—Control methods or devices therefor, e.g. driver circuits, control circuits detecting distance to paper
    • 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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04586—Control methods or devices therefor, e.g. driver circuits, control circuits controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type

Definitions

  • the present invention relates to an apparatus and method for improving printing quality, and particularly to printing devices and methods in which ink drops are ejected from a printhead towards a print media in which there is relative movement between the printhead and print media.
  • the present invention has particular application in the field of inkjet printing, although as will be appreciated is not limited to this field of application.
  • inkjet printers a scanning carriage carrying a number of inkjet printheads moves reciprocally above a print media while each printhead ejects drops of ink towards the print media.
  • the print media is normally stationary during the deposition of ink drops and is incrementally advanced between printing passes of the carriage.
  • the ink drops must be accurately positioned on the print media, for example paper. Errors in the positioning of drops of ink on paper (where they are known as dots), are a major cause of printing quality degradation. These errors are known as DPE (dot placement errors) and can be due to a large number of causes.
  • DPE dot placement errors
  • DPE DPE-induced ejection speed
  • a typical thermal inkjet ejection speed for an ink drop is about 10m/s and variations in this speed of up to 3 m/s are possible.
  • a further known printhead source of DPE is that of the misdirected nozzle.
  • one or more of the many nozzles of an inkjet printhead may be incorrectly formed or may be partially blocked by dried ink. This can lead to the nozzle ejecting ink at an angle other than 90 degrees to the nozzle plate of the printhead which will also lead to DPE.
  • DPE digital image stabilization
  • the greatest source of DPE is variation in the PPS (printhead to paper spacing).
  • the PPS is kept as small as possible so as to minimise DPE (and to reduce ink aerosol) and must also be accurately controlled over the entire length of the print zone of the printer.
  • the PPS is of the order of 1mm and must be accurately maintained over a length of up to 60 inches.
  • the carriage of these printers could be travelling at 20 or 40 ips (inches per second) while firing ink drops which are travelling at approximately 10m/s, so any variation in the PPS along the length of the print zone will be translated to DPE since, due to the trajectory of the ink drops through the air, the ink drops will land on the paper either before their target position (in the case of a locally reduced PPS) or after their target position (in the case of a locally increased PPS).
  • Prior art attempts to solve this problem have focused in two areas. Firstly, rigorous mechanical design of the printer chassis and carriage mounting elements so as to attempt to minimise the actual variations in PPS, for example as disclosed in EP 1 029 697 and US serial No. 09/484185 filed on 18 January 2000.
  • Both DPE and irregular dot shapes can lead to a number of problems in the images printed for example banding (in which horizontal or vertical bands in the image can be discerned), fuzzy lines and colour or tone problems. Since for many printers, such as four colour CMYK (cyan, magenta, yellow, black) printers, the majority of desired colours are achieved by a combination of a small set of basic colours, the combination of DPE and variable dot shape can lead to severe colour inconsistencies and inaccuracy.
  • CMYK cyan, magenta, yellow, black
  • a printing device for marking print media comprising a printhead for ejecting ink drops, a holder in which the printhead is mounted, and a mechanism for positioning print media relative to the printhead, wherein during printing operation of the printing device there is relative movement between the printhead and the print media, while ink drops are being ejected from the printhead, and wherein the ejection direction of the ink drops is angled relative to the print media so as to substantially compensate for said relative movement.
  • the ejection direction of the ink drops forms a non-zero angle with the normal to the plane of the print media, as opposed to the usual prior art arrangement which attempts to align the ejection direction of the ink drops with the normal to the print media.
  • the non-zero angle can be arranged to compensate for the relative movement between the print media and the printhead during the ejection of ink drops from the printhead.
  • a particularly preferred result of the angling of the ink drops ejection direction is that the tangent to the trajectory of the ink drops, at the print media surface, is substantially parallel to the normal to the plane of the print media.
  • the printhead eject one or more satellite ink drops in addition to the intended main ink drop, if they are all travelling substantially normally to the print media, in accordance with embodiments of the present invention, then all drops should land on the print media close to each other. This aids in forming a more regularly shaped ink dot on the print media, more consistently and thus aids image quality.
  • the ink drop ejection angle is determined so that the ink drops are ejected from the printhead with a first velocity component which is substantially equal in magnitude and substantially opposite in direction to the velocity between the printhead and the print media, relative to the print media, and with a second non-zero velocity component towards the print media.
  • a first velocity component which is substantially equal in magnitude and substantially opposite in direction to the velocity between the printhead and the print media, relative to the print media, and with a second non-zero velocity component towards the print media.
  • the relative velocity between the print media and the printhead can be compensated for, so that, relative to the print media, the ink drops are ejected with a low velocity vector, in ideal circumstance a substantially zero velocity vector, within the plane of the print media.
  • the ejection direction of ink drops from the printhead makes an angle ⁇ of greater than 90 degrees with the relative velocity vector between the printhead and the print media in order to compensate for this relative velocity.
  • an angle ⁇ of greater than 90 degrees with the relative velocity vector between the printhead and the print media in order to compensate for this relative velocity.
  • Numerous embodiments of the present invention are disclosed in which such an angle can be achieved.
  • the optimum angle for compensating for the relative velocity is generally dependent on the magnitude of this relative velocity and in preferred embodiments the angle ⁇ can be varied between a plurality of predetermined values each of which is optimised for a different predetermined relative velocity between the printhead and the print media.
  • the relative velocity between the print media and the printhead may be generated by a number of alternative or complementary arrangements, for example the printhead may be stationary while the print media is moved during ink drop ejection or vice versa.
  • the printing device has a holder which comprises a carriage capable of moving at least one printhead at a predetermined velocity relative to the print media along a scanning axis, while ink drops are being ejected from the printhead, to generate said relative movement between the printhead and the print media .
  • the printing device may have a plurality of printheads mounted on the carriage, and advantageously at least two of the printheads may have different ink drop ejection directions relative to the direction of carriage motion along the scanning axis so that the leading printhead ejects drops at a smaller angle to the carriage motion direction than the trailing printhead.
  • This arrangement is particularly useful when it is found that ink drops fired from the leading printhead experience greater air resistance than those fired from the trailing printhead.
  • Embodiments of the present invention provide numerous arrangements for compensating for relative movement between a printhead and print media whose direction is periodically reversed.
  • the present invention also encompasses printing devices wherein the scanning axis makes an angle with the plane of the print media so as to substantially compensate for the relative movement between the printhead and the media.
  • This arrangement has the advantage that only the mounting of the scan axis of a conventional printer need be altered, which may be achieved at minimum cost.
  • a mechanism to alter the angle of the scan axis between two predetermined angles relative to the print media may be provided so that in operation the mechanism alters the angle for each direction of motion of the carriage so that for each direction the angle substantially compensates for the relative movement between the printhead and the print media.
  • the print media positioning mechanism may hold the print media at an angle to the relative direction of movement between the printhead and the print media so as to substantially compensate for relative movement between the printhead and the media.
  • a method of printing comprising the steps of mounting a print media in a printing device in a printing relationship with a printhead, generating relative movement between the printhead and the print media so that the printhead accesses different parts of the print media for printing, ejecting ink drops from the printhead in a direction, relative to the print media, which makes an angle with the print media so that, when the ink drops impact the print media, the effects of the relative movement between the printhead and the print media are substantially ameliorated.
  • ink should be understood to be a shorthand reference to any form of marking material that a printing device may utilise and that may be ejected from a printhead in quantised amounts towards a print media.
  • “ink” and “ink drops” encompass for example dry toner particles, solid ink, carbon, dye based inks, pigment based inks.
  • the present invention in its broadest aspects has equal application for all such marking particles, as will be appreciated by those skilled in this art. However, greatest benefit from certain embodiments of the present invention will be obtained when liquid ink drops are utilised.
  • Typical embodiments of the invention are exemplified in a large format colour inkjet printer (sometimes know as a plotter) and will be described in relation to the such a printer.
  • a large format colour inkjet printer sometimes know as a plotter
  • the present invention has application to many other types of printer.
  • FIG. 1 is a perspective view of a large format inkjet printer 1 having a housing 2 mounted on a stand 3.
  • the housing has left and right drive mechanism enclosures 4 and 5.
  • a control panel 6 is mounted on the right enclosure 5 via which the user may input data to the printer.
  • a carriage assembly 7, illustrated in phantom under a cover 8, is adapted for reciprocal motion along a carriage bar 9, also shown in phantom.
  • the position of the carriage assembly 7 in a horizontal or carriage scan axis is determined by a carriage positioning mechanism 10 with respect to an encoder strip 11 (see Figure 2).
  • a print media 12 such as paper is positioned along a vertical or media advance axis by a media axis drive mechanism (not shown).
  • the media advance axis also known as the X axis is denoted as 13, and the scan axis, also know as the Y axis, is denoted as 14.
  • the printer 1 is loaded with a roll of print media 12 which is held in rollfeed housing 15. The end of the roll of media extends out of the housing 15 through the print zone of the printer, located below the carriage assembly 7, and out the front of the printer.
  • a cut sheet of media may be loaded into the front of the printer 1 where the media positioning system shown in Figure 3 will draw the sheet into the printer. The user may switch between printing on roll media and printing on cut sheet at will.
  • FIG. 2 is a perspective view of the carriage assembly 7, the carriage positioning mechanism 16 and the encoder strip 17.
  • the carriage positioning mechanism 16 includes a carriage position motor 16A which has a shaft 16B which drives a belt 16C which is secured by idler 16D and which is attached to the carriage 7.
  • the position of the carriage assembly in the scan axis is determined precisely by the encoder strip 11.
  • the encoder strip 11 is secured by a first stanchion 17A on one end and a second stanchion 17B on the other end.
  • An optical reader (not shown) is disposed on the carriage assembly and provides carriage position signals which are utilised to achieve image registration when printing and distance measurement when the carriage is scanning a printed test pattern.
  • FIG 3 is a perspective view of a simplified representation of a media positioning system 18 which can be utilised in the printer 1.
  • the media positioning system 18 includes a motor 18A which is normal to and drives a media roller 18B.
  • the position of the media roller 18B is determined by a media position encoder 18C on the motor.
  • An optical reader 18D senses the position of the encoder 18C and provides a plurality of output pulses which indirectly determines the position of the roller 18B and, therefore, the position of the media 12 in the Y axis.
  • the carriage mounted optical sensor 19 used for scanning printed test patterns.
  • the media and carriage position information from the encoder strip and the media position optical reader 18D is provided to a processor 26 on a circuit board 27 disposed on the carriage assembly 7.
  • a memory element 28 in which the various printing parameters are stored for access by processor 26.
  • the printer 1 has four inkjet printheads 29, 30, 31 and 32 that store ink of different colours, e.g. cyan, magenta, yellow and black ink, respectively.
  • Each of the printheads is mounted in a stall 50, 51, 52 and 53 within the carriage 7 and a nose of the printhead protrudes through the base of the carriage towards the print media 12.
  • the distance from the ink ejection surface 40 at the end of the nose of the printhead to the print media 12 is known as the PPS 41.
  • the usual mode of operation of the printer 1 is for the media 12 to be advanced along the X-axis by the media positioning system while the printheads of the carriage 7 are not ejecting ink.
  • the carriage 7 is scanned along the Y-axis as ink is ejected by the printheads 29, 30, 31 and 32 onto the media 12.
  • Selected nozzles in the inkjet printheads are activated by signals received from processor 26 when the carriage is at certain positions along the Y-axis determined by the encoder strip 11 so as to deposit ink at appropriate locations on the media to form a desired image. Relative movement between the print media 12 and the printheads 29, 30, 31 and 32 during the ejection of ink is thus generated by the movement of the carriage 7.
  • each of the printheads 29, 30, 31 and 32 is mounted at a slight angle within its respective stall 50, 51, 52 and 53 so that the ink ejection direction 57 for each printhead is at an angle ⁇ to the carriage scan direction 54 of greater than 90 degrees.
  • Figure 5a is a schematic diagram of a prior art printer arrangement in which the printhead 42 is positioned to eject ink drops at velocity Vd and in a direction 43 which, when the printhead is stationary, is normal to the plane of the print media 44.
  • the printhead 42 is moving in a direction 45 relative to the print media at a velocity Vp the direction 46 of ejection of the ink drops relative to the print media 12 is no longer parallel to the normal of the print media surface.
  • the ink drop landing position 47 where a dot is formed on the media 44 is offset by a distance 49 from the drop ejection position 48, that is the point on the media above which the ink drop leaves the printhead.
  • this offset can be compensated for by the printer processor 26.
  • Values for the offset 49 for each printhead 42 and for each predetermined printhead velocity 45 are stored in memory 28 and when printing the processor calculates the appropriate timing delay or advance in sending a firing signal to the printhead so as to ensure that the ink drop lands in the correct position on the media.
  • a typical PPS error y2 -y1 in a large format printer is 0.2mm and a typical drop velocity for thermal inkjet printheads is 10 m/s.
  • a typical printhead velocity of 20 ips (inches per second) this leads to a DPE of 0.01 mm.
  • a printer resolution of 600dpi dots per inch
  • this is equivalent to a DPE of a quarter dot i.e. of a quarter of the printer pixel grid size.
  • Figure 5b shows a schematic diagram of a printer arrangement of the present embodiment.
  • the printhead 56 is mounted within the carriage 7 at an angle ⁇ so that the ejection direction 57 of ink drops, relative to the media 44, is not normal to the media surface.
  • the angle ⁇ is chosen so that the absolute trajectory 58 of the ink drop, when fired from a printhead which is moving at a velocity Vp relative to the media, is normal to the media.
  • This arrangement has the effect that the ink drop landing position 47 is coincident with the drop ejection position 48. In this manner the relative velocity between the printhead and the print media can be compensated so that, from the perspective of the print media, the ejection of the ink drops is similar to that seen from a stationary prior art printhead.
  • V p (ips) 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 ⁇ (°) 0.7 1.5 2.2 2.9 3.6 4.4 5.1 5.8 6.5 7.2 8 8.7 9.4 10.1 10.8 11.5
  • air resistance In practise one of the most important factors, particularly affecting inkjet printers having small drop volumes, in the setting of the angle ⁇ , is air resistance. In general this is likely to reduce the angle at which the printhead should be set since air resistance will act to reduce the velocity Vp of the ink drops. However, under some circumstances of drop velocity, printhead velocity and aerodynamics around the carriage the theoretical angle may need to be increased to obtain optimum performance. The effect of air resistance may also be different for each of the printheads within the carriage, due the shielding effect of one printhead by the other printheads.
  • the 8 dot test patterns were photographed through a microscope and are shown in Figure 8 for the 10ips tests and Figure 9 for the 25ips tests.
  • the length L and height H of each of the 8 dots of each of the eight test patterns was then measured under the microscope and these results are tabulated in Table 2 of Figure 10. The ratio of L/H was calculated for each dot and then these values were averaged for each set of 8 dots in a test pattern.
  • This ranking order is also seen for the 25ips tests, where from table 2 it can be seen that the order is photo 98 first, followed by photos 96, 95 and 97.
  • Such a print quality test can be used to help to optimise the angle ⁇ for each printhead of a particular printer.
  • a process as follows could be employed:
  • the third curve 102 of Figure 11 is the result of subtracting curve 101 from curve 100 and represents a measure of the variation with carriage speed of the remaining factors that affect the offset distance 49.
  • These curves could be used to help decide for a particular printer whether to increase the angle ⁇ beyond that calculated theoretically for a specific carriage speed or whether to decrease it from the calculated value. For example it would seem that for the printer and carriage arrangement tested, at lower carriage speeds the value of ⁇ should be increased from the theoretical value, while for higher carriage speeds the value of ⁇ should be decreased from that calculated theoretically.
  • Figure 12 is a schematic drawing of a printhead according to a further embodiment in which the ink ejection surface 104 of the printhead has been angled relative to the side walls 105 and 106 of the printhead. The appropriate angle ⁇ is then generated between Vd and Vp since the ink drops are ejected normally from the ink ejection surface 104.
  • This embodiment has the advantage that no special mounting arrangements within the printer carriage are required and such printheads could be utilised with existing printer hardware.
  • FIG. 13 A further alternative embodiment is shown in Figure 13.
  • the internal design of the printhead 107 has been altered so that a internal ink pathway 108 is angled relative to the ink ejection surface so that the ink ejection direction is not at 90° to the surface 104. Again the angle ⁇ between the ink ejection direction and the printhead movement direction is achieved.
  • This embodiment has the advantages of the embodiment of Figure 12, but additionally does not increase the PPS potentially required due to the angled ejection surface 104 of the Figure 12 embodiment.
  • Figures 14 and 15 show two further embodiments which both differ somewhat from previously described embodiments.
  • Figure 14 schematically shows a carriage 7 mounted for a movement along a carriage bar 9, the carriage bar itself being mounted at an angle to the print media 44.
  • the ejection direction is at 90° to the printhead direction of motion, but is angled relative to the print media so that the resultant of the two velocity vectors Vp and Vd is normal to the print media surface.
  • This embodiment has the advantage that no modifications are required to a standard printer carriage or printhead and the required angle is simply achieved by a slight offset when mounting the carriage bar 9.
  • the ejection direction is also at 90° to the printhead direction of motion, but is angled relative to the print media so that the resultant of the two velocity vectors Vp and Vd is normal to the print media surface. In this case the angle is achieved via the mounting of the print media positioning mechanism.
  • one of the disadvantages of some embodiments of the invention is that when the printhead or other component of the printer is angled so as to optimise printing for a specific printhead movement direction, the opposite movement direction may be caused to print at worse quality.
  • One alternative embodiment which allows for bi-directional printing at improved image quality for both printing directions is simply to have two sets of printheads. One set may be angled for printing in one direction and the other oppositely angled for printing in the opposite direction.
  • a second alternative bi-directional printing embodiment is shown schematically in Figure 16.
  • Each of the printheads of a printer is mounted for rotation about a central axis 110 within the printer carriage.
  • the rotation is achieved via an electromagnetic pusher 111 which acts against a spring 112 and the rotation of the printhead is limited by a pair of stops 113.
  • the angle of inclination of each of the printheads may be reversed. In this manner the optimum angle is achieved for both printing directions without requiring two sets of printheads.
  • a further enhancement to this embodiment may be achieved by manually or automatically adjusting the position of the stops 113. This would enable different angles of inclination of the printhead to be achieved, each of which could be optimised for different carriage speed.
  • Figures 17 and 18 show modifications to the ejection surface 104 of a printhead which would allow it to print at high quality in accordance with the present invention in two printing directions and to be mounted in a carriage in a normal manner.
  • Figure 17 is a schematic showing a printhead with an ink ejection surface which comprises two angled surfaces meeting at an internal acute angle. Each of the surfaces, as can be seen in Figure 17c, has a row of nozzles 114 which fires ink drops in different directions. Each of the two ejection directions is optimised for a particular carriage speed and direction.
  • Figure 18 is a schematic showing a printhead with an ink ejection surface which comprises two angled surfaces meeting at an internal obtuse angle.
  • each of the surfaces as seen in Figure 18c, has a row of nozzles 114 which fires ink drops in different directions and each of the two ejection directions is optimised for a particular carriage speed and direction.
  • a final embodiment for bi-directional printing is based on the embodiment of Figure 14.
  • the carriage bar 9 is provided with a mechanism for altering its angle relative to the print media 44, for example a stepper motor located at one end of the carriage bar 9 that is able to lift or lower this end. If the moving end of the carriage bar is lowed past the height of the opposite end of the carriage bar the angle between the ejection direction of the printhead and the print media can be changed for each direction of movement of the carriage.
  • This embodiment may also advantageously be used to optimise the ejection angle for printing at different carriage speeds, whether bi-directional or uni-directionally.
  • the present invention may also be applied to printer systems in which the printhead is fixed and the print media moves relative to the printhead.
  • a particular example of such a system within the inkjet printer field is the so called page wide array.
  • Such a device comprises an array of fixed printheads which span across the width of a print media so that no movement of the printheads in the Y-axis is required to print on the print media. The print media is then moved in the X-axis past the printheads.
  • the media could be moved in an incremental manner so that at each printing operation the media is stationary, or it could be moved continuously so that there is relative movement between the print media and the printheads during the ejection of ink drops. In the latter case the principles of the present invention can advantageously be applied to improve print quality.
  • Figure 19 is a view along the Y-axis of a page wide array printing system in which the print media 44 is moved past an array 115 of printheads while they eject ink drops towards the media in direction 116.
  • the print media 44 is moved past an array 115 of printheads while they eject ink drops towards the media in direction 116.
EP00123724A 2000-10-31 2000-10-31 Appareil et méthode pour améliorer la qualité d'impression Withdrawn EP1201432A1 (fr)

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EP00123724A EP1201432A1 (fr) 2000-10-31 2000-10-31 Appareil et méthode pour améliorer la qualité d'impression

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EP1418053A1 (fr) * 2002-11-06 2004-05-12 Océ-Technologies B.V. Méthode d'impression pour améliorer la qualité des bords d'image
EP1534527A1 (fr) * 2002-06-20 2005-06-01 Lexmark International, Inc. Procede pour determiner la vitesse des gouttes d'encre d'une tete d'impression montee sur une porteuse
US7073889B2 (en) 2002-11-06 2006-07-11 Oce-Technologies B.V. Method of printing
WO2012115935A1 (fr) * 2011-02-21 2012-08-30 Olson John Stewart Procédé et appareil destinés à une impression numérique tridimensionnelle
US8430471B2 (en) 2011-07-14 2013-04-30 Hewlett-Packard Development Company, L.P. Printing head alignment adjustment
US9561653B2 (en) 2014-01-31 2017-02-07 Hewlett-Packard Industrial Printing Ltd. Printhead arrangement on a printbar beam member
US9962931B2 (en) 2015-02-18 2018-05-08 Hewlett-Packard Development Company, L.P. Estimation of pen to paper spacing
CN110239097A (zh) * 2019-05-25 2019-09-17 共享智能铸造产业创新中心有限公司 打印头外壳结构及带有该外壳的打印头或打印机
WO2022158308A1 (fr) * 2021-01-20 2022-07-28 株式会社ミマキエンジニアリング Imprimante à jet d'encre

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JPH0516340A (ja) * 1991-07-09 1993-01-26 Canon Inc 記録装置
EP0622237A2 (fr) 1993-04-30 1994-11-02 Hewlett-Packard Company Concept de lame de phase pour l'alignement de cartouches à jet d'encre utilisant le balayage d'un motif de référence
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JP2000218779A (ja) * 1999-01-29 2000-08-08 Sharp Corp インクヘッドおよびそれを搭載したインクジェットプリンタ
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JPH0516340A (ja) * 1991-07-09 1993-01-26 Canon Inc 記録装置
EP0622237A2 (fr) 1993-04-30 1994-11-02 Hewlett-Packard Company Concept de lame de phase pour l'alignement de cartouches à jet d'encre utilisant le balayage d'un motif de référence
US5992968A (en) * 1994-06-15 1999-11-30 Canon Kabushiki Kaisha Ink jet printing method and apparatus
JP2000218779A (ja) * 1999-01-29 2000-08-08 Sharp Corp インクヘッドおよびそれを搭載したインクジェットプリンタ
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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1534527A1 (fr) * 2002-06-20 2005-06-01 Lexmark International, Inc. Procede pour determiner la vitesse des gouttes d'encre d'une tete d'impression montee sur une porteuse
EP1534527A4 (fr) * 2002-06-20 2007-11-07 Lexmark Int Inc Procede pour determiner la vitesse des gouttes d'encre d'une tete d'impression montee sur une porteuse
EP1418053A1 (fr) * 2002-11-06 2004-05-12 Océ-Technologies B.V. Méthode d'impression pour améliorer la qualité des bords d'image
US7073889B2 (en) 2002-11-06 2006-07-11 Oce-Technologies B.V. Method of printing
US9061521B2 (en) 2010-09-22 2015-06-23 3Dphotoworks Llc Method and apparatus for three-dimensional digital printing
US10843458B1 (en) 2010-09-22 2020-11-24 3Dphotoworks Llc Method and apparatus for three-dimensional digital printing
WO2012115935A1 (fr) * 2011-02-21 2012-08-30 Olson John Stewart Procédé et appareil destinés à une impression numérique tridimensionnelle
AU2012220834B2 (en) * 2011-02-21 2016-07-28 3Dphotoworks Llc Method and apparatus for three-dimensional digital printing
US8430471B2 (en) 2011-07-14 2013-04-30 Hewlett-Packard Development Company, L.P. Printing head alignment adjustment
US9561653B2 (en) 2014-01-31 2017-02-07 Hewlett-Packard Industrial Printing Ltd. Printhead arrangement on a printbar beam member
US9962931B2 (en) 2015-02-18 2018-05-08 Hewlett-Packard Development Company, L.P. Estimation of pen to paper spacing
CN110239097A (zh) * 2019-05-25 2019-09-17 共享智能铸造产业创新中心有限公司 打印头外壳结构及带有该外壳的打印头或打印机
CN110239097B (zh) * 2019-05-25 2024-04-19 共享智能装备(安徽)有限公司 打印头外壳结构及带有该外壳的打印头或打印机
WO2022158308A1 (fr) * 2021-01-20 2022-07-28 株式会社ミマキエンジニアリング Imprimante à jet d'encre

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