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EP-3802136-B1 - PRINTHEAD ADJUSTMENT APPARATUS

EP3802136B1EP 3802136 B1EP3802136 B1EP 3802136B1EP-3802136-B1

Inventors

  • CAMPBELL, Nicholas John

Dates

Publication Date
20260513
Application Date
20190607

Claims (14)

  1. A printhead adjustment apparatus (100) for adjusting the translation and rotation of a printhead (210), comprising: a first portion (103) arranged for coupling to the printhead (210); a second portion (104) arranged for coupling to the printhead (210); a first arm, and a first actuator (101) positioned at a first end of the first arm, wherein the first arm is coupled to the first portion by a first flexure arrangement (105); a second arm, and a second actuator (102) positioned at a first end of the second arm, wherein the second arm is coupled to the second portion by a second flexure arrangement (106); a central body (109) arranged between the first actuator (101) and the second actuator (102); a first pivot (101a) at a second end of the first arm opposite the first end of the first arm, the first pivot (101a) connecting the first arm to the central body (109) for permitting movement of the first arm relative to the central body (109) in response to translation of the first actuator (101); a second pivot (102a) at a second end of the second arm opposite the first end of the second arm, the second pivot (102a) connecting the second arm to the central body (109) for permitting movement of the second arm relative to the central body (109) in response to translation of the second actuator (102); wherein translation of the first and second actuators (101, 102) in the same direction as each other causes translation of the first and second portions (103, 104) in the same direction as each other to provide translation of the printhead (210); wherein translation of the first and second actuators (101, 102) in opposite directions to each other causes translation of the first and second portions (103, 104) in opposite directions to each other to provide rotation of the printhead (210); wherein the first flexure arrangement (105) is coupled to the first arm at a position along the first arm between the first end of the first arm and the second end of the first arm and closer to the first pivot (101a) at the second end of the first arm than to the first actuator (101) at the first end of the first arm to provide a reduction ratio such that a magnitude of the translation of the first portion (103) and a magnitude of the translation of the first actuator (101) are in a ratio of less than one and/or wherein the second flexure arrangement (106) is coupled to the second arm at a position along the second arm between the first end of the second arm and the second end of the second arm and closer to the second pivot (102a) at the second end of the second arm than to the second actuator (102) at the first end of the second arm to provide a reduction ratio such that a magnitude of the translation of the second portion (104) and a magnitude of the translation of the second actuator (102) are in a ratio of less than one.
  2. A printhead adjustment apparatus (100) according to claim 1, wherein each flexure arrangement (105, 106) comprises at least two flexural pivots (105a, 105b, 106a, 106b).
  3. A printhead adjustment apparatus (100) according to any preceding claim, wherein the first and second portions (103, 104) are arranged in the same plane.
  4. A printhead adjustment apparatus (100) according to any preceding claim, wherein the translation of the first actuator (101) causes translation of the first portion (103) in substantially the same direction as the translation of the first actuator (101) and/or wherein the translation of the second actuator (102) causes translation of the second portion (104) in substantially the same direction as the translation of the second actuator (102).
  5. A printhead adjustment apparatus (100) according to any preceding claim, wherein more than one of the following are formed from the same body: the first and second portions (103, 104), the first and second flexure arrangements (105, 106), the central body (109), and/or the first and second actuators (101, 102).
  6. A printhead adjustment apparatus (100) according to claim 5 , further comprising a first pivot (101a) arranged between the first actuator (101) and the central body (109) for converting the translation of the first actuator (101) into translation of the first portion (103) via the first flexure arrangement (105), optionally wherein the first pivot (101a) is a flexural pivot, optionally wherein translation of the first actuator (10) causes rotation of the first actuator (10) about the first pivot (101a) and wherein the first flexure arrangement (105) is configured to convert the rotation of the first actuator (101) into translation of the first portion (103).
  7. A printhead adjustment apparatus (100) according to any of claims 5 to 6 further comprising a second pivot (102a) arranged between the second actuator (102) and the central body (104) for converting the translation of the second actuator (102) into translation of the second portion (104) via the second flexure arrangement (106), optionally wherein the second pivot (102a) is a flexural pivot, optionally wherein translation of the second actuator (102) causes rotation of the second actuator (102) about the second pivot (102a) and wherein the second flexure arrangement (106) is configured to convert the rotation of the second actuator (102) into translation of the second portion (104).
  8. A printhead adjustment apparatus (100) according to any preceding claim, further comprising a printhead (210) coupled to the first and second portions (103, 104), wherein the printhead (210) comprises an array of nozzles for depositing ink, the array of nozzles arranged in a plane, optionally further comprising a printhead coupler coupled to and arranged between the printhead (210) and the first and second portions (103, 104), and optionally wherein the printhead coupler is configured to couple the translation and/or rotation of the first and second portions (103, 104) to the printhead (210).
  9. A printhead adjustment apparatus (100) according to claim 8, wherein the translation of the first and second portions (103, 104) occurs in a plane parallel to the array of nozzles of the printhead (210).
  10. A printhead adjustment apparatus (100) according to any preceding claim, wherein the first and second portions (103, 104) are each constrained to move predominantly in a first direction (107) and a second direction (108), wherein the second direction (108) is opposite to the first direction (107).
  11. A printhead assembly comprising: a plurality of printheads (210) arranged in a print carriage, each of the plurality of printheads (210) comprising an array of nozzles for depositing ink onto a substrate; a printhead adjustment apparatus (100) according to any of claims 1 to 10 coupled to each of the plurality of printheads (210) for adjusting the translation and rotation of each of the plurality of printheads (210).
  12. A method of manufacturing a printhead adjustment apparatus (100) according to any of claims 1 to 10, comprising the steps of: providing a printhead attachment; and removing selected parts of the printhead adjustment apparatus (100) to form a first flexure arrangement (105) between a first actuator (101) and a first portion (103), and to form a second flexure arrangement (106) between a second actuator (102) and a second portion (104).
  13. A method of adjusting a printhead (210), comprising: translating a first actuator (101) positioned at a first end of a first arm, wherein the first arm is coupled to a first portion (103) via a first flexure arrangement (105); translating a second actuator (102) positioned at a first end of a second arm, wherein the second arm is coupled to a second portion (104) via a second flexure arrangement (106); wherein the first portion (103) and the second portion (104) are coupled to a printhead (210); wherein a central body is (109) arranged between the first actuator (101) and the second actuator (102); wherein translation of the first actuator (101) and the second actuator (102) in the same direction as each other causes translation of the printhead (210); wherein translation of the first actuator (101) and the second actuator (102) in opposite directions to each other causes rotation of the printhead (210); wherein a first pivot (101a) is arranged at a second end of the first arm opposite the first end of the first arm, the first pivot (101a) connecting the first arm to the central body (109) for permitting movement of the first arm relative to the central body (109) in response to translation of the first actuator (101); and wherein a second pivot (102a) is arranged at a second end of the second arm opposite the first end of the second arm, the second pivot (102a) connecting the second arm to the central body (109) for permitting movement of the second arm relative to the central body (109) in response to translation of the second actuator (102); wherein the first flexure arrangement (105) is coupled to the first arm at a position along the first arm between the first end of the first arm and the second end of the first arm and closer to the first pivot (101a) at the second end of the first arm than to the first actuator (101) at the first end of the first arm to provide a reduction ratio such that a magnitude of the translation of the first portion (103) and a magnitude of the translation of the first actuator (101) are in a ratio of less than one and/or wherein the second flexure arrangement (106) is coupled to the second arm at a position along the second arm between the first end of the second arm and the second end of the second arm and closer to the second pivot (102a) at the second end of the second arm than to the second actuator (102) at the first end of the second arm to provide a reduction ratio such that a magnitude of the translation of the second portion (104) and a magnitude of the translation of the second actuator (102) are in a ratio of less than one.
  14. A method of adjusting a printhead (210) according to claim 13 wherein more than one of the following are formed from a same body: the first and second portions, the first and second flexure arrangements, the central body, and/or the first and second actuators.

Description

The present invention relates to a printhead adjustment attachment for adjusting the translation and rotation of a printhead. Printers are well-known devices for applying text and graphic images to a variety of substrates. A wide variety of different printers are available which are suitable for printing onto different types and sizes of substrate. Large-scale industrial printers are adapted to print images onto larger substrates than, for example, office-based printers used for printing onto A4-size paper. Large-scale printers may be used for printing onto, for example, advertising boards, posters, and/or large batches of smaller substrates. In an inkjet printing process, droplets of ink are deposited onto the surface of a substrate in a pattern to form the required image. The droplets of ink are typically emitted from a plurality of nozzles on an inkjet printhead. A typical printer includes several printheads arranged along a print carriage. For example, the print carriage may be up to around 2m in width. A print carriage may have up to 150 printheads. Printer manufacturers aim to provide a dense and continuous array of printheads across the whole width of the print carriage. Usually, the printheads are arranged in multiple rows to give a 2-D array of printheads. Recent advances in inkjet printhead manufacture have allowed manufacturers to integrate several thousand inkjet nozzles on a single printhead: this is frequently achieved by arranging the nozzles in a 2-D grid pattern. In order to achieve good positional registration (i.e. relative positioning) between nozzles within a printhead, the correct angle of rotation of the printheads in the plane of the nozzles of the printheads should be established. When the printhead is correctly rotationally aligned, the lines of ink laid down by the nozzles are equally spaced. However, if the array of nozzles is rotated and incorrectly rotationally aligned, the printed lines of ink are no longer equally spaced. In addition to the rotation of the printhead, translational alignment should also be considered. Registration between printheads, in the printing process direction, may be achieved by altering the firing times of the individual printheads, and vertical positioning and other rotations can be set by manufacturing tolerances. However, as printheads with higher resolutions and smaller drop sizes are developed, rotational and translational positioning are difficult to achieve using standard manufacturing tolerances so some degree of mechanical adjustment can be used to enable alignment of the printheads within the print carriage. Printheads are usually manufactured individually and fixed to a print carriage, on which they are aligned. Some printheads are modular, with every printhead individually replaceable in the field, requiring them to be individually adjustable for alignment. While technically challenging, this can provide improvements in the accuracy of alignment, because there is no stack up of tolerances, and because the final adjustment is done with the head in its operating condition. This also means that the final printed position of droplets is used for alignment, rather than nozzle position, so it includes any systematic jet deviations. A typical print carriage may have around 150 printheads, and the initial aligning and maintaining the alignment of that number of printheads is quite a demanding task. Further, when building large arrays of printheads, it is desirable to make the assembly as compact as is reasonably possible, as this improves the registration between printheads both within and between colours. However, this also means it is more difficult to make adjustments. When using a single pass printer comprising an array of printheads arranged in an arc-like shape around a cylindrical drum, adjustment is particularly difficult. Space can be especially tight, and adjustment at the plane of the printheads is extremely difficult. US 2006/077225 A1 discloses an ink-jet head mount to guide positions of ink-jet heads with a high precision and an ink-jet printing apparatus including the same. The ink-jet printing apparatus includes an ink-jet head having a plurality of nozzles to eject ink, an ink-jet head mount in which the ink-jet head is installed and is movable according to three-degrees-of-freedom, and a frame in which the ink-jet head mount is installed. US 2017/080728 A1 discloses a printer including a print head fastening facing a medium support surface; a scanning print carriage being movable along a guide in a scanning direction (Y); and a transporter for transporting the medium in a transport direction (X). The printer includes a suspension structure connecting the print head fastening to the scanning print carriage while allowing movement of the print head fastening with respect to the scanning print carriage in a direction (X) parallel to the transport direction. The suspension structure is elastically deformable to allow for the movement