Swath-height error involves the variation in the swath of ink that printheads in a printing device, such as in an inkjet printer, print on media. Variation in the swath height may directly impact print quality, and may be responsible for so-called swath boundary banding. Single-pass printing is especially sensitive to boundary banding, because errors may be difficult to cover up with masking techniques. As printer carriage speeds have increased over time, dynamic swath-height error due to aerodynamic effects has become more and more prevalent, especially during single-pass, bidirectional printing. Single-pass printing, and rapid carriage speeds, are typical today to meet expected printer throughput goals. In the ink-dispensing printhead structure carried by a typical printer carriage, the end printheads in the usual group of printheads are the most affected by this phenomena of swath-height error.
A printing device is provided which includes ink-dispensing structure which carries a printhead with a leading edge, and which moves in a printing sweep downstream across a printzone, a fairing structure, and a mounting which supports mounting the fairing structure for movement with the printhead downstream from the leading edge of the printhead in a position configured to reduce aerodynamic turbulence associated with the leading edge of the printhead during movement of the printhead downstream across the printzone.
As we have discovered, if printheads, and particularly leading edges of end printheads, are barriered aerodynamically by a skirt or a fairing, aerodynamic swath-height error can be reduced. For such a fairing to be effective, it typically will be proximate the printheads nozzle location, and proximate the surface of media being printed on in the printzone. As a consequence, aerosol ink may build up on such a fairing, and may attract fibers, both of which conditions can collectively result in fiber tracts. Effective use of a fairing therefore suggests cleaning the fairing structure periodically to deal with the build-up of ink and fibers.
A fairing structure which is deployable and undeployable (retractable in the service station between deployed and nondeployed positions) may help to deal with space considerations as described above. To aid in handling the deployment/retraction matters, an actuator may be provided adjacent (or in) the service station for shifting the fairing structure between a deployed position (to which it may be biased normally by a yieldable biasing spring), and a nondeployed position. This actuator may also be associated with a wiping/blotting/doctoring structure in the form of a pad or wiper that may act to remove, or otherwise deal -with, buildup of aerosol ink and/or media fibers. Actuator structure may be provided adjacent opposite ends of the printzone to permit doctoring of the fairing structure selectively at different times when the carriage and printhead structure are either within and outside of the service station.
Turning attention now to the drawings, and referring first to
Included in printer 20, and mounted on the printer's frame, which is shown fragmentarily at 24, is a bidirectionally reciprocating carriage 26 which rides back and forth on a supporting carriage rail 28. Carriage 26 carries ink-dispensing printhead structure 30, which here includes a group of four printheads 30a, 30b, 30c, 30d, in which group, printheads 30a and 30d are referred to as end printheads. Each printhead includes an array of plural ink-dispensing nozzles, such as the several nozzles whose ink exit faces are shown generally at 31 for printhead 30d in
Under the influence of appropriate reciprocal drive mechanism, carriage 26, during a printing operation, may move the printhead structure back and forth in successive reverse-direction printing sweeps single—pass printing sweeps—generally in the direction of double-ended arrow 32 over a printzone 34 (
Located appropriately adjacent one end of the printzone, near one end of carriage travel along rail 28, is a home or service station shown generally at 36, wherein carriage 26 and printhead structure 30 may park and remain between printing operations. In this service station, servicing activities for the printhead structure take place, such as protective capping of the printhead nozzles by a capping structure shown generally at 38 in
Turning attention now to
Referring now particularly to
One thing which should be noted with respect to printheads 30a–30d, and as can be seen particularly well in
Apparatus 22, in the embodiment of the invention now being described, includes a pair of downwardly spring-biased fairing structures 44, 46 which are carried for vertical, reversible reciprocation adjacent the opposite ends of carriage 26 and printhead structure 30. These fairing structures 44, 46 may be carried by mounting structures 48, 50, respectively. Yieldable biasing springs 52, 54, in turn may be operatively interposed, and acting between, the respecting associated fairing and mounting structures to produce actions which will shortly be described.
Fairing structure 44, its associated mounting structure 48, and biasing spring 52 are shown adjacent printhead 30a, with mounting structure 48 being suitably anchored to the corresponding adjacent side of carriage 26. Fairing structure 46, its associated mounting structure 50, and biasing spring 54 are shown adjacent printhead 30d, with mounting structure 50 being suitably anchored to the corresponding adjacent side of carriage 26. These fairing, mounting and biasing structures are substantially mirror-images of one another, and accordingly, only the structural assembly of structures 46 and biasing spring 54 will now be described in further detail.
Fairing structure 46 typically includes a downwardly-facing plate 46a which has a perimeter outline that is most clearly shown in
In fairing structure 46, plate 46a is joined to a pair of laterally-spaced, upwardly-extending legs 46c, which may be slidably received in downwardly-extending tubes 50a of mounting structure 50. An appropriate travel-limit interference structure (not shown) associated with the interface between legs 46c and tubes 50a may limit downward travel of fairing structure 46 relative to mounting structure 50 to that which is pictured for this fairing structure in
With the fairing structures in their deployed positions relative to the printhead structure during a printing operation, these fairing structures (and particularly the plates thereof, like plate 46a) may act as leading-edge surrogates for printhead edges 30a1, 30d1, depending upon the direction of travel of the carriage and printhead structure through and across the printzone. As such, these fairing structures may change the aerodynamic experience of the leading edges of the end printheads, and may do so in a fashion which reduces turbulence normally experienced by these printhead edges such that swath-height error discussed earlier may be significantly reduced.
While certain dimensions have been given as useful illustrations for the fairing structures described so far, there is a range of sizes and dimensions in each of the categories mentioned earlier which have been found to produce operating structures that are very satisfactory for different operating conditions. For example, while the Y dimension of the fairing structures' plates (such as plate 46a) typically may be at least the same as the Y dimensions of the printheads' leading edges, the X dimension of these fairing plate structures might typically lie in the range of between just a few millimeters and approximately 15-millimeters. The Z-axis dimension of the plates in the fairing structures might typically lie in the range of approximately 1- to 4-millimeters. The distance, shown at D2 in
Referring now to
Included in actuators 56, 58, are fairing plate engagement pads 56a, 58a, respectively, which may be blotter-like pads. These pads may be configured to engage the undersides of the fairing plates (such as underside 46b of fairing plate 46a), and to doctor and clean them of accumulated aerosol ink and fibers (or to compress such deposits so that they are effectively not the creators of problems, such as fiber tract problems, during a printing operation).
When the carriage and the printhead structures have moved into service station 36, initially the capping structure may be spaced beneath the carriage and the printhead structure, as illustrated in
When a new printing operation is called for, the capping structure may return to the condition shown in
Thus, on the right side of carriage 26 in
With the fairing plates in apparatus 72 deployed as indicated in
Apparatus 72 may employ camming, ramp-like curved actuators, such as actuator 84 which is shown fragmentarily at the right sides of
Joined to the upper surface of ramp 84, at the location generally indicated, there may be an upwardly-extending and slightly inclined, thin and very flexible wiper blade 86. Wiper blade 86 may function herein, along with the ramp, as a servicing and doctoring structure to deal with the build-up of ink and fiber accumulation on fairing plate 74, and on its undersurface 74a. Wiper blade 86 may be formed of any suitable material, such as synthetic rubber material, which typically is compatible with wiping ink.
As the carriage and printhead structure continue to advance into the service station, ramp 84 may cause plate 74 to swing upwardly about axis 76 toward a nondeployed, retracted angular position relative to mounting structure 80. As this occurs, the upper surface portion of ramp 84 (which engages plate 74), along with flexible blade 86, may perform a wiping, doctoring and cleaning action with respect to fairing plate 74. When the carriage and printhead structure are fully stationed in service station 36, as illustrated fragmentarily in
A printing device equipped with the apparatus form of the invention pictured in
The leading edges of printheads that move back and forth across a printzone in an inkjet printer are prone to generate a printing quality issue called swath-height error. This error occurs as a consequence of aerodynamic turbulence associated with leading-edge motion of a printhead as it advances at high speed, and close to print media, across such a zone. Illustrated herein are structure and methodology which reduces swath-height error by introducing and employing aerodynamic barriering and guarding of these edges through fairing structure which is selectively disposed operatively downstream (in advance) of printhead leading-edge structure.
While the invention has been particularly shown and described with reference to the foregoing preferred embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. The description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.
This is a continuation of application Ser. No. 10/066,114 filed on Jan. 31, 2002, now U.S. Pat. No. 6,565,182 which is hereby incorporated by reference herein.
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Number | Date | Country | |
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20030206209 A1 | Nov 2003 | US |
Number | Date | Country | |
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Parent | 10066114 | Jan 2002 | US |
Child | 10401924 | US |