Wiper for ink-jet printhead

A rotary wiper for cleaning the orifice plate of a printhead of a thermal ink-jet printer. The wiper includes a plurality of blades which successively wipe contaminants from the orifice plate of the printhead during rotation of the wiper. Apparatus is provided for automatically cleaning the contaminants from the blades of the rotating wiper. The wiper blades are either radially or non-radially oriented. The cleaning apparatus includes either a plurality of scrapers, or a roll of liquid absorbing material. The wiper is rotated by a motor, or by a rack and pinion arrangement, in which the rack is disposed on the printhead carriage and actuates the wiper as the printhead moves into the service station area. In one embodiment the wiper is used in conjunction with a cap in the service station area to clean and then seal the printhead.

FIELD OF THE INVENTION 
This invention relates generally to ink-jet printers and printheads and 
more particularly to a wiper for automatic cleaning of the printhead. 
BACKGROUND OF THE INVENTION 
The orifice plate of the printhead of an ink-jet printer, particularly a 
thermal ink-jet printer, tends to pick up contaminants, such as paper 
dust, and the like, during the printing process. Such contaminants adhere 
to the orifice plate either because of the presence of ink on the 
printhead, or because of electrostatic charges. In addition, excess ink 
can accumulate around the printhead, if all the ink is not pumped out of 
the printhead. The accumulation of either ink or other contaminants can 
impair the quality of the output by interfering with the proper 
application of ink to the printing medium. For these reasons, it is 
desirable to clear the printhead orifice plate of such contaminants on a 
routine basis to prevent the build-up thereof. 
Wipers are known in the prior art for removal of contaminants from the 
orifice plate of the printhead. One type of stationary wiper found on 
existing machines is described in U.S. patent application Ser. No. 
149,454, now U.S. Pat. No. 4,872,026 issued Oct. 3, 1989 filed on Jan. 28, 
1988 and assigned to the assignee of the present application. This wiper 
typically comprises a resilient material, such as nitrile rubber, and is 
disposed in the service station area of the printer. The service station 
provides a region at one end of the bi-directional movement of the print 
head carriage which holds the printhead carriage in locked alignment. 
Typically, the printhead is dragged across a stationary wiper blade as the 
printhead carriage moves into the service station area. The wiper itself 
is cleaned by downwardly facing edges on a lower side of the printhead 
which are dragged across the wiper subsequent to the printhead. 
Another type of prior art printhead wiper includes a flat ring having a 
plurality of upstanding, resilient, widely spaced blades disposed on an 
outer surface thereof. The blades are disposed generally orthogonally of 
the ring. The ring typically is stretched between two shafts, and this 
ring is selectively driven by a motor or other like device which is 
coupled to the pulleys. No means for automatically cleaning the blades is 
provided. An example of this wiper is described in U.S. Pat. No. 
4,577,203. 
Prior art wipers, including those described hereinabove, suffer from a 
number of drawbacks. In the first place, inadequate means are provided to 
remove contaminants from the wiper itself after it has cleaned the 
printhead orifice plate. Contaminants are only periodically removed and 
the apparatus used for removal does not entirely clean the wiper after 
each use. As a result, subsequent passes of the wiper over the printhead 
tend to recontaminate the printhead. Secondly, inadequate cleaning is 
provided because typically only one upstanding wiper blade wipes the 
printhead during each pass of the printhead over the wiper, thus removing 
only some of the contaminants during any one pass. A number of passes is 
required to remove a sufficient amount of such contaminants. 
It is therefore an object of the present invention to provide a wiper for 
an ink-jet printer which removes substantially all of the dust, ink and 
other contaminants from the printhead orifice plate during each pass of 
the printhead over the wiper. 
It is a further object of the present invention to provide a wiper for an 
ink-jet printer which includes means for automatically cleaning the wiper 
as it wipes the orifice plate of the printhead. 
It is another object of the present invention to provide a simplified wiper 
mechanism which is effective in removing paper dust, ink and other 
contaminants from the printhead orifice plate of an ink-jet printer. 
It is another further object of the present invention to provide a 
simplified wiper for ink-jet printers which is actuated only when the 
printhead passes thereover. 
SUMMARY OF THE INVENTION 
The above and other objects are achieved in accordance with the present 
invention in which a multi-blade, rotary wiper is provided for removal of 
ink, dust and other contaminants from the orifice plate of a printhead of 
an ink-jet printer. Furthermore, apparatus is provided for continual, 
automatic cleaning of the wiper blades. 
The wiper has one or a plurality of blades which extend outwardly from the 
center or axis of rotation of the wiper. These blades are closely spaced, 
and typically are formed of a resilient material, such as nitrile rubber. 
The blades may have a radial orientation or they may be disposed at an 
angle with respect to a wiper radius. 
Arrayed around the perimeter of the wiper at locations spaced from the 
cleaning area where the wiper blades engage the printhead are a plurality 
of rigid cleaning blades formed of metal or another like material. These 
rigid blades have upper edges, across which the wiper blades pass after 
cleaning of the printhead orifice plate to scrape the ink, dust and other 
contaminants off the wiper blades. 
Alternatively, the cleaning apparatus may comprise a roller covered with an 
absorbent material. This roller is disposed just below the wiper and 
spaced from the cleaning area, so that the wiper blades pass over and rub 
against the roller after cleaning of the printhead. Contaminants are 
removed by rubbing of the wiper blades against the roller, and by 
absorption of the ink. 
In a preferred embodiment, the rotary wiper of this invention is disposed 
in the service station area of the ink jet printer. Typically, although 
not necessarily, operation of the wiper is triggered by entry of the 
printhead carriage into the service station area. The rotary wiper can be 
driven either by a servomotor, or by a rack and pinion arrangement. In the 
latter embodiment, a rack is disposed on the lower surface of the 
printhead carriage, and as the rack approaches the service station area, 
it produces rotation of the rotary wiper through interaction with a pinion 
gear disposed on the wiper shaft. The wiper then cleans the printhead 
orifice through multiple strikes, and after the printhead has passed, the 
wiper ceases rotation. 
Use of the foregoing rotary wiper permits automatic, effective and complete 
removal of ink, dust and other contaminants from the printhead orifice 
plate when the printhead carriage is in the service station area, and 
automatic cleaning of the wiper blades while the printhead is being wiped. 
As a consequence, the quality of the printing process is not impaired by 
contaminants on the printhead, regardless of the length of time during 
which the printer is operated without maintenance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference now to the drawings, and more particularly to FIG. 1 
thereof, a typical ink-jet printer 10 will be described with which the 
wiper of this invention may be used. Ink-jet printer 10, as shown in the 
drawings, is of the type in which printing is done in a substantially 
horizontal plane. However, it is to be understood that the wiper of this 
invention is shown used in conjunction with this type of printer for 
purposes of illustration only and that the wiper of this invention can be 
used with other types of ink-jet printers in which printing is not done in 
a substantially horizontal plane and which have different configurations. 
Ink-jet printer 10 includes a housing 12, a printhead carriage 14, a 
carriage guide 16, a carriage rod 18, drive roller assembly 20, platen 22, 
paper supply 26, and service station 36. Drive roller assembly 20 feeds 
paper, or another print medium, supplied to it by paper supply 26 to a 
printing zone disposed between print head carriage 14 and platen 22 in a 
manner well known to those skilled in the art. Printhead carriage 14 
travels back and forth on carriage rod 18 and carriage guide 16 through 
the printing zone. Printhead carriage 14 is moved bi-directionally 
typically by means of a belt (not shown) connected to a carriage motor 27. 
Printhead carriage 14 includes a print cartridge 32 which is connected by 
flexible electrical interconnect strip 24 to a microprocessor 29. 
Microprocessor 29 also controls carriage motor 27. A control panel 28 is 
electrically associated with microprocessor 29 for selection of various 
options relating to the printing operation. Such control operations, 
provided by presently available microprocessors, are well known in the 
prior art and form no part of this invention. 
Printhead cartridge 32 includes a printhead 33 provided on a bottom surface 
34 thereof. Typically, printhead 33 is a thermal ink-jet printhead. 
However, printer 10 could operate with other ink jet printheads, if the 
carriage interfaces are compatible, or with other carriage configurations. 
Furthermore, reconfiguration of cartridge 32 would permit use of other ink 
jet technologies, such as piezoelectric. Printhead 33 typically comprises 
a plurality of resistors (not shown) associated with a plurality of 
nozzles (not shown) formed in a nozzle plate 35. Ink (not shown) is stored 
in a reservoir within cartridge 32. Printhead cartridge 32 and printhead 
33 operate in a manner well known to those skilled in the art. 
An assembled service station 36 which includes the wiper of this invention 
is depicted in FIGS. 2A and 2B. Service station 36 is a region at one end 
of the bi-directional movement of carriage 14 which holds cartridge 32 in 
locked alignment. Service station 36 includes a wiper mechanism, 
designated generally as 42. In the exemplary printer 10 with which this 
invention is being described, service station 36 also may include a sled 
38, a sled support 40 and a peristaltic pump (not shown). However, the 
sled 38 and pump form no part of this invention and are not required for 
its operation. 
Bosses 44 disposed on the sides of sled 38 rest on ramps 46 of sled support 
40. Sled 38 is moveable along ramps 46 of sled support 40 from left to 
right and right to left as shown in FIG. 2A. Bosses 44 ride up along 
associated ramps 46 as the sled moves from left to right as shown in FIG. 
2A, from a lower portion 48 to an upper portion 50, and visa versa. As 
sled 38 is in its most left-hand position, as shown in FIG. 2A, bosses 44 
reside in lower portion 48, while when sled 38 is in its most right-hand 
position as shown in FIG. 2B, bosses 44 reside in upper portion 50 of ramp 
46. Sled 38 includes an upwardly extending projection 52 which is engaged 
by a surface of carriage 14, typically a pen support 54, as it moves into 
service station 36. As pen support 54 strikes projection 52, cap 56 on 
sled 38 is automatically aligned with printhead 33. Further movement to 
the right of sled 38 causes sled 38 to rise upwardly on ramps 46 and 
causes cap 56 to be pressed against the perimeter of the orifice plate of 
printhead 33 for sealing thereof. Also, as sled 38 rises upwardly on ramps 
46, a pen catcher 57 enters into a slot 58 in printhead 33. Thus, when 
carriage 14 subsequently leaves service station 36, pen catcher 57 ensures 
that the sled 38 is returned to its inactive, lower position as shown in 
FIG. 2, in which bosses 44 reside in lower portion 48 of ramp 46. Pen 
catcher 57 drops out of slot 58 as sled 38 is lowered to its inactive 
position. 
The purpose of the ramped sled motion is to prevent wear on cap 56 so that 
it will not need to be replaced during the life of the printer. This 
ramped motion also allows movement of printhead 33 into a position to 
activate the peristaltic pump while being capped. 
The wiper mechanism of this invention will now be described with particular 
reference to FIGS. 2-10. Typically, wiper mechanism 42 is disposed in 
service station 36 on a side of sled 38 facing the center of the printer 
so that printhead 33 moves across mechanism 42 prior to capping. Wiper 
mechanism 42 includes a wiper 60 having at least one blade 62, apparatus 
64 for cleaning blades 62 and mechanism 66 for rotating wiper 60 about 
central shaft 68. 
In a preferred embodiment, as shown in FIGS. 2A and 2B, wiper 60 includes a 
plurality of blades 62 which are about equally spaced and extend radially 
from a central axis coincident with shaft 68. Blades 62 each have distal 
tips 65 which serve to wipe the orifice plate of the printhead. Wiper 60 
is centrally mounted on shaft 68 which is journaled in supporting walls 70 
in service station 36 to permit rotation of wiper 60 about shaft 68. All 
blades 62 are of substantially the same length, and tips 65 generally 
define a circle, whether stationary or rotating. An upper portion of that 
circle extends above the upper edge 71 of wall 70 into the cleaning area 
where tips 65 wipe printhead 33 and a lower portion of that circle extends 
into apparatus 64. Rotation of wiper 60 produces multiple passes of blade 
tips 65 over orifice plate 35 each time printhead 33 enters service 
station 36. Also, rotation permits the blades 62 to be automatically 
cleaned by apparatus 64, as will be described hereinbelow. Preferably, 
wiper 60 has a large number of blades 62 to facilitate the desired 
repeated wiping action. Wiper 60 should be formed of a resilient material, 
such as a nitrile rubber and the like, so that as tips 65 of blades 62 
pass over and wipe printhead 33, they flex to accommodate the irregular 
surface of printhead 33 and return to their original configuration without 
substantial deformation. The radial orientation of blades 62 provides a 
firm and aggressive wiping action along tips 65 which is preferred for 
satisfactory removal of dust, ink and other contaminants from printhead 
33. 
Rotation of wiper 60 can be produced either by a separate servomotor or the 
like, as shown in FIG. 3, or, rotation can be produced mechanically by 
movement of carriage 14. In a preferred embodiment, a gearing arrangement 
produces the desired rotation, as shown in FIGS. 2 and 4-6. In this 
embodiment, a driving gear 72 is disposed on shaft 68. Typically, although 
not necessarily, pear 72 is driven by another, larger pinion gear 74, and 
pear 74 is in turn rotated by a rack 76. It should be understood that any 
number of gears may be used to couple rack 76 to gear 72, or rack 76 may 
directly engage gear 72, depending upon the speed and direction of 
rotation desired for shaft 68. Rack 76 is coupled to or driven by 
printhead carriage 14. 
The preferred arrangement shown in FIGS. 2, and 4-6 which utilizes gears 72 
and 74 and rack 76 rotates wiper 60, at the desired speed and in the 
desired direction, as printhead 33 moves into and out of service station 
36. This arrangement causes blade tips 65 of wiper 60 to move in a 
direction which is opposite of the direction of movement of printhead 33 
during wiping thereof in the cleaning area. Wiper 60 rotates in a 
counterclockwise direction as viewed in FIG. 4, so that blade tips 65 
travel from right to left in the cleaning area as printhead carriage 14 
moves from left to right in FIG. 4. Similarly, wiper 60 rotates in a 
clockwise direction so that blade tips 65 travel from left to right in the 
cleaning area as printhead carriage 14 moves from right to left in FIG. 4. 
In this manner, printhead 33 is cleaned both upon its arrival in service 
station 36, and as it departs, so that it is clean and ready for use as it 
returns to the printing zone. This travel of blade tips 65 in a direction 
opposite of the direction of movement of printhead 33 produces a more 
vigorous and effective wiping action of blade 62 against printhead 33. It 
should be understood that while pears 72 and 74 provide a preferred speed 
of rotation for wiper 60, other gears of different sizes and other numbers 
of gears may be provided to change the rotational speed and direction of 
wiper 60. However, only an even number of additional gears should be added 
to the gear train of FIG. 2 if the preferred opposite direction of 
rotation for wiper blade tips 65 is to be maintained. The particular pear 
reduction ratio selected depends on the desired speed of rotation of wiper 
60. 
In a preferred embodiment, rack 76 is permanently secured to a lower 
surface of printhead carriage 14. In this manner, rotation of wiper 60 
occurs only when carriage 14 is entering or leaving service station 36 and 
when printhead 33 is disposed above wiper 60 in the cleaning area. 
Preferably, rack 76 should extend sufficiently far beyond printhead 
carriage 14 in its direction of motion toward service station 36 that 
rotation of shaft of 68, and thus wiper 60 is commenced prior to the 
passage of printhead 33 over wiper 60. 
In an alternative embodiment, (not shown) rack 76 need not be secured 
directly to printhead carriage 14, but could be actuable by printhead 
carriage 14 as it moves into service station 36, either by a mechanical 
coupling or by an electrical stimulus. 
The rack and pinion wiper driving arrangement of FIGS. 2A and 2B can be 
replaced by the embodiment of FIG. 3 in which like numbers are used for 
like parts, where possible. As shown in FIG. 3, shaft 68 and thus wiper 60 
is rotated by a servomotor 120. Motor 120 typically is controlled by the 
microprocessor to operate only when carriage 14 is entering or leaving 
service station 36. However, motor 120 may also be continuously running. 
Preferably, motor 120 rotates wiper 60 so that blade tips 65 travel in a 
direction opposite of the direction of movement of carriage 14, as 
previously described for the embodiment of FIGS. 2 and 4-6. In all other 
respects, the embodiment of FIG. 3 operates like the embodiment of FIGS. 2 
and 4-6. 
Apparatus 64 for cleaning blades 62 renders wiper 60 continually self 
cleaning, so that as blades 62 pass over printhead 33, they do not 
recontaminate printhead 33. This self-cleaning action reduces the 
servicing requirements, since wiper 60 need not be replaced except after a 
long period of use. 
In a preferred embodiment, cleaning apparatus 64 comprises at least one and 
preferably a plurality of scrapers 80 arrayed around at least a portion of 
the circumference of the circle defined by the rotating blade tips 65 of 
wiper 60. Scrapers 80 comprise rigid blades having an edge 82 that faces 
inwardly toward shaft 68 and that rides along a portion of each blade 62 
that passes thereover to perform the desired scraping action. Edge 82 may 
or may not be sharpened. Preferably, scrapers 80 have an orientation 
generally parallel to blades 62 and to a radius of the circle defined by 
tips 65. Scrapers 80 typically have approximately the same circumferential 
spacing as tips 65 alone the circumference of the circle defined by 
rotating tips 65. Scrapers 80 may also have a non-radial alignment and any 
other spacing that does not conform to that of tips 65, so long as tips 65 
are dragged across edges 82 of the scrapers during rotation of wiper 60. 
Scrapers 80 are rigidly mounted onto wall 70 so that they do not move or 
flex as blades 62 pass thereover. As shown in FIGS. 4-6, edges 82 of 
scrapers 80 extend beyond tips 65 of blades 62 and edges 82 are spaced 
inwardly from tips 65 toward shaft 68 so that edges 82 scrape along the 
lateral surfaces of blade 62 as it flexes while passing over edges 82. 
This flexing of blades 62 produces a "flicking" action, as the blade tip 
65 returns to its original configuration which also helps propel 
contaminants off tips 65. Scrapers 80 may be disposed around the entire 
circumference of the circle defined by tips 65 below upper edge 71 of wall 
70, as shown in FIG. 2, or only along a portion of the circumference, but 
there are no scrapers 80 in the area above wall 70. 
Because of the rotation of wiper 60, the same side of tips 65 of blade 62 
which wipe printhead 33 also are drapped across edges 82 of scrapers 80, 
so that contaminants removed from printhead 33 are immediately scraped off 
blades 62 by scrapers 80. In addition, when more than one scraper 80 is 
provided, each blade 62 is scraped a number of times before it again 
cleans printhead 33, providing multiple opportunities for removal of 
contaminants. The number of scrapers 80, the length thereof, as well as 
their orientation is not critical, so long as the desired scraping action 
is provided. 
Ink and contaminants which are removed from wiper 60 by scrapers 80 tend to 
move under the influence of gravity by centrifugal acceleration caused by 
rotation of the wiper, and as a result of the flicking action of blades 
62, down the lateral surfaces of scrapers 80 and away from edges 82 until 
they fall off edges 83 and into machine 10. The ink tends to carry solid 
contaminants with it. Thus, scrapers 80 are self-cleaning, and need only 
be cleaned when solid contaminants have built up to an undesirably high 
level. 
An alternative embodiment of the wiper of this invention is shown in FIGS. 
7-9. Like numbers are used for like parts, where possible. In this 
embodiment, wiper 90 rotates about a shaft 94 and again includes a 
plurality of blades 92. While four blades are shown, wiper 90 may have any 
number of blades 92, so long as the desired wiping is performed. Blades 92 
are oriented at an angle with respect to a radius extending from shaft 94. 
This angle is typically about 90.degree., although the angle may be 
anywhere in the range of 0.degree. to 90.degree.. Blades 92 have a 
somewhat greater lateral extent than that of blades 62, because of their 
angular orientation, so that tips 97 thereof can still reach the cleaning 
area to provide the desired wiping action. In this embodiment, as in the 
previous embodiment, wiper 90 rotates in a counterclockwise direction as 
carriage 14 moves in a direction from left to right into service station 
36, as shown in FIG. 7. However, as carriage 14 moves from right to left 
as it leaves service station 36, it is preferred that no rotation of wiper 
90 occur, or that if wiper 90 is rotated, it is again rotated only in a 
counterclockwise direction. If rotated in a clockwise direction, the tips 
97 of blades 92 could interfere with the smooth movement of printhead 
carriage 14, because of their angular orientation. 
Wiper 90 of FIGS. 7-9 preferably is driven by a selectively actuated 
servomotor 122, as shown in FIG. 7. Servomotor 122 is preferred, rather 
than the rack and pinion arrangement of FIG. 2 because it permits the 
wiper to be easily selectively stopped or rotated only in a single 
direction, as desired. Other drive mechanisms can be used for actuating 
wiper 90 which are well-known to those skilled in the art to provide the 
desired rotation of wiper 90. Cleaning apparatus 64 as described for use 
with wiper 60, can be employed to remove contaminants from wiper 90. In 
all other respects, wiper 90 operates in the same manner as wiper 60. 
An alternative embodiment of the cleaning apparatus for wipers 60 and 90 of 
this invention will now be described with particular reference to FIGS. 7 
and 8. While this cleaning apparatus is shown used in conjunction with 
wiper 90 for purposes of illustration, it is to be understood that this 
cleaning apparatus may also be used in conjunction with wiper 60. Like 
numbers are used for like parts, where possible. In this embodiment, the 
cleaning apparatus includes a roller 100 having a layer 102 of absorbent 
material. Roller 100 is rotatably mounted on a shaft 104 which is disposed 
generally parallel to, but spaced from either shaft 94 or shaft 68. Roller 
100 is disposed below edge 71 and is spaced from the cleaning area above 
edge 71. Roller 100 is positioned so that the outer surface thereof engage 
tips 97 of wiper 90, or tips 65 of wiper 60 as they rotate about their 
respective shafts, 68 and 94, after wiping the printhead orifice plate, so 
that tips 97 of blades 92, or tips 65 of blades 62 are wiped clean. Layer 
102 is wrapped about shaft 104, and is comprised of a contaminant free, 
ink absorbing material. An acceptable, commercially available material is 
sold under the trademark TEXWIPE, by Texwipe Corporation. Layer 102 should 
be removed and replaced at regular intervals as it becomes saturated with 
ink or other liquids, or as it becomes sufficiently contaminated. 
Roller 100 can be stationary, freely rotatable, or rotating under the 
control of a servomotor. It is preferred that roller 100 be freely 
rotating, so that as tips 65 or 97 are rubbed against roller 100, they 
impart a rotation to roller 100 through friction. Roller 100 is then 
incrementally rotated by each tip 65 or 97 to present a fresh surface to 
the next tip 65 or 97. 
The number of blades provided on wiper 60 or wiper 90 depends on several 
factors, such as the speed with which the wiper rotates and the number of 
passes required for the blades over the printhead orifice plate. The 
number of passes required is a function of the viscosity of the ink, the 
type of solid contaminants to be removed, and the rate of build-up of 
contaminants. More passes of the wiper blades over the printhead orifice 
may be required for more viscous ink, for finer and more gritty solid 
contaminants and for a faster build-up. For wiper 60, for most 
applications, it is preferred that at least three blade tips 65 strike the 
printhead orifice plate each time the carriage 14 enters service station 
36. A preferred number of blades 62 is 12, as shown in FIG. 7, although 
any other number may be used, so long as the desired number of strikes of 
provided. The speed of rotation can be adjusted, depending on the number 
of blades provided by appropriate control of the servomotor or by 
adjusting the gear reduction ratio between gears 72 and rack 76, in a 
manner known to those skilled in the art. The length of the wiper blades 
depends on the application, and manufacturing tolerances. For most 
applications, blades 62 or 92 typically are about 0.25" long, although it 
is to be understood that the provision of these exemplary dimensions does 
not serve in any way to limit the scope of the invention. The number and 
size of scrapers 80 is again a function of the particular application. 
Typically, more than one scraper is used, and a minimum of three scrapers 
80 is recommended. 
The operation of the preferred embodiment of this invention will now be 
described with particular reference to FIGS. 4-6. Typically, carriage 14 
enters service station 36 at the completion of each line of print on a 
printing medium, although the printer could be designed for less frequent 
servicing operations, in accordance with the printing requirements of the 
user. As printhead carriage 14 passes from left to right toward service 
station 36, as shown in FIG. 4 rack 76, which is mounted to the underside 
of carriage 14, engages pinion gear 74. Further movement of carriage 14 
into service station 36 produces a clockwise rotation of pinion pear 74, 
which in turn produces a counterclockwise rotation of gear 72, and wiper 
60, as shown in FIG. 4. Blades 62 of wiper 60 pass across printhead 33 in 
the cleaning area, wiping the printhead orifice plate 35, and removing 
ink, dust and other contaminants therefrom. Preferably, three tips 65 of 
blades 62 strike the printhead 33 during this pass of printhead 33 over 
wiper 60. After each blade 62 wipes printhead 33, it passes immediately 
over edges 82 of scrapers 80, which scrape the contaminants from blades 
62. Passage of tips 65 of blades 62 over edges 82 produces a flicking 
action, which, when combined with the centrifugal acceleration produced by 
rotation of wiper 60 and with the effects of gravity, causes contaminants 
to travel downwardly along the surfaces of scrapers 80 toward edges 83 and 
into the machine. 
In the printer with which this invention has been illustratively described 
and which utilizes a cap for the printhead, after completion of the wiping 
of printhead 33, pen support 54 engages projection 52, urging sled 38 to 
the right, as shown in FIG. 5, and bringing cap 56 into alignment with 
printhead 33 and pen catcher 57 into alignment with slot 58. Bosses 44 of 
sled 38 ride up ramps 46 from position 48 to position 50. This movement 
raises cap 56 upwardly to cap printhead 33 and raises pen catcher 57 into 
slot 58 on carriage 14, as carriage 14 comes to rest at the extreme 
right-hand end of service station 36, as shown in FIG. 6. 
As printhead carriage 14 moves from right to left out of service station 
36, the operation is reversed. Pen catcher 57, which resides in slot 58, 
urges sled 38 in a leftward direction, causing it to slide down ramps 46 
from position 50 to position 48. At this point, printhead 38 is uncapped 
and pen catcher 57 pops out of slot 58. As pinion gear 74 is rotated in a 
counterclockwise direction by rack 76, pear 72 and wiper 60 are rotated in 
a clockwise direction. Wiper 60 again wipes printhead 33 in a direction 
opposite of the movement of printhead 33. Thereafter, carriage 14 
continues traveling to the left, as shown in FIG. 4, to perform the 
desired printing operation. 
The wiper of this invention permits the removal of dust, ink and other 
contaminants from printhead 33, and prevents their buildup during use. The 
wiper of this invention is superior to that found in the prior art, since 
the rapidly rotating wiper blades provide multiple wipes of printhead 33 
in a very short period of time providing an efficient wiping action and 
one which will not damage printhead 33. The repeated wipings are 
sufficient to adequately clean the printhead. The scrapers allow automatic 
self cleaning of the blades after each pass over the printhead orifice 
plate, so that as a wiper blade strikes the orifice plate, it has just 
been cleaned and does not recontaminate the orifice plate with previously 
removed ink or other contaminants. The wiper may be automatically actuated 
by passage of the printhead carriage into the service station, by a 
simplified, dependable mechanical design which is not easily subject to 
failure, or by a servomotor. 
In view of the above description, it is likely that modifications and 
improvements will occur to those skilled in the art which are within the 
scope of this invention The above description is intended to be exemplary 
only, the scope of the invention being defined by the following claims and 
their equivalents.