Manual pen selection for clearing nozzles without removal from pen carriage

A thermal ink jet printhead cartridge priming apparatus that includes a plurality of caps respectively associated with a plurality of printhead nozzle arrays for controllably sealing printhead nozzle arrays pursuant to engagement thereof against the printhead cartridge to surround the nozzle arrays, a plurality of vacuum conveying elements respectively associated with the caps for individually conveying priming vacuum to an associated cap, a manually actuated selector assembly for connecting a selected one of the vacuum conveying elements to a source of priming vacuum, and a source of priming vacuum spaced apart from the manually actuated selection means for selectively engaging the selector assembly for application of vacuum thereto, such that a selected printhead cartridge is primed without removal thereof from the carriage and without use of a motorized vacuum pump. By separating the vacuum source from the selector, positive pressure is not applied to the nozzle arrays when the caps are brought into engagement with the printhead cartridges since venting is provided by the unobstructed vacuum conveying elements.

BACKGROUND OF THE INVENTION 
The subject invention generally relates to ink-jet printer technology, and 
is directed more particularly to an apparatus for priming a thermal ink 
jet printhead cartridge without removal of the printhead cartridge from 
the printer carriage. 
Thermal ink jet printers commonly utilize printhead cartridges, often 
called pens, which typically include one or more ink reservoirs and an 
integrated circuit printhead that includes a nozzle plate having an array 
of ink ejecting nozzles which emit ink droplets in response to electrical 
pulses provided to the printhead. 
An important consideration with thermal ink jet printhead cartridges is the 
need to ready a printhead for printing. For example, when a new printhead 
cartridge is installed in a printer or after a period of non-usage, the 
cartridge might be unable to produce ink drops at one or more nozzles, for 
example as a result of foreign contamination of the nozzles, dried ink in 
the nozzles, or air ingested into the nozzles. 
Known systems for priming include those which are involve the application 
of pressure to the ink supply in order to cause ink flow into the ink 
containing chambers that are adjacent the ink ejecting nozzles. 
Considerations with such known systems is need for access to the ink 
reservoir, and the various mechanical impedances between the ink reservoir 
and the nozzles which reduce the pressure that eventually reaches the 
nozzles. 
Another known system requires that a printhead cartridge be removed from 
the printer carriage and inserted into a separate priming station for 
priming, which further requires that the printhead cartridge be removed 
from the priming station after priming and inserted back into the 
carriage. Considerations with these systems include the additional wear 
and tear on the electrical contacts of the printhead cartridge and the 
printer carriage, as well as the inconvenience of having to perform the 
remove and insert procedure two times for one priming. 
A further known system includes a movable cap that is engageable with a 
printhead nozzle array and is directly connected to a tube of a 
peristaltic pump. Considerations with this system, however, include the 
need for separate pump for each printhead of a multiple printhead 
carriage, and clogging of the pump tube with ink. 
SUMMARY OF THE INVENTION 
It would therefore be an advantage to provide an improved ink jet printhead 
cartridge primer which provides for priming of a printhead cartridge 
nozzle array without removal of the printhead cartridge from the printer, 
avoids application of positive pressure to the printhead nozzle array, 
avoids clogging of vacuum conveying elements, and allows the use of a 
single vacuum source for priming each of a plurality of printhead 
cartridges of a multiple printhead printer. 
The foregoing and other advantages are provided by the invention in a 
thermal ink jet printer that includes a print carriage, a printhead 
cartridge supported by the print carriage, and a manually actuated priming 
structure for conveying priming vacuum to the nozzle array of the 
printhead cartridge while the printhead cartridge is supported by the 
print carriage, such that the printhead cartridge is primed without 
removal thereof from the carriage and without use of a motorized vacuum 
pump.

DETAILED DESCRIPTION OF THE DISCLOSURE 
In the following detailed description and in the several figures of the 
drawing, like elements are identified with like reference numerals. 
Referring now to FIG. 1, set forth therein is a schematic frontal quarter 
perspective view depicting, by way of illustrative example, major 
mechanical components of a multiple printhead ink jet printer in which the 
techniques of the invention can be implemented. The printer includes a 
movable carriage 51 mounted on a guide rail 53 for translational movement 
along the carriage scan axis (commonly called the Y-axis in the printer 
art). The carriage 51 is driven along the guide rail 53 by an endless belt 
57 which can be driven in a conventional manner, and a linear encoder 
strip 59 is utilized to detect position of the carriage 51 along the 
carriage scan axis, for example in accordance with conventional 
techniques. 
The carriage 51 removably retains four printhead cartridges C1, C2, C3, C4 
(sometimes called "pens," "print cartridges," or "cartridges") which are 
side by side along the carriage axis. Each of the cartridges C1, C2, C3, 
C4 includes a nozzle array generally indicated by the reference numeral 61 
in FIGS. 3 and 18, comprised of a plurality of downwardly facing nozzles 
for ejecting ink generally downwardly to a print media which is supported 
in an appropriate manner below the path traversed by printhead cartridges 
when the carriage 51 is scanned along the carriage axis. The print media 
is moved along a print media axis which is orthogonal to the carriage scan 
axis. In accordance with conventional thermal ink jet printhead 
architecture, ink drops are fired from the nozzles pursuant to ink firing 
pulses applied to heater resistors respectively associated with the 
nozzles and located in the printhead interiorly of the nozzles. 
By way of illustrative example, the cartridges C1, C2, C3 comprise 
non-black color printing cartridges for producing the base colors of 
yellow, cyan, and magenta as commonly utilized in color printing, while 
the cartridge C4 comprises a black printing cartridge. 
The printer of FIG. 1 further includes a service station located to one 
side of the media print area and generally indicated by the reference 
numeral 10. The service station functions to cap the nozzle arrays of the 
printhead cartridges, and wipe the nozzle arrays. The station more 
particularly includes a movable sled 111 that includes respective caps 113 
configured to cap respective nozzle arrays of the cartridges when the 
carriage is moved into position over the caps 113. In particular, the caps 
113 are designed to a surround the printhead nozzle arrays rather than 
contact them, so as to reduce drying of ink. The caps 113 further function 
to convey priming vacuum to the nozzle arrays of the printhead cartridges. 
The movable sled 111 also includes resilient wipers 115 for wiping the 
nozzle arrays of the printhead cartridges as described more fully herein. 
The movable sled 111 further includes vertical side panels 217 in front of 
and behind the caps 113, and cam surfaces 219 are formed in the side 
panels generally adjacent the distal caps. The cam surfaces 219 are mirror 
images of each other across a vertical plane that is parallel to the 
carriage axis. The sled also includes two vertically extending cam 
follower prongs 221 that formed on the front side panel between the cam 
surfaces 219, and two vertically extending cam follower prongs 221 on a 
forwardly extending panel 223. The cam following prongs 221 are mirror 
images of each other across a vertical plane that is parallel to the 
carriage axis. As shown more fully in FIGS. 17-22, vertical and horizontal 
movement of the sled 111 is controlled by engagement of the vertical 
prongs 221 by cam surfaces 233 and slots 231 in the carriage 51 and by the 
upward engagement of the cam surfaces 219 against stationary guide pegs 
237 pursuant to upwardly biasing springs 235. In particular, the cam 
surfaces 219 and the vertical prongs 221 of the sled, stationary guide 
pegs 237 engaged with the cam surfaces 219, and the cam surfaces 233 and 
slots 231 of the carriage 51 that engage the vertical prongs 221 are 
configured such that the sled 111 is in its vertically highest position, 
called the capping position, when it is furthest from the print media 
(i.e., towards the right side of the printer), and is in its vertically 
lowest position, called the down position, when it is closest to the print 
media region (i.e., towards the center of the printer). In the capped 
position, the caps 113 of the sled 111 are in engagement with the nozzle 
arrays of the printhead cartridges, while in the down position the caps 
113 and the wipers 115 are away from the path of the nozzle arrays. The 
carriage 51 and the sled 111 are configured such that wiping only takes 
place when the carriage moves to left after positioning the sled in the 
capping position pursuant to movement of the carriage to the right. 
As shown in FIG. 3 for one of the caps 113, each cap 113 is secured to the 
top opening of a chamber 115 that extends downwardly and includes a lower 
port 117 that is connected to one end of a flexible tube 119 whose other 
end is connected to a corresponding fitting 121 of a slider 123 which 
includes a base 125 on which the fittings 121 are located. Respective 
bores 127 extend from the bottom of the base 125 through the top ends of 
the fittings 121 The slider 123 is part of a selector assembly, generally 
indicated by the reference numeral 20, that is located at the front of the 
service station to enable operator selection of the capped nozzle array 
that is to receive priming vacuum via a corresponding cap 113 engaged 
therewith. Each chamber 115 of the movable sled 111 can contain a filter 
129 for trapping ink to prevent ink from entering and clogging the 
flexible tube 119. It should be appreciated that most of the ink that 
emerges from the nozzles pursuant to priming remains on the nozzle plate 
and is removed by the wipers 115 when the carriage 51 leaves the service 
station. 
As shown generally in FIGS. 4 and 5, the selector assembly includes a 
selector lever 139 that is linked to the slider 123 to cause the slider to 
move along a linear path that is parallel to the carriage axis. The 
fittings 121 are arranged linearly parallel to the carriage axis, and the 
slider is selectively positionable by means of detents at predetermined 
positions along its travel path at which a respective fitting is aligned 
with a vacuum cap 251 of a vacuum source 253. Pursuant to appropriate 
actuation, the vacuum source cap 251 travels upwardly through an opening 
163 in a horizontal panel of the selector assembly 20 to briefly engage 
the bottom surface of the slider while negative pressure is at the opening 
of the vacuum source cap 251. Such negative pressure is transmitted to the 
printhead cartridge that is capped by the cap that is connected to the 
slider bore aligned with the vacuum source cap 251 at the time the vacuum 
source is actuated. By separating the vacuum source cap 251 from the bores 
of the slider, positive pressure is not applied to the nozzle arrays when 
the caps are brought into engagement with the printhead cartridges since 
venting is provided by the unobstructed bores in the slider. In other 
words, positive pressure is prevented by providing a vent path between the 
caps and the lower ends of the bores in the slider. 
Referring more particularly to FIGS. 8-11, the slider 123 more particularly 
travels along the carriage axis in a guideway comprised of the top surface 
of the horizontal panel 131 of the selector assembly, two vertical walls 
133, 135 disposed on the horizontal panel 131, and guide tabs 137 
extending inwardly from the vertical walls. The slider 125 is moved by 
operator actuation of the lever 139 that includes a guide peg 141 attached 
thereto and slidably captured in an arcuate slot 143 formed in a vertical 
panel 145 that is attached to the horizontal panel 131. The lever 139 
includes parallel arms 147 which extend downwardly relative to the guide 
peg 141 and are slidably engaged with a slide block 149 that is rotatably 
secured between the vertical panel 145 and a vertical wall 155 that is 
adjacent the vertical panel 145. In particular, the slide block 149 
includes co-axial pins 151, 153 that are rotatably secured in openings in 
the vertical panel 145 and the vertical wall 155. A crank 157 extends from 
the pin 153 on the side of the vertical wall 155 that is away from the 
slide block 149 and is parallel to the parallel arms of the lever 139 when 
such parallel arms are engaged with the slide block 149. A pin 159 is 
located at the end of the crank away from the pin 153 and is slidably 
engaged in a slot 161 formed in a vertical wall 162 located adjacent the 
edge of the slider base 125 that is adjacent the vertical wall 155. 
Pursuant to the foregoing structure, movement of the selector lever 139 
causes the slider block to rotate as the parallel arms 147 rotate and 
slide relative the slider block 149. Rotation of the slider block 149 
causes the crank 157 to pivot such that the pin 159 moves in an arc. The 
arcuate motion of the pin 159 causes the slider 123 to move linearly since 
it is constrained to move only linearly and since the crank pin 159 slides 
up and down in the slot 161 as the horizontal component of its motion is 
transmitted to the slider 123. 
As described earlier, a purpose of the selector assembly is to selectively 
position the slider 123 such that a selected bore 127 is aligned with the 
vacuum applying cap 251 that is located below the slider and which is 
controllably engaged against the bottom of the slider base through the 
opening 163 in a horizontal panel 131 of the selector assembly 20. In that 
regard, primary detent slots 167 are provided in a short vertical wall 169 
located on the slider base 125 inboard of the guide tabs 137. The detent 
slots 167 are engaged by a V-shaped section of a wire detent spring 165 
which includes ends that are located in holes at the ends of the vertical 
wall 135. The detent slots 167 and the V-shaped section of the detent 
spring 165 are configured such that engagement of the detent spring in a 
detent slot positions the slider with a corresponding slider bore 127 
aligned with the vacuum cap 251. For tactile feedback in regard to the 
detent positioning of the slider 123, the selector lever 139 includes a 
detent arm 171 that extends upwardly from the parallel arms 147 and 
includes a detent bump 173 at an end thereof that is below the arcuate 
slot 143. The vertical panel 145 includes four auxiliary detent slots 175 
that are located such that each detent slot secures the selector lever 139 
at an angular position at which the slider is in a corresponding detent 
position with a corresponding slider bore 127 aligned with the vacuum cap 
251. 
In the foregoing selector assembly, by virtue of the arcuate slot 143 and 
the sliding engagement of the selector lever parallel arms 147 with the 
slider block 149, the top end of selector lever 139 tends to remain at 
approximately the same elevation while it changes angle pursuant to 
movement of the lever end generally along the carriage axis. Further, by 
virtue of the crank 157, the slider moves oppositely from the direction in 
which the end of the selector lever 139 is moved. Both of these factors 
provide for correlation of the selector lever position with the bore 
aligned with the vacuum source cap 251. For example, positioning the lever 
139 to the left most detent position locates the slider to the rightmost 
position such that the leftmost slider bore is in alignment with the 
vacuum source cap 251. Lever position is further correlated with selection 
of a capped printhead cartridge for receiving priming vacuum by connecting 
each sled fitting 121 to the sled chamber that is correspondingly located 
along the carriage axis. In this manner, when the carriage 51 is in the 
capping position, the position of the selector lever 139 correlates with 
the printhead cartridge that can receive priming vacuum, such that a 
printhead cartridge is selected for priming by positioning the selector 
lever 139 at the position that corresponds to the position of the 
printhead cartridge on the carriage. 
The priming vacuum source 253 can comprise a manually actuated vacuum 
generating primer which is selectively actuated to cause the vacuum source 
cap 251 to briefly engage the bottom surface of the slider base 125 while 
negative pressure is at the opening of the vacuum source cap 251, for 
example pursuant to manual actuation of a plunger. Such negative pressure 
is transmitted to the printhead cartridge that is capped by the cap that 
is connected to the slider bore aligned with the vacuum source cap 251 at 
the time the vacuum source is actuated. 
Referring now to FIGS. 12-14, schematically depicted therein are components 
of an illustrative implementation of the vacuum source 253. Referring in 
particular to FIG. 12, set forth therein is a schematic sectional view of 
a bellows assembly 350 which supports the cap 251 and is a component of 
the vacuum source, as discussed further herein relative to FIG. 14. The 
bellows assembly 350 includes upper and lower end caps 401, 403, and an 
internal spring 405 having ends engaged in retaining recesses 407, 409 in 
the end caps 401, 403. A flexible, pliable sleeve 411 snugly surrounds the 
spring 405 and has its ends securely engaged around annular convex beads 
413,415 formed in the proximal portions of the end caps 401, 403. The 
sleeve 411 is configured such that the internal spring 405 is slightly 
compressed when the bellows is fully expanded, whereby the length of the 
uncompressed bellows assembly is determined by the sleeve 411. 
The upper end cap 401 (further shown in top plan view in FIG. 13) includes 
an axially oriented projection 417 having an opening that extends into the 
inside volume of the bellows assembly, and the cap 251 is fitted over the 
end of the projection 417 with its opening in communication with the 
opening of the projection 417. A top plate 402 surrounds the projection 
417, and is separated therefrom by an intervening recess. The upper end 
cap 401 further includes pins 421 aligned with the longitudinal extent of 
the bellows assembly and located at diametrically opposite locations. As 
described further herein in conjunction with FIG. 14, the pins 421 are 
slidably engaged in corresponding openings in the overlying horizontal 
panel 131, and allow for movement of the upper end cap 401 along the 
longitudinal extent of the bellows assembly 350. Such movement is imparted 
to the upper end cap 401 by movement of laterally extending cam follower 
pegs 431 which are downwardly offset relative to the horizontal panel 131 
so as to be lower than the peripheral edges of the horizontal panel 131. 
The lower end cap 403 includes a centrally located bore 423 for retaining 
an ink permeable plug 425 that is sufficiently impermeable to air to allow 
the bellows assembly 350 to produce negative pressure at the opening of 
the cap 251 pursuant to expansion of the bellows assembly 350. The lower 
end cap 403 further includes diametrically opposite L-shaped guides 426, 
each having a radially extending section and an upwardly extending 
section. Cam follower pegs 427 extend radially from the guides 426. 
In the vacuum source, the bellows assembly 350 is compressed and expanded 
by controllably moving the upper end cap 401 and the lower end cap 403 
relative to each other. In particular, the end caps 401, 403 are 
constrained to be movable only along the longitudinal extent of the 
bellows assembly 350, and the cam follower pegs 431 of the upper end cap 
401 and the cam follower pegs 427 of the lower end cap 403 are engaged 
against respective cam surfaces that control the movement of the end caps 
along the longitudinal extent of the bellows assembly. By way of 
illustrative implementation, cam surfaces for the cam follower pegs 431 of 
the upper end cap 401 engage the top portion of the pegs while the cam 
surfaces for the cam follower pegs 427 of the lower end cap 403 engage the 
bottom portion of the pegs, and the bellows assembly 350 is of sufficient 
length such that it is partially compressed when it is at its maximum 
expansion as allowed by the cam surfaces. In this manner, the cam follower 
pegs 427, 431 are continuously providing an expanding bias against their 
associated cam surfaces. 
Referring now to FIG. 14, set forth therein is an exploded perspective view 
of components of the vacuum source that cooperate with the bellows 
assembly 350 to achieve the application of priming negative pressure to 
the cap 251. The L-shaped guides 426 of the bellows assembly are slidably 
engaged in vertical slots 429 formed by the adjacent edges of vertically 
extending guide members 432 attached to the bottom of a base housing 353, 
while the pegs 421 of the bellows assembly upper end cap 401 are slidably 
engaged in apertures in the overlying horizontal panel 131 which are 
located such that the upper and lower end caps 401, 403 are aligned with 
each other along the longitudinal extent of the bellows assembly 350, and 
the displacement of the end caps 401, 403 will be along the longitudinal 
extent of the bellows assembly 350. 
The vertical position of the upper end cap 401 is controlled by engagement 
of the cam follower pegs 431 against cam surfaces on the bottom of 
parallel cam members 364 of a rectangular slider 370 that surrounds the 
top plate 402 of the upper end cap 401. The parallel cam members 364 are 
positioned tangentially to corresponding edges of the upper end cap top 
plate 402, and are fixed relative to each other by parallel support 
members 366 located between the ends of the parallel cam members 364. The 
parallel cam members 364 are slidably biased against the inside surface of 
the horizontal panel 131 by the cam follower pegs 431 of the upper end cap 
401. Pursuant to the position of the cam members 364 relative to the 
horizontal panel 131, the movement of the slider 370 is constrained to be 
along the cam members 364 as indicated by the double arrow 265 in FIG. 14. 
Actuating pegs 393 extend laterally from the parallel cam members 364 and 
are engaged to move the slider 370 along the axis 265, as described more 
fully herein. 
The vertical position of the lower end cap 403 is controlled by engagement 
of the cam follower pegs 427 against cam surfaces 395 formed on the inner 
opposing surfaces of parallel plate-like gear sectors 365 of a rotatable 
cam assembly 360. A helper spring 433 is located between the lower end cap 
403 and an ink absorbing pad located at the bottom of the base housing 353 
provide an upward bias on the lower end cap that facilitates the upward 
movement of the lower end cap 403 pursuant to movement of the cam surfaces 
395 against the cam follower pegs 427 of the lower end cap. The gear 
sectors 365 of the cam assembly 60 are fixed to each other by cross 
members 367,369, and the cam surfaces 395 on their inside surfaces are 
mirror images of each other. A cylindrical spacer 371 and a spindle 373 
are located on each gear sector 365 with both spacers and both spindles 
being coaxial on the line formed by the axial centers of gear sections 375 
of each gear sector. Torsional coiled wire springs 377 are positioned 
around the cylindrical spacers 371 with the ends 377a, 377b of each wire 
forming a spring extending beyond positioning stops 381a, 381b formed on 
the gear sectors at appropriate locations. The spindles 373 are rotatably 
supported in slots 379 formed in the upper edges of the front and rear 
walls of the base housing 353. Rotation of the cam assembly 360 in 
conjunction with the downward bias of the lower end cap 403 and the upward 
bias of the helper spring causes the lower end cap 403 to move up and down 
along the slots 429. The upwardly extending portions of the L-shaped 
guides 426 prevent the rotation of the guides 426 as they move up an down 
in the vertical slots 429, thereby maintaining the orientation of the 
lower end cap as it moves up an down in the slots 429. 
The gear sectors of the cam assembly 360 further include slider engaging 
edges 374a, 374b formed in the gear sectors at locations opposite the gear 
teeth. The engaging edges 374a, 374b are configured to move the slider 370 
by engagement with the actuating pegs 393 of the slider at appropriate 
positions in the rotations of the cam assembly 360. 
Referring now to FIG. 15, schematically illustrated therein is the profile 
of each of the cam surfaces 395. The profile includes a lower dwell 
section D1 that defines the lowest vertical position for the lower end cap 
403, a vertical movement section M, and an upper dwell section D2 that 
defines the highest position for the lower end cap 403. The lower dwell 
section D1 and the upper dwell section D2 are of respective constant radii 
relative to the spindle axis, wherein the radius of the lower dwell 
section D1 is greater than the radius of the upper dwell section D2. The 
points of the vertical movement section M are at different distances from 
the spindle axis with such distance decreasing from the radius of the 
lower dwell section at the end of the vertical displacement section 
closest to the lower dwell section D1 to the radius of the upper dwell 
section at the end of the vertical movement section M closest to the upper 
dwell section D2. 
The gear sectors 365 of the cam assembly 360 include gear teeth 375 which 
are engaged with pinion gears 385 located on either side of a cylindrical 
flywheel 383 and coaxial therewith. Spindles 387 outboard of the pinion 
gears are slidably engaged in slots of flywheel supporting members 389 
formed on the inside of the front and rear walls of the base support 353. 
Thus, the flywheel rotates with the rotation of the cam assembly 360. 
For reference, clockwise rotation of the cam assembly will refer to 
rotation of the cam assembly which moves the support member 367 toward the 
cam follower pegs 427 of the lower end cap 403, which is consistent with 
the perspective view of FIG. 14, and the cam profile of FIG. 15. 
The operation as well as further details of the vacuum source will now be 
discussed relative to the clockwise (CW) and counterclockwise (CCW) 
rotation of the cam assembly 360, the displacements of the upper end cap 
401, the lower end cap 403, and the slider 370; the cam assembly rotation 
interval during which the spring ends 377a are tensioned; the cam assembly 
rotation interval during which one of the spring ends 377b is tensioned; 
and the negative pressure (suction) at the opening of the cap 251. 
A resting angular position for the cam assembly 360 is defined by the lower 
dwell section D1 of the cam surfaces 395 and a stop 352b located on the 
inside surface of the rear wall of the base housing 353 and engageable by 
the spring end 377b of the spring 377 adjacent such rear wall. In 
particular, the resting angular position is defined by locating the stop 
352b such that spring end 377b rests in a non-tensioned manner on the stop 
352b when the cam assembly is angularly positioned with a portion of the 
dwell section D1 close to the vertical displacement section M engaged with 
the cam follower pegs 427. If the cam assembly 360 is rotated in the 
counterclockwise direction from the angular resting position, the spring 
end 377b will be tensioned which will cause the cam assembly 360 to rotate 
clockwise to its angular resting position when the rotation causing force 
is removed. If the cam assembly 360 is rotated clockwise away from its 
angular resting position, the lower end cap 403 is raised by engagement of 
the vertical movement section M of the cam surfaces 395 with the cam 
follower pegs 427, and the downward bias of the cam follower pegs 427 will 
tend to rotate the cam assembly 360 counterclockwise to its angular 
resting position when the rotation cause force is removed. 
The slider 370 is in the leftmost position at the start of a priming 
operation, and it will be placed at such position at the end of a vacuum 
generating operation as described further herein. The slider 370 is 
readily initialized to the leftmost position by operating the vacuum 
source as more particularly described herein. 
The cam assembly 360 is configured such that the support member 367 is at 
its highest position when the cam assembly is at its angular resting 
position. The support member 367 is engageable by an actuating tab 362 of 
a plunger 361 pursuant to depression of the plunger 361 which is 
constrained for vertical travel along a guide rod 368 secured to the 
bottom of the base housing 353. The upward vertical movement of the 
plunger is appropriately limited, and a coil spring 372 provides expanding 
bias that restores the plunger to a raised position when it is released 
after being depressed. 
Depression of the plunger 361 with the actuating tab 362 engaged on the top 
of the support member 367 causes the cam assembly 360 to rotate in the 
clockwise direction. As the cam assembly rotates, the vertical movement 
section M of the cam surfaces 395 causes the lower end cap 403 to move 
upwardly, thereby compressing the bellows assembly 350, and the cam edges 
377b eventually engage the cam follower pegs 393 of the slider 370. The 
movement of the slider to the right eventually slides the angled cam 
surfaces 364c of the slider 370 into engagement with the cam follower pegs 
431 of the upper end cap, which then causes the slider 370 to snap to the 
right pursuant to upward bias exerted by the cam follower pegs 431 against 
the angled ramp surfaces 364c, which allows the upper end cap 401 of the 
bellows assembly to move upwardly as the angled cam surfaces 364a and then 
the recessed cam surfaces 364c of the cam members 364 slide against the 
cam follower pegs 431. The slider 370 and the cam surfaces 395 are 
configured such that only the upper dwell section D1 is sliding against 
the cam follower pegs 427 of the lower end cap 403 when the upper end cap 
401 moves upwardly to engage the cap 251 against the bottom surface of the 
base 125 of the slider 123. In this manner, the lower end cap 403 is 
stationary while the upper end cap 401 moves upwardly, which produces 
negative pressure at the opening of the cap 251 as it seals against the 
bottom surface of the base 125 of the slider 123. 
As the cam assembly 360 continues to rotate clockwise pursuant to continued 
depression of the plunger 361, the spring ends 377a engage stops 352a 
located on the front and rear walls of the lower base 353. Pursuant to 
such engagement, the spring 377 is tensioned as the cam assembly 360 
continues to be rotated clockwise by the downward movement of the plunger 
361. The engagement of the spring ends 377a against the stops 352a is 
represented in FIG. 16 by the line A. 
As the cam assembly rotates clockwise, the support member 367 moves further 
away from the plunger by virtue of the circular path it is following, and 
the actuating tab 362 eventually bypasses the support member 367. After 
the support member 367 is free of the actuating tab 362, the cam assembly 
slows and then begins rotating in the counter-clockwise direction pursuant 
to the tension of the springs 377. At the beginning portion of the 
counter-clockwise rotation, the pressure at the opening of the vacuum 
source cap 251 does not change by virtue of the upper dwell section D2 of 
the cam surfaces 395. With continuation of the counterclockwise rotation, 
the lower end cap 403 moves downwardly by virtue of the vertical 
displacement section M of the cam surfaces 395, whereby the bellows 
assembly 350 expands to make the pressure at the opening of the vacuum 
source cap 251 more negative than the initial negative pressure produced 
upon engagement of the cap 251 against the bottom surface of the base 125 
of the slider 123, which causes ink to be suctioned out of the nozzle 
array whose cap is connected to slider bore that is selectively aligned 
with the cap 251. As a result of the inertia of the flywheel 383, the 
rotation of the cam assembly 360 is slowed, whereby the ink suctioning 
negative pressure is applied over a longer time interval than would be 
provided if the cam assembly 360 were rotated without the flywheel 383. 
As the cam assembly 360 continues its counterclockwise rotation, the spring 
ends 377a eventually become disengaged from the stops 352a, but the cam 
assembly 360 continues to rotate counterclockwise pursuant to the 
rotational momentum of the flywheel 383. Prior to reaching its resting 
angular position, the cam edges 374a engage the cam follower pegs 395 of 
the slider and move the slider 370 to the left with the counterclockwise 
rotation, which causes the angled surfaces 64c and then the non-recessed 
surfaces 364 to slide over the cam follower pegs 431, thereby causing the 
upper end cap to be moved downwardly. The slider 370, the cam edges 374a, 
and the cam surfaces 395 are configured such that while the upper end cap 
401 is moving downwardly, the lower end cap 403 moves downwardly at a 
greater rate than the rate of the downward movement of the upper cap, 
whereby negative pressure is present at the opening of the cap 251 as it 
is being disengaged from the bottom surface of the base 125 of the slider 
123. The negative pressure during disengagement of the cap 251 from the 
bottom surface of the base 125 can be less than the ink suctioning 
negative pressure. 
By virtue of the momentum of the flywheel as well as its own momentum, the 
cam assembly continues to rotate in the counterclockwise direction past 
its resting angular position until the spring end 377b engages the stop 
352. This causes the cam assembly 360 to stop its counterclockwise 
rotation and then rotate clockwise to its resting angular position, which 
insures that the support member 367 is in the path of the actuating tab 
362 and therefore ready for the next priming operation. The engagement of 
the spring end 377b against the stop 352b is represented in FIG. 16 by the 
line B. 
Release of the pressure on the plunger 361 allows it to move upwardly 
pursuant to the upward bias of the spring 372. The top edge of the 
actuating tab 362 eventually contacts the support member and causes the 
cam assembly to the rotate counterclockwise, which tensions the spring end 
377b against the stop 352b. When the actuating tab 362 clears the support 
member 367, the tension of the spring 377 causes the cam assembly to 
rotate clockwise to its resting angular position. 
For further description of the vacuum source described above and shown in 
FIGS. 12-14, reference is made to copending U.S. application Ser. No. 
08/056,012, filed Apr. 30, 1993, by K. L. Glassett and S. W. Bauer for 
"IN-LINE/OFF-LINE PRIMER FOR INK JET CARTRIDGE," U.S. Pat. No. 5,420,619 
which is incorporated herein by reference. 
Referring now to FIGS. 17-22, the sled 111 and the carriage 51 cooperate as 
follows to cap the nozzle arrays of the printhead cartridges and to wipe 
the nozzle arrays when the carriage moves away from engagement of the sled 
in the capped position. As shown in FIG. 17, when the sled is in the 
capping position, it is in its vertically highest position such that the 
caps 113 are in engagement with the printhead nozzle arrays that are 
overlying the caps as a result of movement of the carriage to the right to 
position the sled in the capping position. In the capping position, the 
prongs 221 of the sled are engaged in slots 231 of the carriage, and the 
lowest portion of the cam surfaces 219 are engaged against the stationary 
pegs 237 pursuant to the upward bias of the sled by the springs 235. As 
the carriage is moved to the left toward the center of the printer, the 
sled is moved to the left by virtue of the prongs 221 being contained in 
the slots 231 of the carriage. As the sled is moved to the left, it is 
vertically lowered away from the printhead cartridges as sloped portions 
of the cam surfaces 219 slide across the stationary pegs 237. Notches in 
the cam surfaces eventually engage the stationary pegs, at which time the 
sled prongs 221 are clear of slots 231 in the carriage 51. As the carriage 
continues its movement to the left, the prongs 221 remain clear of the cam 
surfaces 233 of the carriage 51, and sled remains stationary while the 
nozzle arrays of the printhead cartridges slide over the resilient wipers 
115. Continued movement of the carriage causes bumps in the cam surfaces 
233 of the carriage 51 to engage the prongs 221 which causes the sled to 
move downward and to the left as the notches in the sled cam surfaces 219 
disengage from the stationary pegs 237 sloped portions of the sled cam 
surfaces slide against the stationary pegs. The downward and to the left 
movement of the sled continues until horizontal portions of the sled cam 
surfaces become engaged with the stationary pegs 237 at which time the 
prongs 221 are clear of the bumps in the carriage cam surfaces 233. The 
sled is then in its down position wherein the upper edges of the wipers 
are vertically lower than the printhead nozzle arrays. 
The sled is moved to the capping position pursuant to engagement of the 
prongs 221 by the carriage slots 231 as the carriage moves to the right. 
Since the sled is in the down position, the printhead nozzle arrays remain 
higher than the wipers until the carriage slots engage the prongs 221, at 
which time the printhead nozzle arrays are positioned over the caps 113. 
Continued movement of the carriage to the right causes the sled to move up 
and to the right with the carriage as the sled cam surfaces 219 slide 
across the stationary pegs 237. Eventually, the caps come into engagement 
with the printhead nozzle arrays, with the alignment between the nozzle 
arrays and the caps being controlled by the relative positioning of the 
slots 231 of the carriage and the prongs 221 of the sled 111. 
More specific information as to the operation of the sled 111 relative to 
the carriage 51 is more particularly described in commonly assigned 
copending U.S. application Ser. No. 08/056,327, filed Apr. 30, 1993, by 
Heinz Waschhauser and William Osborne for "SERVICE STATION HAVING REDUCED 
NOISE, INCREASED EASE OF ASSEMBLY AND VARIABLE WIPING CAPABILITY," which 
is incorporated herein by reference; and in commonly assigned copending 
U.S. application Ser. No 07/949,197, filed Sep. 21, 1992, by William S. 
Osborne for "INK-JET PRINTHEAD CAPPING AND WIPING METHOD AND APATUS," 
which also incorporated herein by reference. 
Although the foregoing has been a description and illustration of specific 
embodiments of the invention, various modifications and changes thereto 
can be made by persons skilled in the art without departing from the scope 
and spirit of the invention as defined by the following claims.