Cleaning system and method for ink jet printer

Apparatus for cleaning contaminants from the face and orifice(s) of the print head of an ink jet printer includes a cleaning card having a foam strip secured across the front face of the card near its bottom edge, the upper portion of the card forming step-like protrusions from each lateral or side edge of the narrower lower portion of the card, the foam strip being saturated with a cleaning solvent, the lower portion of the card being adapted for insertion between a card guide and the face of said print head, causing squeezing of the foam strip for release of the solvent upon and wiping of the face of the print head and orifice(s) as the foam strip is moved thereagainst.

The field of the present invention relates generally to ink jet printers, 
and more specifically to apparatus and methods for cleaning the face and 
orifices of an ink jet print head. 
In an ink jet printer the face of the print head thereof may in time become 
contaminated with stray droplets of ink, paper dust, and other extraneous 
and undesireable material, all of which if allowed to accumulate would 
interfere with reliable operation of the print head. A number of different 
devices and systems have been developed for cleaning or protecting the 
face of the print head of an ink jet printer from the deleterious effects 
of various contaminants. Kattner U.S. Pat. No. 4,112,435, issued on Sept. 
5, 1978, for "Protective and Cleaning Device for Writing Heads in Ink 
Recorder Devices", teaches a protective and cleaning combination shield 
and wiper for ink jet recording device writing heads, consisting of a 
shield member mounted on the writing head and movable between a blocking 
position in front of the orifices of the writing head, and an operating or 
non-blocking position clear of the orifices. The shield is equipped with a 
resilient wiping arm which wipes across the face of the writing head 
during movement between the positions. 
Another example of a prior ink jet printer head tending system shown in 
Hoffmann et al U.S. Pat. No. 4,210,918, includes a collecting apparatus 
provided with a knife edge for collecting and discharging droplets of a 
specific charge, and a recording support arranged downstream of the 
movable knife edge wherein the collecting apparatus is provided with a 
cleaning device and an extraction device which are such that a new or 
freshly clean part of a knife edge always faces droplets being separated 
in the subject continuous ink jet printer system. A third example of a 
head tending system shown in Krull U.S. Pat. No. 4,228,442, for "Means for 
Preventing Drying of Ink at Nozzles of Print Heads", includes the mounting 
of an absorbent material with one end in an ink chamber, and the other end 
positioned in the proximity of the nozzle or nozzles of the print head for 
carrying fluid or vapor therearound to form a moist or humid atmosphere at 
the nozzle or nozzles, thereby preventing drying of the ink. 
The present inventor observed that in laboratory conditions, experienced 
technicians often clean the face and orifices of an ink jet print head by 
wiping or scrubbing the face with a solvent saturated lint-free cloth. He 
noted that although this head cleaning approach is rather straight 
forward, much judgement and experience is required for the operator to 
properly clean the head in this manner. Also, the cleaning operator must 
handle the solvent-wetted material directly, and the face of the print 
head must be directly accessable to the operator. In practical 
applications, the print head is not directly accessable to an operator, 
and the typical operator lacks the experience and judgement necessary to 
properly clean the print head as previously described. 
The present invention overcomes the problems in the prior art by providing 
a cleaning card having a foam strip saturated with a cleaning solvent, 
whereby the portion of the card with the foam strip is insertable between 
a card guide and the face of the ink jet print head for causing the card 
guide to squeeze the foam to release the cleaning solvent upon the head as 
the card is being inserted, thereby permitting the face of the print head 
to be scrubbed and cleaned via the rubbing or wiping action of the foam 
and cleansing properties of the solvent. The card guide is designed to 
further coact with the cleaning card by providing stops for limiting the 
depth of insertion of the cleaning card, while providing for compression 
of the foam strip against the face. The card guide is also designed to 
provide a narrow tapered gap between the inside face of the card guide and 
the face of the print head below the orifices and just beyond the depth of 
penetration of an inserted cleaning card, for trapping cleaning solvent 
flowing down the face of the print head upon insertion of the cleaning 
card, whereby the trapped solvent is carried away from the print head by a 
wick material having one end mounted in the narrowest portion of the gap 
between the card guide and print head.

With reference to FIG. 1, the cleaning card 1 has an elongated top portion 
3, and a lower central portion 5 that is stepped down or narrower than the 
former. The card can be fabricated from any suitable material, such as 
plastic, for example. The lateral edges 7 and 9 of the lower portion 5 
terminate at step-like projections 11 and 13, respectively of the upper 
portion 3. A foam-like strip 15 is secured to the lowermost face of the 
bottom portion 5 (typically by ultrasonic bonding or with a suitable 
adhesive by thermal bonding), with the bottom edge of the foam-strip 15 
being aligned with the bottom edge of the lower portion 5. Polyurethane 
open-cell foam is a typical material for strip 15. Further reference is 
made to FIG. 2 showing a front view of the card 1, FIG. 3 showing a 
left-side plan view thereof, and FIG. 4 showing a right-side plan view 
thereof. Note that in this example the depth of the steps formed by 
projections 11 and 13 with the lower portion of the card 5 have different 
heights or depths from the bottom or lower edge of the lower portion 5. In 
this manner, the card 1 when inserted into the card guide 17 shown in FIG. 
5 will seat at an angle when step 11 is "stopped" via tab 19, and step 13 
is "stopped" via tab 21. In this manner, the foam-strip 15 can be made to 
wipe across orifices (not shown) linearly arranged on a slant with the 
horizontal on the face 25 of the print head 23, so long as the card 1 is 
inserted to the "stopped position". The depth of the steps 11 and 13 can 
be adjusted for making the card "stop" at any desired angle, or at a 
position where the length of the foam strip 15 is horizontal, depending 
upon the particular application. The interaction between the card 1, card 
guide 17, and print head 23 will be discussed in further detail in the 
following paragraphs. 
In FIG. 5, the card guide 17 of the present example, includes a plurality 
of holes 27 linearly arranged on a slant as shown. Each hole 27 is 
associated with an ink jet orifice located immediately behind the hole on 
the face 25 of the ink jet print head 23. The purpose of the holes 27 is 
to permit the associated ink jets to be operated for ejecting from their 
respective orifices droplets of ink that travel through their associated 
hole 27 onto a print medium (not shown) located in front of card guide 17. 
The card guide 17 can be made of any suitable material, a typical material 
being stainless steel sheeting or a plastic material, wherein the sheet 
material should have spring like characteristics. With further reference 
to FIGS. 6 and 7, the card guide 17 is mounted on the print head 23 via 
spacers 29 and screws 31. The spacer 29 at the right side of the print 
head is shorter than the spacer 29 used at the left side of the print 
head, with the spacer 29 in the center of the print head being 
intermediate in length between the spacers at the right and left, causing 
the card guide 17 to have its longitudinal axis mounted at an angle with 
the face 25 of print head 23 (see FIG. 7). Because of this nonparallel 
mounting of the card guide 17 to the print head 23, the region of 
narrowest gap or closest contact of the portion of the card guide 17 above 
the mounting screws 31 and spacers 29 occurs near the right side of print 
head 23, in this example. Also, card guide 17 generally has a region of 
closer contact with the face 25 along the bend lines 33, with the closest 
contact being to the right, as previously described. The basic design of 
the card guide 17 satisfies all of the usual functions of a typical card 
guide used in a printer system. For example, the curved upper portion of 
card guide 17 facilitates printing near the upper free edges of a sheet of 
paper or print medium prior to the edge being held to a platen by bail 
rollers (not shown). The wings 35 on each side of the card guide 17 
prevent the edges of such a free standing sheet of paper or print medium 
from jamming into the sides of the print head 23, thereby protecting the 
face 25 from damage. The card guide 17, in serving the aforementioned 
functions, limits operator access to the face 25 of print head 23, 
generally making cleaning difficult. The cleaning card 1 and card guide 17 
were designed to substantially alleviate the print head 23 cleaning and 
access problem. 
The curvature and degree of bending from the vertical of the card guide 17 
is such that when the cleaning card 1 is inserted into the space between 
the card guide 17 and face 25 of print head 23, as shown in FIG. 5, a 
pre-determined squeezing force is applied by the card guide 17 to the foam 
strip 15 of cleaning card 1. When the foam strip 15 has been saturated 
with an appropriate cleaning solvent, such as ethyl alcohol, isopropanol, 
or some other suitable solvent depending upon the particular application. 
The solvent used partly depends on the composition of the printing ink 
being run through the printing head 23. 
In operation of the present invention, the cleaning card 1 is stored either 
with a dry foam strip 15, or with the foam strip 15 saturated with an 
appropriate cleaning solvent, within a sealed package, such as a plastic 
or metal foil envelope, for example. If the cleaning card is shipped with 
the foam strip 15 previously saturated with cleaning solvent, the card is 
ready for use when removed from the envelope. Otherwise, when removed from 
its storage envelope or pouch, the cleaning card 1 must have the foam 
strip 15 saturated with the cleaning solvent prior to use. With reference 
to FIG. 5, the cleaning card 1 is inserted as shown with the foam strip 15 
facing the face 25 of the print head 23. As the cleaning card 1 is 
inserted between the card guide 17 and face 25 of print head 23, the 
curvature of the card guide 17 is such that prior to the foam strip wiping 
over the orifices on the face 25, a compressive force or squeezing force 
is applied to the foam strip 15, causing it to release cleaning solvent 
onto the face 25, followed by the foam strip 15 wiping across the 
orifices. Full insertion of the cleaning card 1 is obtained when the steps 
11 and 13 of card 1 seat against tabs 19 and 21, respectively, of card 
guide 17, thereby preventing further insertion thereof. Also, as 
previously described, the height of the steps 11 and 13 from the bottom 
edge of the cleaning card 1 determine the angle that the foam strip 15 
will attain at the extreme of the insertion of the cleaning card 1. The 
depth of insertion of the cleaning card 1 is made sufficiently deep to 
insure that the foam strip 15 wipes all of the orifices on the face 25 of 
the print head 23. 
The thickness and width of the foam strip 15 is pre-determined to insure 
that in combination with the compressive force applied by the card guide 
17 to the cleaning card 1, excessive cleaning solvent is not applied to 
the face 25. As the cleaning card 1 is inserted and wiped across the face 
25 of print head 23, cleaning solvent released from the foam strip 15 runs 
down the face 25 and is trapped between that face, and the inside face of 
the card guide 17 along the bend line 33. Because of the previously 
described longitudinal tapering of the space between the card guide 17 and 
face 25, the solvent is made to move by capillary action to the right side 
of the face 25, where it is collected by a wick material 37 securely 
mounted between the card guide 17 and the face 25, as shown. The wick 
material 37 drains off the cleaning solvent to an open area where the 
solvent can evaporate from the wick 37, or be dripped into a suitable 
container 39. Accordingly, in this manner, when the cleaning card 1 is 
inserted between the card guide 17 and the print head 23, the cleaning 
solvent flooding down the face is controlled and prevented from dripping 
off the bottom of the print head face 25, while the foam 15 gently scrubs 
or wipes the area around the orifices as the cleaning card 1 is inserted 
downward to its maximum depth. 
In the preferred embodiment of the invention, for convenience, it is 
preferred that the cleaning card be supplied in a pouch with the foam 15 
pre-wetted with an appropriate cleaning solvent, as previously mentioned. 
Alternatively, the cleaning card 1 may be supplied dry in a sealed pouch 
for maintaining cleanliness thereof, and a small dispensing bottle of 
cleaning solvent supplied to an operator or service man for wetting the 
foam 15 after the cleaning card 1 is removed from the storage pouch area. 
Even when the ultimate user applies the cleaning solvent to the foam 15, 
the pre-determined volume of foam used on the cleaning card 1, along with 
the dimentional characteristics of the foam strip 15, will control the 
amount of solvent that is ultimately applied to the face 25 of print head 
23, as previously described. 
Although specific embodiments of the present invention have been shown and 
described herein, they are not meant to be limiting, and other embodiments 
or variations thereof may occur to those skilled in the art, which 
variations are still within the spirit and scope of the present invention.