Ink-jet recording head

An ink-jet recording head has ejection outlets formed by treating a face of a plate for the ejection outlets with a water-repellent and irradiating the plate with a laser beam from the backside of the plate. The head is provided with a sealing member for sealing the ejection outlets. The water-repellent has a hardness of higher than the pencil hardness 6B at room temperature. A decomposition product layer is formed on the layer of the water repellent at peripheral portions of the ejection outlets.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a recording head, including a recording 
head unified with an ink tank, which is applicable to business machines 
such as printers, copying machines, ink-jet recording apparatuses, and so 
forth, particularly to a recording head which is detachable from the main 
body of a machine. The present invention also relates to a method of 
storing the recording head. 
2. Related Background Art 
In conventional ink-jet recording apparatuses, recording heads, and 
recording units having an integral recording head and ink tank, there are 
known those which eject fine liquid droplets by utilizing thermal energy, 
an electromechanical transducer or the combination thereof, and those 
which eject deflected liquid droplets by utilizing a pair of electrodes. 
From among these recording heads, ink-jet recording heads which eject 
recording liquid by utilizing thermal energy are widely used practically. 
This is because the liquid-ejection outlets can readily be arranged in 
high density for formation of shooting recording-liquid droplets to give 
high resolution of recording, and also because the apparatus can be 
readily made compact advantageously. Such recording heads, however, are 
liable disadvantageously to cause leakage of ink during storage and 
transportation thereof. 
To prevent the leakage of ink from the recording head, a seal tape is stuck 
onto the tip portion of the head (or ejection outlets) when shipping the 
recording heads. 
However, increase of the adhesiveness of the seal tape to prevent surely 
the ink leakage gives rise to need for stronger force on the seal tape 
removal, which may disadvantageously cause accidental drop-off of the 
recording head or scattering of the ink from the recording head to soil 
the apparatus, or otherwise may cause deformation of the ejection outlet 
and result in poor recording. 
Accordingly, the countermeasures as below are considered to avoid the above 
disadvantages even if the peeling force to remove the seal tape is strong: 
(1) The orifice plate is made thicker, and 
(2) The orifice plate is fixed more tightly. 
However, a larger thickness of the orifice plate causes problems in design 
such as decrease of the area of the ejection outlet owing to the taper 
formed in boring of the orifice, which decreases the ink ejection volume. 
Further, for sure fixing of the orifice, the head has to be made larger, 
which raises the cost of the production. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a recording head which is 
free from ink leakage and from which a seal tape is readily peelable. 
Another object of the present invention is to provide a recording head 
which can be stored stably for a long term, and is instantly usable 
without an adverse effect of a residual solvent or adhesive of the seal 
tape. 
The present invention provides an ink-jet recording head having ejection 
outlets formed by treating a face of a plate for the ejection outlets with 
a water-repellent and irradiating the plate with a laser beam from the 
backside of the face having been treated with the water-repellent, and 
provided with a sealing member for sealing the ejection outlets, said 
water-repellent having a hardness of higher than the pencil hardness 6B at 
room temperature, and a second layer being formed on the layer of the 
water repellent in peripheral portions of the ejection outlets.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In a preferred embodiment, the present invention enables satisfactory 
prevention of ink leakage independently of environmental conditions. That 
is, an ink container portion of a recording head having at least an air 
communication device is provided with a means for covering the air 
communication device via a pressure-sensitive adhesive and for adjusting 
the variation of pressure in the ink container portion. In this 
embodiment, the recording head is kept in a stable state in any 
environmental conditions by the pressure-adjusting means fixed tightly to 
the recording head by use of the pressure-sensitive adhesive. When the 
pressure adjusting means is removed from the recording head, the air 
communication device can surely be restored to a desired state by the 
peeling property of the pressure-sensitive adhesive. Particularly 
remarkable effects are attained when a seal tape having such a 
pressure-sensitive adhesive is applied not only to the air communication 
device but also to the ejection portion of the recording head. 
The pressure-sensitive adhesive preferably contains, as the adhesive 
component, an acrylate ester copolymer crosslinked by an isocyanate, the 
acrylate ester copolymer being derived from at least 80% by weight in 
total of an alkyl and/or alkoxyalkyl acrylate containing a hydroxy group, 
and an acrylate ester having a side chain of an alkyl or alkoxyalkyl group 
of 4 to 9 carbons. 
Preferably, the pressure-adjusting means closes tightly the ink container 
when the internal pressure is normal, but brings the internal pressure 
near to the external pressure when the internal pressure becomes 
abnormally high. An example is a member or a mechanism which has a normal 
volume (being in a shrinked state) and increases the internal volume with 
a rise in the internal pressure so as to cancel the increase of the 
internal pressure while maintaining the closed state. Another example is a 
member or a mechanism which forms temporarily a communication portion to 
communicate with the external atmosphere in response to the rise of the 
internal pressure to some degree to exclude the abnormal state of the 
pressure. In the latter example, it has been found that the internal 
pressure can practically be maintained stably if the communication portion 
to be formed temporarily has an area of 0.005 mm.sup.2 or more but is 
smaller than the opening area of the air-communication device. In usual 
transportation of the recording heads, an area of not more than 0.1 
mm.sup.2 thereof causes no problem. The area is preferably not more than 
0.05 mm.sup.2 to prevent ink leakage as a result of extreme tossing during 
transportation. 
In a particularly preferred embodiment, the ink cartridge comprises an ink 
container portion which has a pressure absorber to form a negative 
pressure by absorbing ink, an opening portion for communicating the 
interior of the ink container portion to an exterior atmosphere, an 
ink-ejection portion enclosed in the container portion, and an 
electrothermal transducer for generating thermal energy for causing film 
boiling of the ink in accordance with electric signals. The ink cartridge 
having a sealing member provided at the opening portion which comprises a 
bonding portion with an adhesive to cover the opening, a 
pressure-adjusting portion to control the pressure variation in the 
container portion, and a closing portion to close tightly the ink-ejecting 
portion. The adhesive component of the adhesive is an acrylate copolymer 
being composed of at least 80% by weight in total of an alkyl and/or 
alkoxyalkyl acrylate containing a hydroxy group, and an acrylate ester 
having a side chain of an alkyl or alkoxyalkyl group of 4 to 9 carbons. 
The ink-jet cartridge is made ready for use by separating the sealing 
member including the adjusting portion to release the opening portion and 
removing the sealing member from the recording head to expose the ejection 
portion. This method prevents ink scattering on removal of the sealing 
member even when the sealing member is peeled quickly. 
The above preferred pressure-sensitive adhesive is of an acrylic resin 
type, the novel adhesive having been obtained after comprehensive 
investigation for achieving the above objects, and particularly for use 
for ink-jet recording head. 
The acrylic monomer for the pressure-sensitive acrylic material includes 
alkyl ester monomers such as methyl acrylate, ethyl acrylate, propyl 
acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, 
2-methylbutyl acrylate, 2-ethylbutyl acrylate, 3-methylbutyl acrylate, 
1,3-dimethylbutyl acrylate, pentyl acrylate, 3-pentyl acrylate, hexyl 
acrylate, 2-ethylhexyl acrylate, heptyl acrylate, 2-heptyl acrylate, octyl 
acrylate, 2-octyl acrylate, nonyl acrylate, and the like, and alkoxyalkyl 
ester monomers such as 2-ethoxyethyl acrylate, 3-ethoxypropyl acrylate, 
2-ethoxybutyl acrylate, 3-methoxybutyl acrylate, 2-ethoxyethyl acrylate, 
3-methoxypropyl acrylate, and the like. Such a monomer is used in 
combination with the hydroxy-group-containing monomer, discussed below, in 
a total amount ranging from 50 to 100% by weight, preferably from 50 to 
80% by weight. 
The polyvalent isocyanate compound includes tolylene diisocyanate, 
hexamethylene diisocyanate, diphenylmethane diisocyanate, isophorone 
diisocyanate, xylylene diisocyanate, bis(isocyanatomethyl)-cyclohexane, 
dicyclohexylmethane diisocyanate, lysine diisocyanate, 
trimethylhexamethylene diisocyanate, adducts of tolylene diisocyanate with 
hexamethylene diisocyanate, urethane-modified compounds, 
allophanate-modified compounds, biuret-modified compounds, 
isocyanurate-modified compounds, urethane prepolymers (oligomeric 
compounds having an isocyanate group at each end), and the like. 
The cohesion property of the pressure-sensitive adhesives can be adjusted 
by various methods. 
A first method of adjusting the cohesion property of the pressure-sensitive 
adhesive is copolymerization with a hydroxy-group-containing monomer and 
crosslinking by use of a polyvalent isocyanate compound. The 
hydroxy-group-containing monomer includes 2-hydroxyethyl acrylate, 
2-hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxyethyl 
methacrylate, 2-hydroxypropyl methacrylate, hydroxybutyl methacrylate, 
acrylate esters of polyhydric alcohol, methacrylate ester of polyhydric 
alcohol, an acrylate ester of ethylcarbitol, an acrylate ester of 
methyltriglycol, 2-hydroxyethyl acryloylphosphate, propoxyethyl acrylate, 
and so forth. The hydroxy-group-containing monomer is used preferably in 
an amount ranging from 5 to 25% by weight, and a part or the whole thereof 
is crosslinked by polyvalent isocyanate. 
A second method of adjusting the cohesion property of the 
pressure-sensitive adhesive is appropriate use of copolymerization 
component such as a methacrylate monomer, vinyl acetate, styrene, 
acrylonitrile, acrylamide, and methacrylamide. From among the components, 
acrylonitrile, acrylamide, and methacryamide are particularly suitable for 
the ink-jet recording head of the present invention. Such a component is 
preferably used in an amount ranging from 5 to 15% by weight. 
A third method of adjusting the cohesion property of the pressure-sensitive 
adhesive is crosslinking with a crosslinking monomer such as 
N-methylolacrylamide, N-methylolmethacrylamide, diacetonacrylamide, and 
butoxymethylacrylamide. The crosslinking monomer is preferably used in an 
amount ranging from 5 to 15% by weight. 
For a more suitable pressure-sensitive adhesive, the first method of the 
adjustment is employed preferably in combination with the second or the 
third method. 
The seal tape having the above acrylic type adhesive is capable of 
maintaining stably a fine opening corresponding to the air communication 
opening. In the case where the fine opening is formed on the seal tape 
after sealing the air communication opening by use of a needling or a 
punching, the seal tape is never peeled by this opening formation 
operation. 
The alkyl acrylate ester and/or the alkoxyalkyl acrylate ester which 
contains the one having a short side chain of four carbons or less in an 
amount of 90% by weight or more has a high Tg, which may cause leakage of 
ink due to low adhesion strength to the nozzle surface, or partial peeling 
of the seal tape on forming the fine opening on the air communication 
opening. Otherwise, the alkyl acrylate ester and/or the alkoxyalkyl 
acrylate ester which contains the one having a side chain of nine carbons 
or more in an amount of 90% by weight or more has a low Tg, exhibits high 
adhesion strength, and adheres excessively tightly to the nozzle surface, 
causing separation of the adhesive from the supporting material thereof 
and soiling the nozzle surface. 
The aforementioned pressure-sensitive adhesive preferably has chemical 
resistance to the ink-jet ink, gives less elution of an organic matter, 
contains less amount of polyvalent metal, and satisfactorily protects the 
surface of the ink-jet head. To obtain such properties, the 
pressure-sensitive adhesive may be prepared as below with the 
aforementioned materials. (1) In one method, the aforementioned monomers 
are solution-polymerized in an organic solvent such as a ketone, an ester, 
and an aromatic solvent to prepare a high polymer having a weight-average 
molecular weight of from 250,000 to 700,000. In the polymerization, it is 
important that the polymer does not contain a low polymer having a 
molecular weight of less than 10,000, nor a remaining monomer. Therefore, 
the polymerization is controlled and the low polymer is removed. The 
removal of the low polymer is conducted most surely by precipitation of 
the polymer. The precipitated polymer is dissolved again. (2) In another 
method, the aforementioned monomer is polymerized by emulsion 
polymerization using an emulsifier or soap-free emulsion polymerization to 
obtain a high polymer having a weight-average molecular weight of from 
250,000 to 1,000,000. The polymer obtained by the emulsion polymerization 
is preferably treated for removal of an unpolymerized monomer and a low 
polymer having a molecular weight of lower than 10,000 by dissolving again 
in a good solvent such as xylene and ethyl acetate. To the polymer 
prepared by either method (1) or (2), a diisocyanate is added to provide a 
coating solution. This coating solution containing the diisocyanate is 
applied onto a supporting film in a thickness of from 5 .mu.m to 100 
.mu.m, preferably from 5 .mu.m to 50 .mu.m, and is dried by means of a 
conventional drier. The drying conditions are depend on the kind of 
solvent. Usually the drying temperature being in the range of from 
60.degree. C. to 150.degree. C. Preferably the heat-dried film is aged at 
room temperature for three to ten days. 
In the case where the polymer as the pressure-sensitive adhesive component 
is derived from the alkyl. acrylate ester and/or the alkoxyalkyl acrylate 
ester which has an OH group and has a side chain of an alkyl group or 
alkoxyalkyl group of 4 to 9 carbons, and is crosslinked by an isocyanate, 
the pressure-sensitive adhesive is capable of surely preventing leakage of 
ink from the ink-ejecting outlets and retaining the fine opening 
corresponding to the air communication opening. In this case, during 
formation of the fine opening, by needling or punching after the air 
communication opening is sealed with a seal tape, the seal tape will not 
peel off. Furthermore when a user peels the seal tape forcibly in order to 
use the ink-jet head, the adhesive will not cause cohesion failure and the 
tape will not remain on the ejection outlet surface. Thus instant use of 
the ink-jet head and high-quality of recording is permitted. 
In particular, when the acrylic polymer in the adhesive component contains 
butyl acrylate at a content of not less than 70% by weight, the 
deterioration of the seal tape and the migration of the component thereof 
into the ink can be avoided and peelability of the seal tape from the 
recording head is satisfactory. In the construction of the recording head 
described later, a resin or glass is frequently employed in addition to 
the silicon substrate. The present invention is not affected by the 
difference therebetween in peeling characteristic and the adhesive does 
not remain on the surface of the ejection outlets by cohesive failure, 
therefore being not limited in its use. 
The acrylic polymer prepared by polymerizing an alkyl acrylate ester and/or 
an alkoxyalkyl acrylate ester and crosslinking it with an isocyanate into 
the pressure-sensitive adhesive is preferably contained in an amount of 
90% by weight or more in the adhesive since such adhesive does not 
deteriorate on contact with ink and does not cause migration of the 
component thereof into the ink, producing no clogging or unstable ejection 
during use of the printer. 
The material of the film used as the support of the pressure-sensitive 
adhesive of the present invention includes polyethylene terephthalate, 
polypropylene, polyethylene, poly-4-methylpentene-1, polyvinyl chloride, 
vinylidene chloride-vinyl chloride copolymers, polyvinyl fluoride, 
polyvinylidene fluoride, tetrafluoroethyene-ethylene copolymers, 
tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether 
copolymers, and the like. The film may be subjected to a surface treatment 
such as corona discharge treatment, flame treatment, and plasma treatment 
for improvement of bonding of the pressure-sensitive adhesive thereon. The 
thickness of the supporting material in the present invention is 
preferably in the range of from 20 to 50 .mu.m, more preferably from 25 to 
35 .mu.m. 
In addition to the above requirements, overall stability of the sealing is 
attained when the peel strength of the seal tape from stainless steel (SUS 
304) is adjusted to be in the range of from 200 g/25 mm to 1,200 g/25 mm. 
Therefore, this is one of the favorable conditions. Under this condition, 
peeling of the pressure-sensitive adhesive tape from the air communication 
opening does not occur upon forming a fine opening in the air 
communication opening. 
Herein, the peel strength is measured at a stress rate of 300 mm/min by 
means of a tester specified in JIS-B-7721 having a capacity of 2.0 Kg by 
use of a SUS304 plate as the base plate at 180.degree. peeling at 
25.degree. C. The thickness of the pressure-sensitive adhesive layer is 
closely related to the peel strength, the thickness at the peel strength 
measurement being preferably in the range of from 5 to 70 .mu.m, more 
preferably from 20 to 50 .mu.m. The seal tape is preferred which does not 
leave the adhesive even at a large thickness of the adhesive layer. 
The pressure-sensitive adhesive mentioned above is effective also to the 
nozzle surface treated for ink repellency, retaining satisfactory 
adhesiveness without deterioration of the tape and nozzle surface. 
The aforementioned "surface treated for ink repellency" means a surface 
having been treated with a treating agent such as a silicone oil, a 
fluorine-containing low molecular or high molecular compound, specifically 
including KP-801 (trade name, made by Shin-Etsu Silicone K.K.), Defennser 
(trade name, made by Dainippon Ink and Chemicals, Inc.), CTX-105 and -805 
(trade name, made by Asahi Glass Co., Ltd.), Teflon AF (trade name, made 
by DuPont Co.), and so forth. The fine opening provided on a seal tape on 
the air communication opening has most suitably a cross-sectional area of 
not more than 0.05 mm.sup.2 Naturally, the fine opening is not limited to 
be single, but may be provided in a plural number, or may be a slit-shaped 
cut. The fine opening may be provided by needling, or laser beam 
projection, but is not limited thereto. 
FIGS. 2 to 6 are shown to explain each of a ink-jet unit IJU, an ink-jet 
head IJH, an ink tank IT, an ink-jet cartridge IJC, a main body of an 
ink-jet recording apparatus IJRA, and a carriage HC, and the mutual 
relations thereof. The constitution of the respective parts is described 
below by reference to these drawings. 
The ink-jet cartridge IJC of the example holds a larger volume of ink as 
shown in the perspective view of FIG. 3. The tip portion of the ink-jet 
unit IJU protrudes slightly from the front face of the ink tank IT. This 
ink-jet cartridge IJC is held and supported by, the positioning means and 
the electric contact point mentioned later of the carriage HC (FIG. 5) 
mounted on the main body of an ink-jet recording apparatus IJRA, and is 
detachable from the carriage HC and is disposable. FIGS. 2 to 6 illustrate 
various novel techniques established in the development of the present 
invention. The whole apparatus is described by briefly explaining the 
constitution of the respective drawings. 
(i) Construction of Ink-Jet Unit (IJU): 
The ink-jet unit IJU is a unit for recording by a bubble jet method 
employing thermal energy generated by a electrothermal transducer to cause 
film boiling of ink in accordance with electric signals. 
In FIG. 2, the heater board 100 is formed by a film forming method and 
comprises an Si substrate, and electrothermal transducers (ejection 
heaters) arranged in lines on the substrate, and electric wiring for 
supplying electric power to the transducer. The wiring substrate 200 has a 
wiring for the wiring of the heater board 100 (connected, for example, by 
wire-bonding) and pads 201 for receiving electrical signals from the main 
apparatus placed at the end of the wiring. 
The grooved cover plate 1300 has separators for separating the plurality of 
ink flow paths and common liquid chamber for holding ink for supplying the 
ink to ink flow paths, and is integrally formed with an ink inlet 1500 for 
introducing ink from the ink tank IT to the common liquid chamber and an 
orifice plate 400 having a plurality of ejection outlets corresponding to 
the ink flow paths. The material therefor is preferably a polysulfone 
resin. Other molding resins may also applicable. 
A support 300 made of a metal or the like supports the wiring base board 
200 at the back side, and serves as the bottom plate of the ink-jet unit. 
The presser bar spring 500 in an M-shape presses the common liquid chamber 
at a low pressure with the center portion of the M-shape. The apron 
portion 501 presses concentratedly a portion of the liquid paths, 
preferably the region around the ejection outlets with a line pressure. 
The heater board 100 and the cover plate 1300 are engaged between the 
presser bar spring 500 and the support 300 with the foot portion of the 
presser bar spring engaged with the back side of the support 300 through 
the holes 3121, and thereby press-fixed with each other by the 
concentrated force of the presser bar spring 500 and the apron portion 501 
thereof. The support 300 has holes 312, 1900, 2000 corresponding to the 
two positioning projections 1012 of the ink tank IT, and positioning and 
heat-fusion-holding projections, 1800 and 1801, and further has 
positioning projections 2500 and 2600 at the back side corresponding to 
the carriage HC of the main apparatus IJRA. The support 300 further has a 
hole 320 through which an ink-supplying tube 2200 (described later) from 
the ink tank passes. Onto the support 300, wiring base plate 200 is bonded 
by use of an adhesive or the like. The hollow portions 2400, 2400 of the 
support 300 are respectively made in the vicinity (backside) of the 
projections 2500, 2600. Therefore, in the assembled ink-Jet cartridge IJC 
(FIG. 3), they are on extension lines of parallel grooves 3000, 3001, in 
surrounding three sides of the tip region of the head, thereby preventing 
the movement of an undesired matter, such as dust, and ink from reaching 
the projections 2500, 2600 along the parallel grooves 3000, 3001. The 
cover member 800 having parallel grooves 3000 forms the external wall of 
the ink cartridge IJC, and also forms a space with the ink tank for 
holding the ink-jet unit IJU as shown in FIG. 5. In the ink-supplying 
member 600 having parallel grooves 3001 formed thereon, the ink 
introducing tube 1600 connected to the ink supplying tube 2200 is fixed in 
the form of a cantilever at the side of ink supplying tube 2200. In order 
to ensure a capillary phenomenon between the fixed side of the 
ink-introducing tube and the ink-feeding tube 2200, a sealing pin 602 is 
inserted therein. A packing 601 is employed for connection of the ink tank 
IT with the ink supplying tube 2200. A filter 700 is provided at the end 
portion of the ink supplying tube 2200 at the side end of the ink tank. 
Since the ink-supplying means 600 is prepared by mold-forming, it is 
inexpensive and is positionally precise, and the production accuracy is 
maintained high. Owing to the cantilever structure of the ink-introducing 
tube 1600, the pressure-contact of the ink-introducing tube with the ink 
inlet 1500 is kept stable even in mass production. In this example, the 
communication state is ensured simply by flowing a sealing adhesive from 
the side of the ink-supplying member under the pressure contact state. The 
ink-supplying member 600 is readily fixed to the support 300 in such a 
manner that two pins (not shown in the drawing) at the back side of the 
ink-supplying member 600 are projected through the holes 1901, 1902 on the 
support 300 respectively and fusion-bonded. The small projections formed 
by fusion bonding are accommodated by hollows (not shown in the drawing) 
on the lateral side of the ink tank IT on which the ink-jet unit IJU is 
attached, so that the ink-jet unit IJU is positioned precisely. 
(ii) Construction of Ink Tank IT 
The ink tank is comprised of the main body of the cartridge 1000, the ink 
absorbing body 900, and the cover member 1100, and is formed by inserting 
the ink-absorbing body 900 into the main body of the cartridge 1000 from 
the side opposite to the ink-jet unit IT, and subsequently sealing it with 
the cover member 1100. 
The ink-absorbing body 900 is employed for holding the ink by impregnation, 
and is placed in the main body of the cartridge 1000. The ink supply inlet 
1200 is provided to supply ink to the ink-jet unit IJU, and also serves, 
before assembling the unit with the portion 1010 of the main body of the 
ink-jet cartridge 1000, as an ink supply inlet for filling ink into the 
ink-absorbing body 900. 
In this example, the ink can be supplied either through the air 
communication hole or through this supply inlet. For supplying ink 
satisfactorily from the ink-absorbing body, a continuous air space is 
formed by the ribs 2300 in the main body of the cartridge 1000 and the 
partial ribs 2302, 2301 of the cover member 1100 in the region from the 
air communication hole 1401 to the corner portion most distant from the 
ink supply inlet 1200. Therefore, ink is supplied relatively 
satisfactorily from the ink supply inlet 1200 to the ink absorbing body 
900, which is important. This method is extremely effective in practice. 
The four ribs 2300 are provided on the back face of the main body of the 
ink tank 1000 in a direction parallel to the moving direction of the 
carriage to prevent the close contact of the ink-absorbing body 900 with 
the back face. The partial ribs 2302, 2301 are placed at the positions on 
extension lines of the ribs 2300 respectively and on the inside face of 
the cover member 1100, and are in a divided state different from that of 
the ribs 2300, so that the air space is enlarged in comparison with the 
former. The partial ribs 2302, 2301 are distributed in the area not more 
than half of the area of the cover member 1100. The ribs make it possible 
to introduce the ink by capillary force to the ink supply outlet 1200 from 
the farthest corner portion. Through an air communication hole 1401 on the 
cover member, the interior of the cartridge communicates with the external 
air. A liquid repelling member 1400 is provided inside the air 
communication hole 1401 to prevent ink leakage from the air communication 
hole 1400. 
The aforementioned constitution and the arrangement of the ribs are 
particularly effective for the above ink tank IT, since the ink holding 
space thereof is in a form of a rectangular solid having its long side on 
the side face. In the case where the ink tank IT is in a form of a 
rectangular solid having its long side along the direction of moving 
direction of the carriage or is in a form of a cube, the ink supply from 
the ink-absorbing body 900 can be stabilized by providing the ribs over 
the whole face of the cover member 1100. The rectangular solid form is 
suitable for holding as much ink as possible in a limited amount of space. 
In order to use the stored ink effectively for recording without loss, the 
ribs playing the above role are preferably provided on two face regions 
neighboring the corner portion. Further, the inside ribs of the ink tank 
IT in this example are distributed uniformly in the thickness direction of 
the ink-absorbing body in a rectangular solid form. This constitution is 
important in enabling maximum utilization of substantially all the ink in 
the ink-absorbing body by uniformizing the atmospheric pressure 
distribution. The distribution of the ribs is based on the technical idea 
below. When the position of the ink supply inlet 1200 is projected onto 
the rectangular upper face of the rectangular solid and a circle is drawn 
with the projected position as a center with a radius of the length of the 
long side of the rectangle, it is important to provide the ribs at the 
area outside the circle line in order to give early the atmospheric 
pressure state. In this case, the position of the air hole of the ink tank 
is not limited to that in this example provided that the air is introduced 
to the rib-distributed region. 
Further, in this example, the back side of the ink-jet cartridge IJC 
opposite to the head is made planar to minimize the necessary space when 
incorporated in the apparatus and to maximize the quantity of the ink held 
therein, whereby the apparatus can be miniaturized and the frequency of 
cartridge exchange is decreased desirably. Behind the space for 
integrating the ink-jet unit IJU, a projection portion of the air 
communication hole 1401 is formed and the inside of the projected portion 
is made vacant to form an atmospheric pressure supplying space 1402 over 
the entire thickness of the ink-absorbing body 900. Such an arrangement 
produce an excellent cartridge which has not ever been met. This 
atmospheric pressure supplying space 1402 is much larger than conventional 
ones, and the air communication hole 1401 is placed at a higher position. 
Therefore, if the ink come off from the ink-absorbing body, this 
atmospheric pressure supplying space 1402 is capable of retaining the ink 
temporarily, enabling steady recovery of the ink to the ink-absorbing 
body, thus providing an efficient and excellent cartridge. 
The constitution of the face of the ink tank IT on which the ink-jet unit 
IJU is fitted is shown in FIG. 4. Two projections 1012 for positioning 
engaging with the holes 312 on the support 300 is on a straight line 
L.sub.1 which passes near the center of the ejection outlet of the orifice 
plate 400 and is parallel to the bottom face of the ink tank IT or a base 
face of the mounting of the carriage. The projection 1012 has a height 
slightly less than the thickness of the support 300, and positions the 
support 300. On the extension line of L.sub.1 in this drawing, a claw 2100 
is provided which engages with an engaging face 4002 perpendicular to the 
hook 4001 for positioning the carriage 16. Thus the force for positioning 
the carriage 16 exerts in the a planar region parallel to the base face 
containing the line L.sub.1. As mentioned later by reference to FIG. 5, 
such construction relation is effective since the accuracy of positioning 
of the ink tank itself is nearly equal to the accuracy of the positional 
positioning of the ejection outlet of the head. 
The projections 1800, 1801 of the ink tank 14 corresponding respectively to 
the holes 1900, 2000 on the support 300 for fixing it to the side face of 
the ink tank are longer than the aforementioned projection 1012, and are 
utilized for fixing the support 300 by bonding by fusion of the portion 
projecting through the support 300. On a line L.sub.3 perpendicular to the 
above-mentioned line L.sub.1 and passing the projection 1800, approximate 
center of the ink supply inlet 1200 is placed. Thereby the bonding of the 
ink supply inlet 1200 with the ink supply tube 2200 is stabilized, and a 
load caused by dropping or impact exerted to the bonding portion is 
reduced preferably. The line L.sub.2 passes the projection 1801. The lines 
L.sub.2, and L.sub.3 are not coincident with each other. The projections 
1800, 1801, around the projection 1012 at the ejection outlet side of the 
head IJH, also serve for positioning the head IJH relative to the tank. 
The curve L.sub.4 denotes position of the outside wall when the ink 
supplying member 600 is mounted. The projections 1800, 1801 are arranged 
along the curve L.sub.4, which give sufficient strength and positional 
precision against the weight of the construction of tip portion of the 
head IJH. The tip collar 2700 of the ink tank IT is inserted to the hole 
of the front plate 4000 of the carriage, to meet abnormality such as 
extreme displacement of the ink tank. The stopper 2101 against slipping 
from the carriage 16 is provided to fit a bar (not shown in the drawing) 
of the carriage HC, and is a protecting member for maintaining the mounted 
state when the cartridge IJC comes under the bar as described later at the 
position where cartridge IJC had been mounted and receives a vertical 
force to displace it from the determined position. 
The unit IJU is fitted up to the ink tank IT, and then covered with the 
cover member 800 to enclose the unit IJU except the bottom opening 
portion. In the ink-jet cartridge IJC, however, the bottom opening for 
mounting on the carriage HC comes close to the carriage HC, substantially 
forming a four-side-enclosed space. Although the enclosed space serves 
effectively for thermal insulation for heat generated by the head IJH, 
slight temperature elevation will occur after a long period of operation. 
As the counter-measure thereto in this example, a slit 1700 is provided 
which has a smaller width than the enclosed space to prevent temperature 
elevation and simultaneously make the temperature distribution throughout 
the the entire unit IJU uniform, independent of the environment. 
After the ink-jet cartridge IJC is assembled, the ink is supplied to the 
ink supplying tank 600 from the interior of the cartridge through the ink 
supply inlet 1200, the hole 320 on the support 300, and an introducing 
opening at the back side of the ink supplying tank 600, and then flows 
into the common liquid chamber through an outlet hole, a suitable supply 
tube, and the ink inlet 1500 on the cover plate 1300. The ink supply path 
is ensured by sealing the connecting portion of the ink path with packings 
made of silicone rubber, butyl rubber or the like. 
In this example, the cover plate 1300 is made of an ink-resistant resin 
such as polysulfone, polyether sulfone, polyphenylene oxide, and 
polypropylene, and is formed integrally with the orifice plate portion 
400. 
As described above, the ink supplying member 600, the cover plate 1300 
with-the orifice plate 400, and the main body of the ink tank 1000 are 
respectively molded as an integrated part, which makes the assemblage 
precise and is effective in high-quality mass production. The number of 
parts is less than conventional recording heads, so that the intended 
superior characteristics are surely obtained. 
In this example, as shown in FIGS. 2 to 4, after the head is assembled as 
above, the upper face 603 of the ink-supplying member 600 forms a slit S 
with the end 4008 of the roof having the slit 1700 of the ink tank IT as 
shown in FIG. 3, and the lower face 604 thereof forms a slit (not shown in 
the drawing) similar to the above slit S with the head side end portion 
4011 of a thin plate bonded to the lower cover 800 of the ink tank IT. 
These slits accelerate the heat release from the aforementioned opening 
1700, and will prevent any direct action of force to the ink-supplying 
member 600 or the ink-jet unit IJU if undesired force is given to the ink 
tank IT. 
(iii) Fitting of Ink-Jet Cartridge IJC to Carriage HC 
In FIG. 5, the platen roller 5000 guides the recording medium P (e.g., 
recording paper) from the back side of the plane of the drawing to the 
front side thereof. The carriage HC, which moves along the length 
direction of the platen roller 5000, is provided with a front plate 4000 
(2 mm thick) in the front side of the carriage 16, namely the platen 
roller side, a flexible plate 4005 having pads 2011 corresponding to the 
pads 201 on the wiring plate 200, a supporting plate 4003 for electric 
connection for holding rubber pad sheet 4007 exhibiting elasticity to 
press the pads 2011 from the backside, and a positioning hook 4001 for 
fixing the ink-jet cartridge IJC at a predetermined recording position. 
The front plate 4000 has two projected face 4010 for positioning in 
correspondence with the projection 2500, 2600 of the support 300 of the 
cartridge, and receives a force perpendicular to the projected face 4010 
after the cartridge is mounted. Therefore, a plurality of strengthening 
ribs (not shown in the drawing) are provided on the platen roller side of 
the front plate. These ribs also form head-protecting projection portions 
which project slightly (about 0.1 mm) from the front face position L5 of 
the mounted ink-jet cartridge IJC toward the platen roller. The supporting 
plate 4003 for electric connection has a plurality of strengthening ribs 
4004 which are directed vertical to the above ribs. The projection length 
of these ribs decreases from the one at the platen side to the one at the 
hook 4001 side, whereby the cartridge is fitted obliquely as shown in the 
drawing. The supporting plate 4003 has a flexible sheet 4005 provided with 
pads 2011 corresponding to the pads 201 on the wiring base board 200 of 
the ink cartridge 11, and a rubber pad sheet 4007 with botches providing 
elasticity for pressing the flexible sheet to each of pads 2011 from the 
back side. For stabilizing the electric contact between the pads 201 and 
the pads 2011, the supporting plate 4003 has a positioning face 4006 at 
the hook 4001 side which exerts a force to the ink-jet cartridge in a 
direction reverse to the exertion direction of the above projected face 
4010. Pad contact is made therebetween, and the deformation of the botches 
of the rubber sheet 4007 corresponding to the pads 2011 is decided 
definitely. When the cartridge IJC is fixed at the recording position, the 
positioning face is in contact with the surface of the wiring base board 
200. Since the pads 201 are distributed symmetrically regarding the 
aforementioned line L.sub.1 the rubber pad sheet 4007 having botches 
deformed uniformly, and the contact pressure between the pads 2011 and the 
pads 201 is stabilized. In this example, the distribution of the pads 201 
is in two lines vertically and in two lines laterally. 
The hook 4001 has a long slit for engaging with a fixing axis 4009. After 
counterclockwise rotational movement from the position shown in the 
drawing, through the space provided, the ink-jet cartridge IJC is 
positioned relative to the carriage HC by movement to the left along the 
length direction of the platen roller 5000. The movement of the hook 4001 
may be made in any manner, but preferably made by a lever manipulation. In 
any way, in the rotational movement of the hook 4001, the cartridge IJC 
moves toward the platen roller side to the point where the positioning 
projections 2500, 2600 can come into contact with the positioning face 
4010 of the front plate. By the lefthand movement of the hook 4001, with 
hook face 4002 at 90.degree. being kept in close contact with the 
90.degree. face of the claw 2100 of the cartridge IJC, the cartridge IJC 
rotates horizontally around the contact region of the positioning face 
2500 with the positioning face 4010, finally causing the contact of pads 
201 with pads 2011. When the hook 4001 is to be held at the predetermined 
position, or a fixing position, the complete contact of the pads 201 with 
the pads 2011, complete facial contact of positioning face 2500 with the 
positioning face 4010, and facial contact of the 90.degree. face of hook 
4002 with the 90.degree. face of the claw are realized, thus finishing the 
mounting of the cartridge IJC on the carriage. 
(iv) Outline of Main Body of Apparatus 
An ink-jet recording apparatus IJRA applicable in the present invention is 
shown schematically in FIG. 6. A leading screw 5005 having a spiral groove 
5004 is driven to rotate in normal or reversed direction by interlocking 
with a driving motor 5013 through driving force-transmitting gears 5011 
and 5009. The carriage HC is engaged with the spiral groove 5004 by a pin 
(not shown in the drawing), and is guided slidably to move in the 
direction shown by arrow marks a and b reciprocally. A paper-pressing 
plate 5002 pushes and presses a recording medium (or paper) toward the 
platen roller 5000 throughout the moving direction of the carriage. 
Photocouplers 5007, 5008 form a home-position-detecting means to confirm 
the position of the lever 5006 of the carriage 16 to be within the region 
and to control the driving direction, etc. of the motor 5013. A capping 
member 5022 for capping the front face of the recording head is supported 
by the supporting member 5016 and has a suction means 5015 for recovering 
the suction of the recording head through an opening 5023 in the cap. The 
main-body-supporting plate 5018 has a supporting plate 5019. A cleaning 
blade 5017 supported slidably by the supporting plate 5019 is driven 
forward and backward. The shape of the cleaning blade is not limited to 
the one shown in the drawing, but a variety of known shape of blades are 
applicable in the present example. The lever 5021 is provided to start the 
suction-recovery operation, moving with the movement of a cam 5020 
engaging with the carriage. The movement is caused by the driving force of 
the driving motor transmitted by a known transmitting means such as a 
shift clutch. 
The respective operations of capping, cleaning, and suction recovery are 
conducted at the corresponding site by action of the leading screw 5005 
when the carriage comes to the home position. Any of the operations are 
applicable in the present invention, if the operations are conducted at a 
known timing and in a desired manner. The respective constructions are 
superior separately or combination, and are preferred in the present 
invention. 
The present invention relating technically to the constructions shown in 
FIGS. 2 to 6 is explained below by reference to FIGS. 1A and 1B, and FIGS. 
7 to 9. 
FIG. 7 is an enlarged sectional view of the combination of an integrally 
molded member comprising an orifice plate 400 and a grooved cover plate 
1300, and a heater board 100 shown in FIG. 2. The ejection outlets 4 are 
formed at the portion 41 by piercing the orifice plate with excimer laser. 
A heater portion 91 of an electrothermal transducer as the thermal energy 
generating element generates thermal energy for ejecting ink. Input of 
pulse signals to heaters 91 in accordance with inputted data causes 
bubbling of ink on the heater, and by this energy the ink is ejected from 
the orifices 41 in liquid droplets. The droplets shoot against a paper 
surface 0.5 to 1.0 mm away from the orifices 41, thus achieving recording 
in accordance with the inputted data. 
In this example, the grooved cover plate 1300 and the orifice plate 400 
placed vertically at the end of the cover plate are molded integrally by 
casting or a like method. A water repellent in a molten state is applied 
thereon to form a solid layer of the water repellent. Then a laser beam is 
projected to the portion 41 from the backside opposite to the ejection 
direction at a predetermined angle .theta. of from 5.degree. to 10.degree. 
to form the ejection outlet 4. The drawing shows a state before the 
formation of the ejection outlet. 
In this arrangement, the face of the orifice plate comprises three planes 
forming steps in gentle slope in consideration of the strength of the 
orifice plate and sure cleaning by wiping. 
The preferred material for the integral molding of the grooved cover plate 
1300 with the orifice plate 400 includes thermoplastic resins such as 
polyether-ether-ketones, polyimides, polysulfones, and the like in view of 
the material cost and the resistance to ink. In this example, a 
polysulfone is used which is deformed less even at a high temperature. 
In the constitution like this example, a decomposition product is observed 
to be produced in the process of formation of orifice 41 by piercing with 
a laser, and the product was confirmed to adhere around the ejection 
outlet after the outlet formation. FIGS. 1A and 1B illustrate the state of 
the face 1 (hereinafter referred to as a "face plane") where the ejection 
outlets 4 are formed. FIG. 1A illustrates the orifice plate 400 viewed 
from the face plane side, and FIG. 1B illustrates it viewed from a lateral 
side. As shown in the drawings, the decomposition product 2 which is 
formed in the ejection outlet formation adheres in a layer formed around 
the ejection outlet 4 on the layer of the water repellent 3. As a result 
of analysis, the product 2 was determined to be a mixture of carbon and 
the water repellent. The formation state of the mixture was found to 
depend on the power of the laser and on heat treatment after the ejection 
outlet formation. 
The product around the ejection outlet increases the adhesion strength of 
the seal tape there to prevent the ink leakage. Specific examples of the 
present invention are shown below. 
Example 1 
On the ejection face 1, a water repellent, Sitop (trade name, made by Asahi 
Glass Co., Ltd.) was applied. The orifice plate was subjected to orifice 
formation processing by use of excimer laser (output power: 1 J/cm.sup.2 
pulse) from the face opposite to the ejection face 1. After the orifice 
formation, the orifice plate was heat treated in an oven at 150.degree. C. 
for 3 hours. 
With this orifice plate 400, an ink-jet cartridge was prepared as shown in 
FIG. 9. 
Then the ejection face was scanned with Rubisel (trade name, made by Toyo 
Polymer Co.) as a cleaning member 5017 in a direction shown by the arrow 
mark in FIG. 8 to remove ink and dust on the ejection face. Subsequently, 
a seal tape 5 (comprising a support made of PET (27 mm thick) and an 
acrylic adhesive (25 .mu.m)) was sticked onto the ejection face. 
Example 2 
An ink cartridge was prepared in the same manner as in Example 1 except 
that Defennsa (trade name, made by Dainippon Ink and Chemicals, Inc.) was 
used as the water repellent. 
Comparative Example 1 
An ink cartridge was prepared in the same manner as in Example 1 except 
that Kp801 (trade name, made by Shin-Etsu Chemical Co,. Ltd.) was used as 
the water repellent. 
The effect of the present invention was evaluated by measuring the peel 
strength of the tape and by the minimum pressure at the air communication 
outlet 1401 to cause leakage of ink from the ejection outlet. 
For evaluation of the effect of the present invention, comparison samples 
were prepared in which the water repellency treatment and the orifice 
formation processing were conducted in the reverse order for both the 
Examples and the Comparative Example (the comparative example not having 
the "product 2" on the ejection face). 
As the results show in Table 1, ink leakage was reduced with little change 
of the peel strength in Examples 1 and 2, while the ink leakage was not 
improved in Comparative Example 1. The reason is that the water repellent 
Kp801 employed in Comparative Example has a hardness of not higher than 
the pencil hardness 6B (not measureable), and the product 2 had been 
removed in an ejection face cleaning step before the application of the 
tape. The absence of the product 2 was confirmed by observation of the 
ejection face.) 
TABLE 1 
______________________________________ 
Minimum pressure 
Peel 
to cause ink leakage 
strength 
______________________________________ 
Example 1 Improved Changed little 
Example 2 Improved Changed little 
Comparative Not changed Not changed 
example 1 
______________________________________ 
As described above, the adhesiveness of the tape is strengthened only at 
the vicinity of the ejection outlet by the presence of the product 
adhering on the ejection face, whereby the ink leakage is prevented with 
little increase in the peel strength required to remove the tape. 
This increases the freedom in design of the orifice plate thickness, the 
fixing method, and so forth, enabling developement of a new head having 
more desirable ejection properties, and lowering the production cost. 
Furthermore, since no strong force is required to peel the tape, the 
inconveniences of tape peeling, such as accidental dismounting of the head 
and soiling by scattering of ink, can be avoided.