Detachable ink jet unit and ink jet apparatus

An ink jet head for ejecting ink, has an ink ejecting portion having an ink ejecting port formed thereon so as to eject ink through the ink ejecting port, a positioning portion for definitely determining the position of the ink jet head relative to an apparatus using the ink jet head when the ink jet head is fitted to the apparatus, an ink supplying portion adapted to be connected an ink supplying unit while ink is supplied to the ink jet head, and an electric connecting portion adapted to be electrically connected to an electric connecting portion on the apparatus side so as to send and receive signals. The positioning portion, the ink supplying portion and the electric connecting portion are disposed on a different surface from a surface on which the ink ejecting portion is disposed and at least one of the electric portion and the ink supplying portion is disposed on an opposite side surface to a surface on which the positioning portion is disposed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an ink jet apparatus, and more 
particularly, to an ink jet recording apparatus employable for a printer, 
a facsimile, a copying machine or the like. 
In a description below, a term. "recording" is used as a word which also 
includes "printing" of an image or the like on a paper, a texture or the 
like. 
2. Description of the Related Art 
In contrast with other types of printing systems, an ink jet printing 
system has advantages that a small-sized printing apparatus having a light 
weight can easily be realized on the actual machine basis, it generates 
little noise, and moreover, a printing operation can be performed with the 
apparatus using plain papers. For this reason, in recent years, most of 
low cost printers are designed and constructed to operate in accordance 
with a principle of the ink jet printing system. With a bubble jet 
printing system, i.e., one type of the ink jet printing system, a number 
of ink ejecting ports formed on an ink jet head can easily be arranged at 
a high density, and an ink jet printing apparatus having the bubble jet 
printing system employed therefor consumes a small quantity of electricity 
during each printing operation. In view of the foregoing fact, many 
printers each having the bubble jet printing system employed therefor are 
shipped to a commercial market. 
At present, the ink jet printing system is classified into two types 
depending on a manner of supplying ink. 
A first type of them is such that an ink jet head is mounted on a carriage, 
and a large volume ink tank is arranged at a predetermined position on the 
apparatus side so that ink is supplied to an ink jet head via an ink tube. 
In the case that the above-mentioned type ink jet printing system is 
employed, each printing operation can be achieved at a very low running 
cost. However, since it is required that the running life of an ink jet 
head is substantially equal to or longer than that of an ink jet printing 
apparatus having the ink jet head mounted thereon, the structure of the 
ink jet head, associated component and materials employed therefor should 
be improved, resulting in a cost of the ink jet printing apparatus being 
unavoidably increased. 
Secondly, there is known an ink jet printing system in which an ink jet 
unit consisting of an ink tank and an ink jet head is detachably mounted 
on a carriage. 
In the case that the second-mentioned type ink jet printing system is 
employed, small extension of the ink tube is required, and an ink tank 
replacing operation can easily be achieved, and moreover, an ink jet 
printing apparatus having this ink jet printing system employed therefor 
can be constructed with small dimensions. However, when ink contained in 
the ink tank is consumed, the empty ink tank is replaced with a new one 
together with an ink jet head, resulting in a running cost of the ink jet 
printing apparatus being likewise increased. Especially, since the ink jet 
head having a running life at least until the ink contained in the ink 
tank is completely consumed should uselessly be wasted, the foregoing ink 
jet printing system is not acceptable from the viewpoint of ecology or a 
similar factor. 
To eliminate the problems inherent to the last-mentioned type ink jet 
printing system, a proposal has been made with respect to an ink jet 
printing apparatus wherein an ink jet head and an ink tank are separately 
arranged and they are detachably mounted on a carriage as disclosed in 
Japanese Patent Application Laying-Open No. 4953/1988. The proposed ink 
jet printing apparatus has an advantage that the problem of an increased 
cost of the ink jet printing apparatus can be solved because the ink jet 
head and the ink tank can independently be replaced with new ones. 
In the case that the ink jet unit is detachably mounted on the carriage, it 
is required that correct locating of the ink jet unit (the ink jet head 
and the ink tank) on the carriage and electrical connection between the 
ink jet unit and the main body side of the ink jet printing apparatus for 
transmitting signals to the former from the latter are taken into account. 
To satisfactorily meet the requirement, proposals have been made with 
respect to an improved ink jet printing apparatus as disclosed in Japanese 
Patent Application Laying-open Nos. 204342/1985 and 204343/1985. According 
to each of the prior arts, a plurality of electrical contacts for making 
electrical connection between an ink jet head and the main body side of an 
ink jet printing apparatus are arranged on the upper surface of the ink 
jet head located above an ink ejecting port, and moreover, other 
electrical contacts of the main body side of the ink jet printing 
apparatus are arranged on the carriage corresponding to the 
first-mentioned electrical contacts. To assure that the ink jet unit is 
correctly mounted at a predetermined position on the carriage, the ink jet 
printing apparatus is additionally provided with an engagement member. 
With the ink jet printing apparatus constructed according to each of the 
prior art systems, however, since the ink jet unit is made of the ink jet 
head being integrated with an ink tank, the arrangement of the electrical 
contacts in the above-described manner is not necessarily acceptable in 
the case that modification is made so as to enable the ink tank to be 
separated from the ink jet head. In other words, in the ink jet unit with 
a structure such that the ink jet head and the ink tank are detachable 
from each other, on the ink jet head, there are disposed not only 
electrical contacts and a position determining member but also an ink 
supply portion for receiving ink from the ink tank. Therefore, the number 
of pieces of equipment to be provided for the ink jet head is increased. 
In addition, the arrangement of these pieces of equipment should be 
determined in consideration of an attaching/detaching operation to be 
performed when the ink tank is attached to and detached from the ink jet 
head and the connection structure of an ink path for supplying ink to the 
ink jet head. As a result, in the structure such that the attachment and 
detachment of the ink jet unit is performed relative to the carriage and 
such that the ink jet head and the ink tank which form the ink jet unit 
are detachable from each other, it has been requested that the following 
items are taken into account when the ink jet head and the ink jet unit 
are designed and constructed. 
1) To prevent electrical reliability of the ink jet head from being 
deteriorated due to adhesive deposition of ink and paper particles on the 
ink jet head. 
2) To improve a positional accuracy of the ink jet head when the ink jet 
head and the ink tank are mounted on the carriage. 
3) To assure that the empty ink tank is easily replaced with a new one 
after the ink contained in it is consumed. 
4) To improve an accuracy of positional relation among plurality of ink jet 
heads when a color printing operation is performed using the plurality of 
ink jet heads. 
5) To easily produce ink jet heads, ink tanks and associated components. 
SUMMARY OF THE INVENTION 
The present invention has been made in consideration of the aforementioned 
background. 
An object of the present invention is to provide an ink jet head, an ink 
jet unit and an ink jet apparatus which can be produced at an inexpensive 
cost with small dimensions and which assures that a high quality of image 
can be printed on a sheet of paper with high reliability and high 
operability. 
Another object of the present invention is to provide an ink jet head, an 
ink jet unit and an ink jet apparatus with which an ink tank can be 
attached to and detached from the ink jet head mounted on the ink jet 
apparatus with high operability. 
A further object of the present invention is to provide an ink jet head, 
ink jet unit and an ink jet apparatus which can practically be used at a 
low running cost and which are employable especially for a colored ink 
ejecting type printing apparatus. 
A further object of the present invention is to provide an ink jet head, 
and an ink jet unit which assure that an ink ejecting portion is disposed 
on a portion of the ink jet head which portion differs from a portion on 
which an ink supply portion or an electric connecting portion is disposed 
so that reliability of the ink jet unit is increased without any 
interference with the ink supplying portion and the electric connecting 
portion but also without any deterioration of a function of each of the 
ink supplying portion and the electric connecting portion. 
In the first aspect of the present invention, there is provided an ink jet 
head for ejecting ink, comprising: 
an ink ejecting portion having an ink ejecting port formed thereon so as to 
eject ink through the ink ejecting port; 
a positioning portion for definitely determining the position of the ink 
jet head relative to an apparatus using the ink jet head when the ink jet 
head is fitted to the apparatus; 
an ink supplying portion adapted to be connected to ink supplying means 
while ink is supplied to the ink jet head; and 
an electric connecting portion adapted to be electrically connected to an 
electric connecting portion on the apparatus side so as to send and 
receive signals; 
wherein the positioning portion, the ink supplying portion and the electric 
connecting portion are disposed on a different surface from a surface on 
which the ink ejecting portion and at least one of the electric portion 
and the ink supplying portion is disposed on an opposite side surface to a 
surface on which the positioning portion is disposed. 
In the second aspect of the present invention, there is provided an ink jet 
unit comprising: 
an ink ejecting portion having an ink ejecting port formed thereon so as to 
eject ink through the ink ejecting port; 
a positioning portion for definitely determining the position of the ink 
jet head relative to an apparatus using the ink jet head when the ink jet 
head is fitted to the apparatus; 
an ink supplying portion adapted to be connected to ink supplying means 
while ink is supplied to the ink jet head; and 
an electric connecting portion adapted to be electrically connected to an 
electric connecting portion on the apparatus side so as to send and 
receive signals; 
the ink jet head including a plurality of outer surfaces which are 
individually assigned to the ink ejecting portion, the locating portion, 
the ink supplying portion and the electric connecting portion each of 
which is separately disposed on one of the outer surfaces, and 
an ink tank which is detachably connected to the ink jet head and which 
stores ink to be supplied to the ink jet head through the ink supplying 
portion. 
In the third aspect of the present invention, there is provided an ink jet 
apparatus for ejecting ink to a medium so as to allow the ink to adhere to 
the medium, comprising: 
an ink jet head comprising an ink ejecting portion having an ink ejecting 
port formed thereon so as to eject ink through the ink ejecting port; 
a positioning portion for definitely determining the position of the ink 
jet head relative to an apparatus using the ink jet head when the ink jet 
head is fitted to the apparatus; 
an ink supplying portion adapted to be connected to ink supplying means 
while ink is supplied to the ink jet head; and 
an electric connecting portion adapted to be electrically connected to an 
electric connecting portion on the apparatus side so as to send and 
receive signals; 
wherein the positioning portion, the ink supplying portion and the electric 
connecting portion are disposed on a different surface from a surface on 
which the ink ejecting portion and at least one of the electric portion 
and the ink supplying portion is disposed on an opposite side surface to a 
surface on which the positioning portion is disposed and being adapted to 
be detachably fitted to the ink jet apparatus; and 
a carriage on which the ink jet head is detachably mounted and which is 
provided for moving. 
The above and other objects, effects, features and advantages of the 
present invention will become more apparent from the following description 
of embodiments thereof taken in conjunction with the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be described in detail hereinafter with 
reference to the accompanying drawings which illustrate several preferred 
embodiments thereof. 
To facilitate understanding of the present invention, the fundamental 
structure of an ink jet head (hereinafter also referred as a printing 
head) to which the present invention is applied will be described below 
prior to description of the preferred embodiments of the present 
invention. 
According to the present invention, an ink jet unit includes an ink tank 
and an ink jet head both of which are detachably mounted on a carriage and 
both of which are detachable from each other, and the ink jet head 
includes the following main four functional portions on respective 
surfaces thereof. 
(A) a portion for receiving a series of electric signals from the main body 
side of an ink jet apparatus (hereinafter referred to simply as an 
electric connecting portion), 
(B) a portion for receiving an ink from the ink tank (hereinafter referred 
to simply as an ink supplying portion), 
(C) a portion for ejecting the ink (hereinafter referred to simply as an 
ink ejecting portion), 
(D) a portion for correctly positioning the ink jet head relative to the 
carriage (hereinafter referred to simply as a positioning portion). 
In connection with the practical construction of these four main functional 
portions, since high reliability of the ink jet head, a high quality of 
each image and easy replacement of each used ink jet head and each empty 
ink tank with new ones are highly required, it is desirable that the 
following structural conditions are taken into account when the ink jet 
head is designed and constructed. 
(1) In the case that the ink supplying portion or the electric connecting 
portion is additionally arranged on the exact surface having the ink 
ejecting portion arranged thereon, there arises a necessity for enlarging 
the space for arranging these portions in the ink ejecting direction, 
causing the distance between the surface having the ink ejecting portion 
disposed thereon and the surface of a printing medium such as a sheet of 
printing paper or the like to be enlarged. Consequently, the deflection of 
ejected ink is increased, causing a quality of image to be unavoidably 
degraded. 
(2) The ink tank is frequently replaced with another one compared with 
replacement of the ink jet head with another one, therefore, a force in an 
ink tank attaching/detaching direction is applied to the ink jet head 
during an attaching/detaching operation of the ink tank to/from the ink 
jet head. In the case that the ink jet head is displaced under the 
influence of the force appearing when the ink tank is attached to or 
detached from the ink jet head, the position of the ink jet head can not 
exactly be determined. For this reason, each ejected ink droplet ejected 
from the ink jet head can not exactly be shot to a predetermined position, 
resulting in a quality of image being degraded. 
(3) Ink mist and paper particles are deposited on the ink ejecting portion 
of the ink jet head which confronts a printing medium, causing the ink jet 
head to be contaminated with them. For this reason, in the case that the 
positioning portion and the ink supplying portion of the ink jet head are 
additionally arranged on the surface on which the ink ejecting portion is 
disposed, there arise malfunctions that the ink ejecting position is 
dislocated from the original position, and moreover, a filter disposed at 
an ink supplying path is clogged with foreign material. Therefore, it is 
preferable that the positioning portion and the ink supply portion are 
arranged on another surface than the surface on which the ink ejecting 
portion is disposed. Especially, in the case that the electric connecting 
portion is additionally disposed on the ink ejecting portion, there 
occasionally arise malfunctions that incorrect electrical connection or 
short-circuit occurs due to the electrical conductivity of the ink induced 
by the deposition of the foreign material, and ink is incorrectly ejected 
or ejected ink droplets are erroneously shot to locations having no image 
signal transmitted thereto, resulting in incorrect dots being printed on 
the printing medium. 
FIG. 1 shows an ink jet head, an ink tank and a structure for attaching 
them Lo a carriage of an embodiment of the present invention which take 
into account of the above-described conditions (1)-(3). 
In FIG. 1, reference numeral 100 designates an ink jet head, and reference 
numerals 101, 102, 103 and 104 designate an ink ejecting portion, an ink 
supplying portion, an electric connecting portion and a positioning 
portion for positioning the ink jet head to a carriage of the main body of 
an apparatus, which are components of the ink jet head 100. Reference 
numeral 105 designates an ink supplying tube as an ink supplying member 
secured to the ink supplying portion 102 of the ink jet head 100, and 
reference numeral 106 designates an ink tank. When the ink tank 106 is 
fitted to the ink supplying portion 102 of the ink jet head 100 in the 
arrow-marked direction via the ink supplying tube 105, an ink supplying 
path built between the ink tank 106 and the ink supplying portion 102 is 
kept in the liquid tight state with the aid of a sealing member (not 
shown) interposed therebetween, whereby ink is supplied to the ink jet 
head 100 from the ink tank 106 without any occurrence of ink leakage. 
Reference numeral 107 designates a carriage, which is a component of an ink 
jet apparatus, adapted to be slidably displaced along a guide shaft 108 by 
actuating a driving unit (not shown) while carrying the printing head 100 
and the ink tank 106 thereon. In this embodiment, the carriage 107 is 
composed of a head supporting portion 107A for holding the ink ejecting 
portion 101 in the correctly located state on which an ink ejection port 
is disposed, a head fitting portion 107B having three locating holes 118 
formed therethrough so as to allow three locating pins 104A to be inserted 
into the locating holes 118 when the locating portion 104 of the ink jet 
head 100 comes in contact with the front surface of the carriage 107, and 
a connector portion 107C turnably supported on the head fitting portion 
107B via a hinge pin 109 while including a number of electrical contacts 
110 on the inner surface thereof. Reference numeral 111 designates a 
number of electrical contacts constituting an electric connecting portion 
103 of the ink jet head 100 to make electrical connection to the opponent 
electrical contacts 110 on the connector portion 107C. The connector 
portion 107C is turnably displaced in the arrow-marked direction so as to 
allow the front surface of the connector portion 107C including the 
electrical contacts 110 to come in contact with the electric connecting 
portion 103 while the ink jet head 100 is firmly supported by the carriage 
107, so that the main body side of the ink jet apparatus can electrically 
be connected to the ink jet head 100 side. Incidentally, reference numeral 
112 designates a printing medium in the form of a sheet of printing paper 
to be conveyed while facing to the ink ejecting portion 101 of the ink jet 
head 100. 
FIG. 2 schematically shows by way of illustrative view how the ink jet head 
100 is connected to the ink tank 106, the head supporting portion 107A, 
the head fitting portion 107B, and the connector portion 107C of the 
cartridge 107 while each connected state is represented by an arrow-marked 
direction. 
In this embodiment, the electric connecting, the ink supplying, the ink 
ejecting and the positioning portions of the ink jet head described above 
are arranged on the ink jet head so as to satisfy the following 
conditions. 
The portions except the ink ejecting portion are arranged on different 
surfaces from the surface on which the ink ejecting portion is disposed. 
As a result, it is not necessary to enlarge a distance between the ink 
ejecting portion and the recording medium to the extent such that it is 
greater than the minimum distance need for ejecting ink to the recording 
medium so as to perform recording, so that an amount of deflection of an 
ejected ink from the ink jet head is not increased. In addition, according 
to the above-described structure, the electric connecting portion and the 
positioning portion are prevented from being affected by a splashing ink 
or the like, so that a fault in an electric connection produced by wetting 
of ink and a fault in a positioning does not occur. 
In this embodiment, especially, the electric connecting portion, which is 
mostly affected by wetting of ink among the portions, is arranged on the 
opposite side surface to the surface on which the ink ejecting portion is 
arranged, and is arranged above the ink ejecting portion. Therefore, the 
above-described fault in the electric connection by wetting of ink is more 
effectively prevented. The positioning portion is also arranged above the 
ink ejecting portion so as to prevent positioning accuracy effectively 
from being decreased by wetting of ink or contamination. 
In addition, wetting of ink arisen through the ink supplying portion is not 
as serious as that caused by the ink splash at the ink ejecting portion. 
However, according to the present embodiment, latter wetting of ink is 
effectively restricted because the ink supplying portion is arranged on 
the surface which is different from the surfaces on which the electric 
connecting portion and the positioning portion are arranged and especially 
the electric connecting portion is arranged above the ink supplying 
portion. 
Furthermore, in this embodiment, the direction of allowing the ink tank 106 
to be connected to the ink jet head 100 is coincident with the direction 
of allowing the three locating pins 104A on the ink jet head 100 (see FIG. 
1) to be inserted into the opponent three locating pins 118 formed through 
the fitting portion 107B (see FIG. 1). That is, on the ink jet head 100, 
the positioning portion 104 is arranged on the opposite side surface to 
the surface on which the ink supplying portion 102 is arranged. According 
to a arrangement of the respective portions 101-104, when the ink tank 106 
is attached to the ink jet head 100, a pressing force (designated by arrow 
C in FIG. 2) applied to the ink jet head 100 can be received by the 
positioning portion 104 and the fitting portion 107B of the carriage 107, 
so that the positioning of the ink jet head relative to the main body side 
of the ink jet apparatus is not affected by the force when the ink tank is 
attached to the ink jet head. 
In addition to the above-described arrangement of the respective portions 
101-104, as shown in FIG. 2, the ink ejecting portion 101, the ink 
supplying portion 102, the electric connecting portion 103 and the 
locating portion 104 are individually arranged on four different side 
surfaces of the ink jet bead 100, whereby each of these portions 101, 102, 
103 and 104 serves as a specific surface at an attaching operation of the 
ink tank so as to enable it to sufficiently exhibit its own function and 
to raise in operability. 
In addition, there are formed a taper portions 101T as additional structure 
on the neighborhood of the ink ejecting portion, which portions engage 
with the carriage 107 in the main body of the ink jet apparatus. 
Therefore, the direction of allowing the ink tank 106 to be connected to 
the ink jet head 100 is oriented at a right angle relative to the 
direction of allowing of the ink jet head 100 to be connected to the head 
supporting portion 107A in the state that tapered portions 101T of the ink 
ejecting portion 101 are brought in contact with the opponent tapered 
surfaces 107T of the head supporting portion 107A. In addition, the 
direction of allowing the connector portion 107C to be connected to the 
electric connecting portion 103 is coincident with the direction of 
allowing the ink jet head 100 to be engaged with the head supporting 
portion 107A. 
With such construction, when the force identified by an arrow mark C in 
FIG. 2 is applied to the ink jet head 100 at the time of replacing each 
empty ink tank 106 with a new one, there does not arise a malfunction that 
the ink jet head 100 is dislocated because the tapered surfaces 101T of 
the ink ejecting portion 101 are engaged with the opponent tapered 
surfaces 107T of the head supporting portion 107A. At this time, as 
described above, the head fitting portion 107B of the carriage 107 stands 
against the force identified by the C arrow mark in FIG. 2. Especially, 
when the connector portion 107C of the carriage 107 is turnably depressed 
against the ink jet head 100 with the downward orienting force, 
dislocation of the ink jet head 100 from the original position can 
reliably be prevented. 
Furthermore, in this embodiment, since a connecting portion between the ink 
jet head 100 and the ink tank 106, at which portion attaching/detaching 
operation is performed most frequently, is disposed isolutedly from other 
portions on the ink jet head 100 and in the carriage 107, the operation 
for attaching/detaching of the ink tank 106 to/from the ink jet head 100 
can be easily performed. 
Next, an ink jet head and an ink jet unit constructed according to other 
embodiments of the present invention will be described below with 
reference to FIG. 3 to FIG. 7. 
FIG. 3A shows by way of perspective view the structure of an ink jet head 
100 constructed according to a second embodiment of the present invention 
wherein an ink ejecting portion 101 on 10 which the ink ejection port is 
disposed and an ink supplying portion 102 are arranged on the upper and 
lower surfaces of the ink jet head 100, that is, opposite surfaces to each 
other, an electric connecting portion 103 is disposed on the front surface 
of the ink jet head 100 extending at a right angle relative to the ink 
ejecting portion 101 and the ink supplying portion 102, and the 
positioning portion 104 is disposed on the opposite side relative to the 
electric connecting portion 103. FIG. 3B shows by way of illustrative view 
of the structure of an ink jet unit inclusive of the ink jet head 100 
wherein securing of the ink jet head 100 to the carriage 107, electrical 
connection to be made between electrical components, connecting relation 
of an ink tank 106, and connecting directions of respective portions are 
represented. 
According to this embodiment, similar to the aforementioned embodiment, the 
electric connecting portion 103, the ink supply portion 102 and the 
positioning portion 104 are arranged at other surfaces, respectively from 
the surface of the ink jet head on which the ink ejecting portion 101 is 
arranged. Especially, the electric connecting portion 103 and the 
positioning portion 104 are disposed above the ink ejecting portion 101. 
With the above-described structure, there can be obtained the similar 
effect to the aforementioned embodiment which is caused by a positional 
relationship between the ink ejecting portion and other portions. 
The structure of this embodiment especially aims at preventing the ink jet 
head from being dislocated by an attaching operation of the ink jet head 
to the ink jet apparatus. Therefore, the electric connecting portion 103 
to be connected with the connector portion 107C of the carriage 107 is 
arranged, on the opposite side surface to the surface on which the 
positioning portion 104 is arranged, differently from the aforementioned 
embodiment. According to the above-described structure, the ink jet head 
100 can be prevented from being dislocated by force applied during an 
electric connecting operation. The structure shown in FIG. 2 is suitable 
for such an ink jet apparatus that greater force is applied to the ink jet 
head when the ink tank is attached thereto than that applied when the 
electric connecting operation is performed. In the structure shown in 
FIGS. 3A and 3B, the reverse is true. 
The ink ejecting portion 101, the ink supplying portion 102, the electric 
connecting portion 103 and the positioning portion 104 are also arranged 
on different surfaces from each other, so that similar effects to that of 
the aforementioned embodiment can be obtained. In addition, the taper 
portions 101T are formed at the neighborhood of the ink ejecting portion 
101. 
In this embodiment, attaching of the ink tank 106 to arid detaching the 
same from the ink jet head 100 are achieved in the same direction as that 
of allowing the ink jet head 100 to be engaged with a head supporting 
portion 107A. Dislocation of the ink jet head 100 from the original 
position which may occur at the attaching/detaching operation of the ink 
tank 106 can satisfactorily be prevented by fitting two locating pins 104 
into the opponent locating holes 118 and bringing tapered portions 101T of 
the ink jet head 100 in engagement with the opponent tapered portions 107T 
of the head supporting portion 107A. 
In view of positioned relationship between the ink supplying portion and 
other portions and of easiness of attaching/detaching operations of the 
ink tank to/from the ink jet head, the ink supplying portion is disposed 
above other portions. In this case, even if ink leaks from a connected 
portion between the ink jet head and the ink tank, the electric connecting 
portion 103 can be prevented from being affected by wetting of ink because 
a wall 108 is formed on border portion of the ink supplying portion 102. 
FIGS. 4A and 4B show a further embodiment of the present invention. FIG. 4A 
shows by way of perspective view the structure of an ink jet head 100 
constructed according to a third embodiment of the present invention 
wherein an ink supplying portion 102 and an ink ejecting portion 101 are 
disposed on the upper and lower surfaces of the ink jet head 100, that is 
on the opposite surfaces to each other, the positioning portion 104 is 
disposed on the same side as the ink ejecting portion 101 and different 
surface from the surface on which the ink ejecting portion 101 is 
disposed, and a pair of electric connecting portions 103 are disposed on 
the same side as the ink supplying portion 102 and different surfaces from 
the surface on which the ink supplying portion 102 is disposed. FIG. 4B 
shows by way of illustrative view the structure of an ink jet unit 
inclusive of the ink jet head 100 wherein securing of the ink jet head 100 
to the carriage 107, electrical connection to be made between electrical 
components, connecting relationship between the ink tank 106 and the ink 
jet head 100 and connecting directions in which connecting operations 
between the ink jet head and other components are likewise represented. 
Similarly to aforementioned embodiments, the ink supplying portion 102, the 
electric connecting portion 103 and the positioning portion 104 are 
arranged on different surfaces, respectively from the surface on which the 
ink ejecting portion is arranged. In addition, the electric connecting 
portion is arranged on the opposite side surface to the surface on which 
the ink ejecting portion is arranged, and is disposed on the same side as 
and above the ink ejecting portion, so as to be prevented from being 
affected by ink. On the other hand, the positioning portion is arranged on 
the same side surface as the ink ejecting portion. In this case, ink 
splash caused by the ink ejection more occasionally affects the 
positioning portion than that affected in the aforementioned embodiments. 
However, since the positioning portion is disposed above the ink ejecting 
portion, the former is prevented from being affected by leaked ink from 
the latter. 
Furthermore, in this embodiment, the ink supplying portion 102 and the 
electric connecting portion 103 are arranged on the same side surfaces, 
and the positioning portion 104 is arranged on opposite side surface to 
the surfaces, thereby, the direction in which the ink tank 106 is attached 
to the ink jet head 100 coincides with the direction in which the electric 
connector 107C of the carriage 107 is connected to the electric connecting 
portion 103 of the ink jet head 100, and the force applied to the ink jet 
head 100 during a connecting operation at the electric connecting portion 
103 is received by the positioning portion 104 and the fitting portion 
107B, so that the ink jet head 100 is not dislocated from the carriage 
107. 
In last-described embodiment and the following embodiments to be described, 
the respective portions are arranged on different surfaces from each 
other, however, a plurality of portions are arranged on the same side 
surfaces. For this reason, advantage of attaching/detaching operability is 
less than that of the embodiments shown in FIGS. 1-3. 
Next, a further embodiment will be described below. 
A FIG. 5 shows by way of perspective view the structure of an ink jet head 
100 constructed according to a fourth embodiment of the present invention 
wherein the ink ejecting portion 101 and the positioning portion 104 are 
disposed on the sane side and the different surfaces from each other in 
the stepped relationship, the electric connecting portion 103 is disposed 
on the upper surface of the ink jet head 100 located opposite to the ink 
ejecting portion 101, and the ink supplying portion 102 is disposed on one 
of four side surfaces extending at a right angle relative to the electric 
connecting portion 103. FIG. 5B shows by way of side view the direction of 
allowing the ink jet head 100 shown in FIG. 5A to be located on a 
carriage, the direction and electrical signals to be supplied to the ink 
jet head 100 at the time of a printing operation, and the direction of ink 
droplets to be ejected toward a printing paper. 
Similarly to the aforementioned embodiments, the ink ejecting portion is 
arranged on the opposite side surface to the surfaces on which the 
respective portions are arranged respectively. The positional 
relationships between the electric connecting portion and the ink 
supplying portion, and between the electric connecting portion and the ink 
ejecting portion are same as that of the embodiment shown FIGS. 1 and 2 so 
that the same effect can be obtained. The positional relationship between 
the positioning portion, the ink ejecting portion and the electric 
connecting portion, and the effect by the relationship are the same as 
that of the embodiment shown in FIGS. 4A and 4B. 
FIG. 6A shows by way of perspective view the structure of an ink jet head 
100 constructed according to a fifth embodiment of the present invention 
wherein the positioning portion 104 is disposed on one of side surfaces 
extending at a right angle relative to the surface on which an ink 
ejecting portion 101 is disposed and the ink supplying portion 102 and the 
electric connecting portion 103 are disposed on the opposite side surfaces 
to the positioning portion 104 in the stepped state. FIG. 6B shows by way 
of schematic side view the contour of the ink jet head 100 shown in FIG. 
6A wherein the direction of allowing each of the aforementioned portions 
to be connected is likewise represented by arrow marks. 
Similarly to the aforementioned embodiments, the ink ejecting portion 101 
is arranged on the different surface from the surfaces on which other 
portions 102-104 are arranged, respectively. The electric connecting 
portion 103 is disposed above the ink ejecting portion 101 and the ink 
supplying portion 102, and is disposed on the same side surface of the ink 
supplying portion 102. The border portion of the electric connecting 
portion 103 has stepped shape, so that the portion 103 can be prevented 
from being affected by the ink. 
The arrangement of the positioning portion 104, the electric connecting 
portion 103 and the ink supplying portion 102, and the directions in which 
they are connected to the ink jet head 100 are the same as that of the 
embodiment shown in FIG. 4. The same effect can be also obtained. 
Further embodiment will be described below. 
FIG. 7A shows by way of perspective view the structure of an ink jet head 
100 constructed according to a sixth embodiment of the present invention 
wherein the ink ejecting portion 101 and the positioning portion 104 are 
disposed on the lower surface side of the ink jet head 100 in the stepped 
relationship, that is, on the same side as and the different surface from 
the ink jet head 100, and the ink supplying portion 102 is disposed on the 
upper surface of the ink jet head 100 opposite to the ink ejecting portion 
101 and the positioning portion 104, and the electric connecting portion 
103 is disposed on one of four side surfaces of the ink jet head 100 
extending at a right angle relative to the upper and lower surfaces of the 
same. FIG. 7B shows by way of schematic side view the contour of the ink 
jet head 100 wherein the direction of allowing each of the aforementioned 
portions to be connected is likewise represented by arrow marks. 
The arrangement of the ink ejecting portion, the ink supply portion and the 
electric connecting portion, and the effect according to this arrangement 
are same as that of the embodiment shown in FIG. 3. 
The positional relationships between the positioning portion and the ink 
supplying portion or the ink ejecting portion, and the effect of this 
relationship are same as that of the embodiment shown in FIG. 4. 
The ink supplying portion 102 is surrounded by a wall member which projects 
from the ink supplying portion 102 so that the electric connecting portion 
103 and other portions can be prevented from being wetted by ink from the 
ink supplying portion. 
As is apparent from the above description regarding the embodiments 
according to the present invention, at least the ink ejecting portion is 
disposed on the different surface of the ink jet head from the surfaces on 
which other portions are disposed, and at least one of the electric 
connecting portion or the ink supplying portion is disposed on the 
opposite side surface to the surface on which the positioning portion is 
disposed. 
With this construction, there does not arise a malfunction that electric 
contact between electrical components on the electrical connecting portion 
can not correctly be attained due to the deposition of ink mist and paper 
particles during each ink ejecting operation. In addition, the ink jet 
head can easily be located at a predetermined position and the dislocation 
of the ink jet head is restricted. Further, an assembly of the ink jet 
head and the ink tank can easily be attached to and detached from the 
carriage. In the case of a color printing apparatus including a plurality 
of ink jet units arranged on a common carriage in the parallel 
relationship wherein each empty ink tank and each used ink jet head can be 
replaced with new ones as desired, each locating operation can easily be 
achieved with the color printing apparatus. This can contribute to 
substantial improvement of a quality of recorded image. 
Next, an example of an ink jet head constructed according to a modified 
embodiment of the present invention will be described below. 
Specifically, FIG. 8 and FIG. 9 show an ink jet head (hereinafter referred 
to as an IJH) 100 constructed according to a seventh embodiment of the 
present invention. 
The ink jet head 100 includes a base plate 1 having an ink ejecting 
pressure generating element disposed thereon (hereinafter referred to as a 
heater board) and a ceiling plate 2 connected to the base plate 1 so as to 
form a liquid chamber 7 and a liquid path 8. An orifice plate 4 having an 
ink ejecting port 9 formed thereon is integrated with the ceiling plate 2, 
and the ink ejecting port 9 is communicated with the liquid path 8 so as 
to allow ink to be ejected therefrom. 
The heater board 1 is fixedly secured to a support base plate 3 using an 
adhesive. In addition, the ceiling plate 2 is provisionally secured to the 
heater board 1 using an adhesive in such a manner that a heater section 
(not shown) serving as an ink ejecting pressure generating element is 
located in positional alignment with a groove constituting the liquid path 
8, and the grooved orifice plate 4 is disposed in the form of an apron 
ahead of the foremost end surface of the support base plate 3. 
Ink is supplied from an ink supplying member 5 to an ink supply port 2A 
formed through the ceiling plate 2. The ink supplying member 5 includes 
projection rods (not shown). Each of the projection rods is inserted into 
a through hole formed through the support base plate 3 so that it is 
immovably held in the support base plate 3 by thermal caulking. 
Referring to FIG. 9, gaps 10A and 10B between the ink supplying member 5, 
the heater board 1 and the ceiling plate 2 and a gap between the grooved 
orifice plate 4 and the foremost end surface of the support base plate 3 
are filled with an adhesive based sealing material. 
It is acceptable that the gap between the grooved orifice plate 4 and the 
support base plate 3, i.e., a groove 3A therebetween is dimensioned to be 
wide enough to enable the groove 3A to be sufficiently filled with a 
certain sealing material. After completion of the provisional securing of 
the ceiling plate 2 to the heater board 1, the ceiling plate 2 is firmly 
retained by a retaining spring 6. 
It should be noted that it is important that the groove 3A recessed in the 
support base plate 3 forms a space which is communicated with the gap 
between the grooved orifice plate 4 and the support base plate 3. It is 
not desirable that the groove 3A is fully covered with the grooved orifice 
plate 4 or it is isolated from the gaps 10A and 10B. This is because that 
the flow path for the sealing material is shut out with the fully covered 
groove 3A, resulting in good sealing failing to be attained. 
The sealing material is poured through a sealing material pouring port (not 
shown) formed at the upper part of the ink supplying member 5 so that a 
wire bonding portion serving to transmit a series of electrical signals is 
covered with the sealing material, and at the same time, the gaps 10A and 
10B are filled with the same. In addition, the sealing material flows past 
the groove 3A formed in the support base plate 3 so that the gap range 
between the grooved orifice plate 4 and the support base plate 3 is fully 
filled with the sealing material as represented by hatched lines in FIG. 
9. To assure that each gap is filled with the sealing material without any 
possibility that the ink ejecting port 9 is closed with it, it is 
necessary that the sealing material exhibits adequate thixotropy and 
viscosity. If the sealing material exhibits an excessively low viscosity, 
it penetrates into the liquid path 8 and the ink ejecting port 9 formed in 
the ceiling plate 2, causing them to be closed with the sealing material. 
On the contrary, if it exhibits an excessively high viscosity, the 
peripheral part of the grooved orifice plate 4 is not covered with the 
sealing material. 
According to the present invention, the viscosity of the sealing material 
is set to 1,000 to 15,000 cps, more preferably 2,000 to 10,000 cps and 
most preferably 4,000 to 10,000 cps. 
It is required that the sealing material exhibits an excellent property of 
adhesiveness to the heater board 1 made of a silicon wafer, the support 
base plate 3 be made of a metallic material, the base plate 2, the grooved 
ceiling plate 4 and the ink supplying member 5 each be molded of a 
synthetic resin. In addition, to assure that a plurality of components 
each made of a different kind of material having a different thermal 
expansion coefficient are connected to each other, it is necessary that a 
soft material capable of absorbing a difference of the thermal expansion 
coefficients among these different materials attributable to variation of 
the environmental temperature, i.e., a sealing material exhibiting a 
hardness of JIS Standard A100 or less is employed for the purpose of 
connecting the associated components to each other. 
On the other hand, since the sealing material serves to cover a wire 
bonding portion 10C therewith for the purpose of protection, it is 
necessary that a material which does not corrode an aluminum wire bonding 
portion and an aluminum electrode is employed for the sealing material. To 
assure that the electrode and the wire bonding portion are not corroded at 
all, it is preferable that a concentration of ions of impurities involved 
in the sealing material such as Cl.sup.-, Na.sup.+ or the like is set to 
30 ppm or less. 
Since the sealing material is locally brought in contact with the ink, it 
is required that it has excellent properties in respect of ink-resisting 
capability, solvent-resisting capability and alkali-resisting capability. 
Additionally, it is required that it exhibits low permeability against 
oxygen, nitrogen and steam. 
Next, a process of assembling the aforementioned essential components 
constituting the ink jet head together will be described below with 
reference to FIG. 10. 
In FIG. 10, reference numeral 1A designates a wiring board. The wiring 
board 1A includes a plurality of electrothermal converting elements (each 
serving as an ejecting heater) and two electricity feeding aluminum wires 
formed on a silicon substrate by employing a film forming process. In 
addition, the wiring board 1A includes a heater board 1 and a pad (not 
shown) located at the end of each wire extending from the heater board 1 
to receive a series of signals from the main body side of an ink jet 
apparatus (not shown), and wires extending from the heater board 1 are 
connected to the opponent wires extending from the wiring board 1A via, 
e.g., a wire bonding portion). 
Reference numeral 2 designates a ceiling plate. The ceiling plate 2 
includes an ink receiving port 2A for receiving the ink supplied from an 
ink tank (not shown) and then delivering it to a common liquid chamber 
therethrough. A grooved orifice plate 4 having a plurality of ejecting 
ports 9 formed thereon corresponding to a plurality of ink paths 8 is 
integrated with the ceiling plate 2. It is preferable that the integrated 
assembly consisting of the ceiling plate 2 and the grooved orifice plate 4 
is molded of a polysulfone resin. Alternatively, it may be molded of any 
other kind of synthetic resin preferably employable for the purpose of ink 
ejection. 
Reference numeral 3 designates a support base plate made of a metallic 
material to support the wiring base plate 1A from below. Reference numeral 
6 designates a retaining spring having a substantially M-shape contour. 
The common liquid chamber is slightly resiliently squeezed by the central 
part of the retaining spring 6 corresponding to the central part of the 
substantially M-shaped contour, and moreover, a part of the liquid paths 
8, preferably, the range of the ceiling plate 2 in the vicinity of the 
ejection ports 9 is slightly resiliently squeezed by an apron portion 6A 
of the retaining spring 6. Since both the foot portions of the retaining 
spring 6 vertically extend through holes 3A of the heater board 1 so as to 
allow the ceiling plate 2 to be secured to the heater board 1 while the 
heater board 1 is clamped between the ceiling plate 2 and the support base 
plate 3, the ceiling plate 2 is firmly held on the heater board 1 by the 
resilient force of the retaining spring 6. An ink supplying member 5 
includes an ink introduction tube 5A communicated with an ink supplying 
tube 105, and the ink introduction tube 5A is held in the cantilever-like 
fashion while the ink supplying tube 105 serves as a stationary side. To 
assure that a capillary phenomenon appears in the region between the 
stationary side of the ink introduction tube SA and the ink supplying tube 
105, a sealing ball (not shown) is inserted in the foregoing region. In 
addition, reference numeral 7 designate a filter disposed on the inlet 
side of the ink supplying tube 105. 
Since the ink supplying member 5 is molded of a synthetic resin by 
employing an injection molding process, it can be produced not only at an 
inexpensive cost but also at a high accuracy. Additionally, since the ink 
introduction tube 5A is brought in close contact with the ink receiving 
port 2A of the ceiling plate 2 by the elastic force of the ink 
introduction tube 5A designed in the cantilever-like contour, the close 
contact state of the ink introduction tube 5A relative to the ink 
receiving port 2A of the ceiling plate 2 can stably be maintained also in 
the case that a number of ink jet heads are produced on a mass production 
line. In this embodiment, the completely communicated state can be 
obtained merely by pouring a sealing adhesive from the ink supplying 
member 5 side while the foregoing close contact state is maintained. It 
should be noted that fixing of the ink supplying member 5 to the support 
base plate 3 can simply be achieved by fitting a plurality of pins (not 
shown) projecting from the lower surface of the ink supplying member 5 
into the corresponding holes formed through the support base plate 3 and 
then thermally fusing a part of each pin projected from the lower surface 
of the support base plate 3 to weld the pins to the support base plate 3. 
Next, an example of the case that the present invention is applied to a 
plurality of ink jet heads, i.e., the case that a plurality of ink jet 
heads are assembled together as an integrated unit and the corresponding 
ink tanks are attached to and detached from the integrated unit to 
constitute an ink head unit (hereinafter referred to as a head device) 
will be described below. 
FIG. 11 to FIG. 13 show a head device of the foregoing type constructed 
according to an eighth embodiment of the present invention. In this 
embodiment, four ink jet heads 100A, 100B, 100C and 100D for ejecting four 
kinds of inks each having a different color are held in a unit frame 200 
in the fitted state. Otherwise, in the case that the ink jet heads 100A, 
100B, 100C and 100D contain a single kind of ink, a recording operation 
can be performed at a high speed by simultaneously ejecting the ink from 
the respective ink jet heads 100A, 100B, 100C and 100D. At any rate, it 
goes without saying that it is necessary that they are held in the unit 
frame 200 while maintaining a high accuracy relative to each other. 
As shown in FIG. 11, the unit frame 200 includes two outer frames 201 and 
three inner partition plates 202 to define four unit holding portions 203. 
In the shown case, the ink jet heads 100A, 100B, 100C and 100D are fitted 
into the unit holding portions 203 in the arrow-marked direction while 
each ink ejecting portion 101 is oriented in the downward direction. 
Reference numeral 214 designates a plurality of color mixing preventive 
members each made of a porous material. Each color mixing preventive 
member 214 is disposed between adjacent ink jet heads in order to prevent 
an ink received in one ink jet head while having a different color from 
being delivered to the ink ejecting surface of the adjacent ink jet head 
when the ink ejecting surface is wiped by actuating a wiper at the time of 
a color printing operation. 
FIG. 12 shows by way of perspective view a step of assembling the 
aforementioned components together to build a single head device 210 after 
the ink jet heads 100A, 100B, 100C and 100D are fitted into the 
corresponding unit holding portions 203 as shown in FIG. 11. Here, 
reference numeral 204 designates a connector plate including an electrical 
connecting portion 103 having a plurality of electrical contacts 111 
formed on the upper surface thereof. A plurality of connector pins 205A, 
205B, 205C and 205D for connecting the electrical contacts 111 to a 
plurality of contacts (not shown) disposed on the ink jet heads 100A, 
100B, 100C and 100D are arranged on the lower surface side of the 
connector plate 204. Reference numerals 204A designates a fixing arm, and 
reference numeral 204B designates a locating pin. The fixing arms 204A and 
the locating pins 204B are projected downward from the opposite ends of 
the connector plate 204 toward fixing grooves 200A and pin holes 200B 
formed on the unit frame 200. In addition, reference numeral 204C 
designates two locating holes, respectively, which serve to locate the 
assembled head device 210 at a predetermined position on a carriage. 
Reference numeral 206 designates a cover member for protecting the 
components received in the head device 210 from damage or injury. Four 
holes 206A are formed through the cover member 206 so as to allow ink 
supplying ports 105 of the ink jet heads 100A, 100B, 100C and 100D to be 
inserted therethrough. Fixing arms 206B projecting from the opposite ends 
of the cover plate 206 are fitted into fixing grooves 200B on the unit 
frame 200. FIG. 13 shows by way of perspective view the structure of the 
head device 210 to be assembled with the ink tanks 106A, 106B, 106C and 
106D in order to build an ink jet unit. The ink tanks 106A, 106B, 106C and 
106D are fitted to the corresponding ink jet heads received in the head 
device 210 via ink supplying ports 105. When inks contained in the ink 
tanks 106A, 106B, 106C and 106D are consumed, they are replaced with new 
ones. 
FIG. 14 shows by way of perspective view the structure of an ink jet 
printing apparatus constructed according to a ninth embodiment of the 
present invention wherein each printing operation is performed with the 
ink jet printing apparatus while the head device 210 shown in FIG. 13 is 
mounted on a carriage 107. 
Reference numeral 301 designates a lead screw threadably engaged with a 
part of the carriage 107 to displace the latter along a printing sheet 
112, reference numeral 302 designates a driving motor for rotationally 
driving the lead screw 301, reference numeral 303 designates a pair of 
gears for transmitting the driving power of the driving motor 302 to the 
lead screw 301 via the gears 303, reference numeral 304 designates 
photo-couplers for detecting the carriage 107 when the latter is displaced 
in the vicinity of a home position, and reference numeral 305 designates a 
lever projected from the carriage 107 side to open or shut out a light 
path for the photo-couplers 304. With this construction, when the carriage 
107 is displaced to the position operatively associated with the 
photo-couplers 304, this is detected by the photo-couplers 304 in order to 
shift the rotation of the driving motor 302 in the normal direction to the 
rotation of the same in the reverse direction, and vice versa. 
On the other hand, the printing sheet 112 is thrust against a platen 307 
via a retaining plate 306 by activating a sheet feeding unit (not shown) 
so that it is fed in the forward direction via the platen 307 every time a 
printing operation is achieved by the head device 210 in accordance with 
the information derived from scanning. Reference numeral 308 designates a 
cap member, reference numeral 309 designates a cleaning blade, reference 
numeral 310 designates a pumping unit for activating each recording head 
received in the head device 210, and reference numeral 311 designates a 
supporting member for supporting the cap member 308, the cleaning blade 
309 and so forth. 
Since a printing operation to be performed by the ink jet printing 
apparatus and an activating operation to be performed for each printing 
head received in the head device are well known for any expert in the art, 
description on these operations is herein neglected for the purpose of 
simplification. In this embodiment, since the respective ink jet heads are 
held in the head device 210 while they are correctly registered relative 
to the ink jet unit at a high accuracy, a high quality of printed image is 
assured with the ink jet printing apparatus. Additionally, the used 
printing head can easily be replaced with new one, and moreover, when ink 
contained in each ink tank is consumed, the empty ink tank can easily be 
replaced with a new one. 
The present invention achieves distinct effects when applied to a recording 
head or a recording apparatus which has means for generating thermal 
energy such as electrothermal transducers or laser light, and which causes 
changes in ink by the thermal energy so as to eject ink. This is because 
such a system can achieve a high density and high resolution recording. 
A typical structure and operational principle thereof is disclosed in U.S. 
Pat. Nos. 4,723,129 and 4,740,796, and it is preferable to use this basic 
principle to implement such a system. Although this system can be applied 
either to on-demand type or continuous type ink jet recording systems, it 
is particularly suitable for the on-demand type apparatus. This is because 
the on-demand type apparatus has electrothermal transducers, each disposed 
on a sheet or liquid passage that retains liquid (ink), and operates as 
follows: first, one or more drive signals are applied to the 
electrothermal transducers to cause thermal energy corresponding to 
recording information; second, the thermal energy induces sudden 
temperature rise that exceeds the nucleate boiling so as to cause the film 
boiling on heating portions of the recording head; and third, bubbles are 
grown in the liquid (ink) corresponding to the drive signals. By using the 
growth and collapse of the bubbles, the ink is expelled from at least one 
of the ink ejection orifices of the head to form one or more ink drops. 
The drive signal in the form of a pulse is preferable because the growth 
and collapse of the bubbles can be achieved instantaneously and suitably 
by this form of drive signal. As a drive signal in the form of a pulse, 
those described in U.S. Pat. Nos. 4,463,359 and 4,345,262 are preferable. 
In addition, it is preferable that the rate of temperature rise of the 
heating portions described in U.S. Pat. No. 4,313,124 be adopted to 
achieve better recording. 
U.S. Pat. Nos. 4,558,333 and 4,459,600 disclose the following structure of 
a recording head, which is incorporated to the present invention: this 
structure includes heating portions disposed on bent portions in addition 
to a combination of the ejection orifices, liquid passages and the 
electrothermal transducers disclosed in the above patents. Moreover, the 
present invention can be applied to structures disclosed in Japanese 
Patent Application Laying-open Nos. 123670/1984 and 138461/1984 in order 
to achieve similar effects. The former discloses a structure in which a 
slit common to all the electrothermal transducers is used as ejection 
orifices of the electrothermal transducers, and the latter discloses a 
structure in which openings for absorbing pressure waves caused by thermal 
energy are formed corresponding to the ejection orifices. Thus, 
irrespective of the type of the recording head, the present invention can 
achieve recording positively and effectively. 
It is further preferable to add a recovery system, or a preliminary 
auxiliary system for a recording head as a constituent of the recording 
apparatus because they serve to make the effect of the present invention 
more reliable. Examples of the recovery system are a capping means and a 
cleaning means for the recording head, and a pressure or suction means for 
the recording head. Examples of the preliminary auxiliary system are a 
preliminary heating means utilizing electrothermal transducers or a 
combination of other heater elements and the electrothermal transducers, 
and a means for carrying out preliminary ejection of ink independently of 
the ejection for recording. These systems are effective for reliable 
recording. 
The number and type of recording heads to be mounted on a recording 
apparatus can be also changed. For example, only one recording head 
corresponding to a single color ink, or a plurality of recording heads 
corresponding to a plurality of inks different in color or concentration 
can be used. In other words, the present invention can be effectively 
applied to an apparatus having at least one of the monochromatic, 
multi-color and full-color modes. Here, the monochromatic mode performs 
recording by using only one major color such as black. The multi-color 
mode carries out recording by using different color inks, and the 
full-color mode performs recording by color mixing. 
Furthermore, although the above-described embodiments use liquid ink, inks 
that are liquid when the recording signal is applied can be used: for 
example, inks can be employed that solidify at a temperature lower than 
the room temperature and are softened or liquefied in the room 
temperature. This is because in the ink jet system, the ink is generally 
temperature adjusted in a range of 30.degree. C.-70.degree. C. so that the 
viscosity of the ink is maintained at such a value that the ink can be 
ejected reliably. 
Furthermore, the ink jet recording apparatus of the present invention can 
be employed not only as an image output terminal of an information 
processing device such as a computer, but also as an output device of a 
copying machine including a reader, and as an output device of a facsimile 
apparatus having a transmission and receiving function. 
The present invention has been described in detail with respect to 
preferred embodiments, and it will now be apparent from the foregoing to 
those skilled in the art that changes and modifications may be made 
without departing from the invention in its broader aspects, and it is the 
intention, therefore, in the appended claims to cover all such changes and 
modifications as fall within the true spirit of the invention.