Ink jet recording apparatus and recovering mechanism thereof

An ejection recovering unit includes tube pumps which generate pressure for performing ink enforced discharge of ink jet heads by sequentially deforming flexible tubes under pressure. Pressing rollers are spring biased toward a direction of preliminary pressurizing a spring for sequentially pressure deformation of tubes. This suppresses an increase in drive torque due to dispersion of accuracy of tubes, pressing rollers and mounting parts thereof. A guide is provided to place the corresponding roller in a state corresponding to a pressurizing state before the guide presses the corresponding tube. This prevents any change in torque due to sudden production of the pressurizing state.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an ink jet recording apparatus and a 
recovering mechanism for an ink jet head, and particularly relates to a 
recovering unit for maintaining the ink jet head of an ink jet recording 
apparatus in a normal ink ejection state or recovering the ink jet head to 
the normal ejection state. 
2. Description of the Related Art 
Among the conventional ink jet recording apparatus, there is one which has 
a recovering pump arranged for the purposes of maintaining an ink jet head 
in a normal ink emission state or recovering the ink jet heads to the 
normal state when clogging takes place in an orifice or orifices. Ink is 
sucked out of the orifice or orifices, using vacuum produced by the 
recovering pump. Examples of such technique include the use of a tube pump 
as the recovering pump (for instance, see Japanese Laid-Open Patent 
Application Nos. 73352/1991 and 73354/1991. The tube pump produces vacuum 
by changing a volume in each flexible tube. 
FIGS. 1A and 1B diagrammatically illustrate the tube pump. An opening of a 
cap 30 is brought into contact with a ink jet head 1 to perform capping of 
a face 1A on which orifices are formed. The cap 30 is provided in the rear 
side thereof with another opening, which is connected to a tube 3 as a 
member of the tube pump. A pressurizing roller 5 is provided to each tube 
3 for pressurizing, and a shaft 5A thereof is rotatably supported to a 
guide roller 4. The guide roller 4 is rotatably mounted at a shaft 4A 
thereof to a pump base 6. The pump base 6 has an arcuate groove 6A formed 
concentrically with the shaft 4A of the guide roller 4. 
When in such a construction, the guide roller 4 is rotated in the direction 
of the arrow a by a drive mechanism (not shown), the pressurizing roller 5 
on the guide roller 4 is brought into contact with the tube 3 in the 
portion X in FIG. 1A to press the tube 3, so that the tube is resiliently 
deformed to bring the cross-sectional area of the interior thereof at the 
portion X to substantially naught. The guide roller 4 is further rotated 
in the direction of the arrows a from this state. This makes the 
pressurizing roller 5 to rotate in the direction of the arrow b in a 
following manner, collapsing the tube 3. The pressurizing roller 5 is 
temporarily stopped at a portion Y of the tube 3 as shown in FIG. 1B. 
During this operation, negative pressure is produced in the face 1A of the 
head 1 due to change in volume of the interior of the tube while the 
roller 5 presses the tube 3 between the portions X and Y thereof. The 
negative pressure enables suction of ink from the orifices. A waste ink 
container 7 is arranged downstream of the tube 3 for containing ink sucked 
from the orifices. 
Such a tube pump is advantageous in that it is simple in construction and 
it is capable of constitute a small and low cost suction recovering unit. 
The inventors however have found that the tube pump can raise problems 
below. 
The amount of overlapping of the pressurizing roller 5 with the 
corresponding tube 3 (the amount of penetration of the pressurizing roller 
5 upon the tube 3) depends on the distance from the axis of the guide 
roller 4 to the axis of the pressurizing roller shaft 5A, the outer 
diameter of the pressurizing roller 5, the shape of the arcuate groove 6A 
concentric with the guide roller 4, the thickness of the tube 3, plays to 
these members, etc. The minimum amount of penetration which bring the 
cross-sectional area of the interior of the tube 3 to substantially naught 
must be determined in view of a tolerance of each of the members. In the 
case where the amount of penetration of the pressurizing roller 5 
increases due to the tolerance, the torque to drive the pump, that is, the 
torque to rotate the guide roller 4 in the direction of arrow a, must be 
also increased. This necessitates the torque of a pump drive motor to be 
enlarged, and therefore it is like to raise a cost of the motor. In the 
case of excessively large amount of penetration, wear of the tubes is 
accelerated, durability of the tubes is deteriorated, and hence the tubes 
are liable to be broken. 
For the purpose of obtaining a small and low cost recording apparatus, in 
the case where a motor is commonly used as the pump drive motor and a 
recording medium feeding motor (vertical or subscanning motor) or a 
carriage drive motor (horizontal or main scanning motor), the following 
problems are likely to be produced: the motor can be stepped out due to 
change in torque at an instant when tubes 3 are pressed by the 
pressurizing roller 5 or are released from the pressurizing rollers 5; 
accuracy of feed of the recording medium is adversely affected; the 
picture of printing is deteriorated in quality due to nonuniform scanning. 
In the case where a plurality of heads are used, a plurality of tubes 3 and 
pressurizing rollers 5 are provided. Thus, an increase in the amount of 
penetration according to the tolerance of each component become larger as 
the increase of the number of the heads. This makes influences of the 
problems previously described larger. 
SUMMARY OF THE INVENTION 
An object of the invention is to prevent the increase in drive torque of a 
tube pump due to variations of component tolerances, thereby reducing the 
size and cost of a pump drive motor. 
Another object of the invention is to suppress the increase in torque in 
the case where a pump is assembled using tubes and pressurizing rollers 
with a plurality of recording heads, as compared to the conventional 
construction. 
A further object of the invention is to minimize a change in torque 
produced at the instant when a tube is pressed by or released from a 
pressurizing member, thereby eliminating step-out of a pump drive motor 
and an irregularity of horizontal or vertical scanning in the case where 
the motor is commonly used as a horizontal or a vertical scanning motor. 
Still further object of the invention is to provide small sized and low 
cost recovering unit and ink jet recording apparatus. 
In the first aspect of the present invention, a recovering mechanism for an 
ink jet recording apparatus, for maintaining or recovering an ejection 
state of an ink jet head by discharging ink through or orifice or orifices 
of the ink jet head in an enforced manner, comprises: 
a flexible tube; 
a pressurizing member for producing pressure in a pressurizing state to 
perform the enforced discharging of ink by resiliently deforming the tube 
continuously along an axial direction of the tube; 
biasing means for resiliently biasing the pressurizing member in a 
direction to press the tube; 
guide means, arranged adjacent to a region to press the tube by the 
pressurizing member, for placing the pressurizing member in a state, 
substantially corresponding to the pressurizing state. 
Here, a recovering mechanism for ink jet recording apparatus may further 
comprise a base of the unit and a restraining member for restraining the 
tube of the base, and wherein the guide means and the restraining member 
are integrally formed. 
The guide means may be disposed before and/or behind the region to press 
the tube. 
The guide means may be disposed along a path of the pressurizing member 
except the region to press the tube, and may place the pressurizing member 
in the state, substantially corresponding to the pressurizing state, all 
the way along the path. 
The pressurizing member may have a roller, and the biasing means may have a 
spring. 
The pressurizing member and the biasing means may be integrally formed as 
one member which has a roller having a portion made of an elastic 
material, the portion performing pressurizing of the tube. 
In the second aspect of the present invention, an ink jet recording 
apparatus comprises: 
at least one ink jet head; 
at least one recovering mechanism as claimed in claim 1; and 
transporting means for transporting a recording medium to a recording 
position in which recording is carried out by the at least one ink jet 
head. 
Here, an ink jet recording apparatus may further comprise drive means for 
driving the pressurizing member to deform the tube continuously in the 
pressurizing state, the drive means including a drive source, the drive 
source being also used as a drive source for the transporting means. 
An ink jet recording apparatus may further comprise scanning means for 
performing horizontal scanning of the ink jet head over the recording 
medium. 
An ink jet recording apparatus may further comprise drive means for driving 
the pressurizing member to deform the tube continuously in the 
pressurizing state, the drive means including a drive source, the drive 
source being also used as a drive source for the scanning means. 
The at least one ink jet head may have an element or elements for 
generating thermal energy to produce film boiling in ink, the thermal 
energy being to be used for ink ejection. 
In the third aspect of the present invention, a liquid transporting 
apparatus comprise: 
a hollow resilient member adapted to flow liquid therethrough; 
a pressurizing member; 
a member to be pressed; 
pressure producing means for placing the pressurizing member in a 
pressurizing state in a first region, in the pressurizing state the 
pressurizing member being urged against the member to be pressed with the 
hollow resilient member sandwiched therebetween, and for moving the 
pressurizing member in the pressurizing state for producing pressure to 
cause liquid to flow; and 
guide means for previously guiding the pressurizing means in a state, 
corresponding to the pressurizing state, in a second region before the 
first region in which the pressurizing member and the member to be pressed 
urged the hollow resilient member in cooperation with each other. 
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 
.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
First Embodiment 
Referring to FIGS. 2 to 6, an ink jet recording apparatus according to the 
present invention will be described. In FIG. 2, the reference character C 
designates an ink jet cartridge. Each of the ink jet cartridges C is 
integrally provided with an ink tank and a recording head. The ink tank is 
mounted to an upper portion of the cartridge C whereas the recording head 
is provided at a lower portion thereof. Each ink jet cartridge C is 
moreover provided with a connector for receiving signals to drive the 
recording head. The recording head of each ink jet cartridge C has 
orifices formed at the bottom thereof. Elements for generating energy used 
for ejecting ink are arranged in respective liquid passages of the 
recording head, the liquid passages being communicated to the 
corresponding orifices. The liquid passages communicate to a common liquid 
chamber, where ink which is supplied from the ink tank is contained. As 
the energy generating elements, electro-thermal converting elements are 
preferably used since they enable the orifices and the liquid passages to 
be largely integrated. 
The reference numeral 2 designates a carriage which mounts four cartridges 
C1, C2, C3 and C4 on it in predetermined respective positions. The 
cartridges C1, C2, C3 and C4 correspond to different inks, yellow, 
magenta, cyan and black inks, for example. The carriage 2 is provided with 
a connector holder (not shown) for electrical connection with the 
recording head to transmit signals to drive the recording head. The 
carriage 2 is further provided on its bottom portion with ink absorbers, 
the absorbers being located on the opposite sides of each recording head. 
The reference numeral 11 designates a scanning rail which extends in the 
main scanning direction of the carriage 2 to slidably support the carriage 
2. The reference numeral 52 designates an endless drive belt for 
transmitting a driving force produced by a main scanning motor 61 to 
reciprocally move the carriage 2. There are provided two pairs of feed 
rollers 15, 16; 17, 18 which are arranged before and behind a recording 
position of the recording heads to hold and feed a recording medium P such 
as paper sheet. These rollers are connected to a sub scanning motor 62 via 
a suitable driving mechanism. The recording medium P is tightened against 
a platen (not shown) for flattening a recording surface of the recording 
medium P. The recording heads of the ink jet cartridges C are arranged to 
project downwardly through the carriage 2 and to intervene between the 
feed rollers 16 and 18. A face on which the orifices are formed of each 
recording head is disposed to oppositely face to the recording medium 
which is pressed over the guide surface of the platen. 
In the ink jet recording apparatus of this embodiment, a recovering unit 
200 as recovering means is arranged on the home position side in the left 
side of FIG. 2. In the recovering unit 200, cap units 300 are provided to 
correspond to the ink jet cartridges C which have recording heads. The cap 
units 300 are slidable in the lateral directions shown by the arrow in 
FIG. 2 as the carriage 2 moves, and are also vertically slidable as they 
laterally slide. When the carriage 2 is in the home position, each of the 
cap units 300 makes a contact with the corresponding recording head for 
capping. The cap units 300 prevent ink in the orifices of corresponding 
recording heads from increasing in viscosity due to evaporation, so that 
poor ejection or ejection error of ink due to adhesion is positively 
prevented. 
In the recovering unit 200, the reference numeral 500 indicates a pump unit 
which communicates to the cap units 300. In the case where ejection error 
takes place in one or more of the recording heads, the pump unit 500 is 
used to produce negative pressure to perform a suction recovery operation 
in which cap units 300 and the corresponding recording heads are brought 
into contact to each other. In the recovering unit 200, the reference 
numeral 401 designates a blade, made of a resilient material such as a 
rubber, as a wiping member, and 402 a blade holder for holding a blade 
401. In this embodiment, the blade 401 is selectively set by a blade 
elevating mechanism (not shown) to two positions: a wiping position in 
which the blade 401 is projected or raised to wipe ink stained on the face 
on which the orifices are disposed of each recording head; and a lowered 
or waiting position in which the blade 401 is retracted or lowered not to 
contact the face. The blade elevating mechanism is driven by the movement 
of the carriage 2. 
In this embodiment, wiping is carried out by the blade 401 only when the 
carriage 2 is removed from the left, where the recovering unit 200 is 
located, to the right in FIG. 2. This is because as the blade 401 is 
located between the cap units 300 and the feeding units of the recording 
medium P, there is a possibility that the recording medium is 
unintentionally spoiled by ink which has been scattered around the feed 
unit of the recording medium P by resilient wiping of the blade 401 when 
the carriage 2 is moved from the right to the left in FIG. 2. In the case 
where there is no such a possibility, wiping in the opposite directions 
may be carried out. 
For performing and releasing of capping by sliding or elevating the cap 
units 300, wiping by vertical movement of the blade 401 and controlling of 
the direction of wiping, mechanisms disclosed in Japanese Patent 
Application Laying-open No. 73352/1991 or No. 73354/1991 may be used. The 
Japanese patent applications were assigned to the assignee of the subject 
application, and the disclosures thereof are incorporated herein by 
reference. Alternatively, driving means, having a motor or a solenoid, for 
elevating the cap unit 300 and the blade 401 and means for controlling the 
driving means may be used. 
FIGS. 3 to 6 illustrate one embodiment of the recovering unit 200 according 
to the present invention. In the case where clogging takes place in the 
orifice of one of the ink jet heads 1, a suction recovering operation is 
carried out in the home position. The construction of this embodiment will 
be described together with the suction recovering operation. 
In the home position, capping of the face 1A is conducted by bringing an 
opening of corresponding one of the cap units 300 into contact with the 
ink jet head 1. The cap 300 is provided in the rear side thereof with 
another opening, which is connected to a tube 503 as a member of a tube 
pump. 
The tube 503 has a resiliency at at least a portion to be pressed by a 
pressurizing roller 505. The pressurizing roller 505 is rotatably mounted 
at a rotary shaft 505A thereof to a roller bearing 508. The roller bearing 
508 is supported on a cylindrical shaft 508A, which is received in a hole 
504B formed in a guide roller 504 with a compression spring 510 mounted 
around it. The roller bearing 508 is secured to the guide roller 504 by an 
E-shaped retaining ring 509. The pressurizing roller 505 is spring biased 
by the compression spring 510 radially outwardly of the guide roller 504 
or in a direction to press the tube 503 when the pressurizing roller 505 
is placed to contact the tube 503. The positioning of the roller bearing 
508 is achieved by guiding a positioning pin 508B mounted on the roller 
bearing 508 along a guide slot 504C provided in the guide roller 504. 
Also, the positioning of the roller bearing 508 is carried out by guiding 
the cylindrical shaft 508A along the guide hole 504B in the guide roller 
504. To reduce the volume of the pump, positioning pins 508B and 508B of 
adjacent roller bearings 508 and 508 are, as shown in FIG. 5, arranged in 
an overlapping manner in the same guide slot by changing the positioning 
pins 508B and 508B in height. 
The shaft 504A of the guide roller 504 is rotatably attached to the pump 
base 506 through bearings 511 and 511. To prevent the bearings 511 and 511 
from slipping out, E-shaped retaining rings 512 and 512 are arranged. The 
pump base 506 is provided with arcuate grooves 506A which are concentric 
with the guide roller 504. The pump base 506 is mounted to the base 513 of 
the recording apparatus with the lower openings of the grooves 506A being 
faced to the base 513. This enables the pump base 506 to serve as a 
closure. The pump base 506 covers the pump operating portion, and thereby 
malfunction of the pump due to careless touching of the pump operating 
portion and entering of foreign materials into the pump operation portion 
are prevented. Each of the tubes 503 is placed into tube securing grooves 
506B and 506B for securing. 
With such a construction, a roller 514 is driven by a drive source (not 
shown), and a drive gear 515 mounted on the roller 514 transmits the 
torque to a gear 504D provided to the guide roller 504. The roller 514 may 
e one of the paper feed rollers (rollers 15 to 18 of FIG. 1), for example. 
A retaining member 516 is disposed to prevent the drive gear 515 from 
slipping out. 
When the drive gear 515 rotates in a forward rotational direction, that is, 
e direction (FIG. 6) corresponding to the paper feed direction during 
recording, of the roller 514 which is one of the paper feed rollers (for 
example, roller 15), the guide roller 504 is rotated to turn in the 
direction of the arrow a. This causes the pressurizing rollers 505 to be 
brought into contact with respective roller guide portions 506C, which are 
integrally formed with tube securing grooves 506B disposed on the pump 
base 506, at position shown by the dots-and-dash line in FIG. 3. In this 
event, the pressurizing rollers 505 are guided by the roller guide 
portions 506C and thereby gradually move in the direction of the arrow f 
or toward the axis of the roller 504 while rotating in the direction of 
the arrow b in a following manner. Thus, each of the pressurizing roller 
505 is raised to a position to press the tube 503. The guide roller 504 is 
further rotated in the direction of the arrow a, causing each of the 
pressurizing rollers 505 to be brought into contact with the corresponding 
tube 503 at the position X shown by the dot-and-dash line, so that the 
interior of the tube 503 is reduced in cross-sectional area to naught. 
Before movement of each of the pressurizing rollers 505 from the Z 
position to the X position, the pressurizing roller 505 is moved to a 
position, corresponding to a position to press the tube 503, in the f 
direction, and therefore a sudden raise of force to be applied to the 
pressurizing roller 505 is removed when the pressurizing roller 505 moves 
to the position X. Each pressurizing roller 505 gradually pressed the 
corresponding tube 504 while it moves along the roller guide portion 504C, 
and change in torque applied to the roller 514 therefore becomes very 
small when each pressurizing roller 505 comes into contact with the tube 
503. 
In this embodiment, shown in FIG. 4, the width of the tube grooves close to 
the roller guide portions 506C is enlarged. This is made so that any 
undesirable reaction force of each of the tubes 503 may not affect on the 
corresponding pressurizing roller 505 at a position where the guide roller 
504 begins to contact the tube 503. More specifically, the width h of the 
groove adjacent to the roller guide portion 506C is made larger than the 
width i of the tube 503 when the tube 503 is pressed by the corresponding 
pressurizing roller 505, and thereby undesirable reaction force due to 
restriction of deformation of the tube 503 by the groove is prevented from 
being produced. The width h of the grooves must be smaller than the 
thickness g of the respective pressurizing rollers 505 since the grooves 
serve as guides of the rollers 505. 
When the guide roller 504 further rotates in the direction of the arrow a, 
the pressurizing rollers 505 are rotated in the direction of the arrow b 
in a following fashion, squashing the corresponding tubes 503. The, the 
pressurizing rollers 505 are temporarily stopped at the position Y shown 
by the broken line in FIG. 3. Negative pressure is produced on the 
orifices defining the face 1A of each head due to changes in volume within 
the corresponding tube 503 squashed by the pressurizing roller 505 while 
the pressurizing roller 505 moves from the position X to the position Y, 
and thereby suction operation at orifices is performed. 
Similarly to the unit of FIGS. 1A and 1B, a waste ink container 507 is 
arranged downstream of the corresponding tube 503 to contain ink sucked 
out from the corresponding orifices. 
After the suction is completed, the guide roller 504 further rotates in the 
direction of the arrow a, and the pressurizing rollers 505 are thereby 
guided along respective roller guides 506C' which have the structure as 
the roller guides 506C, so that the pressurizing rollers 505 gradually 
move away from the corresponding tubes 503. The pressurizing rollers 505 
perform operation opposite to the operation when the pressurizing rollers 
505 come into contact with tubes 503. Also in this event, the change in 
torque is minimized when the tubes 503 are released from respective 
pressurizing rollers 505. 
The series of operations previously described may be controlled as follows: 
a transmission type photosensor 157 is, as shown in FIG. 6, mounted on the 
pump base 506 so that projections 504E, provided on the roller 504, may 
pass over the photosensor 517; and the positioning of the pressurizing 
rollers 505 is achieved according to detection signals of the photosensor 
517. Such a control may be conducted using a control system disclosed in 
Japanese patent application Laying-open No. 73354/1991. 
Other Embodiments 
In the preceding embodiment, the paper feed motor (sub scanning motor) is 
used as a drive motor of the pump, and the torque is transmitted through 
one of the paper feed rollers but the torque may be transmitted through 
other transmission mechanisms. A single motor may be used as both the 
carriage drive motor (main scanning motor) and the pump drive motor. These 
motors may be separately used. 
According to the embodiment previously described, guides are integrally 
formed with groove defining members which define grooves to secure tubes, 
each guide being to guide the corresponding pressurizing roller to a 
position to press the tube. The guides may be separately formed, in which 
case each pair of guides for introducing and releasing the pressurizing 
roller may be integrally formed. 
FIG. 7 illustrate such a modified form. The guide member 518 is formed as 
shown, and the corresponding pressurizing roller 505 is always displaced 
to a position corresponding to a position to press the tube 503 by the 
guide member 518 while the pressurizing roller 505 is not in contact with 
the tube 503. This modification achieves an advantage in that changes in 
torque due to movement of the pressurizing rollers 505 radially of the 
guide roller 504 are removed. The movement of the pressurizing rollers 505 
radially of the guide roller 504 includes the movement of the pressurizing 
rollers 505 in the f direction by the respective roller guides 506C and 
due to releasing of the pressurizing rollers 505 from respective roller 
guides 506C. The other parts indicated by the same reference numerals as 
the parts of the first embodiment are corresponding parts, and therefore 
descriptions thereof are omitted. 
In the first embodiment, the guide roller 504 is rotated in the direction 
of the arrow a for performing ejection recovering by suction. The present 
invention may be applied to another modified form of the recovering unit 
in which ink is forcedly discharged through orifices by pressurizing the 
ink supply system for achieving recovering. In this case, the recovering 
system is connected to the ink supply system, and the pressurizing rollers 
are reversely rotated (that is, the guide roller 504 is reversely 
rotated). Although in this modification, the introduction side and the 
releasing side of each pressurizing roller 505 are located oppositely to 
those in FIG. 3, and hence there is no difference in change in torque, and 
the same effect is produced. 
In the first embodiment, the pressurizing rollers 505 are spring biased by 
the compression spring 510 against the tubes 503, but the same effect may 
be achieved by making the pressurizing rollers 505 of an elastic material. 
FIG. 8 illustrates such a modified pressurizing roller 505'. The 
pressurizing roller 505' is rotatably mounted at a shaft 505'A thereof to 
a guide roller 504, and the portion thereof which performs pressurizing of 
the tube 503 is made of an elastic material such as a rubber. Parts 
corresponding to parts of FIG. 7 are designated by the same reference 
numerals, and descriptions thereof are hence omitted. 
As described above, in a tube pump in which suction and pressurization is 
carried out, utilizing deformation of the tube, pressurizing member, such 
as a roller, for deforming the tube is, according to the present 
invention, resiliently biased in a direction to pressurize the tube. Thus, 
the amount of penetration of the pressurizing member into the tube is 
flexibly determined according to resilient biasing, not component 
accuracy. This enables that any increase in drive torque of the pump due 
to variation of component tolerances is prevented, and that reduction in 
size and cost of a pump drive motor is realized. This construction also 
enables that an increase in torque is suppressed as compared to the 
conventional construction in the case where the pump is assembled using 
tubes and pressurizing rollers with a plurality of heads. 
Furthermore, according to the present invention, the guides means is 
provided for guiding the pressurizing member to a state corresponding to a 
tube pressurizing state before or behind a tube pressurizing region. This 
feature enables change in torque to be minimized, the change being 
produced at instant when the tube is pressed by or released from the 
pressurizing member, so that step-out of drive motor and dispersion in 
paper feed accuracy or in main scanning in the case where the pump drive 
motor is commonly used as the main or the sub scanning motor are 
effectively eliminated. Thus, the pump drive motor and the main or the 
such scanning motors may be constituted by a single motor, and reduction 
in scale and cost of the system is therefore realized. 
Further Description 
In the case that the present invention is applied to an ink jet printer, 
the present invention is particularly suitably useable in an ink jet 
recording head having heating elements that produce thermal energy as 
energy used for ink ejection or discharge and recording apparatus using 
the head. This is because, the high density of the picture element, and 
the high resolution of the recording are possible. 
The typical structure and the operational principle are preferably the one 
disclosed in U.S. Pat. Nos. 4,723,129 and 4,740,796. The principle is 
applicable to a so-called on-demand type recording system and a continuous 
type recording system particularly however, it is suitable for the 
on-demand type because the principle is such that at least one driving 
signal is applied to an electrothermal transducer disposed on liquid (ink) 
retaining sheet or ink passage, the driving signal being enough to provide 
such a quick temperature rise beyond a departure from nucleation boiling 
point, by which the thermal energy is provided by the electrothermal 
transducer to produce film boiling on the heating portion of the recording 
head, whereby a bubble can be formed in the liquid (ink) corresponding to 
each of the driving signals. By the development and collapse of the 
bubble, the liquid (ink) is ejected through an ejection outlet to produce 
at least one droplet. The driving signal is preferably in the form of a 
pulse, because the development and collapse of the bubble can be effected 
instantaneously, and therefore, the liquid (ink) is ejected from quick 
response. The driving signal in the form of the pulse is preferably such 
as disclosed in U.S. Pat. No. 4,463,359 and 4,345,262. In addition, the 
temperature increasing rate of the heating surface is preferably such as 
disclosed in U.S. Pat. No. 4,313,124. 
The structure of the recording head may be as shown in U.S. Pat. Nos. 
4,558,333 and 4,459,600 wherein the heating portion is disposed at a bent 
portion in addition to the structure of the combination of the ejection 
outlet, liquid passage and the electrothermal transducer as disclosed in 
the above-mentioned patents. In addition, the present invention is 
applicable to the structure disclosed in Japanese Patent Application 
Laying-open No. 123670/1984 wherein a common slit is used as the ejection 
outlet for plurality electrothermal transducers, and to the structure 
disclosed in Japanese Patent Application Laying-open No. 138461/1984 
wherein an opening for absorbing pressure wave of the thermal energy is 
formed corresponding to the ejecting portion. This is because, the present 
invention is effective to perform the recording operation with certainty 
and at high efficiency irrespective of the type of the recording head. 
The present invention can be also applied to a so-called full-line type 
recording head whose length equals the maximum length across a recording 
medium. Such a recording head may consists of a plurality of recording 
heads combined together, or one integrally arranged recording head. 
In addition, the present invention is applicable to a serial type recording 
head wherein the recording head is fixed on the main assembly, to a 
replaceable chip type recording head which is connected electrically with 
the main apparatus and can be supplied with the ink by being mounted in 
the main assembly, or to a cartridge type recording head having an 
integral ink container. 
The provision of the recovery means and the auxiliary means for the 
preliminary operation are preferable, because they can further stabilize 
the effect of the present invention. As for such means, there are capping 
means for the recording head, cleaning means therefor, pressing or sucking 
means, preliminary heating means by the ejection electrothermal transducer 
or by a combination of the ejection electrothermal transducer and 
additional heating element and means for preliminary ejection not for the 
recording operation, which can stabilize the recording operation. 
As regards the kinds and the number of the recording heads mounted, a 
single head corresponding to a single color ink may be equipped, or a 
plurality of heads corresponding respectively to a plurality of ink 
materials having different recording color or density may be equipped. The 
present invention is effectively applicable to an apparatus having at 
least one of a monochromatic mode solely with main color such as black and 
a multi-color mode with different color ink materials or a full-color mode 
by color mixture. The multi-color or full-color mode may be realized by a 
single recording head unit having a plurality of heads formed integrally 
or by a combination of a plurality of recording heads. 
Furthermore, in the foregoing embodiment, the ink has been liquid. It may, 
however, be an ink material solidified at the room temperature or below 
and liquefied at the room temperature. Since in the ink jet recording 
system, the ink is controlled within the temperature not less than 
30.degree. C. and not more than 70.degree. C. to stabilize the viscosity 
of the ink to provide the stabilized ejection, in usual recording 
apparatus of this type, the ink is such that it is liquid within the 
temperature range when the recording signal is applied. In addition, the 
temperature rise due to the thermal energy is positively prevented by 
consuming it for the state change of the ink from the solid state to the 
liquid state, or the ink material is solidified when it is left is used to 
prevent the evaporation of the ink. In either of the cases, the 
application of the recording signal producing thermal energy, the ink may 
be liquefied, and the liquefied ink may be ejected. The ink may start to 
be solidified at the time when it reaches the recording material. The 
present invention is applicable to such an ink material as is liquefied by 
the application of the thermal energy. Such an ink material may be 
retained as a liquid or solid material on through holes or recesses formed 
in a porous sheet as disclosed in Japanese Patent Application Laying-open 
No. 56847/1979 and Japanese Patent Application Laying-open No. 71260/1985. 
The sheet is faced to the electrothermal transducers. The most effective 
one for the ink materials described above is the film boiling system. 
The ink jet recording apparatus may be used as an output means of various 
types of information processing apparatus such as a work station, personal 
or host computer, a word processor, a copying apparatus combined with an 
image reader, a facsimile machine having functions for transmitting and 
receiving information, or an optical disc apparatus for recording and/or 
reproducing information into and/or from an optical disc. These apparatus 
requires means for outputting processed information in the form of hand 
copy. 
FIG. 9 schematically illustrates one embodiment of a utilizing apparatus in 
accordance with the present invention to which the ink jet recording 
system shown in FIG. 2 is equipped as an output means for outputting 
processed information. 
In FIG. 9, reference numeral 10000 schematically denotes a utilizing 
apparatus which can be a work station, a personal or host computer, a word 
processor, a copying machine, a facsimile machine or an optical disc 
apparatus. Reference numeral 11000 denotes the ink jet recording apparatus 
(IJRA) shown in FIG. 2. The ink jet recording apparatus (IJRA) 11000 
receives processed information from the utilizing apparatus 10000 and 
provides a print output a hand copy under the control of the utilizing 
apparatus 10000. 
FIG. 10 schematically illustrates another embodiment of a portable printer 
in accordance with the present invention to which a utilizing apparatus 
such as a work station, a personal or host computer, a word processor, a 
copying machine, a facsimile machine or an optical disc apparatus can be 
coupled. 
In FIG. 10, reference numeral 10001 schematically denotes such a utilizing 
apparatus. Reference numeral 12000 schematically denotes a portable 
printer having the ink jet recording apparatus (IJRA) 11000 shown in FIG. 
2 is incorporated thereinto and interface circuits 13000 and 14000 
receiving information processed by the utilizing apparatus 11001 and 
various controlling data for controlling the ink jet recording apparatus 
11000, including hand shake and interruption control from the utilizing 
apparatus 11001. Such control per se is realized by conventional printer 
control technology. 
The present invention has been described in detail with respect to 
preferred embodiments, and it 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.