Note: Descriptions are shown in the official language in which they were submitted.
20401 ~0
1 DISCHARGE RECOVERY METHOD FOR
AN INK JET RECORDING HEAD AND DEVICE
FOR CARRYING OUT THE SAME
5 BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a recovery method for
an ink jet recording head and a recording head or an
integral ink tank type recording head applicable to
a printer, a copying apparatus, a facsimile apparatus,
an ink jet recording apparatus or the like generally
used as a business machine, and to a recording apparatus
using a recording head removably mountable on the
apparatus body.
1~ Description of the Prior Art
In the conventional ink jet recording head
and apparatus, a heat energy recording system utilizing
film boiling is especially excellent as compared with
a system utilizing a piezo-electric element, and has
been put into practice as a system excellent as compared
with other recording by heat energy such as light energy.
In order to eliminate any inconvenience attrib-
utable to the use of ink which is liquid as a recording
agent, there is provided in an ink jet recording appara-
tus a construction which is not seen in other recordingapparatuses, i.e., means for refreshing the interior
of liquid paths or bringing the discharge port forming
- 2 - 2040 1 20
1 surface into a good condition, for example, a so-called
discharge recovery system for a recording head.
There are discharge recovery systems of various
constructions, and as first to be mentioned as one
for refreshing the interior of liquid paths, there
is a system which drives a discharge energy generating
element during the other time than recording to cause
a predetermined ink receiving medium to effect ink
discharge (called also preliminary discharge or idle
discharge)
As a patent which discloses this, mention can
be made of British Patent No. 2,169,855. This patent
discloses, in addition to the above-described content,
heating ink preliminarily, and then effecting preliminary
discharge
There is also a system which causes predetermined
pressure to act on liquid paths, as by pressurizing
an ink supply system or effecting suction from ink
discharge ports, to thereby force ink to be discharged
from the discharge ports.
A typical patent which discloses this system
is U.S. Patent No. 4,600,931. This suction recovery
is not effected at all times, but is effected immediately
before there comes a situation in which unsatisfactory
recording occurs or in a non-discharge condition. There
have been filed numerous patent applications for the
invention of suction recovery, and above all, there
- 3 - 2 0 4 0 1 20
1 lS known an invention which changes over great recovery
for making suction condition great and normal recovery
for effecting ordinary suction.
Also, as a system for refreshing the discharge
port forming surface and preventing the deflection
of the discharge direction, there is one in which provi-
sion is made of a wiping member for contacting with
the discharge port forming surface and the two are
moved relative to each other to thereby wipe off ink
droplets, dust or the like adhering to the neighborhood
of the discharge ports.
Description of the Re ated Prior Art
We have studied prior-art recovery means and
have found that it is effective to vary preliminary
lS discharge conditions in the environmental changes during
recording (including the temperature of a head, the
ambient temperature, the steps in the sequence, etc.)
and forced discharge by suction or a pressure pump
are also usually effective, but there is the following
problem.
In some cases, it has been impossible to attain
high-level recovery from the loss of more ink even
in a long time. This has particularly posed a problem
during forced discharge by suction or pressing, and
a suction force or a pressing force has not uniformly
acted from all of a plurality of discharge ports, thus
wasting the ink. Especially, it has been found that
~ 4 - 2 04 0 1 20
1 even if the pump is made large in an effort to strengthen
this recovery force, it is not so effective, but rather
the amount of loss of the ink has been increased.
Also, an increased amount of ink discharged
from each discharge port by preliminary discharge leads
to a lengthened time spent for the recovery process
and accordingly to a reduced throughput of recording.
These are remarkable in the recovery process under
low temperature environment.
SUMMARY OF THE INVENTION
It is an object of the present invention to
provide a recovery method for an ink jet recording
head which can efficiently improve the given recovering
ability of forcible recovery means and can achieve
reliable recovery without making an apparatus bulky,
and an apparatus for carrying out the same method.
It is another object of the present invention
to provide a recovery method and a recording apparatus
which can execute a reliable recovery process in spite
of the presence of the influence of an absorbing member
which is a negative pressure generation source in an
ink containing portion for ink supplied to a recording
head.
It is still another object of the present
invention to provide a recovery method and a recording
apparatus which are excellent in the degree of recovery
- 5 - 2 04 0 1 20
1 as compared with the prior art and in which the proces-
sing time can be shortened and optimally the amount
of loss of ink can be decreased.
More specifically, it is a further object of
the present invention to provide a recovery method
and a recording apparatus which can achieve efficient
suction from the start of the recovery process without
making a mechanism such as a tube pump bulky.
The present invention provides a recovery proces-
sing method of carrying out a recovery process on an
ink jet recording head provided with discharge energy
generating elements corresponding to a plurality of
discharge ports, including:
a recovery mode for effecting at a time the
element driving step of driving said discharge energy
generating elements to discharge ink from said plurality
of discharge ports and the step of forcibly discharging
the ink from the interior of the head through said
discharge ports.
The present invention provides a recovery
processing method of carrying out a recovery process
on an ink jet recording head provided with discharge
energy generating elements corresponding to a plurality
of discharge ports, including:
the heating step of heating ink in said recording
head in response to the start of recovery; and
a recovery mode for effecting at a time after
- 6 - 204 ~ 1 20
1 said heating step the element driving step of driving
said discharge energy generating elements to discharge
the ink from said plurality of discharge ports and
the step of forcibly discharging the ink from the
interior of the head through said discharge ports.
The present invention provides a recording
apparatus for effecting recording with an ink jet
recording head carried thereon, said head integrally
having an ink containing portion provided with an ink
absorbing member therein, said apparatus having:
a recording mode for driving a plurality of
discharge energy generating elements provided in said
recording head in conformity with a recording signal
to effect recording on a recording medium;
lS a recovery mode for effecting suction from
the discharge ports of said recording head substantially
simultaneously with the driving of said plurality of
discharge energy generating elements provided in said
recording head; and
a mechanism for selecting said recording mode
and said recovery mode.
The present invention is more effective
particularly in heat generating elements as the
discharge energy generating elements, and above all,
in an electro-thermal conversion member for forming
a bubble, and preferably provides a recording apparatus
as described above, wherein said recovery mode starts
- ~ 7 ~ 2040120
l said suction during the growth of said bubble and
effects timing drive for causing the maximum suction
force during said suction to act during the extinction
of said bubble, and further provides as an optimum
construction a recording apparatus as described above,
wherein the driving frequency of said discharge energy
generating elements in said discharge recovery process
is set to a value higher than the limit refill frequency
of the ink.
The present invention displays an effect more
excellent than expected by a construction which has
heretofore not been anticipated, and can increase the
throughput of ink jet recording and greatly extend
the interval between the recovery processes.
Other objects or detailed construction of the
present invention will become apparent from the following
detailed description of some embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l is a perspective view of a unitary
recording head-ink tank type cartridge used in an
embodiment of the present invention.
Figures 2A and 2B are a front view and a side
cross-sectional view, respectively, showing an example
of the construction of the recording head.
Figures 3 and 4 are a perspective view and
a plan view, respectively, showing the surroundings
- 8 - 20q O 1 20
1 of the carriage of the apparatus of the present
embodiment in which the cartridge shown in Figure 1
is mounted.
Figure 5 is a schematic perspective view of
the apparatus according to the present embodiment for
schematically showing a recovery system unit which
is the essential portion of the apparatus.
Figures 6 and 7 are a plan view and a side
view, respectively, showing an example of the detailed
construction of the recovery system unit.
Figure 8 is a front view for illustrating the
detailed construction and operation of a cap unit dispos-
ed on the recovery system unit.
Figure 9 illustrates the manner of wiping by
a blade moved up and down by a blade lifting mechanism.
Figures lOA and lOB illustrate the manner of
cleaning for the blade.
Figures 11 and 12 illustrate the recovery using
period of the present invention.
Figure 13 illustrates the operation of an ink
suction mechanism adopted in the present embodiment.
Figures 14A - 14D illustrate the carriage posi-
tion during the recovery process in the present
embodiment.
Figures 15A - 15E illustrate the relation between
the operative positions of the ink suction mechanism
of Figure 13 and the carriage of Figure 14 during the
20401 20
1 execution of the sequence in the present embodiment.
Figure 16 is a block diagram showing an example
of the construction of a control system according to
the present embodiment.
Figure 17 is a flow chart schematically showing
an example of the recording operation procedure by
the control system shown in Figure 16.
Figures 18A - 18E are flow charts showing
examples of the detailed procedures of the initial
process, the recording preparation process, the recovery
process during recording, the recording termination
process and the great recovery process, respectively,
by the control system shown in Figure 16.
Figure 19 illustrates the state of a bubble
present in a head chip.
Figure 20 illustrates the effect of the present
embodiment.
Figures 21A, 21B and 21C are timing charts
showing the driving condition during the great recovery
process in respective embodiments of the present
invention.
Figure 22 shows the main flow chart of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinafter be
described in detail with reference to the drawings.
20401 20
1 (1) Cartridge
Figure 1 shows an example of the construction
of a cartridge C which can be carried on the carriage
(which will be described later with reference to Figure
3) of an ink jet recording apparatus according to an
embodiment of the present invention. The cartridge
C according to the present embodiment has above it
an ink tank portion 80 having an ink absorbing member
(sponge) therein and has below it a recording head
86, and further, a head side connector 85 for receiving
-a signal or the like for driving the recording head
86 and effecting the outputting of the detection of
the amount of remaining ink is provided in juxtaposed
relationship with the ink tank portion 80. Accordingly,
when this cartridge C is loaded onto the carriage to
be described, the height H thereof can be m; n; mi zed.
Also, by making the thickness W of the cartridge in
the scanning direction small, it is possible to construct
the carriage small when the cartridge C is disposed
as will be described later with reference to Figure
2.
The reference numeral 83 designates a connector
cover formed integrally with the outer wall of the
tank to prevent the inadvertent contact with the
connector 85. The reference numeral 81 denotes a
positioning portion formed with dash surfaces 81a and
81b in two directions. By providing a sufficient
- - 11- 2040120
1 distance between these positioning surfaces and a
positioning dash surface provided on the recording
head 86, the reliable fixed positioning of the recording
head becomes possible with the aid of the pressing
against an inclined surface 84 by a push pin which
will be described later. The reference numeral 82
designates a knob for use when the cartridge C is to
be mounted or dismounted with respect to a loading
portion. The reference character 82a denotes an
atmosphere communication hole formed in the knob 82
to communicate the interior of the ink tank portion
80 with the atmosphere. The reference character 82a
designates a cut-away portion, and the reference
character 83b denotes a guide. Both of these provide
a guide when loading the cartridge C onto the loading
portion.
The recording head 86 according to the present
embodiment has a plurality of discharge ports opening
into the bottom surface side as viewed in Figure 1,
and discharge energy generating elements generating
energy available for ink discharge are disposed in
a liquid path portion communicating with the discharge
ports. These discharge energy generating elements
may suitably be heat energy generating elements because
the high integration of the discharge ports or liquid
paths is possible.
Figures 2A and 2B are a front view and a side
- - 12 - 2040120
1 sectional view, respectively, of the recording head
86 as it is seen from ahead in the discharge direction.
In Figures 2A and 2B, the reference numeral
101 designates the base plate of the recording head
86 which is formed of aluminum. A substrate (heater
board) 102 formed of Si or the like is adhesively secured
onto the base plate 101. On the surface of the heater
board 102, there is formed an electro-thermal conversion
member (not shown) as an heat energy generating element
and a diode or the like as a functional element for
driving this electro-thermal conversion member. The
reference numeral 103 denotes an orifice plate (discharge
port forming member) which is formed integrally with
a top plate 103A formed with a groove for forming an
ink liquid chamber.
The formation of discharge ports in this orifice
port 103 can be accurately accomplished, for example,
by the application of an excimer laser beam or the
photoetching process, whereby a highly accurate shape
can be obtained over a plurality of discharge ports.
This orifice plate 103 is also used to prevent the
deflection of the discharge direction which occurs
due to the difference in wettability between a plurality
of different materials when these materials are exposed
on the discharge port forming surface.
The reference numeral 104 designates a filter
provided in an ink supply port leading from a chip
- 13 - 2040120
1 tank 105 to a common liquid chamber 106. The filter
104 removes the impurities of the ink and dust flowing
as indicated by an arrow in the figure. The ink which
has passed through the filter 104 flows into the common
liquid chamber 106, and is supplied to each of a plurality
of liquid paths 107 communicating with this liquid
chamber, in conformity with the discharge of the ink.
The reference numeral 109 denotes a keep member for
holding down the orifice plate 103 by its resilient
force or the like and bringing it into intimate contact
with the surface of openings (here, particularly the
end surface of the heater board 102). In the present
embodiment, SUS (stainless steel) is used as the keep
member 109.
In the above-described construction, ink is
supplied from the ink tank portion 80 made integral
with the recording head 86 to the chip tank 105, where-
after the ink flows as indicated by arrow. The ink
first passes through the filter 104, whereby dust or
impurities in the ink are removed, and the ink passes
to the common liquid chamber 106 and is directed
therefrom to the liquid paths 107. The electro-thermal
conversion members disposed in the liquid paths 107
are driven to thereby create a bubble in the ink, and
by a change in the state of this bubble, the ink is
discharged through the discharge ports 108.
- 14 ~ 204 0 1 2 0
1 (2) Carriage
Figures 3 and 4 are a perspective view and
a plan view, respectively, showing an example of the
construction of the surroundings of the carriage of
the ink jet recording apparatus on which the cartridge
C shown in Figure 1 is mountable. These figures show
an example in which four cartridges Cl, C2, C3 and
C4 (containing therein inks of different colors, for
example, yellow, magenta, cyan and black) are positioned
and loaded on the carriage 2.
Four push pins 10 (push pins A - D) are in
engagement with a connection holder 40 as a holding
member, and are biased leftwardly as viewed in Figure
3 by springs lOa (springs A - D). The connector holder
40 as a holding member is engaged with links 21 (link
I and link II) through shafts 20 (shaft I and shaft
II), and is movable to the left as viewed in Figure
4 in accordance with the rotational movement (in
clockwise or counter-clockwise direction) of an operating
lever 7 engaged with the links 21, and is moved to
the right to release pressing and enable the interchange
of the cartridges, and on the other hand, is moved
to the left to thereby receive the cartridges loaded.
If the operating lever 7 is pivoted clockwised
about a shaft 9, the holder 40 will come forward and
the pins 10 will come into engagement with the cartridges
C, which will thus be loaded onto the loading portion.
- 15 - 2040120
1 The tip ends lOb of the push pins 10 bear against the
dash surfaces ld, respectively, of the four cartridges
C, and press the cartridges. Also, the outer peripheral
surfaces lOc of the push pins 10 are designed to bear
against the dash surface 2S of the carriage 2 and
independently receive thrust forces created in a direc-
tion perpendicular to the axes of the pins. Accordingly,
the holding member 40 receives only the reaction forces
of the springs lOa (springs A - D) and is not acted
on by the thrust forces and therefore, even when a
plurality of cartridges are to be released at a time,
a release lever 7 may be operated by a small operating
force to thereby make the mounting and dismounting
operations possible.
Description will now be made of a mechanism
or an operation for the fitting and separation of the
head connector 85 of the cartridge C side with respect
to a connector (body connector) 6 provided on the body
side for engagement with the head connector.
When the body connector 6 is inserted into
the head connector 85, if the lever 7 is operated,
the body connector 6 and a connector holder 40 will
move as a unit. An engagement shaft 6a integral with
the body connector 6 is fitted to the slit-shaped
engagement hole fitting portion 40b of the connector
holder 40 by the resilient force of a tension spring
41 (see Figure 4). Thereupon, the head connector 85
- 16 ~ 2 04 0 1 20
1 meets the body connector 6, and is guided by the inclined
surface (not shown) of the body connector 6, whereby
the body connector 6 is fitted (coupled) to the head
connector 85. Thereafter, the connector holder 40
moves rightwardly by a predetermined distance Q toward
a scanning rail 11 (this movement is accomplished by
the rotation of the lever 7). This predetermined distance
is the distance of movement of the connector holder
40 for bringing the body connector 6 from its positioned
state into its movable (liberated) state.
Since the body connector 6 is coupled to the
head connector 85 with a force stronger than the force
of the tension spring 41, the body connector 6 is
liberated from the connector holder 40. That is, the
engagement between the two is released. Accordingly,
during the fitting (coupling) of the body connector
6 to the head connector 85, the body connector 6 is
in a separated state relative to the connector holder
40 and thus, the cartridges C are positioned relative
to the carriage 2 by only the pressing forces of the
push pins 10 and the accurate positioning of the record-
ing head 86 relative to the carriage 2 is ensured.
Next, when the cartridges C are to be removed
(liberated), the lever 7 is rotated counter-clockwise
from its upright position to its horizontal position
(the position of Figure 3). Thereupon, although the
engagement shaft 6a is in engagement with the head
- 17 - 204nl 20
1 connector 85 with a strong force, the side of the large-
diametered portion of the engagement hole 40a strikes
against the engagement shaft 6a as the connector holder
40 moves rightwardly, and said side separates (liberates)
the body connector 6 from the head connector 8 while
pushing the engagement shaft 6a toward the inmost part
as viewed in Figure 3. At the same time, the push
pins 10 also move with the connector holder 40 and
thus, becomes separate from the recording head 86.
(3) Outline of the Recording Apparatus
In Figures 3 to 5, the reference numeral 11
designates a scanning rail extending in the main scanning
direction of the carriage 2 and slidably supporting
the carriage 2, the reference character lla denotes
a bearing, the reference numeral 51 designates a flexible
cable for giving and receiving various signals between
it and the cartridges C through a connector, and the
reference numeral 52 denotes a belt for transmitting
a driving force for reciprocally moving the carriage
2. The reference numerals 17, 18 and 15, 16 designate
pairs of rollers disposed before and behind the recording
position by the recording head 86 to nip and convey
a recording medium therebetween, and the reference
numeral 50 denotes a platen for regulating the recording
surface of the recording medium flat.
Figure 4 schematically shows a recording apparatus
such as a printer, a copying apparatus or a facsimile
- 18 ~ 204 0 1 20
1 apparatus to which the above-described construction
is applied.
The recording apparatus body 1000 has a cover
1101 whose operated side is openable and closable.
When this cover 1101 is opened about the rotational
center axis thereof, the interior of the body is opened.
By this opening, the rotational movement of the afore-
described lever 7 becomes possible to make the mounting
and dismounting of the cartridges Cl - C4 with respect
to the apparatus body possible. The lever 7 indicated
by a solid line in Figure 4 shows a position in which
the cartridge shown in Figure 1 is mountable, and in
this position, the lever 7 precludes the movement of
the cover 1101 to its closed position. The cartridges
indicated by broken lines show ones being mounted,
and the cartridges indicated by solid lines are in
predetermined positions wherein they are positioned
for recording in the apparatus body. At this time,
the discharge port forming surface of the recording
head 86 of each cartridge is opposed to the guide surface
of the platen 50 in parallelism to the latter, and
the protruding recording head portion protrudes down-
wardly from the carriage and lies between rollers 16
and 18 for conveying the recording medium. The reference
numeral 1102 designates a flexible sheet in an electric
wiring portion, and the reference numeral 12 denotes
a rail which cooperates with the rail 11 to support
19 - 20401 20
1 and guide the carriage 2.
The connector holder 40 is shown as being in
a state in which after the cartridges have been mounted,
the lever 7 is brought into its broken-line position
and the fixing of the cartridges to the carriage has
been completed. The reference numerals 20 and 202
designate shafts on both sides with respect to the
direction of movement of the connector holder 40 relative
to the carriage. The shafts 20 and 202 are juxtaposed
at positions whereat their positional levels are the
same. These shafts are of a cylindrical shape movable
in two elliptical holes having their central major
axes on a straight line on both sides of the carriage.
In Figure 4, the shafts 20 and 202 correspond to the
lever 7 indicated by a solid line in the positions
indicated by solid lines. These shafts 20 and 202
more ensure the parallel movement of the connector
holder. In the present embodiment, the shafts 20 and
202 are provided outside the connector body and are
disposed above and near the push pins 10 for positioning
the recording head, and this leads to the improved
positional accuracy of the push pins 10 for positioning
the recording head. It is also possible to provide
shafts similar to the shafts 20 and 202 in the connector
body, stabilize the parallel movement of the connector
body and moreover provide a degree of freedom in the
longitudinal direction and the left to right direction
- 20 - 204 0 1 2 0
1 corresponding to the gap thereof with respect to a
side plate after the connection of the connector. In
the present embodiment, it is preferable that a slot
for the shaft 202 be made such that after the connector
body is connector-connected, the shaft 202 is not fixed
in the longitudinal direction but the positioning of
the push pins 10 for positioning the recording head
becomes dominant only over the shaft 20.
(4) Outline of the Recovery System Unit
The recovery system unit according to the present
embodiment will now be described.
Figure 5 is a schematic view for schematically
illustrating the disposition region and construction
of the recovery system unit, and in the present embodi-
ment, the recovery system unit is disposed on the homeposition side.
In the recovery system unit, the reference
numeral 300 designates cap units provided correspondingly
to a plurality of cartridges C each having a recording
head 86. The cap units 300 are slidable in the left
to right direction as indicated in Figure 14 with the
movement of the carriage 2 and are movable in a vertical
direction. When the carriage 2 is in the home position,
the cap units join with the recording heads 86 to cap
the latter.
Also, in the recovery system unit, the reference
numerals 401 and 402 denote first and second blades
- 21 ~ 204 0 1 20
1 as wiping members, and the reference numeral 403
designates a blade cleaner formed, for example, of
an absorbing material to clean the first blade 401.
In the present embodiment, the first blade 401 is held
S by a blade lifting mechanism driven by the movement
of the carriage, whereby the first blade 401 can be
set to a position in which it is protruded (lifted)
to wipe the exposed surface of an orifice plate 103
of the discharge port forming surfaces of the recording
heads 86, and a position in which it is retracted
(lowered) so as not to interfere with said exposed
surface. In the present embodiment, it is to be under-
stood that each recording head 86 is mounted so that
the portion thereof having a width b in Figure 2A lies
on the left side as viewed in Figure 5, and design
is made such that the wiping by the first blade 401
is effected when the carriage 2 is moved from left
to right as viewed in Figure 5. Thereby, the exposed
surface of the orifice plate 103 is wiped only from
a narrow portion (a portion of width a) defined by
the location at which the discharge ports shown in
Figure 2A are disposed toward a wide portion (a portion
of width b). The second blade 402 is fixed at a position
for wiping the discharge port forming surfaces of the
recording heads 86 which are not wiped by the first
blade, i.e., the surface of the keep member 109 lying
on the opposite side portions of the exposed surface
- 22 ~ 2~ 40 1 2 0
1 of the orifice plate in Figure 2A.
Further, in the recovery system unit, the
reference numeral 500 denotes a pump unit communicating
with the cap units 300. The pump unit 500 is used
to create negative pressure during the suction process
or the like carried out with the cap units 300 joined
to the recording heads 86.
(4.1) Cap Unit
Figure 6 is a plan view showing an example
of the detailed construction of the recovery system
unit.
First, the cap unit 300 has caps 302 which
are in intimate contact with the discharge ports of
the recording heads 86, holders 303 supporting the
caps, absorbing members 306 for receiving the ink during
the idle discharge process and the suction process,
sunction tubes 304 for sucking the received ink, and
a connection tube 305 communicating with the pump unit
500. The same number of (in the present embodiment,
four) such cap units 300 as the cartridges C are provided
at locations corresponding to the cartridges C and
are supported by a cap holder 330.
The reference numerals 332 and 334 designate
pins projected from the cap holder 330 and engaged
with cam slots (not shown) formed in a fixed recovery
system base 350 to guide the cap holder 330 in the
left to right direction and vertical direction as viewed
- 23 - 204 0 1 20
l in Figure 6.
As shown in Figure 14, the reference numeral
342 in Figure 6 denotes an engagement portion rising
from the cap holder 330 and engaged with the carriage
2 at a position leftward from the start position. As
the carriage 2 moves leftwardly from the start position,
the cap holder 330 is moved by the engagement portion
342 against the biasing force of a spring 360. At
this time, the cap holder 330 is displaced leftwardly
and upwardly. Accordingly, the caps 302 come into
intimate contact with the surroundings of the discharge
ports of the recording heads 86 to thereby accomplish
capping. It is to be noted that the position of the
carriage 2 in which this capping is done is the home
pOSition
Reference is now had to Figure 8 to describe
the construction and operation of the cap unit 300
according to the present embodiment. In Figure 8,
the absorbing members 306 are omitted.
The cap 302 is formed of an elastic material,
and comprises a fixed portion 302a joined to the holder
303, and an edge portion 302c for stretching a tubular
structure 302b over the fixed portion 302a, the portions
302a and 302c being molded as a unit.
The cap 302 can be formed of an elastic material
such as silicone rubber or butyl rubber.
By making the thickness of a portion t (edge
- 24 ~ 204 0 1 20
l portion 302c) shown in Figure 8 as small as possible,
the follow-up property of the cap 302 relative to the
discharge port forming surface of the recording head
can be improved. The thickness t of the edge portion
302c may preferably be greater than 0.4 mm and less
than l mm.
By virtue of such structure, the tubular struc-
ture 302b of the cap 302 has elasticity in the direction
in which the discharge port sealing means bears against
the discharge port forming surface, and this elasticity
is utilized to achieve the equalization of the cap
to the discharge port forming surface. The bearing
of the cap unit 300 against the discharge port forming
surface is accomplished by the movement of the cap
holder 330 relative to the recovery system base 350.
If at this time, the rear end side of the connection
tube 304 is opened into the atmosphere and said bearing
is effected, the interior of the cap will be held at
the atmospheric pressure and the ink meniscus in the
discharge ports will not retract even if the space
in the cap decreases.
When the cap is to be separated, a pump action
(negative pressure action) by the restitution of the
cap resulting from the separating operation is created
because the space in the cap has greatly decreased
when the cap 302 is caused to bear against the recording
head 86, and accordingly it becomes easier to retain
- 25 - 2 04 0 1 2 0
1 the ink in the cap. This is because the shrinked cap
restores its original state when the cap separates
from the recording head. Further, when the cap separates
from the recording head, the interior of the cap changes
from the negative pressure condition to the atmospheric
pressure condition and therefore, the ink is prevented
from overflowing from within the cap and the ink can
be continuedly retained in the cap. This action can
be obtained more effectively by setting a space wider
than the inner diameter of the cap right beneath the
holder 303.
(4.2) Blade Lifting Mechanism, etc.
A lifting mechanism for the first blade 401
will now be described.
Referring again to Figure 7, the reference
numeral 410 designates a vertically movable blade holder,
on the upper portion of which the first blade 401 is
mounted by a mounting means 411. The reference numeral
412 denotes a holder returning spring for biasing the
blade holder 410 to its lowered position.
The reference numeral 430 designal a lock lever
pivotally movable about a pin 414 projectedly provided
on the blade holder 410 and engageable with the upper
surface portion of a stopper 432 to thereby lock the
blade holder 410 in its elevated position. The lock
lever 430 is biased upwardly as viewed in Figure 7
by a spring 434. Also, in the state shown in Figure
- 26 - 2040120
1 7, the lock lever 430 is engaged with a portion project-
edly provided on the blade holder 410 and is held in
the position shown.
The reference numeral 440 denotes a release
lever pivotally movable about a pin 418 projected from
the blade holder 410 to release the locking state of
the lock lever 430 in the elevated position of the
blade holder 410. The release lever 440 releases said
locking by moving upwardly of the pin 418. That is,
a pin 442 engageable with the lock lever 430 is studded
on the release lever 440, and when the release lever
440 pivots counter-clockwise about the pin 418 as viewed
in Figure 7, the pin 442 pivotably moves the lock lever
430 about the pin 414, thereby releasing the engagement
between the lock lever 430 and the upper surface portion
of the stopper 432.
These mechanisms are for elevating the blade
holder 410 by a driving force from a cam (not shown)
operated with the movement of the carriage 2, and are
not of restrictive construction to the present invention.
Figure 9 is a side cross-sectional view showing
the details when the blade 401 effects wiping. As
shown in this figure, in the present embodiment, wiping
is effected only from the portion in which the width
from the discharge ports to the level difference portion
is small to the portion in which said width is great.
That is, wiping is effected in the direction in which
~ 7 ~ 2040 1 20
1 the arrangement of the discharge ports is biased on
the orifice plate 103. By doing so, a clean discharge
port surface is represented by wiping and it becomes
possible to keep a good dishcarge condition even if
the neighborhood of the discharge ports is wet or dust
or the like adheres to the discharge port surface.
If conversely, wiping is effected from the
portion in which the distance from the discharge ports
to the level difference portion is great to the portion
in which said distance is small, any ink and dust which
could not be removed will collect in the narrowed
level difference portion with the result that the short
distance may cause the orifices to be closed by the
remaining ink and dust, and this is not preferable.
In the present embodiment, the first blade
is appropriately moved up and down as described above,
whereby wiping is effected from the portion in which
the distance to the level difference portion is small
to the portion in which said distance is great, and
even in the worst case, the ink and dust do not come
to the discharge ports 108 and therefore, it becomes
possible to maintain a stable discharge condition without
affecting the discharge ports.
Now, in the present embodiment, the wiping
direction is prescribed as shown in Figure 9 and there-
fore, if no consideration is paid to the wiping speed,
i.e., the movement speed of the carriage 2, there may
204Q 1 20
1 arise a problem in the follow-up property with respect
to the unevenness of the discharge port forming surface,
due to various factors (such as modulus of elasticity,
etc.) determined by the material, shape, etc. of the
blade 401. That is, there may occur the inconvenience
that the first blade 401 cannot follow up the level
difference portion and when this restitutes, the first
blade has already skipped over the discharge ports
108. So, in the present embodiment, those factors
are taken into consideration so that during wiping,
the carriage 2 may be moved at a lower speed than during
the ordinary scanning to thereby ensure the neighborhood
of the discharge ports to be reliably wiped.
Figure 12 illustrates the manner of cleaning
by the blade 401. As described above, with the sliding
of the cap unit 300, the blade 401 is elevated, where-
after wiping is effected with the rightward movement
of the carriage 2. At this time, in the present embodi-
ment, the ink wiped off and received by the blade 401
flows only along the surface of the blade 401 and does
not drip into the apparatus.
As shown in Figure 12, the blade 401 is lowered
when the carriage 2 moves from right. The blade cleaner
403, even if mounted on the cap unit 300, is in contact
with the blade 401 because the cap unit 300 has already
returned to its original position. Accordingly, with
the lowering of the blade 401, any ink or the like
2040 1 20
1 adhering to the surface thereof is received by the
cleaner 403 in the form of an absorbing member and
thus, is reliably wiped off by the blade 401.
(4.3) Pump Unit
The pump unit 500 will now be described with
reference to Figures 6 and 7.
The reference numeral 502 designates the
regulation surface of the recovery system base provided
in the form of a semicylindrical surface. Tubes 304
constructed as flexible members are caused to creep
on at least the regulation surface 502. The reference
numeral 510 denotes a pressing roller which rotates
about a pump shaft 504 while urging the tube 304 against
the regulation surface 502. The pressing roller 510
rotates while pressing the tubes 304 in the direction
of arrow, thereby creating negative pressure in the
space leading to the cap unit 300 and effecting ink
suction from the discharge ports.
The reference numeral 520 designates a guide
roller for rotating the pressing roller 510. The guide
roller 520 is supported on the pump shaft 504. The
reference numeral 522 denotes a holder for mounting
the shaft 512 of the pressing roller 510 on the guide
roller 520. The reference numeral 524 designates a
partition wall as a guide provided integrally with
the guide roller 520 to suppress the tubes 304 and
separate them from one another. The reference numeral
~ 30 ~ 204 0 1 20
1 526 denotes a position cam made integral with the guide
roller 520 to receive the transmission of a driving
force for rotating the guide roller 520. The reference
numeral 528 designates a pump driving gear having a
gear meshing with a gear 15A provided on the shaft
of a recording medium conveying (sub-scanning) roller
15 and a gear provided integrally with a position cam
526. That is, in the present embodiment, the driving
force for pump driving (the rotation of the pressing
roller) is received from the roller 15.
The reference numeral 530 denotes a leaf switch
as detection means provided to recognize the roller
position. The leaf switch 530 is switched by a cam
532 rotating about the pump shaft 504 with the guide
roller 520.
(5) Sequence of the Recording Apparatus
(5.1) Position Setting of the Pressing Roller
Description will first be made of the setting
of the position of the pressing roller of the pump
unit 500 for causing a suction force to act to forcibly
discharge the ink from the recording head 86.
In Figure 13 which is an illustration of it,
~ - ~ are the set positions of the pressing roller
510. Also, in Figure 13, it is to be understood that
the counter-clockwise direction (the direction in which
suction is effected) is "t" and the clockwise direction
i s
- 31 - 2040120
1 First, the position ~ is a state in which
the pressing roller 510 is not crushing the tube 304,
and in this state, the interior of the cap or the ink
suction system is in communication with the atmosphere
even during capping. The positions ~ and ~ are
positions in which the pressing roller 510 is stopped
after it has rotated in the + direction while crushing
the tube 304 along the regulation surface 502, and
in these set positions, the tube 304 is crushed and
therefore, during capping, the interior of the cap
or the suction system is hermetically sealed with
respect to the atmosphere.
In the present embodiment, there are two forms
of recovery process by ink suction. One form is that
effected by the operation of suitable operation means
such as a switch or effected automatically as when
the ink discharge condition does not become good after
a relatively long-period downtime of the apparatus
or even by mere idle discharge, wiping or other recovery
process. At such time, the ink is difficult to be
discharged due to an increase in viscosity or other
cause and therefore, a great suction force is made
to act on the discharge ports in the cap, that is,
the flow speed of the ink is increased, thereby suddenly
discharging the ink. Simultaneously therewith, an
idle discharge operation is executed (this is called
great recovery or recovery using period).
- 32 - 2040120
1 The other form is that effected to better the
discharge condition by refreshing or cooling immediately
after a predetermined amount of recording operation.
Particularly in the apparatus like the present embodiment
which uses heat energy as discharge energy, the temper-
ature of the ink becomes high to some degree and
therefore the viscosity of the ink becomes small at
this time and the ink is relatively easy to be discharged
and therefore, a suction force smaller than that during
the great recovery is made to act on the ink to effect
the discharge of the ink (which will hereinafter be
referred to as small recovery~.
During the great recovery and the small recovery,
in the present embodiment, the pressing roller 510
rotated in the + direction is set at the positions
~ and ~ and held thereat for a predetermined time.
The acting suction force and the amount of suction
are determined by an increase in the content volume
of the ink suction system, i.e., the content volume
corresponding to the length from a position in which
the pressing roller 510 rotated in the + direction
begins to crush the tubes 304 to the stopped position
and therefore, when the pressing roller 510 is stopped
at the position ~ , the suction force becomes smaller
than when the pressing roller is stopped at the position
~ . Thus, the ink is sucked out more slowly from
the discharge ports during the small recovery than
~ 33 ~ 204 0 1 20
1 during the great recovery. According, the state of
the ink flow becomes stable and minute bubbles or the
like which may be present inside the discharge ports,
i.e., such minute bubbles or the like that cannot be
removed due to the creation of turbulence or eddy when
the suction force is great and the state of the ink
flow is not stable, can also be reliably eliminated.
Also, at this time, the amount of ink sucked becomes
smaller and therefore, it never happens that the ink
is consumed more than necessary.
If it is intended to reduce chiefly the amount
of ink consumed, the pressing roller can be set at
the position ~ also during the small recovery and
the time for which the pressing roller is stopped thereat
can be made smaller than during the great recovery.
Also, if it is intended to ensure chiefly the removal
of minute bubbles or the like, the rotational speed
of the pressing roller 510 may be decreased during
the small recovery so that ink suction may be effected
slowly. Further, in this case, if the stopped position
is determined appropriately, a reduction in the amount
of ink consumed can also be achieved.
As the means for forcibly discharging the ink,
use may be made of other form of suction pump or means
for effecting forced discharge by pressing the ink
supply system leading to the discharge ports, but the
use of the pump unit 500 as in the present embodiment
- 34 - 2 04 0 1 20
1 will make the above-described control or regulation
easy to accomplish.
(5.2) Position Setting of the Carriage
The position setting mode of the carriage 2
will now be described with reference to Figure 14.
In Figure 14, ~ - ~ are positions when the head
positioned most adjacent to the recording area is the
reference.
Figure 14A shows the reversing position during
wiping. Further, in the present embodiment, this posi-
tion is defined as a position set when capping is effected
or when the blade 401 is elevated. In the present
embodiment, the operation for capping or the operation
for protruding the blade is performed with the movement
lS of the carriage 2 and therefore, it is necessary that
a force greater than a certain degree be transmitted
from the carriage 2. So, if the carriage 2 is set
at the appropriate position ~ and is moved from this
position to thereby utilize the inertia thereof, a
driving force sufficient to drive the above-described
mechanism will be obtained without bringing about the
bulkiness of a motor which is the drive source of the
carriage 2 and an increase in the driving electric
power.
Next, the position ~ in Figure 14B shows
the start position which is the start position of the
recording operation and the reversing position during
- 35 - 2040 1 20
l the recording operation. At this time, the respective
heads 86 become opposed to the respective caps 300,
but the cap holder 330 and the blade holder 410 are
not yet driven and accordingly, the caps 300 are separate
from the heads 86 and the blade 401 is not yet elevated.
Idle discharge is effected in this position.
The position ~ indicated in Figure 14C is
a position at which the upward movement of the blade
holder 410 is started. The blade holder passes this
position or is set at this position when capping is
effected or when wiping is effected. The position ~
in Figure 14D is a position at which capping is effected
with the cap holder 330 elevated, and in this position,
the great recovery or the small recovery is effected
or the standby during the downtime of recording is
effected.
(5.3) Summary of the Operation Sequence
Figures 15A - 15E show a summary of the operation
sequence in the present embodiment. In these figures,
"1" is a column showing the position of the pressing
roller 510, and "2" is a column showing the position
of the carriage 2. ~ - ~ are the same as the roller
positions shown in Figure 13, and ~ - ~ are the
same as the carriage positions shown in Figures 14A -
14D.
Figure 15A shows the initial process time afterthe closing of the power switch, and in this process,
- 36 - 204 0 1 20
1 the initialization of the positions of the pressing
roller and the carriage is effected. Figure 15B shows
the state when a command for the starting of recording
is given as by the depression of a copy button, and
after this, the feeding of the recording medium by
a cassette or by manual supply is effected. Figure
15C shows the process during wiping or idle dishcarge
effected at suitable timing (for example, each recording
scan of 5 - 10 lines) during the recording process.
Figure 15D shows the recording termination process
including the small recovery process carried out
immediately after the termination of a predetermined
amount of recording (in the present embodiment, recording
of one page onto the recording medium). Figure 15E
shows the process during the great recovery.
The details of these will be described later
with reference to Figures 17 and 18.
37 2040 1 20
1 Figure 16 shows an example of the
construction of the control system of the present
embodiment.
In Figure 16, the reference numeral 800
designates a controller which forms the main
control portion and which has a CPU 801, for
example, in the form of a microcomputer for
executing the procedure shown in Figures 17 and
18, an ROM 803 storing therein a program
corresponding to that procedure and other fixed
data, and an RAM 805 provided with an area for
developing image data and an area for work. The
reference numeral 810 denotes a host device
which forms a supply source of image data (the
host device may be a reader unit, i.e., the means
212 of Figure 6 or the like). Between this host
device and the controller, image data and other
command and status signals, etc. are transmitted
and received through an interface (I/F) 812.
The reference numeral 820 designates
switches for receiving the command input by the
operator, including a power switch 822, a copy
switch 824 for commanding the start of recording
(copying) and a great recovery switch 826 for
commanding the start of the great recovery. The
reference numeral 830 denotes sensors for detecting
the state of the apparatus, such as a sensor 832
38 20401 20
1 for detecting the positions of the carriage 2
such as the home position and the start position,
and a sensor 834 including the leaf switch 530
and used to detect the position of the pump.
The reference numeral 840 designates a
head driver for driving the discharge energy
generating elements (in the present embodiment,
the electro-thermal conversion members) of the
recording heads 86 in conformity with recording
data or the like. The reference numeral 850
denotes a main scan motor for moving the carriage
2 in the main scanning direction (the left to right
direction in Figure 7), and the reference numeral
852 designates a driver for the main scan motor.
The reference numeral 860 denotes a sub-scan motor
which is used to convey (sub-scan) the recording
medium and in the present embodiment, drives the
pressing roller 510 through the roller 15. The
reference numeral 854 designates a driver for the
sub-scan motor. The reference numeral 870 denotes
a suction pump such as the aforedescribed tube
pump, the driving of which is governed by a motor
driver 853.
(5.5) Control Procedure
Figure 17 is a schematic flow chart of
the recording process procedure according to the
present embodiment.
2040 1 20
1 When the power switch 822 is closed, the
present procedure starts, and first at a step SA,
the initial process is carried out. Next, at a
step Sl, a command signal for the starting
of recording, such as a signal for the operation
of the copy switch 824, or a command from the host
device 810, or a paper feeding signal during the
so-called manual paper supply, is waited for. When
this is instructed with the inputting of image
data from the host device 810, a recording prepara-
tion process is carried out at a step SB.
Thereafter, at a step S3, the recording
of a predetermined number of lines (in the present
embodiment, plural lines of 5-10) is effected, and
lS at a step S5, whether the recording of one page
has been terminated is judged. If the judgment is
negative, the recovery process during recording
of a step SC is carried out, that is, one recovery
process is carried out each time the recording of
a predetermined number of lines is terminated,
and if the judgment is affirmative, a record
termination process is carried out at a step SD,
whereafter shift is made to the step Sl.
The details of the steps SA - SD and the
details of the great recovery process will now be
described with reference to Figures 18(A) - (D)
and (E). The sequences in Figures 18(A) - (E)
2040 1 20
1 correspond to Figures 15A - 15E.
First, as shown in Figure 18(A), during the
initial process, the setting of the carriage 2
to the home position (the position ~) is effected
at a step SAl. Also, at this time, the pressing
roller 510 is set at the position ~ (which will
hereinafter be also called the roller's home
position). In the setting of the carriage 2 to
the home position, the movement thereof is utilized
to drive the cap holder 330 and the blade holder
510 and therefore, the carriage 2 is set at a
suitable position in which the carriage does not
overlap with the recovery system unit (for example,
the position ~ in Figure 16) to obtain an
appropriate inertia force so that an approach run
may be effected. By the setting of the carriage
to the home position, the recording heads 86 are
capped and the space in the caps becomes hermetically
sealed. Also, at this time, the blade 401 protrudes
and has passed the position for being locked (the
position ~ in Figure 14) and therefore, the blade
401 is in its elevated position (this operation
is similar also in the following). If the carriage
2 and the roller 510 are in their respective
home positions, the present step may be skipped.
Subsequently, at a step SA3, the carriage
2 is moved toward the position ~, whereby the
41 2040 1 20
1 wiping of the discharge port forming surface is
effected. This is because the blade 401 has
already protruded by the setting of the carriage
2 to the home position. The movement at this
time, as previously described, is effected at a
speed lower than that during the ordinary recording
scan, l.e., a speed at which the blade 401 follows
the level difference to effect reliable wiping.
Next, at a step SA5, the pressing roller
510 is rotated to the position ~, and at a step
SA7, the carriage 2 is set at the start position
(the position B in Figure 14), and idle discharge
is effected at this position. That is, idle
discharge is effected after wiping. This is similar
also in the ensuing process, and in the present
embodiment, idle discharge is effected without
fail after wiping. With the movement to the start
position, the carriage comes into engagement with
the release lever, and in order to operate this,
the blade 401 is lowered as previously described.
The idle discharge is effected to prevent
color mixture or the like which may occur by one
blade wiping a plurality of recording heads, and
in the present embodiment, in order to accomplish
this more effectively, idle discharge is more
deliberately effected for the recording heads
wiped later or the recording heads corresponding to
42 2040 1 20
1 ink having high brightness of color (such as yellow)
because color mixture is readily conspicuous in
such recording heads. That is, for those recording
heads which are readily susceptible to color
mixture, the time for which the idle discharge
process is carried out is lengthened or the
frequency of discharge is increased.
Also, in the present embodiment, the
driving frequency for the electro-thermal conversion
members is made lower (e.g. 114) during idle
discharge than during ordinary recording. This is
because it has been confirmed that a lower driving
frequency results in less wetness of the discharge
port forming surface by the ink. Further, in
effecting idle discharge, the group of discharge
ports is divided into blocks for each predetermined
number (e.g. 8) so that the electro-thermal
conversion members may be successively driven in
each block. It has also been confirmed that this
makes it difficult for wetness to occur. These
modes are similar also in idle discharge effected
in the following.
To make it difficult for wetness to occur,
the width, voltage, shape, etc. of the driving
pulse may be changed instead of or simultaneously
with changing the driving frequency, and the
manner of driving may be suitably determined.
4~ 2040 1 20
1 After such idle discharge, at a step SA9,
the carriage 2 and the roller 510 are set at their
respective home positions. Here, the carriage
2 is first set at its home position to thereby
effect capping, but at this time, at a step SA5,
the roller 510 is set at the position K for
communlcation with the atmosphere and therefore,
positive pressure does not act in the caps even
by a change in the volume in the caps during
capping and accordingly, it never happens that
air comes into the discharge ports. Thereafter,
the roller 510 is rotated in the - direction in
Figure 13 (if rotated in the + direction, the roller
will absorb the ink and this is not preferable
from the viewpoint of reducing the amount of ink
consumed) and is set at the position ~. Thereby
the interior of the tubes 304 or the caps becomes
somewhat pressurized and the ink received during
the previous idle discharge remains without being
sucked and the interior of the caps is kept at a
wet atmosphere and therefore, it becomes difficult
for the evaporation of the ink solvent component
from the discharge ports to occur.
When the starting of recording is commanded
(step Sl), the preparation process is carried out
as shown in Figure 18(B) before shift is made to
the recording operation (step S3). Here, first at
4~ 20401 20
1 a step SBl, wiping similar to the step SA3 is
effected (the present procedure is carried out
after the setting to the home position at a step
SA9 and therefore, the blade 401 is already in
its elevated position and accordingly, wiping is
effected by the movement of the carriage to the
position ~). Subsequently, in a manner similar
to the step SA7, the carriage 2 is set at the
start position and idle discharge is effected.
The subsequent recording operation is performed
always from this position ~.
In the recovery process during recording
which is carried out each time a predetermined
number of lines are recorded, as shown in Figure
18(C), at a step SCl, the carriage 2 is first
moved to the position ~ and the blade holder 410
is driven to protrude the blade 401. Thereafter,
as at the steps SBl and SB3, wiping (step SC3)
and the setting to the start position and idle
discharge (step SC5) are executed. If the
present procedure is executed while the conveying
process of the recording medium is carried out, the
throughput of recording will not be greatly
reduced.
When the recording of one page is
terminated and the recording medium for that page
is discharged, the pressing roller 510 is
2040 1 20
1 subsequently set at the position ~ as shown in
Figure 18(D) (step SDl). In this state, at a
step SD3, the carriage 2 is set at the home
position and capping is effected.
Subsequently, at a step SD5, the small
recovery operation is performed. Here, the
pressing roller is first set at the position ~
and is held in this position for a predetermined
time (e.g. 0.1 second), and ink suction is effected.
Thereafter, at steps SD7, SD9, SDll and SD13,
processes similar to the steps SA3, SA5, SA7 and
SA9 are carried out, and the apparatus holds the
next recording start command with the recording
heads being capped.
When the great recovery switch 826 is
operated, the process shown in Figure 18(E) is
started. In the present procedure, at a step SEl,
the setting of the carriage 2 to the home position
(the position ~) and the setting of the pressing
roller 510 to the home position (the position ~)
are effected, whereafter the great recovery of a
step SE3 is effected. Here, the pressing roller
510 is rotated in the + direction and reset at
the position ~, and is held in this position for
a predetermined time (e.g. 2-3 seconds) and ink
suction is effected. At the same time, a
predetermined idle discharge operation is performed.
46 2040 1 20
1 Thereafter, at steps SE5, SE7, SE9 and SEll,
processes similar to the steps SA3, SA5, SA7 and
SA9 of Figure 18(A) are carried out, thus terminating
the present procedure. To effect suction and
idle discharge at a time, for example, prior to
great recovery, predetermined driving data for
idle discharge can be set in the driver 840 and
this driver can be started at suitable timing.
The purpose and effect of effecting ink
suction and idle discharge at a time during the
great recovery process as in the present embodiment
are as follows.
Figure 19 shows a state in which, in the
head chips, dissolved gases are deposited in the
ink by the apparatus being left as it is or
residual bubbles or the like during the discharge
gather to form many foams.
When in this state, the discharge energy
generating elements such as the electro-thermal
conversion elements 112 are driven to perform
the discharge operation for recording, the ink is
supplied from the liquid chamber 106 into the
liquid paths 107 which have effected discharge
and therefore, the flowage of the ink takes place
in the common liquid chamber 106. As a result,
negative pressure is created and therefore,
bubbles gather in the liquid paths to hinder the
47 2040 1 20
1 supply of the ink to the liquid paths. Accordingly,
discharge becomes unstable and slippage or non-
discharge occurs. In an extreme case, bubbles may
stick to the rear ends of the liquid paths to
completely shut off the supply of the ink into the
liquid paths, thus causing non-discharge.
If a number of bubbles are present in this
manner, discharge will become unstable and
therefore, usually the bubbles are first removed
as by suction or pressurization. However, where
ink of high viscosity is employed or where ink
has become high in viscosity under low temperature
environment, bubbles can hardly be removed even
if recovery is effected as by suction. For from
it, the ink will only be wasted.
Figure 20 shows the size of bubbles and
the rate of bubbles which could not removed even
by suction but remained.
The diameter of the liquid paths in the
recording head at this time was 40 ~m, and a
multinozzle head having sixty-four discharge ports
was used. The maximum negative pressure created
by the suction pump is -0.5 atm.
It can be seen from this figure that
bubbles larger than the diameter of the liquid
paths are difficult to remove, but bubbles larger
than a certain degree of size are easy to remove.
48 2040 1 2~
1 That is, bubbles smaller than the diameter of the
liquid paths can of course be removed, and it is
considered that even bubbles larger than the
diameter of the liquid paths, if they become larger
than a certain degree of size, are deformed and go
into the liquid paths and such bubbles communicate
with the atmosphere through the liquid paths,
whereby the ink fills the liquid paths again.
As shown, the remain rate of bubbles can
be decreased by increasing the negative pressure of
the pump (-0.5 atm ~ -0.6 atm), but a great effect
cannot be expected from doing so, and it is not
desirable from the viewpoint of making the pump
construction compact.
Also, what has been noted above is remarkable
when the dye concentration of the ink is increased
to realize a high concentration or when the size
of the discharge parts are made small to provide
high resolution. The fact that the dye concentration
is high means that viscosity is high, and with
small discharge ports, as compared with large
discharge ports, bubbles must be considerably
deformed and made smaller than the discharge ports
when bubbles of the same size are to be removed.
In addition, it is difficult to remove
bubbles unless use is made of a pump capable of
creating considerable negative pressure during
49 20401 20
1 suction, and in some cases, the ink is discharged
from only the liquid paths which are not blockaded
by bubbles during suction, and the blow of the ink
in those portions become bast and the flow of the
ink in the liquid paths blockaded by bubbles
become slow and therefore, negative pressure
becomes relatively great in the liquid paths
wherein the flow of the ink is bast and thus,
bubbles become more difficult to remove.
So, in the present embodiment, during
the great recovery of the step SE3, the discharge
of the ink is effected simultaneously with suction.
That is, by the ink in the liquid paths
being discharged, the negative pressure in the
liquid paths after discharge momentarily becomes
great, and this, coupled with the negative pressure
for suction, creates considerably stronger negative
pressure than in the case of a pump singly and
moreover, that negative pressure acts equally on
each liquid path and thus, the removal of bubbles
becomes easy. Further, in the case of the present
embodiment, the electro-thermal conversion members
112 as the means for creating bubbles during
discharge (the discharge energy generating elements)
are driven and therefore, the temperature of the
ink in each liquid path rises to reduce the
viscosity of the ink and reduce the surface
so 20401 20
1 tension of the ink and thus, the flow path resistance
power in the liquid paths become smaller and the
removal of bubbles becomes easier. This is
particularly effective because the viscosity
increase when the head has been left as it is for
a long time has considerably progressed.
That is, if as shown in Figure 21A, the
cap is brought into intimate contact with the
entire discharge port forming surface and suction
is effected by the pump and at the same, the ink
is discharged from the discharge ports, bubbles
which have only been drawn near the rear ends of
the liquid paths but have not been absorbed
outwardly by suction alone will go into the
liquid paths and will be discharged outwardly
because, by discharge being effected at the same
time, flows of ink occur in the liquid paths and
the negative pressure in the liquid paths increases.
Thereby, as indicated by a dot-and-dash
line in Figure 20, the bubbles in the inner part
of the discharge ports are removed and it becomes
possible to accomplish stable discharge.
(6) Other Embodiments
In a second embodiment of the present
invention, when discharge is effected simultaneously
with suction, use is made of a driving condition
exceeding the ink refill frequency which is the
51 2040 1 20
1 limit of the discharge characteristic of the head.
By doing so, bubbles in the liquid paths are drawn
rearwardly by suction and further, these bubbles
go into the liquid paths due to the increase in
the negative pressure in the liquid paths caused
by discharge. On the other hand, in the end
portions of the liquid paths, discharge is effected
at a frequency greater than the limit of the
refill frequency and therefore, meniscus is
vibrating. Assuming that the frequency, in other
words, the interval of bubbling, is the time during
which the retraction of meniscus is maximum, bubbles
formed from the electro-thermal conversion elements
(heaters for discharge) and the meniscus will be
united and the rear end of the meniscus will become
sharp.
Consequently, the bubbles in the liquid
chamber which have entered from the rear ends of
the liquid paths and the rear end portion of the
meniscus increased from the fore end will be
united.
When this state is created over the
entire head, air flows at a strike from the outside
into the liquid paths and therefore, there is
brought about a state in which no ink is present
in the liquid chamber (referred to as "ink-fall").
The exhaustion of the ink results in the bubbles
52 2040 1 20
1 being absorbed and becoming null.
In the construction of the cartridge C
like the present embodiment wherein an absorbing
member or the like is placed in the ink tank 80
to thereby render the head into negative pressure
relative to the atmosphere, the above-mentioned
ink fall is expedited. In such a cartridge,
however, only the ink in the inner part of the
discharge ports of the head chip become null
even if the ink fall occurs, and almost all of
the ink corresponding thereto returns into the
tank. Consequently, the ink hardly leaves the
head and thus, the ink is not wasted.
As shown in Figure 21B, suction is effected
after the ink in the inner part of the discharge
ports becomes substantially null. At this time,
the suction capacity of the pump is set such that
the interior of the head chip is filled with ink
and the suction of a further surplus amount can
be accomplished.
Thereby, the amount of waste ink required
for recovery can be minimized and the running cost
of the cartridges, and in its turn, the recording
apparatus, can be reduced.
In a third embodiment of the present
invention, before the process according to the first
or second embodiment is carried out, an external
53 2040 1 20
l heater is driven or a discharge heater is driven
so that such a degree of heat that will not cause
discharge may be generated therein, thereby
raising the temperature of the ink in the liquid
paths and reducing the viscosity and surface
tension of the ink. Thereby, bubbles are united
and readily become large bubbles and further, the
fluidity of the ink increases and therefore, the
effects of the first and second embodiments are
more improved as indicated by a solid line in
Figure 20. Where the present invention is applied
to a method of causing ink fall as in the second
embodiment, the surface tension of the ink is
reduced and therefore the meniscus force at the
fore ends of the liquid paths weakens and further,
the refill frequency is reduced by the reduction
in the surface tension and thus, it becomes
possible to cause ink fall effectively without
making the discharge interval smaller than the
shortest discharge interval of the body (which
corresponds to a case where so-called solid
printing is effected).
In a fourth embodiment of the present
invention, during suction, liquid paths to be driven
are limited to particular ones (for example, the
liquid paths on the opposite sides of a plurality
of liquid paths are driven and conversely the
~4 2040 1 20
1 central area is (not driven). That is, if the
ink is discharged from all liquid paths, it will
become difficult for bubbles to be deformed
because each bubble is subjected to a force from
the plurality of liquid paths, whereas in the
fourth embodiment, negative pressure is made to
act concentratively from predetermined liquid
paths, whereby the degree of deformation of
bubbles can be enhanced.
In a fifth embodiment of the present
invention, as shown in Figure 21C, the start
timings of suction and discharge are not made
completely simultaneous with each other but are
more or less staggered relative to each other.
That is, design is made such that the maximum
generated pressure during suction and the maximum
negative pressure during discharge take place at
the same time. This is because the maximum
negative pressure during discharge takes place
when formed bubbles disappear, and takes place
substantially simultaneously with discharge, while
the maximum generated pressure by the pump is
delayed by a time for which the roller or the like
of the pump is moved. That is, it is better that
the suction operation is effected more or less
earlier than discharge. Thereby, the removal
rate of bubbles can be greatly enhanced.
5~ 2040 1 20
l The present invention is not restricted
to the above-described embodiments, but of course,
any desired modifications can be applied thereto
without departing from the spirit of the invention.
As such modifications, mention may be made, for
example, of the following, in addition to those
described here and there in this specification.
For example, during the small recovery
process as well, if necessary, idle suction may
be effected simultaneously with suction, and the
great recovery process may be suitably divided
into two kinds, i.e., a kind in which suction
alone is effected and a kind in which suction and
idle discharge are used at a time.
Also, the pump for causing a suction
force to act may be not only in the form using a
tube and a rollers as described above, but also in
a form comprising a cylinder and a piston. Further,
the pump may be not only one which sucks the ink
from the discharge ports and effects forced discharge,
but also one which pressurizes the ink supply system.
Figure 22 illustrates the flow chart of a
preferred embodiment of the present invention as
a recovery mode, without sticking to the above-
described preferred forms of the apparatusconstruction.
The recovery state of the present invention
- 56 20401 20
1 becomes more preferable if a greater quantity of
ink can be uniformly discharged from each discharge
port of the head per unit time. In the present
embodiment, the recovery mode STl is adopted as a
flow chart or as ordinary main suction recovery
by a signal from a selection key.
The heating step ST2 for the ink in the
head is a carried out in accordance with a recovery
mode command. This step ST2 may preferably raise
the temperature of the interior of the common
liquid chamber, but may raise the temperature
of only the interior of the liquid paths of the
head. More preferably, this step may raise the
temperatures of both. Well-known means such as
an external heater or a heater in the liquid
chamber can be adopted for the heating of the
common liquid chamber. The heating of the liquid
paths can be accomplished simply by supplying an
electrical signal so as to effect the aforedescribed
preheating if the discharge energy generating
elements are heat generating elements for forming
bubbles. Where conversely, the discharge energy
generating elements are electro-mechanical
conversion elements, heating may be done by the
utilization of a heater capable of heating each or
all of the liquid paths, or light energy or the
like. By this step ST2, the inertial force by
57 2040 1 20
1 the fluid resistance between the ink and the inner
wall of the head can be decreased and the load
during the initial movement can be mitigated.
Subsequently, the driving step ST3 for the
elements for discharging the ink is carried out
substantially simultaneously with the step of
driving the suction means (and/or pressure means).
This brings about the action of initiating the
start of the movement of the ink itself on the spot
with the start of the ink suction of the suction
means or quickening said start. It has already
been described that the uniformization of the ink
suction force acting or respective ones of a
plurality of liquid paths and discharge ports can
be achieved and also the recovery efficiency can
be improved. In the present invention, carrying
out the steps ST3 and ST4 substantially at a time
includes all that can achieve a generally uniform
suction action and a recovery effect excellent as
a whole within a relatively short time without
making the recovery pump device bulky as in the
conventional suction recovery.
In any case, the above-described embodiments
reduce the inertia force of the ink and improve
the initial ink discharge condition and therefore
can solve the problems peculiar to the prior art.
Reference is now had to Figures 11 and 12
5$ 2040 1 20
l to describe another example of the recovery mode
of the present invention having a recovery using
period during which the driving period for the
discharge energy generating elements and the forced
discharge period utilizing the suction or pressing
pump or the like are used together and executed.
A plurality of inventions are covered in the
following description.
Figure ll is a graph in which the abscissa
represents time T and above is shown the pressure
P (static pressure) in the ordinate showing the
variation in pressure during the forced discharge
period and below is shown the pulse voltage V
in the ordinate during the element driving period.
PMAX is the maximum pressure during the forced
discharge period and is produced at a time T4.
This can be mentioned, for example, as the maximum
pressure produced in one stroke of the pump. P2
indicates a pressure value which is 50% of the
maximum pressure PMAX, and Pl indicates a pressure
value which is 30% of the maximum pressure PMAX.
The times when these pressures Pl and P2 are
exhibited are T2 and T3 in succession. The
pressures Pl and P2 are produced during the
pressure rise and during the pressure fall, and
the time when the pressure Pl is produced is a
time T5. A time Tl is the time when the pressure
59 2040 1 20
1 is produced, and a time T6 is the time when the
pressure disappears. T0 is the time when a
start signal for the recovery mode is received.
In the present example, a plurality of
pulses PUL of the voltage Vp for recovery are
input during a time T3 to a time T4. Respective
ones of these pulses are input to all discharge
energy generating elements of the recording head
substantially at a time. In this example, at
least one element driving pulse is supplied during
the forced ink discharge period from a point of
time whereat the pressure is 50% of the maximum
pressure PMAX at static pressure until the pressure
becomes the maximum pressure PMAX. Thus, according
to the present example, the recovery force during
the first half of the pressure rise period is
greatly sharpened in its course and therefore, the
loss of pressure increment which would otherwise
be offset because the initial recovery force
overcomes the inertia force of the ink can be
prevented. From this point of view, it is a
preferable condition to impart the element driving
pulses for more than the time T2, i.e., at 30% or
more of the maximum pressure PMAX. Of course, as
regards the increased pressure, one provided by
the formation of bubbles by heat generating elements
is more preferable than one provided by piezo-electric
60 20401 20
l elements because the former is sharper.
A further example will be described with
reference to Figure ll. In the above-described
example, the element driving pulses PUL are input
during the increase in the pressure P, but an
increase in the recovery force which means an
increase in gross pressure can be achieved by
imparting the element driving pulses during the
fall of the pressure P. From this point of view,
it is preferable to impart said pulses until the
time T5 when pressure Pl is reached, preferably
during the period until the time T6 when the
pressure P is present. Discussing now the termination
of the forced discharge period and the termination
of the element driving period, the pressure P
for forced discharge decreases and therefore,
in some cases, a slight amount of ink which has
been brought to the vicinity of the discharge
ports by slight pressure may remain on the discharge
port forming surface and thus, it is preferable
to continue to supply the element driving pulses
PUL still for a predetermined period after the
time T6 when the pressure P disappears, i.e.,
until the time T7, and more improve the state of
each ink path by a sudden discharge force.
Now, in the aforedescribed flow chart
of Figure 18(E), the sequence in which the great
- 61 2040 l 20
1 recovery, i.e., the recovery mode having the
above-described recovery using period, is executed,
whereafter the discharge port forming surface is
cleaned and thereafter idle discharge is effected
is preferable for the following reason. The great
recovery is used for both of the purpose of
eliminating the stay of bubbles in the head and
the purpose of discharging any cause of clogging
out of the discharge ports. At such time, unnecessary
matters such as dust and solid matters which have
gone out of the discharge parts may remain around
the discharge ports. The cleaning step is impor-
tant to remove these matters effectively, because
even if there are minute unnecessary matters which
will be slightly returned toward the discharge
ports by this cleaning, they can be reliably
separated from the discharge port forming surface
by the discharge force of idle discharge, without
resorting to the great recovery.
Discussion will further be made of the
time when the forced discharge period is started
and the time when the element driving period is
started. At the early stage of the recovery process,
there is the inertia force provided by the intimate
contact between the ink and the ink path wall or
the ink chamber wall, and the loss of energy is
great when the puming force for forced discharge
62 2040 1 20
1 is resorted to as recovery pressure. As an example
which solves this problem, mention may be made of
starting the element driving period at the time Tl
when the pressure P is produced. This preferably
leads to effective utilization of the pumping force.
It is more preferable to effect the element driving
also for the time Tl to the time T2. In addition,
starting the element driving period during the
time T0 when a recovery signal is output before
the time Tl is preferable because the ink flow
state of all discharge ports can be formed before
the forced discharge. The element driving pulses
supplied from such preceding start of the element
driving period until the above-described recovery
using period may preferably be constant in period.
Further, it will provide a preferred embodiment
that in order to obtain a maximum recovery force,
the element driving pulses are applied at the time
T4 and more specifically, the maximum growth times
of bubbles formed by the heat generating elements
are made coincident with each other.
In the present invention, of course, the
foregoing description of the constructions according
to Figure 11 covers all examples in which those
constructions are combined in any manner.
A special embodiment will now be described
with reference to Figure 12. This embodiment is
63 2040 1 20
1 special one of those embodiments in which a
normal recovery mode and the aforedescribed mode
for utilizing both recovery are provided as the
recovery mode and these are switched and executed.
That is, where the ink containing portion has an
ink absorbing member therein, the negative pressure
fluctuation range often is -30 mmHg to -120 mmHg.
Assuming that when the negative pressure is small,
e.g. smaller than -50 mmHg, sufficient recovery
is attained by only the normal recovery, the
above-described great recovery can be effected
within only the range of negative pressure of
-50 mmHg to -120 mmHg. Also, where the amount
of ink used is depended on, when the amount of
ink used exceeds a predetermined value, the great
recovery may be required. In such a case, it will
lead to the loss of ink to effect the great
recovery at all times and therefore, it will
provide a preferred embodiment to effect the
switching as will hereinafter be described. The
flow chart of Figure 12 shows a subroutine in
which, as described above, when a predetermined
value as the reference is discriminated by a
detection mechanism for integration count or
remaining amount detection (SMl), the normal
recovery SM3 for idle discharge alone or for
suction alone is effected for more than the
64 2040 1 20
1 reference value (which assumes an absolute value
in the case of negative pressure) and the above-
described mode for utilizing both recovery SM2
is selected for the reference value or more. As
this reference value, mention can be made of ¦-50¦
mmHg previously described, but this is not restrictive.
In any case, the system in which the mode for
utilizing both recovery is selected as required
is covered by the present invention. Also, the
present invention has the above-described various
embodiments as a plurality of execution processes
in the mode for utilizing both recovery, and covers
any selective use thereof. Above all, the second
embodiment is especially preferable and makes the
recovery force greatest.
The present invention displays a tremendous
effect to a tube pump which will become bulky to
produce great pressure, or a recovery mechanism for
a plurality of color heads.
(7) Others
The present invention brings about excellent
effects particularly in the bubble jet type
recording head and recording apparatus proposed
by Canon Inc., among the ink jet recording systems,
because such system can achieve higher density
and higher accuracy of recording.
The typical construction and principle of
6~ 20401 20
1 this system may preferably be approached by the
use of the basic principle disclosed, for example,
in U.S. Patent No. 4,723,129 or U.S. Patent No.
4,740,796. This system is also applicable
to both of the so-called on-demand type and the
so-called continuous type, and particularly in
the case of the on-demand type, it is effective
because at least one driving signal corresponding
to recording information and providing a rapid
temperature rise exceeding nuclear boiling is
applied to electro-thermal conversion members
disposed correspondingly to sheets or liquid paths
retaining liquid (ink) therein, whereby heat
energy is generated in the electro-thermal
conversion members to cause film boiling on the
heat acting surface of a recording head with the
result that a bubble in the liquid (ink)
corresponding at one to one to this driving signal
can be formed. By the growth and shrinkage of
this bubble, the liquid (ink) is discharged
through a discharge opening to thereby form at
least one droplet. If this driving signal is made
into a pulse shape, the growth and shrinkage of
the bubble take place appropriately on the spot
and therefore, discharge of the liquid (ink)
excellent particularly in responsiveness can be
accomplished, and this is more preferable. This
66 20401 20
1 pulse-shaped driving signal may suitably be one
as described in U.S. Patent No. 4,463,359 or U.S.
Patent No. 4,345,262. If the conditions described
in U.S. Patent No. 4,313,124 which discloses an
invention relating to the temperature rise rate
of said heat acting surface are adopted, more
excellent recording can be accomplished.
As the construction of the recording head,
besides the combined construction of discharge
ports, liquid paths and electro-thermal conversion
members as disclosed in the above-mentioned
patents (the straight liquid flow paths or the
right-angled liquid flow paths), the construction
using U.S. Patent No. 4,558,333 and U.S. Patent
No. 4,459,600 which disclose a construction in
which the heat acting portion is disposed in a
crooked area is also covered by the present
invention. In addition, the present invention is
effective for the construction based on Japanese
Laid-Open Patent Application No. 59-123670
which discloses a construction in which a slit
common to a plurality of electro-thermal conversion
members provides the discharge portion of the
electro-thermal conversion members or Japanese
Laid-Open Patent application No. 59-138461
which discloses a construction in which an opening
for absorbing the pressure wave of heat energy
67 20401 20
1 is made to correspond to a discharge portion.
This is because even if the recording head is in
any form, recording can be accomplished reliably
and efficiently.
Further, the present invention can be
effectively applied to a full line type recording
head having a length corresponding to the maximum
width of a recording medium on which a recording
apparatus can effect recording. Such a recording
head may be of a construction in which that
length is satisfied by a combination of a plurality
of recording heads or a construction as a single
recording head formed as a unit.
In addition, the present invention is
effective for a case where use is made of a
recording head of the serial type as described
above which is fixed to an apparatus body, or a
recording head of the interchangeable
type which is mounted on an apparatus body, whereby
the electrical connection thereof to the apparatus
body and the supply of ink thereto from the
apparatus body become possible.
Also, as regards the kinds or number of
recording heads mounted, only one head may be
provided, for example, correspondingly to ink of
single color and besides, a plurality of heads may
be provided correspondingly to a plurality of
68 2040 1 20
1 kinds of ink differing in recording color or
concentration.
Furthermore, the ink jet recording apparatus
of the present invention may take the form of an
apparatus used as the image output end of an
information processing instrument such as a
computer, and in addition, the form of a copying
apparatus combined with a reader or the like,
and further the form of a facsimile apparatus
having the signal transmitting and receiving
functions.
As described above, according to the
present invention, timing drive is carried out so
that the forced discharge operation by suction
or pressing and the discharge operation by the
driving of the discharge energy generating elements
may be performed substantially at a time, whereby
it becomes possible to simply remove bubbles in
the inner part of the discharge ports. Also, it
becomes unnecessary that the ability of the
forcible recovery means such as a pump for effecting
suction or pressing be made great, and this leads
to the possibility of making the recording apparatus
body compact and low in cost.
