Information
-
Patent Grant
-
6168268
-
Patent Number
6,168,268
-
Date Filed
Wednesday, October 14, 199825 years ago
-
Date Issued
Tuesday, January 2, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Fitzpatrick, Cella, Harper &Scinto
-
CPC
-
US Classifications
Field of Search
US
- 347 85
- 347 7
- 347 86
- 347 89
-
International Classifications
-
Abstract
A liquid replenishing method into a liquid supply mechanism, the liquid supply mechanism comprising three or more liquid supply paths, each liquid supply path having a sub-tank for temporarily retaining a liquid and for supplying the liquid by guiding the atmosphere thereinto, the liquid replenishing method comprising the steps of preparing a plurality of negative pressure generators, each for replenishing the sub-tank with the liquid, the number of negative pressure generators being smaller than the number of liquid supply paths, and grouping the plurality of liquid supply paths into groups according to the number of negative pressure generators, and establishing a hermetically closed space in a sub-tank with a greatest liquid consumption in each group, and replenishing the liquid while depressurizing the inside of the sub-tank kept as the hermetically closed space, by the negative pressure generator associated with each group.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid replenishing method in a liquid supplying mechanism capable of supplying a plurality of liquids of different kinds and to a liquid ejection recording apparatus for ejecting the liquids to effect recording by making use of the foregoing method. More particularly, the invention concerns a color ink jet recording apparatus of a type in which ink liquids reserved in main tanks are fed therefrom to be temporarily retained in corresponding sub-tanks, the ink liquids are supplied from the sub-tanks to corresponding printing heads, and a certain ink liquid, when used up in the associated sub-tank, is replenished from the main tank thereof to the sub-tank.
2. Related Background Art
The technology concerning the supply of liquid using liquid supply paths is in practical use in a variety of fields, and an example of the application is an ink jet recording apparatus as a liquid supplying apparatus for ejecting droplets of ink from a recording head to achieve recording on a recording medium.
The ink jet recording apparatus has advantages of capability of recording a high-quality image at high speed but with low noise and capability of readily obtaining a color image, and recently has also been applied as apparatus for recording in large sheet size or in large recording volume, for example, such as a poster output.
Since the ink jet recording apparatus performs recording by ejecting the ink, the ink consumed by ejection always has to be supplied to the recording head. A generally known ink supplying method to the recording head, particularly for apparatus with a large ink consumption, is a method in which a large-volume tank is provided in a form integral with the main body of recording apparatus, an ink flow path is constructed of a pipe such as a tube between the tank and a head cartridge, a mechanism for feeding the ink to the head cartridge is placed in the ink flow path, and this mechanism works to replenish the ink. A specific example of the mechanism for feeding the ink is a mechanism for sending the ink by flattening the tube like a tube pump.
In the ink jet recording apparatus using a large volume of ink as described above there are also demands for downsizing of apparatus and for achieving much higher gradation and quality at high speed.
The method described above, however, for example when adopted in the application using a plurality of recording liquids of different kinds, such as color recording, requires a mechanism for feeding the ink, such as the tube pump, for each color on an independent basis, and there is thus a possibility that the size of the supply units becomes large, particularly in the case of many colors being used, and in turn, the size of the overall recording apparatus becomes large.
In addition, the above-stated method allowed the ink to pass in the mechanisms and it was thus difficult to remove dust etc. with reliability. Particularly, in the application using small apertures of ejection ports for implementing high quality of image, there was a possibility that the dust was deposited in nozzles of the recording head to solidify, so as to cause clogging or the like, and it was thus necessary to provide an extra configuration such as a filter for removing the dust in order to avoid it.
The applicant of the present application filed Japanese Patent Application Laid-open No. 10-6521 to suggest a liquid supplying method and liquid supplying apparatus in which the mechanisms for feeding the ink are provided independent of the ink supply paths, thereby solving the issue about the removal of dust, and facilitating and ensuring the supply of liquid in the liquid supply paths.
The present invention has been accomplished as a result of further intensive and extensive research based on the above suggestion by the present inventor and an object of the invention is to provide a liquid replenishing method for readily and quickly replenishing the liquid to a liquid supplying mechanism provided with plural liquid supply paths.
Another object of the present invention is to provide a liquid ejection recording apparatus that realizes downsizing of the supply unit without the possibility of mixture of dust and that also achieves high-speed recording by shortening ink replenishing time in printing time in a long-term sense.
SUMMARY OF THE INVENTION
For accomplishing the above object, the liquid replenishing method of the present invention is a liquid replenishing method to a liquid supplying mechanism, said liquid supplying mechanism comprising three or more liquid supply paths, each liquid supply path having a sub-tank for temporarily retaining a liquid and for supplying the liquid by guiding the atmosphere thereinto, the liquid replenishing method comprising a step of preparing a plurality of negative pressure generating means, each for replenishing the sub-tank with a liquid, the number of negative pressure generating means being smaller than the number of liquid supply paths, a step of grouping the plurality of liquid supply paths into groups according to the number of negative pressure generating means, a step of establishing a hermetically closed space in a sub-tank with a greatest consumption of the liquid in each group, and a step of replenishing the liquid while depressurizing the inside of the sub-tank kept as the hermetically closed space, by the negative pressure generating means associated with each group.
A liquid ejection recording apparatus of the present invention is a liquid ejection recording apparatus capable of ejecting liquids of mutually different kinds, said liquid ejection recording apparatus having at least three liquid supply paths, each liquid supply path comprising a liquid ejection head for ejecting a liquid to effect recording, a main tank for reserving a liquid to be supplied to the liquid ejection head, and a sub-tank, provided between the liquid ejection head and the main tank, for temporarily retaining the liquid and for supplying the liquid to the head by guiding the atmosphere thereinto, the liquid ejection recording apparatus comprising a plurality of negative pressure generating means, each for depressurizing the inside of the sub-tank in order to replenish the liquid from the main tank to the sub-tank, the number of negative pressure generating means being smaller than the number of liquid supply paths, wherein each of the plurality of liquid supply paths comprises hermetically closing means for establishing a hermetically closed space in the sub-tank, the plurality of liquid supply paths are grouped into groups according to the number of negative pressure generating means, and a sub-tank with a greatest consumption of the liquid in each group is replenished with the liquid by the negative pressure generating means associated therewith.
In the present invention comprising the above, the liquid in each liquid supply path is supplied via a sub-tank to the downstream side. For replenishing the sub-tank with the liquid, the sub-tank is hermetically closed to the atmosphere and is depressurized by use of the negative pressure generating means provided in a path different from the liquid supply path, whereby the liquid is replenished from the upstream side of the liquid supply path into the sub-tank, thus implementing stable replenishment of liquid in spite of the simple structure of the liquid supply path.
In addition, the present invention permits the configuration for selecting a supply path with the greatest liquid consumption in each group, out of the plurality of liquid supply paths grouped corresponding to the negative pressure generating means, and for simultaneously replenishing the selected supply paths with the respective liquids by use of the negative pressure generating means corresponding thereto, thereby implementing efficient replenishment of liquid and decrease in the time necessary for replenishment of liquid.
At this time, particularly, the negative pressure generating means exhaust only the air in the sub-tanks, which can minimize loss in negative pressure generating force of the negative pressure generating means and decrease the replenishing time of liquid. More efficient liquid replenishment can be implemented by detecting liquid amounts in the sub-tanks provided in the respective liquid supply paths and replenishing the liquids when a liquid amount of either one sub-tank falls below a predetermined amount.
When the liquid replenishing method of the present invention is applied to the liquid ejection recording apparatus having the liquid ejection heads at the downstream ends of the liquid supply paths, contamination appearing in the liquid supply paths is decreased and the nozzles of the liquid ejection heads become hard to clog.
The term “hermetically closed” in the present invention means “hermetically closed to the external ambience”. The downstream end of each liquid supply path is open to the external ambience in some form, for example in the form of the liquid ejection head, but disconnection from this part can achieve the hermetically closed state in the present invention, even if the sub-tank is connected to the parts.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a plan view of an embodiment of the ink jet recording apparatus according to the present invention;
FIG. 2
is a front elevation of the ink jet recording apparatus shown in
FIG. 1
;
FIG. 3
is a diagram for explaining ink lines in the ink jet recording apparatus shown in FIG.
1
and
FIG. 2
;
FIG. 4
is a schematic block diagram of the part involved in replenishment of ink to the sub-tanks in the ink jet recording apparatus shown in FIG.
1
and
FIG. 2
;
FIG. 5
is a left side view of a recovery-supply unit of the ink jet recording apparatus shown in FIG.
1
and
FIG. 2
;
FIG. 6
is a top plan view of a cap mechanism shown in
FIG. 5
;
FIG. 7
is a right side view of the cap mechanism shown in
FIG. 5
;
FIG. 8
is an enlarged sectional view of a head cap;
FIG. 9
is a top plan view to show a cross section of a part of a tube pump mechanism shown in
FIG. 5
;
FIG. 10
is a right side view of the tube pump mechanism shown in
FIG. 9
;
FIG. 11
is a vertical, sectional view of the tube pump shown in
FIG. 9
;
FIG. 12
is a side view of a tube receiver shown in
FIG. 11
;
FIG. 13
is a top plan view of a tube valve mechanism shown in
FIG. 5
;
FIG. 14
is a left side view of the part near a tube valve of the second group shown in
FIG. 13
;
FIG. 15
is a left side view of the part near a tube valve of the first group shown in
FIG. 13
;
FIG. 16
is a top plan view of a wiper mechanism shown in
FIG. 5
;
FIG. 17
is a left side view of the wiper mechanism shown in
FIG. 16
;
FIG. 18
is a front elevation of a wiper blade part of the wiper mechanism shown in
FIG. 16
;
FIG.
19
A and
FIG. 19B
are diagrams for explaining the operation of the wiper mechanism shown in
FIG. 16
to
FIG. 18
;
FIG. 20
is a block diagram of the principal part of an electric system in the recovery-supply unit shown in FIG.
5
and other figures;
FIG. 21
is composed of FIG.
21
A and
FIG. 21B
showing flowcharts of the replenishment operation of ink into the sub-tanks;
FIG. 22
is a drawing for explaining ink lines in a modification of the liquid supplying apparatus of the present invention; and
FIG. 23
is a schematic block diagram of the part involved in replenishment of ink into the sub-tanks in the ink jet recording apparatus shown in FIG.
22
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be described by reference to the drawings.
FIG.
1
and
FIG. 2
are a plan view and a front elevation, respectively, of an embodiment of the ink jet recording apparatus according to the present invention.
In the ink jet recording apparatus of the present embodiment, a carriage
1
carrying a plurality of printing heads
11
is provided so as to be slidable in directions of arrow A on a guide rail
3
supported by two side plates
2
a
,
2
b
. The carriage
1
is coupled with a part of timing belt
4
stretched between two pulleys
4
a
and
4
b
and the carriage
1
is arranged to reciprocally move in the directions of arrow A by rotating one pulley
4
a
forward and backward by carriage motor
5
.
Each printing head
11
has nozzles (not illustrated) for respectively ejecting the ink and heat generating elements (not illustrated) for heating the ink in the nozzles to bring about film boiling of the ink inside the nozzles. When a heat generating element is driven to bring about film boiling of the ink in a corresponding nozzle, a bubble appears in the nozzle and the ink is ejected from the nozzle with growth of the bubble.
A recording medium, which is a print object of the printing heads
11
, is conveyed to a position where it faces the nozzles of the printing heads
11
, by a recording medium conveying mechanism not illustrated.
A plurality of main tanks
13
, the number of which is equal to the number of printing heads
11
, are provided in the bottom part of the main body of recording apparatus. These main tanks
13
store respective ink liquids of different colors. The carriage
1
is also equipped with a plurality of sub-tanks
12
, the number of which is equal to the number of printing heads
11
. Each main tank
13
is connected to an associated sub-tank
12
through a tank tube
20
and each sub-tank
12
is connected to the associated printing head
11
through a head tube
21
. Each sub-tank
12
is provided with an ink remainder detecting device (not illustrated) for detecting a residual quantity of the ink retained inside.
In the present embodiment, the numbers of main tanks
13
, sub-tanks
12
, and printing heads
11
are six and ink liquids of different colors (cyan, magenta, yellow, black, light cyan, and light magenta) are stored therein or supplied thereto.
This ink jet recording apparatus is equipped with a recovery-supply unit
6
having a recovery mechanism for maintaining ejection characteristics of the printing heads
11
and a replenishing mechanism for replenishing the sub-tanks with the respective ink liquids. The recovery-supply unit
6
has the recovery mechanism composed of a cap portion for hermetically closing outlet faces, which are surfaces of apertures of the nozzles of the printing heads
11
, wiper blades for wiping the ink outlet faces, and a suction device for forcible suction of the ink in the printing heads. The recovery-supply unit
6
also has the replenishing mechanism composed of negative pressure generators for generating negative pressure in the sub-tanks on the occasion of replenishment of ink into the sub-tanks. The recovery-supply unit
6
also has driving systems for driving these mechanisms etc. (neither of which is illustrated).
Ink lines in the ink jet recording apparatus of the present embodiment will be described referring to FIG.
3
. The ink lines are provided for the respective colors. Since all the ink lines are the same, the following describes the ink line of one color.
The tank tube
20
connects the main tank
13
to the sub-tank
12
. An end of the tank tube
20
on the side of connection with the sub-tank
12
is put in the sub-tank
12
and a filter for preventing contamination from flowing into the sub-tank
12
is attached to the tip of the tank tube
20
. An atmosphere open valve
24
, which is driven by a driving source not illustrated, is provided above the sub-tank
12
.
The sub-tank
12
is connected at the bottom thereof through the head tube
21
to the printing head
11
and the ink is supplied from the sub-tank
12
to the printing head
11
by the capillarity in the nozzles of the printing head
11
. If the position of the printing head
11
were lower than the liquid level of the ink in the sub-tank
12
, the ink would leak out of the nozzles of the printing head
11
. The printing head
11
is thus located at a position higher than the height of the maximum ink level in the sub-tank
12
. Likewise, the main tank
13
is located at a position lower than the height of the minimum ink level in the sub-tank
12
in order to prevent the ink from undesirably being guided from the main tank
13
to the sub-tank
12
.
The head tube
21
is provided with a head tube closing valve
25
for closing the ink line between the sub-tank
12
and the printing head
11
by flattening the head tube
21
.
The head recovery unit
6
is disposed inside a moving range of the printing head
11
and outside a recording area of the recording medium. A cap
16
of the head recovery unit
6
is arranged to be movable in directions of arrow B and is connected to a waste ink tank
14
through a suction tube
22
. The suction tube
22
is provided with a recovery tube pump
18
. When the recovery tube pump
18
is driven with the cap
16
capping the printing head
11
, the ink inside the printing head
11
is drawn into the cap
16
and is guided through the suction tube
22
into the waste ink tank
14
.
A negative pressure tube
23
connects the waste ink tank
14
to the sub-tank
12
. The negative pressure tube
23
is connected at the top end of the sub-tank
12
thereto. A negative pressure tube closing valve
26
and a negative pressure generating tube pump
19
are interposed midway of the negative pressure tube
23
. The negative pressure generating tube pump
19
is provided in the head recovery unit
6
. When the negative pressure generating tube pump
19
is driven with the negative pressure tube closing valve
26
being open, the air in the sub-tank
12
is drawn to be discharged through the negative pressure tube
23
from aperture
14
a
of the waste ink tank
14
to the outside.
The schematic flow of the ink in the ink line illustrated in
FIG. 3
will be described below.
The recording operation is carried out by ejecting the ink from the printing head
11
while repeating running of the printing head
11
by reciprocal movement of the carriage
1
and pitch feed of the recording medium with the negative pressure tube closing valve
26
being closed. The ink in the sub-tank
12
is consumed with ejection of the ink from the printing head
11
. When the residual quantity of ink becomes little in the sub-tank
12
, it is detected by the ink remainder detecting device. With detection thereof, recording on the recording medium is temporarily stopped at that time, and the printing head
11
is moved to the position to face the cap
16
. Then the printing head
11
is capped by the cap
16
. Subsequently, the head tube closing valve
25
and the atmosphere open valve
24
are closed and the negative pressure tube closing valve
26
is opened, so as to establish a hermetically closed space in the sub-tank
12
in the ink supply line.
The negative pressure generating pump
19
is driven in this state, whereupon the air in the sub-tank
12
is discharged through the negative pressure tube
23
and negative pressure appears in the sub-tank
12
. Thus, the sub-tank
12
is kept as a hermetically closed and depressurized space. This causes the ink in the main tank
13
to replenish sub-tank
12
through the tank tube
20
.
After the sub-tank
12
is filled with the ink and it is detected by the ink remainder detecting device, the atmosphere open valve
24
is opened to release the sub-tank
12
from the depressurized state, the head tube closing valve
25
is opened, the negative pressure tube closing valve
26
is closed, the negative pressure generating pump
19
is stopped, and thereafter the recording operation is started again.
Since the replenishment of the ink from the main tank
13
to the sub-tank
12
is carried out by generating the negative pressure in the sub-tank
12
and utilizing the negative pressure as described above, there is no need for provision of a mechanism for feeding the ink between the main tank
13
and the sub-tank
12
. As a consequence, the structure of the ink supply line becomes simpler and the contamination such as the dust appearing in the ink supply line is also decreased, thus implementing stable ink replenishment.
Although it was described before that the ink lines of the respective colors were of the same structure, it should be noted that the recovery tube pump
18
and the negative pressure generating tube pump
19
are not provided for each of the colors, more precisely. The present embodiment is provided with three recovery tube pumps
18
and two negative pressure generating tube pumps
19
and uses them by switching as occasion may demand.
The schematic structure of the part involved in the replenishment of ink to the sub-tanks
12
will be described referring to FIG.
4
.
FIG. 4
is a schematic block diagram of the part involved in the ink replenishment to the sub-tanks in the ink jet recording apparatus of the present embodiment.
As illustrated in
FIG. 4
, the set of six printing heads
11
and six sub-tanks
12
are grouped into the first group
81
and the second group
82
and one negative pressure generating tube pump
19
a
or
19
b
is assigned to each group. For realizing this configuration, the negative pressure tubes
23
connected to the respective sub-tanks
12
in the first group
81
merge together midway into one to be connected to the negative pressure generating tube pump
19
a,
while the negative pressure tubes
23
connected to the respective sub-tanks
12
in the second group
82
also merge together midway into one to be connected to the negative pressure generating tube pump
19
b.
Each group is provided with a valve setting mechanism
90
a
or
90
b
for performing open/close operation of the head tube closing valves
25
and negative pressure tube closing valves
26
. For replenishing the ink, the head tube closing valve
25
is closed and the negative pressure tube closing valve
26
is opened in either one ink path in each group. Further, the present embodiment is adapted so that each head
11
is provided with a dot counter (not illustrated).
In
FIG. 4
, reference numeral
60
designates a tube pump selecting mechanism for selection between the negative pressure generating tube pumps and the recovery tube pumps not illustrated in
FIG. 4
, the pumps sharing a common driving source, the details of which will be described hereinafter. In the case where only one color is always consumed in large volume, the structure of the selecting mechanism is desirably modified so as to be capable of driving only either one of the negative pressure generating tube pumps in the liquid replenishing operation described hereinafter.
The recovery-supply unit
6
will be described in detail.
FIG. 5
is a left side view of the recovery-supply unit illustrated in FIG.
1
. As illustrated in
FIG. 5
, the recovery-supply unit
6
has a cap mechanism CP for capping the printing heads
11
, a tube pump mechanism TP including the aforementioned recovery tube pumps and negative pressure generating tube pumps, a tube valve mechanism TV for driving the tube closing valves, and a wiper mechanism WP for wiping the outlet faces of the printing heads
11
.
First, the cap mechanism CP will be described referring to FIG.
6
and FIG.
7
.
FIG. 6
is a top plan view of the cap mechanism and
FIG. 7
is a right side view of the cap mechanism.
As illustrated in FIG.
6
and
FIG. 7
, between left side plate
30
and right side plate
31
of the recovery-supply unit
6
, a cap clutch shaft
32
and a cap cam shaft
33
are supported thereby so as to be rotatable, and a cap lever shaft
34
is fixed thereto.
The cap clutch shaft
32
is provided with an electromagnetic clutch
35
for cap, which is fixed to the right side plate
31
. The electromagnetic clutch
35
for cap is composed of gear part
35
a
and electromagnetic coil part
35
b.
Rotation of step motor
28
fixed to the right side plate
31
is transmitted to the gear part
35
a
through pinion gear
29
pressed onto a rotational shaft of the step motor
28
and through first cap gears
36
which are double gears rotatably supported on the right side plate
31
. When electric current flows in the electromagnetic coil part
35
b,
the rotation of the gear part
35
a
is transmitted to the cap clutch shaft
32
; while the current is off, the rotation of the gear part
35
a
is not transmitted to the cap clutch shaft
32
.
A second cap gear
37
is fixed to the end of the cap clutch shaft
32
on the left side plate
30
side. The second cap gear
37
is in mesh with fourth cap gear
39
fixed to the end of the cap cam shaft
33
on the left side plate
30
side, through third cap gears
38
which are double gears rotatably supported on the left side plate
30
, so that the rotation of the cap clutch shaft
32
is transmitted to the cap cam shaft
33
.
Fixed on the cap cam shaft
33
are a sensor flag
40
, and two cap cams
41
for respectively swinging two cap levers
43
a,
43
b
described below. The sensor flag
40
is a platelike member having a projection projecting in a radial direction, and a cap sensor
42
such as a photosensor detects this projection, thereby detecting the phase of the cap cams
41
.
A cap lever
43
a
or
43
b
of an L-shape is pivotally arranged opposite to each cap cam
41
on the cap lever shaft
34
. Three caps
16
a
or
16
b
are provided at one end of each cap lever
43
a
or
43
b
extending horizontally. The other end of each cap lever
43
a
or
43
b
extending downward is energized toward the cap cam
41
by cap spring
44
. In this structure, when the cap cams
41
are rotated with rotation of the cap cam shaft
33
, the cap levers
43
a
,
43
b
are pivoted according to the phase thereof in the directions of arrow C illustrated in
FIG. 7
, thereby effecting capping of the printing heads
11
by the caps
16
a
,
16
b
and release thereof.
The operation of the cap mechanism CP will be described.
First, the electromagnetic clutch
35
for cap is switched on and the step motor
28
is rotated in the direction of arrow D in FIG.
7
. The rotation of the step motor
28
is transmitted via the pinion gear
29
, first cap gears
36
, electromagnetic clutch
35
for cap, cap clutch shaft
32
, second cap gear
37
, third cap gears
38
, and fourth cap gear
39
to the cap cam shaft
33
, whereby the cap cams
41
are pivoted in the direction of arrow E of FIG.
7
. Since the cap levers
43
a
,
43
b
are urged against the cap cams
41
, the rotation of the cap cams
41
causes the cap levers
43
a
,
43
b
to be pivoted about the cap lever shaft
34
, whereby the caps
16
a
,
16
b
move up toward the printing heads
11
. This pivotal motion continues before the cap sensor
42
detects the projection of the sensor flag
40
. Once the cap sensor
42
detects the projection of the sensor flag
40
, the step motor
28
is stopped and the electromagnetic clutch
35
for cap is turned off.
This brings the cap levers
43
a
,
43
b
into the posture illustrated by the solid lines in
FIG. 7
, thereby achieving capping of the printing heads
11
by the caps
16
a
,
16
b
. At this time, the cap cams
41
are apart from the cap levers
43
a
,
43
b
, and the caps
16
a
,
16
b
push the printing heads
11
by spring force of the cap springs
44
. The caps
16
a
,
16
b
are made of an elastic material such as rubber and a rib
17
is formed on a contact surface of each cap with the printing head
11
, as illustrated in FIG.
8
. When the caps
16
a
,
16
b
are pressed against the printing heads
11
, the ribs
17
are crushed flat, so as to hermetically close the ejection outlets (not illustrated) of the printing heads
11
.
On the other hand, the releasing operation of the capping by the caps
16
a
,
16
b
is carried out as follows. Like the capping operation described above, the electromagnetic clutch
35
for cap is turned on and the step motor
28
is rotated in the direction of arrow D of
FIG. 7
, whereupon the cap cams
41
rotate in the direction of arrow E. When the cap cams
41
rotate by a predetermined set value after the cap sensor
42
detects the projection of the sensor flag
40
, the step motor
28
is stopped and the electromagnetic clutch
35
for cap is turned off. This set value is preliminarily set to be such a value that the cap cams
41
push the cap levers
43
a
,
43
b
against the energizing force of the cap springs
44
so as to completely depress the caps
16
a,
16
b
down. In this state, the caps
16
a
,
16
b
are completely withdrawn from the printing heads
11
, as illustrated by the chain double-dashed lines in FIG.
7
.
There are two cap levers
43
a
,
43
b
provided, but the operation of the levers is the same. A suction tube
22
is connected to each of three caps
16
b
provided in one cap lever
43
b
and these caps
16
b
are used for the recovery operation of the printing heads
11
.
Next, the tube pump mechanism TP shown in
FIG. 5
will be described.
FIG. 9
is a top plan view to show a cross section of a part of the tube pump mechanism illustrated in FIG.
5
.
FIG. 10
is a right side view of the driving mechanism part of the tube pump mechanism shown in FIG.
9
and
FIG. 11
is a vertical, sectional view of the tube pump illustrated in FIG.
9
.
As illustrated in FIG.
9
and
FIG. 10
, first pump gears
61
, which are double gears rotatably supported on the right side plate
31
, are in mesh with the pinion gear
29
pressed onto the rotational shaft of the step motor
28
described above. Between the left side plate
30
and the right side plate
31
, a first pump shaft
62
is rotatably supported thereby. Provided on the first pump shaft
62
is a second pump gear
63
in mesh with the first pump gear
61
, the second pump gear
63
having a one-way clutch which races in the direction of arrow F of
FIG. 10
but bites in the opposite direction to the direction F while the first pump shaft
62
is in a non-rotating state. The rotation of the step motor
28
is transmitted through the first pump gears
61
to the second pump gear
63
.
Five tube pumps
50
a
,
50
b
,
50
c
,
50
d
,
50
e
are provided on the first pump shaft
62
, as illustrated in FIG.
9
. Each tube pump
50
a-
50
e
has a pump tube
51
in which fluid passes, a tube receiver
52
for receiving the tube pump
51
, and a roller retainer
54
for retaining rollers
53
, which are moved to rotate while flattening the tube pump
51
between the rollers and the tube receiver
52
, as illustrated in FIG.
11
.
The roller retainer
54
is fixed on the first pump shaft
62
and rotatably retains four rollers
53
at equal angular intervals on the same periphery. The tube receiver
52
is pivotally supported on second pump shaft
65
fixed to the left side plate
30
and the right side plate
31
, as illustrated in FIG.
9
and
FIG. 11
, and is energized upward about the second pump shaft
65
by pump spring
66
provided between the tube receiver
52
and base plate
46
. The tube receiver
52
has an arcuate recess part
52
a
, as illustrated in
FIG. 12
, in the portion opposite to the roller retainer
54
, and the pump tube
51
is supported on this recess part
52
a
. Since the tube receiver
52
is energized upward by the pump spring
66
, the pump tube
51
is held between the tube receiver
52
and the roller retainer
54
in a flattened state between the rollers
53
and the recess part
52
a
of the tube receiver
52
.
On the basis of the above structure, when the step motor
28
is rotated in the direction of arrow G of
FIG. 10
, i.e., in the direction opposite to the rotating direction during the operation of the cap mechanism, the rotation is transmitted via the pinion gear
29
and the first pump gears
61
to the second pump gear
63
. The second pump gear
63
has the one-way clutch, and the rotating direction of the second pump gear
63
at this time is the rotating direction in which this one-way clutch acts. Therefore, the rotation of the second pump gear
63
is transmitted to the first pump shaft
62
to rotate each roller retainer
54
in the direction of arrow H of FIG.
11
.
With the rotation of each roller retainer
54
, the rollers
53
move to rotate on the associated pump tube
51
while flattening the pump tube
51
. This squeezes the pump tube
51
, so that the fluid in the pump tube
51
is fed in the squeezing direction of the pump tube
51
to generate the negative pressure on the upstream side.
The present embodiment has the five tube pumps
50
a
to
50
e
as described above, among which the three left tube pumps
50
c
to
50
e
in
FIG. 9
are used for recovery of the printing heads
11
(see
FIG. 3
) and the two right tube pumps
50
a
,
50
b
are used for replenishment of ink to the sub-tanks
12
(see FIG.
3
). These are switched as occasion may demand.
More specifically, the tube pumps
50
c
to
50
e
function as the recovery tube pumps
18
illustrated in
FIG. 3
while the tube pumps
50
a
,
50
b
as the negative pressure generating tube pumps
19
illustrated in FIG.
3
. For achieving this, a suction tube
22
(see
FIG. 3
) is connected through a joint member to the both ends of the pump tube
51
of each recovery tube pump
50
c-
50
e
, and a negative pressure tube
23
(see
FIG. 3
) is connected through a joint member to the both ends of the pump tube
51
of each pump tube
50
a
,
50
b
for replenishment of ink.
The selecting mechanism of each tube pump (the tube pump selecting mechanism
60
of
FIG. 4
) will be described referring to
FIG. 9
to FIG.
11
.
A first intermediate gear
67
in mesh with the first pump gear
61
is fixed to an end on the right side plate
31
side, of a first intermediate shaft
66
rotatably supported by the left side plate
30
and right side plate
31
. Second intermediate gears
68
, which are double gears, are fixed to the other end of the first intermediate shaft
66
on the left side plate
30
side.
An electromagnetic clutch
70
for selection of pump, having a gear part
70
a
in mesh with the second intermediate gear
68
, is provided at an end on the left side plate
30
side, of a pump clutch shaft
69
rotatably supported by the left side plate
30
and the right side plate
31
. This electromagnetic clutch
70
for selection of pump has the structure similar to that of the electromagnetic clutch
35
for cap (see
FIG. 6
) used in the aforementioned cap mechanism. When electric current flows in the electromagnetic clutch
70
for selection of pump, the rotation of the gear part
70
a
is transmitted to the pump clutch shaft
69
.
A second pump gear
71
is fixed to the other end of the pump clutch shaft
69
on the right side plate
31
side, and this second pump gear
71
is in mesh with a fourth pump gear
74
fixed to a pump cam shaft
73
rotatably supported by the left side plate
30
and the right side plate
31
, through a third pump gear
72
. In correspondence to the above tube pumps
50
a-
50
e
, five pump cams
75
are fixed in respective predetermined phases on the pump cam shaft
73
. Each pump cam
75
is adapted to rotate together with the pump cam shaft
73
to push the tube receiver
52
and move the tube receiver
52
down against the energizing force of the pump spring
66
, thereby releasing the pressing of the rollers
53
against the tube receiver
52
.
A sensor flag
76
is fixed to the pump cam shaft
73
like the cap mechanism and the phase of each pump cam
75
can be detected by detecting a projection of this sensor flag
76
by pump sensor
77
.
On the basis of the above structure, the electromagnetic clutch
70
for selection of pump is turned on and the step motor
28
is rotated in the direction of arrow D of
FIG. 10
, whereupon the rotation thereof is transmitted via the pinion gear
29
, first pump gears
61
, first intermediate gear
67
, first intermediate shaft
66
, second intermediate gears
68
, electromagnetic clutch
70
for selection of pump, pump clutch shaft
69
, second pump gear
71
, third pump gear
72
, and fourth pump gear
74
to the pump cam shaft
73
to rotate the pump cams
75
in the direction of arrow I in FIG.
11
. This causes each pump cam
75
to move the tube receiver
52
down, thereby releasing the pressing of the rollers
53
against the tube receiver
52
. At this time, the rotation of the first pump gears
61
also rotates the second pump gear
63
, but the one-way clutch provided in the second pump gear
63
works so that the rotation of the second pump gear
63
is not transmitted to the first pump shaft
62
. Thus the tube pumps
50
a
-
50
e
are not driven.
Since each pump cam
75
is set in the predetermined phase with respect to the pump cam shaft
73
, either one of the tube pumps
50
a
to
50
e
can be selected arbitrarily by the phase. The selection stated herein means a state in which the tube pump
50
a
to
50
e
can function as a pump, that is, a state in which the pump cam
75
does not act on the tube receiver
52
and the pump tube
51
is flattened between the rollers
53
and the tube receiver
52
.
Detection of the phase of the pump cam
75
is similar to that of the phase of the cap cam
41
(see
FIG. 7
) in the aforementioned cap mechanism. Specifically, control is performed so that the step motor
28
is stopped and the electromagnetic clutch
70
for selection of pump is turned off when a pump cam is rotated by a predetermined set amount after the pump sensor
77
detects the sensor flag
76
. This set value is preliminarily set to a value enough for each pump cam
75
to move the tube receiver
52
down so as to release the pressing of the rollers
53
against the pump tube
51
, and five points are provided as shown in Table 1 below.
TABLE 1
|
|
Angle of rotation of pump
|
Pump selected
cam
|
|
Neither pump selected
0°
|
Pumps a and b (negative
90°
|
pressure pumps)
|
Pumps c, d, and e
180°
|
(recovery pumps)
|
|
In Table 1, the pumps a to e represent the tube pumps
50
a
to
50
e
illustrated in FIG.
9
.
Since the present embodiment is arranged so that the five tube pumps
50
a
to
50
e
all are driven by the step motor
28
as described above, power saving is achieved even in the case where a plurality of tube pumps are driven at one time. In addition, the selection of the tube pump
50
a
to
50
e
driven can be performed by simply displacing the tube receiver
52
by the cam mechanism described above, so that the selection can be performed readily.
Next, the tube valve mechanism TV illustrated in
FIG. 5
will be described.
FIG. 13
is a top plan view of the tube valve mechanism illustrated in FIG.
5
.
As illustrated in
FIG. 13
, the tube valve mechanism has totally twelve tube valves
80
for the six sub-tanks
12
(see FIG.
3
), one for hermetically closing the head tube
21
(see
FIG. 3
) and one for hermetically closing the negative pressure tube
23
(see
FIG. 3
) per sub-tank. The tube valves
80
are grouped into the first group
81
corresponding to the sub-tanks of cyan, black, and magenta and the second group
82
corresponding to the sub-tanks of light magenta, yellow, and light cyan, and the first group
81
and the second group
82
are driven independently of each other. The first group
81
is driven in correspondence to the operation of the tube pump
50
a
for replenishment (see
FIG. 9
) and the second group
82
is driven in correspondence to the operation of the tube pump
50
b
for replenishment (see FIG.
9
).
There is no substantial difference in the structure of each tube valve
80
itself between the first group
81
and the second group
82
. The following describes the structure of the tube valves
80
.
FIG. 14
is a left side view of the part near the tube valves of the second group and
FIG. 15
is a left side view of the part near the tube valves of the first group. As illustrated in
FIG. 13
, a tube valve support shaft
83
is fixed to the left side plate
30
and to the right side plate
31
and twelve tube valve levers
84
forming the respective tube valves
80
are rotatably supported on this tube valve support shaft
83
, as illustrated in FIG.
14
and FIG.
15
. Each tube valve lever
84
has a horizontal part supported on the tube valve support shaft
83
and a vertical part extending downwardly from one end of the horizontal part.
A projecting part
84
a
projecting toward the carriage
1
is provided at the tip of the horizontal part. The vertical part is energized toward a first-group cam
87
(see
FIG. 15
) or toward a second-group cam
86
(see FIG.
14
), which will be described hereinafter, by a tube valve spring
85
. Each tube valve lever
84
is arranged so that the projecting portion
84
a
is moved upward when the tube valve lever
84
is pivoted about the tube valve support shaft
83
by the energizing force of the tube valve spring
85
.
On the other hand, a tube pressing member
88
is provided at a position corresponding to each tube valve lever
84
, on the carriage
1
. Each tube pressing member
88
is a platelike member elastically supported in the cantilever structure at stationary part
88
a
is arranged to flatten the head tube
21
or the negative pressure tube
23
to hermetically close the flow path thereof when the tip part is moved up by the projecting portion
84
a
of the tube valve lever
84
. For one sub-tank
12
, one set of tube valve lever
84
and tube pressing member
88
function as a head tube closing valve
25
(see FIG.
3
), while the other set of tube valve lever
84
and tube pressing member
88
as a negative pressure tube closing valve
26
(see FIG.
3
).
Described below is the driving mechanism (the valve setting mechanism
90
b
of
FIG. 4
) of the second group
82
. As illustrated in
FIG. 13
, a second-group clutch shaft
91
is rotatably supported by the left side plate
30
and the right side plate
31
. An electromagnetic clutch
92
for the second group having a gear part
92
a
in mesh with the second intermediate gear
68
described previously is provided on the second-group clutch shaft
91
. The second-group electromagnetic clutch
92
has the structure similar to that of the cap electromagnetic clutch
35
(see
FIG. 6
) described previously, and with flow of electric current the clutch
92
can transmit the rotation of the gear part
92
a
to the second-group clutch shaft
91
.
A pulley
93
is fixed to the end of the second-group clutch shaft
91
on the right side plate
31
side. A timing belt
95
is stretched between this pulley
93
and another pulley
94
rotatably supported on the right side plate
31
. A gear part of the pulley
94
engages with a second-group first gear
97
fixed on a second-group driving shaft
96
rotatably supported by the left side plate
30
and the right side plate
31
.
Six second-group second gears
98
are fixed corresponding to the respective tube valves
80
of the second group
82
on the second-group driving shaft
96
. A tube valve cam shaft
99
is rotatably supported by the left side plate
30
and the right side plate
31
. As illustrated in
FIG. 14
, six second-group cams
86
(only one of which is illustrated in FIG.
14
), each having a gear part
86
a
in mesh with a second-group second gear
98
, are rotatably supported on the tube valve cam shaft
99
, and the rotation of each second-group cam
86
acts on the associated tube valve lever
84
, thereby operating the tube valve lever
84
.
As illustrated in
FIG. 14
, the second-group cam
86
is provided with a sensor flag
100
having an integral projection, so that the phase of the second-group cam
86
can be detected by detecting the projection of the sensor flag
100
by second-group sensor
101
.
On the basis of the above structure, the second-group electromagnetic clutch
92
is turned on and the step motor
28
is rotated in the direction of arrow D illustrated in
FIG. 10
, whereupon the rotation thereof is transmitted via the pinion gear
29
, first pump gears
61
, first intermediate gear
67
, first intermediate shaft
66
, second intermediate gears
68
, second-group electromagnetic clutch
92
, second-group clutch shaft
91
, pulleys
93
,
94
and timing belt
95
, second-group first gear
97
, and second-group driving shaft
96
to the second-group second gears
98
, thereby rotating the second-group cams
86
in the direction of arrow J of FIG.
14
. This rotation is controlled so as to be stopped when the cams are rotated by a predetermined amount after detection of the sensor flag
100
by the second-group sensor
101
.
In this state, a second-group cams
86
is in the posture indicated by the chain double-dashed line in FIG.
14
and is apart from the tube valve lever
84
. Therefore, the tube valve lever
84
is pivoted about the tube valve support shaft
83
by the energizing force of the tube valve spring
85
, so that the projecting portion
84
a
of the tube valve lever
84
lifts the tip of the tube pressing member
88
. This flattens the head tube
21
or the negative pressure tube
23
to close the flow path thereof.
Each second-group cam
86
is in mesh with the second-group second gear
98
with a shift of a predetermined angle in the phase from the other cams. Either one of modes is set as shown in Table 2, depending upon the predetermined rotation set values of the second-group cams
86
.
TABLE 2
|
|
Operat-
|
ing
|
For negative pressure
angle
|
For head tube
tube
of 2nd-
|
light
light
light
light
group
|
Mode
magenta
yellow
cyan
magenta
yellow
cyan
cams
|
|
Replen-
—
o
o
o
—
—
0°
|
ishment
|
of
|
light
|
magenta
|
Replen-
o
—
o
—
o
—
90°
|
ishment
|
of
|
yellow
|
Replen-
o
o
—
—
—
o
180°
|
ishment
|
of
|
light
|
cyan
|
Print
o
o
o
o
o
o
270°
|
|
In Table 2, “-” represents closing of valve and “O” opening of valve. In this way, states of the tube valve
80
of each ink color, light magenta, yellow, or light cyan, are set depending upon the angles of rotation of the second-group cams.
Next, the driving mechanism of the first group
81
(the valve setting mechanism
90
a
of
FIG. 4
) will be described. As illustrated in
FIG. 13
, a first-group clutch shaft
102
is rotatably supported by the left side plate
30
and the right side plate
31
. The first-group clutch shaft
102
is provided with an electromagnetic clutch
103
for the first group having a gear part
103
a
in mesh with the first intermediate gear
67
described previously. The first-group electromagnetic clutch
103
has the structure similar to that of the cap electromagnetic clutch
35
(see
FIG. 6
) described previously and can transmit the rotation of the gear part
103
a
to the first-group clutch shaft
102
with flow of electric current.
A pulley
104
is fixed to the end of the first-group clutch shaft
102
on the left side plate
30
side. A timing belt
106
is stretched between this pulley
104
and another pulley
105
rotatably supported on the left side plate
30
. A gear part of the pulley
105
is in mesh with a first-group first gear
107
fixed on the tube valve cam shaft
99
.
As illustrated in
FIG. 15
, six first-group cams
87
(only one of which is illustrated in
FIG. 15
) are fixed corresponding to the respective tube valves
80
of the first group
81
, on the tube valve cam shaft
99
. The rotation of each first-group cam
87
acts on the associated tube valve lever
84
of the first group
81
, thereby operating the tube valve lever
84
. As illustrated in
FIG. 13
, the tube valve cam shaft
99
is further provided with a sensor flag
108
having an integral projection. The phase of the first-group cam
87
can be detected by detecting the projection of the sensor flag
108
by first-group sensor
109
.
On the basis of the above structure, the first-group electromagnetic clutch
103
is turned on and the step motor
28
is rotated in the direction of arrow D illustrated in
FIG. 10
, whereupon the rotation is transmitted via the pinion gear
29
, first pump gears
61
, first intermediate gear
67
, first-group electromagnetic clutch
103
, first-group clutch shaft
102
, pulleys
104
,
105
and timing belt
106
, and first-group first gear
107
to the tube valve cam shaft
99
to rotate the first-group cams
87
in the direction of arrow K of FIG.
15
. This rotation is controlled so as to be stopped when the cams are rotated by a predetermined amount after the detection of the sensor flag
108
by the first-group sensor
109
.
In this state, a first-group cam
87
is in the posture indicated by the chain double-dashed line in FIG.
15
and is apart from the tube valve lever
84
. Accordingly, the tube valve lever
84
is pivoted about the tube valve support shaft
83
by the energizing force of the tube valve spring
85
, so that the projecting part
84
a
of the tube valve lever
84
lifts the tip of the tube pressing member
88
. This flattens the head tube
21
or the negative pressure tube
23
to close the flow path thereof.
The first-group cams
87
are fixed on the tube valve cam shaft
99
with a shift of a predetermined angle in the phase from the other cams. Either one of modes is set as shown in Table 3, depending upon the predetermined rotation set values of the first-group cams
87
.
TABLE 3
|
|
Operating
|
For negative
angle of
|
For head tube
pressure tube
1st group
|
Mode
cyan
black
magenta
cyan
black
magenta
cams
|
|
Replen-
—
o
o
o
—
—
0°
|
ishment
|
of cyan
|
Replen-
o
—
o
—
o
—
90°
|
ishment
|
of
|
black
|
Replen-
o
o
—
—
—
o
180°
|
ishment
|
of
|
magenta
|
Print
o
o
o
o
o
o
270°
|
|
In Table 3, “−” represents closing of valve, and “O” opening of valve. In this way, states of the tube valve
80
of each ink color, cyan, black, or magenta, are set depending upon the angles of rotation of the first-group cams.
As described above, setting of opening or closing of each flow path of the head tubes
21
and the negative pressure tubes
23
can be effected by simply displacing the tube valve lever
84
by the above-stated cam mechanism so as to flatten or release the head tube
21
or the negative pressure tube
23
through the tube pressing member
88
, and thus the setting is easy.
Next, the wiper mechanism WP illustrated in
FIG. 5
will be described.
FIG. 16
is a top plan view of the wiper mechanism illustrated in FIG.
5
.
FIG. 17
is a left side view of the wiper mechanism illustrated in FIG.
16
and
FIG. 18
is a front elevation of the wiper blade part of the wiper mechanism illustrated in FIG.
16
.
A wiper clutch shaft
110
is rotatably supported by the left side plate
30
and right side plate
31
. The wiper clutch shaft
110
is provided with an electromagnetic clutch
111
for wiper having a gear part
111
a
in mesh with the second pump gear
63
described previously. The wiper electromagnetic clutch
111
has the structure similar to that of the cap electromagnetic clutch
35
(see
FIG. 6
) described previously, and can transmit the rotation of the gear part
111
a
to the wiper clutch shaft
110
with flow of electric current.
A first wiper gear
112
is fixed to the end of the wiper clutch shaft
110
on the left side plate
30
side. The first wiper gear
112
is in mesh with one of second wiper gears
113
, which are double gears rotatably supported on the left side plate
30
, and the other gear of the second wiper gears
113
is further in mesh with one of third wiper gears
114
, which are double gears rotatably supported on the left side plate
30
as well. The other gear of the third wiper gears
114
is a bevel gear.
On a wiper case
120
fixed to the left side plate
30
, fourth wiper gears
123
being double gears are rotatably supported thereby. One of the fourth wiper gears
123
is also a bevel gear, and this bevel gear is in mesh with the bevel gear of the third wiper gears
114
. This permits rotation to be transmitted between two shafts perpendicular to each other. A wiper rotation shaft
121
is rotatably supported in the wiper case
120
and a fifth wiper gear
122
fixed on this wiper rotation shaft
121
is in mesh with the other gear of the fourth wiper gears
123
.
A wiper blade retainer
124
is fixed on the wiper rotation shaft
121
. Three wiper blades
125
are fixed at equal angular intervals with respect to the wiper rotation shaft
121
on the wiper blade retainer
124
, as illustrated in FIG.
18
. The wiper blades
125
are provided for wiping the outlet faces of the printing heads
11
and are made in a thin plate shape of an elastic material such as rubber. A sensor flag
126
is fixed to the wiper blade retainer
124
and the phase of the wiper blades
125
can be detected by detecting this sensor flag
126
by wiper sensor
127
fixed to the wiper case
120
.
A blade cleaner
128
is fixed on the bottom surface of the wiper case
120
. The blade cleaner
128
is made of an absorbing material capable of absorbing the ink and is located at a position where the blade cleaner
128
is in contact with the tip part of the wiper blade
125
which is moved to the lowest position by the rotation of the wiper rotation shaft
121
.
On the basis of the above structure, the wiper electromagnetic clutch
111
is turned on and the step motor
28
is rotated in the direction of arrow G illustrated in
FIG. 10
, whereupon the rotation is transmitted via the pinion gear
29
, first pump gears
61
, second pump gear
63
, wiper electromagnetic clutch
111
, wiper clutch shaft
110
, first wiper gear
112
, second wiper gears
113
, third wiper gears
114
, fourth wiper gears
123
, and fifth wiper gear
122
to the wiper rotation shaft
121
to rotate the wiper blades
125
in the direction of arrow L in FIG.
18
. Then the step motor
28
is stopped at the position where the wiper sensor
127
detects the sensor flag
126
, and the wiper electromagnetic clutch
111
is turned off.
After that, as illustrated in
FIGS. 19A and 19B
, the carriage
1
is moved at constant speed in the direction of arrow P and, in synchronism therewith, the wiper blades
125
are rotated at constant speed in the direction of arrow L. This causes the wiper blades
125
to wipe the outlet faces
11
a
of the printing heads
11
, as illustrated in FIG.
19
B.
Here, the moving speed of the carriage
1
and the rotating speed of the wiper blades
125
are so set that during a period after one wiper blade
125
has wiped the outlet face
11
a
of one printing head
11
above the wiper rotation shaft
121
and before the next wiper blade
125
moves to above the wiper rotation shaft
121
, the next printing head
11
moves to above the wiper rotation shaft
121
. In the present embodiment, one rotation of the wiper rotation shaft
121
is arranged to wipe three printing heads
11
with the different wiper blades
125
and two rotations of the wiper rotation shaft
121
are arranged to wipe all the printing heads
11
accordingly. After wiping a printing head
11
, the wiper blade
125
goes into contact with the blade cleaner
128
with rotation of the wiper rotation shaft
121
, where the ink etc. attaching to the wiper blade
125
is removed.
When the wiper sensor
127
detects the sensor flag
126
, the wiper blades
125
are located so that one wiper blade
125
is in contact with the blade cleaner
128
as illustrated in FIG.
19
A. While the wiper operation is not carried out, the wiper blades
125
is kept in the state where the wiper sensor
127
detects the sensor flag
126
, so that the wiper blades
125
are kept off contact with the printing heads
11
.
The above described the recover-supply unit
6
of the present embodiment, and the ink replenishing operation to the sub-tanks
12
by this recovery-supply unit
6
will be described referring to FIG.
20
and
FIGS. 21A and 21B
.
FIG. 20
is a block diagram of the major part of the electric system of the recovery-supply unit of the present embodiment illustrated in FIG.
15
and other figures, and
FIGS. 21A and 21B
are flowcharts of the replenishing operation of ink to the sub-tanks.
In
FIG. 20
, CPU
200
is provided for carrying out the ink replenishing operation by controlling the step motor
28
, electromagnetic clutch
35
for cap, electromagnetic clutch
70
for selection of pump, electromagnetic clutch
103
for the first group, and electromagnetic clutch
92
for the second group, based on detection results of ink amount detecting sensors
201
provided in the respective sub-tanks, and of ink remainder detecting means
202
for detecting the remainder of ink in the sub-tanks, the ink remainder detecting means being comprised of dot counters for counting shots ejected for printing from the printing heads and a memory for storing counted numbers.
First, the CPU
200
determines whether there are a plurality of colors of the ink liquids to be replenished, based on signals from the respective ink remainder detectors
202
(step
301
).
When the ink to be replenished is only one color, the CPU determines whether the sub-tank
12
to be replenished with the ink belongs to the first group
81
or to the second group
82
(step
303
). When it belongs to the first group
81
, the CPU determines the replenishment to be carried out in combination with a sub-tank
12
with the greatest ink consumption from the signals of the ink detectors of the second group, i.e., in combination with a sub-tank
12
of the liquid supply path having the largest count number in the dot count memory of the second group (step
307
a
). Then the CPU sets the tube valve
80
of the first group
81
and the tube valve
80
of the second group
82
according to the colors of the ink liquids replenished (steps
304
,
306
) and then selects the tube pump
50
a
(step
305
). When the sub-tank
12
to be replenished with the ink belongs to the second group, the CPU also determines a sub-tank for replenishment in combination therewith from the first group in the similar way and sets the valves of the first and second groups, and the tube pumps.
In the present embodiment, the dot count memory is arranged to be capable of storing dot count values for the respective colors of the printing heads and to add up values every ejection of the printing heads
11
to memorize the results. This allows estimation of remaining ink amounts in the respective sub-tanks. After completion of the replenishing operation, the dot counter memory is reset to 0 for the ink supply paths having undergone the replenishment of ink.
On the other hand, if there are a plurality of colors of the ink liquids to be replenished (in the determination of step
301
) the CPU selects a combination of two or three replenishing operations.
When both the first group
81
and the second group
82
include a sub-tank to be replenished with the ink, replenishment is carried out at one time in combination thereof (which is determined in step
302
). When the sub-tanks requiring replenishment of ink are localized in one group, the operation is similar to the aforementioned operation for replenishment of one color; a sub-tank with the greatest liquid consumption is selected out of the three sub-tanks of the different group (e.g., the second group
82
) to be combined (step
307
a
or
307
b
) and concurrent replenishment is carried out.
After setting the tube pumps
50
a,
50
b
by the above-stated sequence according to the number of sub-tanks requiring replenishment, the CPU closes the atmosphere open valves
24
provided for the sub-tanks
12
to which the liquid is supplied (steps
311
a,
311
b
) and then drives the tube pumps
50
a,
50
b
thus selected (step
312
). This achieves the replenishment of the ink in the predetermined sub-tanks
12
. When the ink amount detector
201
detects that the sub-tank
12
undergoing the replenishment of ink is filled with the ink (step S
313
a
or
313
b
), the atmosphere open valve
24
of the full sub-tank is opened (step
314
). Since the full sub-tank is opened to the atmosphere at this time, the replenishment of liquid is stopped; but the unfilled sub-tank is still kept in the hermetically closed state and is thus under the replenishment of liquid. When the ink amount detector
201
detects that the other sub-tank under the replenishment is filled with the ink (step
317
), the atmosphere open valve
24
thereof is opened (step
318
) and the tube pumps
50
a,
50
b
are stopped (step
315
).
This fills one or two sub-tanks
12
with the ink. It is then determined whether there is another sub-tank
12
requiring replenishment of ink (step
316
). If there is no sub-tank requiring replenishment then the replenishing operation of ink is terminated. If there is one then the sequential operation described above will be repeated.
As described above, each sub-tank
12
can be independently replenished with the ink by setting each tube valve
80
according to the sub-tank
12
requiring the replenishment of ink, driving the tube pump
50
a,
50
b,
and matching the operation of the atmosphere open valve of each sub-tank with the detection result of the ink amount detector
201
. This obviates the necessity for providing each sub-tank
12
with a negative pressure generator for generating the negative pressure in the sub-tank
12
during the replenishment of ink, which allows decrease in the size of the recovery unit
6
and, in turn, decrease in the size of the overall ink jet recording apparatus.
Further, concurrent ink replenishment can always be performed in combination with the sub-tank with the greatest ink consumption in each group, either the first group or the second group, in any ink replenishing operation, which can increase the efficiency of ink replenishment and which can achieve decrease in the number of ink replenishing operations and decrease in print wait time for ink replenishment.
The above operation will be described in more detail with a specific example for supplying ink liquids of yellow, black, and magenta. As described previously, the sub-tanks of black and magenta belong to the second group
82
while the sub-tank of yellow to the first group
81
.
First, the CPU
200
selects concurrent replenishment of black and yellow as the first replenishing operation. Then the CPU
200
performs such control as to set the tube valves
80
of the first group
81
in the yellow replenishment mode. This setting is effected by switching the first-group electromagnetic clutch
103
on, rotating the step motor
28
, and setting the angle of rotation of the first-group cams
87
(see
FIG. 15
) to 90° as in Table 2, based on the detection signal of the first-group sensor
109
, as described previously.
Then the CPU
200
performs such control as to set the tube valves
80
of the second group
82
in the black replenishment mode. This setting is effected by switching the second-group electromagnetic clutch
92
on, rotating the step motor
28
, and setting the angle of rotation of the second-group cams
86
(see
FIG. 14
) to 90° as in Table 3, based on the detection signal of the second-group sensor
101
, as described previously.
Then the CPU
200
performs such control as to set selection of the both tube pumps
50
a,
50
b
for replenishment. This setting is accomplished by switching the electromagnetic clutch
70
for selection of pump on, rotating the step motor
28
, and setting the angle of rotation of the pump cams
75
(see
FIG. 9
) to 90° as in Table 1, based on the detection signal of the pump sensor
77
, as described previously. Then the atmosphere open valves
24
are closed to bring the sub-tanks
12
of yellow and black into the hermetically closed state.
In this state the CPU
200
performs such control as to drive the tube pumps
50
a,
50
b.
This establishes the negative pressure in the sub-tanks
12
of yellow and black, whereby the sub-tanks are replenished with the ink from the associated main tanks
13
. This driving of the tube pumps
50
a,
50
b
is carried on until the ink remainder detecting sensors detect that the sub-tanks
12
of yellow and black are filled with the ink. When it is detected, the atmosphere open valves
24
are opened and the tube pumps
50
a,
50
b
are stopped. The above completes the first replenishment operation.
After completion of the first replenishment operation, the CPU
200
determines whether the second replenishment operation should be carried out. Since there still remains the replenishment of the ink of cyan at this point, the CPU returns to the initial step. Since the sub-tank
12
storing the ink of cyan belongs to the first group
81
, the CPU
200
determines that the replenishment is to be carried out in combination with a sub-tank
12
of a liquid supply path having the largest count number in the dot count memory out of the three ink supply paths of the second group (step
307
a
).
Since the replenishment of the yellow ink is already done, a candidate for the combination herein is light magenta or light cyan. After the combination for concurrent replenishment is determined, the operation to follow is carried out in the similar manner to the first replenishment operation; the atmosphere open valves
24
are closed to drive the tube pumps
50
a,
50
b,
the sub-tanks
12
of the ink of cyan and the other color to be simultaneously replenished with cyan are filled with the ink, and then the atmosphere open valves
24
are closed to stop the tube pumps
50
a,
50
b.
This completes the replenishment operation of all the ink.
In the application of color print using the ink liquids of black, cyan, magenta, yellow, light magenta, and light cyan like the present embodiment, consumptions of the black ink and the yellow ink are normally larger than those of the ink of the other colors. Thus black and yellow often have to be replenished on the almost same timing. Therefore, black and yellow are preferably grouped into the different groups as in the present embodiment, whereby the both can be replenished at one time even with coincidence of replenishment timing of black and yellow, so that the ink can be replenished more effectively. In the case where ink liquids with more consumptions are preliminarily determined as described, they are preferably assigned to mutually different groups.
In the present embodiment the six sub-tanks
12
are grouped into the two groups and each group is provided with the tube pump
50
a
or
50
b
being the negative pressure generating means; but the sub-tanks
12
do not always have to be grouped in the two groups. The apparatus may be modified so that an appropriate number of negative pressure generators are provided within the scope smaller than the number of liquid supply paths including the sub-tanks and groups are provided in the number equal to the number of negative pressure generators. Since the concurrent replenishment of plural ink liquids is not possible with only one negative pressure generator, it is necessary to provide two or more negative pressure generators in order to achieve more efficient ink replenishment. The optimum number of negative pressure generators (i.e., the number of groups) is preferably designed in view of the permissible volume and ink replenishment efficiency of the ink jet recording apparatus.
The numbers of liquid supply paths belonging to the respective groups do not always have to be equal. For example, in the case where ink liquids of six different kinds are used like the present embodiment or where liquids used are ink liquids and treatment liquids to react with the ink liquids, if the consumption of one kind among them is extremely large, only the liquid supply path for supplying the liquid of that kind may be handled as a single group.
In the above embodiment the ink replenishment into each sub-tank has to be carried out in the period in which the printing operation is not performed. Next described referring to FIG.
22
and
FIG. 23
is a modification in which the structure of the sub-tanks is modified in order to decrease the stop time.
FIG. 22
is an explanatory drawing to show the modification of the ink supply paths of the present invention and
FIG. 23
is a schematic block diagram of the part involved in the ink replenishment into the sub-tanks in the modification. The present modification is different from the above embodiment in that the ink replenishment can also be performed during printing. When combined with the liquid supplying method of the present invention, the present modification can improve the efficiency of ink replenishment more.
In the following description elements having similar functions to those in the above embodiment will be denoted by the same reference symbols and the description thereof will be omitted.
First described is the flow of the ink in the modification of the present invention.
In
FIG. 22
, a hermetically closed tank
401
is replenished with the ink from the main tank
13
through the tank tube
20
. After that, the sub-tank
12
is replenished with the ink from the hermetically closed tank
401
through a CS tube
404
. Then the ink is supplied to air buffer
402
through closed-tank tube
406
from the hermetically closed tank
401
and through sub-tank tube
407
from the sub-tank
12
.
The ink is supplied from the air buffer
402
through head tube
21
to the printing head
11
.
The flow of the ink will be described in further detail referring to FIG.
22
.
First described is the supply of the ink to the hermetically closed tank
401
.
The atmosphere open valve
24
, AC tube closing valve
403
, and CS tube closing valve
405
are actuated to hermetically close the inside of the hermetically closed tank
401
. Then the negative pressure generating tube pump
19
is driven to establish the negative pressure inside the hermetically closed tank
401
, whereby the ink inside the main tank
13
is supplied through the tank tube
20
into the hermetically closed tank
401
.
When the ink remainder detecting sensor
201
detects “full” as a result of the ink replenishing operation from the main tank
2
to the hermetically closed tank
401
, the atmosphere open valve
24
is opened to make the hermetically closed tank
401
open to the atmosphere and then to stop the flow of ink. After that, an instruction to stop the negative pressure generating tube pump
19
is issued, so that the pump
19
is stopped. The other end of the negative pressure generating tube pump
19
is put in the waste ink tank
14
.
Then the AC tube closing valve
403
and CS tube closing valve
405
are opened, whereupon the ink inside the hermetically closed tank
401
moves through the CS tube
404
into the sub-tank
12
because of the weight of the ink itself. Then the ink inside the hermetically closed tank
401
flows into the sub-tank
12
before the height of the ink inside the hermetically closed tank
401
becomes equal to that of the ink inside the sub-tank
12
.
If air (bubbles) is mixed in the ink in the CS tube
404
, the ink will be hard to flow or will not be allowed to flow in the CS tube
404
in some cases.
In such cases, the atmosphere open valve
24
and AC tube closing valve
403
are closed and thereafter the negative pressure generating tube pump
19
is driven in the counterclockwise direction, whereby positive pressure is established in the hermetically closed tank
401
to push the ink in the hermetically closed tank
401
into the CS tube
404
. This pushes the air (bubbles) from the CS tube
404
into the sub-tank
12
. After that, the negative pressure generating pump
19
is stopped and the atmosphere open valve
24
and AC tube closing valve
403
are opened. As a consequence, the inside of the CS tube
404
is filled with the ink, so that the ink in the hermetically closed tank
401
can flow through the CS tube
404
into the sub-tank
12
before the height of the ink in the hermetically closed tank
401
becomes equal to that of the ink in the sub-tank
12
. The sub-tank
12
has an open-to-atmosphere aperture, through which the sub-tank
12
is open to the atmosphere. Therefore, the air (bubbles) pushed into the sub-tank
12
can be released through the open-to-atmosphere aperture into the atmosphere, so that the inside of the sub-tank
12
is kept at the atmospheric pressure.
After the height of the ink in the hermetically closed tank
401
becomes equal to that of the ink in the sub-tank
12
and when the ink remainder detecting sensor
201
in the hermetically closed tank
401
detects “empty” of the height of the ink in the hermetically closed tank
401
, the ink replenishing operation into the hermetically closed tank
401
is again carried out.
With repetitions of the above ink replenishing operation, the heights of the ink in the hermetically closed tank
401
and in the sub-tank
12
are maintained between the full-line and the empty-line of the ink remainder detecting sensor
201
.
Next described is the ink supply operation from the sub-tank
12
to the air buffer
402
.
First, the atmosphere open valve
24
, CS tube closing valve
405
, and head tube closing valve
25
are closed. After that, the negative pressure generating tube pump
19
is driven, whereupon the negative pressure is established in the hermetically closed tank
401
. Then the negative pressure is also established in the closed-tank tube
406
, so that the negative pressure is established in the air buffer
402
and in the sub-tank tube
407
as well.
This results in supplying the ink in the sub-tank
12
through the sub-tank tube
407
into the air buffer
402
and thereafter supplying the ink through the closed-tank tube
406
into the hermetically closed tank
401
.
Since the negative pressure is also established in the tank tube
20
at this time, the ink is also supplied from the main tank
13
to the hermetically closed tank
401
. Then the negative pressure generating tube pump
19
is stopped.
After that, the atmosphere open valve
24
and CS tube closing valve
405
are opened.
Since the passage resistance against the flow of the ink through the sub-tank tube
407
, air buffer
402
, and closed-tank tube
406
is arranged to be smaller than that against the flow of the ink in the tank tube
20
, the ink can be supplied to the air buffer
402
with reliability.
Next described is the ink supply operation from the air buffer
402
to the printing head
11
.
First, the printing head
11
is capped by the cap
16
. Then the recovery tube pump
18
is driven, whereupon the negative pressure is established in the cap
16
connected through the tube to the recovery tube pump
18
. This results in supplying the ink in the air buffer
401
through the head tube
21
to the printing head
11
and then filling the nozzles in the printing head
11
with the ink. Thereafter, the recovery tube pump
18
is stopped and then the cap
16
is uncapped. At this time a meniscus is created in the nozzles in the printing head
11
, so that the ink can be held even with a difference between the nozzle face of the printing head
11
and the height of the ink in the hermetically closed tank
401
and the sub-tank
12
. The ink drawn into the cap
16
is guided through the suction tube
22
into the waste ink tank
14
.
The ink can be ejected from the printing head
11
by charging the ink into the ink path illustrated in
FIG. 22
, in this way.
When the ink is discharged from the printing head
11
by the printing operation or the recovery suction operation of the printing head
11
, the ink flows from the sub-tank
12
to the printing head
11
because of the capillarity, whereby the meniscus is always maintained in the nozzles of the printing head
11
. Then the liquid level is lowered in the sub-tank
12
and the weight of the ink acts to keep the liquid levels equal in the sub-tank
12
and in the hermetically closed tank
401
. Thus, the ink is supplied from the hermetically closed tank
401
to the sub-tank
12
.
When the ink is consumed because of printing or the like, the ink remainder detecting sensor
201
of the hermetically closed tank
401
detects “empty” and the ink replenishing operation is carried out.
This ink replenishing operation is similar to the operation described in the aforementioned embodiment.
In the modification, the ink is supplied to the hermetically closed tank
401
, instead of the sub-tank
12
of the aforementioned embodiment, and the hermetically closed tank
401
is hermetically closed without closing the head tube closing valve
25
, but, instead, with closing the AC tube closing valve and CS tube closing valve
405
. Therefore, the ink replenishing operation can be performed wherever the carriage
1
is located. The ink can be supplied to the printing head
11
because of the action of the sub-tank
12
, and thus the ink replenishment can be conducted even during printing.
As described in the aforementioned embodiment, sets of sub-tanks
12
, hermetically closed tanks
401
, and main tanks
13
(also including the tubes connected thereto) are grouped into the first group and the second group, each group is provided with the negative pressure generator, and the ink consumption of each hermetically closed tank
401
(sub-tank
12
) is managed by the dot counter for each printing head
11
, and the memory; therefore, a combination of tanks with the greatest ink consumptions in the respective groups can always be replenished with the ink on the concurrent basis.
The ink replenishing operation to the hermetically closed tank
401
will be described below.
The operation of the tube valve is the same as in the aforementioned embodiment.
Reference is made to the flowchart of operation and the block diagram of the aforementioned embodiment, which are the same in the present modification.
When the ink to be replenished is of one color, it is determined whether the hermetically closed tank
401
to be replenished with the ink belongs to the first group
81
or to the second group
82
(step
303
). When it belongs to the first group
81
, the CPU
200
invokes the contents of the dot count memory about the three hermetically closed tanks
401
of the other group (the second group
82
) and chooses a hermetically closed tank
401
with the greatest consumption among them as a counterpart of a combination (step
307
a
) to determine replenishment thereof. Then the tube valves
80
of the first group
81
and the tube valves
80
of the second group
82
are set according to the colors of the ink liquids to be replenished (step
304
and step
306
) and the tube pumps
50
a,
50
b
are selected (step
305
).
In the case of the second group
82
, the CPU also invokes the contents of the dot count memory about the three hermetically closed tanks
401
of the other group (the first group
81
) and selects one hermetically closed tank
401
with the greatest consumption among them as a counterpart of a combination (step
307
b
) to determine replenishment thereof. Then the tube valves
80
of the first group
81
and the tube valves
80
of the second group
82
are set according to the colors of the ink liquids to be replenished (step
304
and step
306
) and the tube pumps
50
a,
50
b
are selected (step
305
).
The dot count memory, similar to that in the aforementioned embodiment, can capture the consumption of the ink of each color and can estimate the remaining ink amount in each hermetically closed tank
401
. The dot count memory is reset to zero after completion of the ink replenishment.
On the other hand, when there are a plurality of ink liquids to be replenished (in the determination in step
301
), replenishment is effected by a combination of two or three replenishment operations.
When the first group
81
and the second group
82
both includes the ink to be replenished at this time, the concurrent replenishment is carried out in combination of the ink liquids to be replenished (in the determination in step
302
). When only either one group includes the ink to be replenished, the CPU invokes the contents of the dot count memory about the three hermetically closed tanks
401
of the other group (the second group
82
), chooses one hermetically closed tank
401
with the greatest consumption among them as a counterpart of a combination (steps
307
a,
307
b
), as described in the case of one color of the ink to be replenished, and then performs concurrent replenishment. As described, the hermetically closed tanks
401
with the greatest ink consumptions in the respective groups of the first group
81
and the second group
82
can always be replenished on the concurrent basis in any ink replenishing operation, which improves the efficiency of ink replenishment.
Then the tube pumps
50
a,
50
b
are set and the atmosphere open valves
24
provided for the hermetically closed tanks
401
are next closed (step
311
a
and step
311
b
). Then the tube pumps
50
a,
50
b
are driven (step
312
). This replenishes the predetermined hermetically closed tanks
401
with the ink. When the ink remainder detecting sensor
201
detects that the corresponding, hermetically closed tank
401
replenished with the ink is filled with the ink (step
313
a
or
313
b
), the atmosphere open valve
24
of the filled, hermetically closed tank
401
is opened (step
314
a
or
314
b
). This results in opening the hermetically closed tank
401
to the atmosphere, so that the negative pressure disappears to stop the replenishment of ink, irrespective of driving of the tube pump
50
a
or
50
b
(in this state the atmosphere open valve
24
of the hermetically closed tank
401
is still closed on the side without detection of the ink remainder detecting sensor
201
, and the ink replenishment is on the way on that side). When the ink remainder detecting sensor
201
detects that the hermetically closed tank
401
on the other side is also filled with the ink (step
317
), the atmosphere open valve
24
thereof is opened (step
318
) and the tube pump
50
a
or
50
b
is stopped (step
315
). Then the CS tube closing valve
405
and AC tube closing valve
403
are opened, whereupon the ink is supplied through the CS tube
404
into the sub-tank
12
because of the weight of the ink itself.
This fills one or two sub-tanks
12
with the ink. Then the CPU determines whether there is another hermetically closed tank
401
necessitating replenishment of ink (step
316
). If no then the replenishment operation of ink is terminated; if any then the sequential operation described above is repeated.
Each tube valve
80
is set and each tube pump
50
a,
50
b
is driven according to the hermetically closed tank
401
(sub-tank
12
) necessitating the replenishment of ink and the operation of the atmosphere open valve
24
of each sub-tank
12
is timed with the ink remainder detecting sensor
201
, as described above, whereby each hermetically closed tank
401
(sub-tank
12
) can be replenished with the ink independently. As a consequence, the recovery-supply unit
6
can be provided without the necessity for provision of the negative pressure generator for generating the negative pressure in the hermetically closed tank
401
during the replenishment of ink for every hermetically closed tank
401
, and, even in any ink replenishing operation, the concurrent replenishment can always be performed for the hermetically closed tanks
401
(sub-tanks
12
) with the greatest ink consumptions in the respective groups of the first group
81
and the second group
82
, which can improve the efficiency of ink replenishment and which can decrease the number of ink replenishing operations.
Even in the case of the above ink path configuration capable of ink replenishment during printing, the decrease in the number of ink replenishing operations presents the advantages of saving of power and decrease of abrasion of parts.
As described above, the present invention permits downsizing of the whole apparatus by the structure in which a plurality of liquid supply paths share one negative pressure generator and also permits the concurrent charge of liquids to the respective liquid supply paths having the sub-tanks with the greatest liquid consumptions in the respective groups separated according to the number of negative pressure generators during replenishment of liquid, whereby the invention can improve the efficiency of liquid replenishment and decrease the number of ink replenishing operations and, in turn, can decrease the time of stop of the apparatus for the ink replenishment.
For replenishing a sub-tank with a liquid, the sub-tank is hermetically closed to the atmosphere and is depressurized by use of the negative pressure generator provided for a path different from the liquid supply path, whereby the liquid is supplied from the upstream side of the liquid supply path into the sub-tank. This can implement stable replenishment of liquid as well as the simple structure of the liquid supply path.
The embodiments described above employed detection of the remainder by use of the dot counters for detecting the remainder of liquid in the sub-tanks, but the method for detecting the remainder is not limited to this method. For example, the remainder can also be detecting by use of one of well-known configurations, such as provision of electrodes in the sub-tanks.
Further, the present invention was described with the examples of the ink jet recording apparatus in the above-stated embodiments, but it should be noted that the present invention can not be applied only to the ink jet recording apparatus but can also be applied to other applications, including supply of liquid to a liquid consuming member except for the recording head. In addition, the applicable liquids are not limited only to the ink and pretreatment solutions and the liquids may be oily liquids. Particularly, the invention is suitably applicable to supply of a liquid that is desired to avoid mixture of contamination in the supply path.
Claims
- 1. A liquid replenishing method into a liquid supply mechanism, said liquid supply mechanism comprising three or more liquid supply paths, each liquid supply path having a sub-tank for temporarily retaining a liquid and for supplying said liquid by guiding atmospheric air thereinto,said replenishing method comprising: a preparing step to prepare a plurality of negative pressure generating means, each for depressurizing an inside of one of said sub-tanks, the number of negative pressure generating means being smaller than the number of said liquid supply paths, and to group said plurality of liquid supply paths into groups according to said number of said negative pressure generating means, an establishing step to establish a hermetically closed space in a sub-tank with a smallest remaining liquid in each group, and a replenishing step to replenish liquid, the liquid being replenished commencing simultaneously in each said sub-tank with a smallest remaining liquid in each group, and being replenished commencing simultaneously by depressurizing the insides of each hermetically closed space using said negative pressure generating means associated with each group.
- 2. The liquid replenishing method according to claim 1, wherein said replenishing step is carried out when the remainder of the liquid in at least one sub-tank out of the sub-tanks provided in said plurality of liquid supply paths falls below a predetermined amount.
- 3. The liquid replenishing method according to claim 1, wherein, after said replenishing step, the sub-tank having been replenished is opened to atmospheric air.
- 4. The liquid replenishing method according to claim 1, wherein depressurizing the inside of each hermetically closed space by said negative pressure generating means is achieved in such a manner that each negative pressure generating means evacuates atmospheric air inside the sub-tank corresponding thereto.
- 5. The liquid replenishing method according to claim 1, wherein two liquid supply paths with large liquid consumptions out of said plurality of liquid supply paths are grouped into mutually different groups.
- 6. A liquid ejection recording apparatus capable of ejecting liquids of mutually different kinds, said apparatus comprising:at least three liquid supply paths, each liquid supply path comprising a liquid ejection head for ejecting a liquid to effect recording, a main tank for reserving the liquid to be supplied to said liquid ejection head, and a sub-tank, provided between said liquid ejection head and the main tank, for temporarily retaining the liquid and for supplying the liquid to said liquid ejection head by guiding atmospheric air thereinto, and a plurality of negative pressure generating means, each for depressurizing an inside of one of said sub-tanks in order to replenish the liquid from said main tank into said sub-tank, the number of said negative pressure generating means being smaller than the number of said liquid supply paths, wherein said liquid supply paths are grouped into groups according to said number of said negative pressure generating means, wherein each of said plurality of liquid supply paths comprises hermetically closing means for establishing a hermetically closed space in said sub-tank, and wherein out of said sub-tanks, a sub-tank with a smallest remaining liquid in each group is depressurized by said negative pressure generating means and said closing means associated therewith, and the liquid is replenished commencing simultaneously to each depressurized sub-tank.
- 7. The liquid ejection recording apparatus according to claim 6, wherein two liquid supply paths with large consumptions, out of said plurality of liquid supply paths, are grouped into mutually different groups.
- 8. The liquid ejection recording apparatus according to claim 6, wherein each of said plurality of negative pressure generating means is provided in a path different from the liquid supply paths in a corresponding group.
- 9. The liquid ejection recording apparatus according to claim 6, wherein each of said plurality of negative pressure generating means is comprised of a pump capable of evacuating air in a sub-tank provided in a liquid supply path in a corresponding group.
- 10. The liquid ejection recording apparatus according to claim 9, wherein each of said negative pressure generating means is comprised of a tube pump, said tube pump comprising a tube pump provided in a tube connected to a sub-tank in a corresponding liquid supply path out of the liquid-supply paths grouped according to the number of negative pressure generating means, a tube receiver for receiving said pump tube, a roller member adapted so as to pinch said pump tube in cooperation with said tube receiver and to be movable along said pump tube thereon, and a tube receiver energizing member for energizing said tube receiver toward said roller member.
- 11. The liquid ejection recording apparatus according to claim 6, wherein each of said plurality of liquid supply paths comprises detecting means for detecting whether the remainder of the liquid in the corresponding sub-tank is not more than a predetermined amount.
- 12. The liquid ejection recording apparatus according to claim 11, wherein said detecting means comprises a dot counter for counting shots ejected for printing from each said liquid ejection head and a memory for storing the number of shots.
- 13. The liquid ejection recording apparatus according to claim 6, wherein each liquid supply path from said sub-tank to said recording head is comprised of a tube, and wherein said hermetically closing means is comprised of a tube valve, said tube valve comprising a tube pressing member elastically supported so as to be capable of pressing said tube, a tube valve lever provided so as to be movable toward said tube pressing member, and a lever energizing member for energizing said tube valve lever toward said tube pressing member, said tube valve being adapted to flatten said tube from outside said tube to close a flow path in said tube.
- 14. The liquid ejection recording apparatus according to claim 13, comprising valve setting means having a tube valve cam mechanism for moving said tube valve lever against an energizing force of said lever energizing member.
- 15. The liquid ejection recording apparatus according to claim 6, wherein each said sub-tank comprises a first chamber in fluid communication with a corresponding main tank and with the negative pressure generating means, said first chamber being replenished with the liquid from the main tank, a second chamber in fluid communication through a communication path with said first chamber and in fluid communication with said recording head, said second chamber supplying the liquid to said recording head by guiding atmospheric air thereinto, and path closing means for closing said communication path.
Priority Claims (2)
Number |
Date |
Country |
Kind |
9-287042 |
Oct 1997 |
JP |
|
10-261797 |
Sep 1998 |
JP |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
10-6521 |
Jan 1998 |
JP |