Information
-
Patent Grant
-
6402311
-
Patent Number
6,402,311
-
Date Filed
Monday, August 21, 200024 years ago
-
Date Issued
Tuesday, June 11, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Fitzpatrick, Cella, Harper & Scinto
-
CPC
-
US Classifications
Field of Search
US
- 347 56
- 347 61
- 347 63
- 347 65
- 347 93
- 347 92
-
International Classifications
-
Abstract
An ink jet recording head comprising a plurality of discharge ports for discharging ink droplets, a plurality of ink flow paths communicated with the respective discharge ports, a common liquid chamber communicated with said ink flow paths and adapted to hold ink to be introduced into said ink flow paths, electro-thermal converting portions disposed in said ink flow paths and adapted to generate heat for bubbling the ink, and bubble trapping portions disposed at communicating portion between said ink flow paths and said common liquid chamber.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head in which a bubble is generated by heating ink by means of an electrothermal converting element and the ink is discharged by pressure upon generation of the bubble, an ink jet recording head cartridge in which such an ink jet recording head and a liquid container for supplying liquid to the ink jet recording head are integrally formed, and an ink jet recording apparatus to which such an ink jet recording head cartridge is mounted.
2. Related Background Art
Almost all of ink jet recording apparatuses have been used as a printing apparatus in an image forming apparatus such as a printer, a facsimile, a word processor, a copying machine and the like. Among them, an ink jet recording apparatus of type in which thermal energy is used as energy utilized for discharging the ink and the bubble is generated in the ink by the thermal energy and the ink is discharged by change in volume upon generation of the bubble has recently been spread.
Further, as another application of the ink jet recording apparatus of this kind, an ink jet print device for printing a predetermined pattern, a design or a composite image on cloth has recently been known. An ink jet recording head used in the above-mentioned ink jet recording heads utilizes electrothermal converting elements (referred to also as “heaters” hereinafter) as means for generating the energy, and, in many cases, one heater corresponds to one discharge port.
To the contrary, an ink jet recording head in which a plurality of heaters are provided with respect to each of discharge ports for the following reasons has also been known.
That is to say, firstly, in order to extend the service life of the ink jet recording head, the plurality of heaters are driven alternately or the heater to be driven is appropriately switched. Secondly, by changing an ink discharged amount by selecting the heater or heaters to be driven, the change in ink discharged amount is realized.
As a concrete construction of the latter, an arrangement in which a plurality of heaters are disposed in each ink flow path (nozzle) communicated with a corresponding ink discharge port of the ink jet recording head along an ink discharging direction so that the ink discharged amount is changed due to the difference in distance between the driven heater and the associated discharge port by selecting the heater to be driven (heated) or the ink discharged amount is changed by changing the number of heaters to be driven has been known.
Further, as another construction, for example, as disclosed in Japanese Patent Application Laid-open No. 55-132259, an arrangement in which a plurality of heaters having different surface areas are disposed in each ink flow path so that the ink discharged amount is changed by similarly changing the heater to be driven or changing the number of heaters to be driven is also known.
An example of such an ink jet recording head is shown in
FIG. 17
as a sectional view. As shown in
FIG. 17
, in this ink jet recording head, two heaters
6002
,
6003
having different dimensions and different distances from a discharge port
6004
are disposed in a nozzle
6001
for communicating the ink discharge port
6004
with a common liquid chamber
6005
for containing ink to be supplied to a plurality of nozzles
6001
so that the amount of ink to be discharged can be changed by driving one or both of the heaters
6002
,
6003
.
Although the above-mentioned ink jet recording head having the plurality of heaters disposed in the respective nozzle has a purpose for realizing high speed and high accurate printing in response to various images by changing the ink discharged amount, there arose the following problem to achieve this purpose.
Nowadays, high density arrangement of the nozzle has been requested to achieve high accurate and finer printing, and, to this end, a width of each nozzle must be narrower. On the other hand, the heaters having large sizes must be used in order to widen the variable range of the ink discharged amount. Accordingly, when the size of the heater tries to be increased in the narrow nozzle, a longitudinal dimension (length) of each heater must be increased along the longitudinal direction of the nozzle, with the result that a length of the nozzle must be increased. If the length of the nozzle is increased, flow resistance of the nozzle will be increased, with the result that a time (re-fill time) for restoring meniscus retarded within the nozzle after the ink discharging to the vicinity of the discharge port again is delayed, thereby reducing the recording speed.
As a method for shortening the ink re-fill time to hasten the recording speed, a method in which the length of the nozzle
6001
is shortened, and, as shown in
FIG. 18
, a method in which a cross-sectional area of the nozzle
6001
at the heater
6002
is selected to be smaller than a cross-sectional area thereof at the inlet of the common liquid chamber
6005
(as disclosed in U.S. Pat. No. 4,752,787) are already known.
However, if the length of the nozzle is smaller than a certain value with respect to the heater position, when the temperature of the recording head is increased, a bubbling volume on the heater is increased, and the bubble formed by the bubbling may protrude from a rear end of the nozzle.
That is to say, as shown in
FIG. 19A
, even in case of a recording head a bubble
6007
is generated within a nozzle
6001
when the ink is bubbled in a condition that the recording head has a room temperature (for example, 25° C.), when ink is generated in a condition that the temperature in the recording head is increased (for example, to about 60° C. or more) due to discharging of ink from all nozzles with high frequency, since the energy required for the bubbling is small, if the energy similar to that shown in
FIG. 19A
is given, as shown in
FIG. 19B
, the bubble will be grown greatly to protrude toward the common liquid chamber
6005
from the nozzle
6001
.
A state in which the ink is discharged in the condition that the temperature in the recording head is increased is shown in
FIGS. 20A
to FIG.
20
E.
FIG. 20A
shows a condition that film boiling is started by heating the heaters
6002
,
6003
. From this condition, when the energy is further applied to the heaters
6002
,
6003
, the bobbles
6007
are grown as shown in
FIG. 20B
, with the result that the ink is discharged from the discharge port
6004
by pressure generated by the growth of the bubbles
6007
.
FIG. 20C
shows a condition that the discharging of the ink is completed and the bubbles
6007
was grown to the maximum extent. In this condition, the bubble
6007
protrudes from the nozzle
6001
to reach the common liquid chamber
6005
. From this condition, when the heating of the heaters
6002
,
6003
is stopped to cool the bubbles
6007
, contraction of the bubbles
6007
is started, and the re-fill of ink from the common liquid chamber is started and the ink near the discharge port is shifted, with the result that the meniscus starts to be retarded within the nozzle
6001
. In the common liquid chamber communicated with the inlet of the nozzle, since the ink is flown into the nozzle at once around the bubble portion
6007
protruded in the common liquid chamber, eddy ink flow is created, with the result that, as shown in
FIG. 20D
, the bubble
6007
is separated. Thereafter, as shown in
FIG. 20E
, the bubbles
6007
on the heaters
6002
,
6003
are disappeared, and the meniscus is restored in the vicinity of the discharge port
6004
as the ink re-fill continues. At this stage, the separated bubble
6007
remains within the common liquid chamber
6005
.
Although the residual bubble
6010
remained within the common liquid chamber
6005
by single ink discharging in this way is small, when the ink is discharged from all of the nozzles with high frequency of about 10 kHz, a large amount of residual bubbles
6010
may be stored in the common liquid chamber for a short time. As shown in
FIG. 21A
, the stored or trapped residual bubbles
6010
is flown together with the ink during the ink re-fill to enter into the nozzle as shown in
FIG. 21B
, with the result that the complete ink re-fill may not be attained. Further, as shown in
FIG. 21B
, if the residual bubble
6010
covers the heater
6003
, even when the heater
6003
is heated, a new bubble
6007
cannot almost be generated, with the result that the ink may not be discharged.
If the amount of residual bubbles in the common liquid chamber
6005
is small, although such residual bubbles can be removed by a suction recovery operation after the recording or during the recording, if the large amount of residual bubbles are generated for a short time, the suction recovery operation must be repeated frequently, with the result that an amount of useless ink sucked during the suction recovery operations is increased and the recording speed is worsened.
Further, if the nozzle
6001
is short, due to pressure energy transmitted from the rear end (connected to the common liquid chamber) of the nozzle
6001
to the common liquid chamber
6005
during the discharging of the ink droplet, a cross-talk phenomenon affecting a bad influence upon the ink discharging of the adjacent nozzle
6001
may occur.
Constructions of a nozzle
6001
suppressing or eliminating such bad influence such as poor discharging are shown in
FIGS. 22A and 22B
. In
FIGS. 22A and 22B
, for a purpose of comparison, the configuration of the nozzle
6001
of
FIG. 17
is shown by the broken line.
In the construction shown in
FIG. 22A
, by lengthening the nozzle
6001
, even when the bubbling is effected in the condition that the temperature in the recording head is increased, the bubble is prevented from protruding in the common liquid chamber
6005
. However, with this construction, when the temperature in the recording head is high and viscosity of ink is low, although the short time re-fill can be achieved narrowly, if the temperature in the recording head is the room temperature, the re-fill time becomes very long and, thus, the recording with high frequency becomes impossible.
In the construction shown in
FIG. 22B
, by providing a restrict
6008
for restricting the flow cross-area at a rear end portion of the nozzle
6001
to increase flow resistance at the restrict (stricture), the bubble
6007
is prevented from growing toward the rearward of the nozzle
6001
. However, in an arrangement in which the plurality of heaters
6002
,
6003
are provided in the single nozzle
6001
, there is the heater
6002
ahead of the rear heater
6003
, and, by the bubbling action of the heater
6002
, the bubble
6007
generated on the rear heater
6003
is pushed toward the rearward of the nozzle
6001
. As a result, even when the flow resistance is increased at the rear portion of the nozzle
6001
, the growing of the bubble
6007
toward the rearward of the nozzle
6001
cannot suppressed completely.
As mentioned above, in the ink jet recording head in which the plurality of heaters
6002
,
6003
are provided in each nozzle
6001
, sizes of areas on which the heaters are located become great in the longitudinal direction of the nozzle without fail. In this arrangement, if the length of the nozzle is increased, the re-fill time is increased; whereas, if the length of the nozzle is reduced, the residual bubbles are stored in the common liquid chamber
6005
and the stored residual bubbles flow back into the nozzle
6001
to generate the bad influence such as poor discharging. Thus, there is a “trade-off” relationship.
Further, if the ink supplying ability is enhanced by approaching the common liquid chamber to the discharge port, even when the single heater is used, the bubble may protrude in the common liquid chamber. The present invention also solve such a problem.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an ink jet recording head which can overcome the conventional trade-off problem and in which the re-fill time is shortened and the residual bubbles are not stored in a common liquid chamber and a high quality image can be recorded at a high speed.
The other objects and features of the present invention will be apparent from the following detailed explanation of the invention.
In order to solve the above problems, the present invention provides an ink jet recording head comprising a plurality of discharge ports for discharging ink droplets, a plurality of ink flow paths communicated with the respective discharge ports, a common liquid chamber communicated with the ink flow paths and adapted to hold ink to be introduced into the ink flow paths, electrothermal converting portions disposed in the ink flow paths and adapted to generate heat for bubbling the ink, and bubble trapping portions disposed at communicating portion between the ink flow paths and the common liquid chamber and including stepped structures each having a cross-sectional area smaller than a main cross-sectional area of the common liquid chamber and greater than a cross-sectional area of the corresponding ink flow path in a direction perpendicular to an ink introducing direction, and wherein each of the ink flow paths is provided with an inclined portion located between an upstream end of the electrothermal converting portion and the communicating portion of the ink flow path with the common liquid chamber in the ink introducing direction and having a cross-sectional area, in the direction perpendicular to an ink introducing direction, gradually increasing toward the upstream bubble trapping portion, and a surface extended from the inclined portion intersects with a ceiling surface of the bubble trapping portion.
By providing such an inclined portion, even if a bubble formed on the electrothermal converting portion is grown rearwardly, since a volume at an upstream side of the electrothermal converting portion is great, the grown bubble can be prevented from protruding in the common liquid chamber, thereby preventing the bubble from being separated during ink re-fill.
Further, even if the bubble protrudes in the common liquid chamber, since a main direction of the ink in the re-fill is inclined along the inclined surface to reduce a difference between this direction and a flow direction of ink going round from above the protruded bubble, eddy current is hard to occur, with the result that the ink is re-filled smoothly without separating the bubble.
Further, since the cross-sectional area of the inclined portion in the ink introducing direction is great and the flow resistance at the inclined portion is small and since the ink flows smoothly in the re-fill, the ink re-fill time can be shortened.
In addition, since the ink jet recording head according to the present invention has the bubble trapping portion, the bubble discharged from the upstream end of the ink flow path can be trapped in the bubble trapping portion, thereby preventing the bubble from flowing back in the ink flow path. In the ink jet recording head having such bubble trapping portions, by the above-mentioned bubble trapping action and the action of the inclined portion for preventing the bubble grown rearwardly of the ink flow path from being separated and stored in the common liquid chamber, the residual bubble can be prevented from being stored in the upstream side of the ink flow path and can be prevented from flowing back in the ink re-fill.
In this case, by adopting the arrangement in which the surface extended from the inclined portion intersects with the ceiling of the bubble trapping portion, since the ink flow in the re-fill has a main flow component advancing substantially straightly toward the ink flow path in an area surrounded by a surface extended from a side surface in the ink flow path in the ink introducing direction, the ink is not almost supplied from the common liquid chamber to a zone near the ink flow path from the intersect portion between the surface extended from the inclined portion and the ceiling of the bubble trapping portion, with the result that the flow of ink at this zone can be reduced, and the residual bubble can be trapped at this zone, thereby preventing the residual bubble from flowing back into the ink flow path.
By applying the present invention to an ink jet recording head in which the plurality of electrothermal converting elements are arranged side by side in the ink introducing direction, and, when the plurality of electrothermal converting elements are driven substantially simultaneously, by the growth of the bubble formed on the downstream electrothermal converting element, the bubble formed on the upstream electrothermal converting element is pushed toward the upstream side to facilitate the growth of the bubble toward the upstream side of the ink flow path (common liquid chamber side), the above-mentioned problem caused by the remarkably rearwardly grown bubble can effectively eliminated.
Further, by providing the restrict having the small cross-sectional area in the direction perpendicular to the ink introducing direction at an upstream side of the upstream end of the upstream-most electrothermal converting element and at a downstream side of the inclined portion, even when ink having low viscosity is used, the ink in the re-fill can be flown at a proper speed, and the ink can be prevented from being discharged from the discharge port during the re-fill. Particularly, by selecting a relationship between the cross-sectional area S
1
of the restrict in the direction perpendicular to the ink introducing direction and the cross-sectional area S
2
of the restrict at the upstream end thereof to S
1
/S
2
≦0.5, it is possible to bring the ink re-fill speed to an optimum value without generating eddy ink flow, thereby achieving this effect sufficiently.
In a case where it is assumed that an angle between the inclined portion and a surface on which the electrothermal converting element is located is α and an angle between the surface on which the electrothermal converting element is located and a surface connecting the upstream end of the upstream-most electrothermal converting element to an upper end of the rear end of the ink flow path is β, if α is too small with respect to β, in order to provide the arrangement in which the surface extended from the inclined portion intersects with the ceiling surface of the bubble trapping portion, it is required that the length of the bubble trapping portion be increased or the inclined portion be located at the downstream area form the upstream end of the electrothermal converting element. However, in the former case, the resistance in the suction recovery operation is increased not to effect the recovery sufficiently or lengthen the recovery time; whereas, in the latter case, the flow resistance rearwardly of the ink flow path becomes too small.
Further, if α is too great with respect to β, the volume of the area where the ink is hard to flow in the re-fill as mentioned above will be reduced.
Thus, it is desirable that a relationship between α and β be selected to as follows:
β≦α<β+10°.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B
are schematic views showing an ink jet recording head according to a first reference example of the present invention;
FIGS. 2A and 2B
are views showing growth of a bubble in the ink jet recording head of
FIGS. 1A and 1B
when internal temperatures are different;
FIG. 3
is a schematic view showing an ink jet recording head according to a second reference example of the present invention;
FIG. 4
is a schematic view showing an ink jet recording head according to a third reference example of the present invention;
FIG. 5
is a schematic view showing an ink jet recording head according to an embodiment of the present invention;
FIG. 6
is a schematic view for explaining a characteristic of the ink jet recording head of
FIG. 5
, showing an ink jet recording head in which a surface extended from an inclined portion does not intersect with a bubble trapping portion;
FIG. 7
is a schematic view for explaining a relationship between angles α and β, showing an ink jet recording head when α is slightly greater than β;
FIG. 8
is a schematic view for explaining a relationship between angles α and β, showing an ink jet recording head when α is slightly smaller than β;
FIG. 9
is a schematic view for explaining a relationship between angle α and β, showing an ink jet recording head when α is equal to β;
FIG. 10
is a schematic view for explaining a relationship between angles α and β, showing an ink jet recording head when α is greater than β;
FIGS. 11A
,
11
B and
11
C are views showing an dimensional example of the ink jet recording head of
FIG. 5
;
FIG. 12
is an exploded perspective view showing an example of an ink jet recording head cartridge on which an ink jet recording head according to the present invention is mounted;
FIG. 13
is a perspective view of the ink jet recording head cartridge of
FIG. 12
after assembled;
FIG. 14
is a schematic view showing an example of an ink jet recording apparatus on which the ink jet recording head cartridge of
FIG. 12
is mounted;
FIG. 15
is a block diagram for recording of the ink jet recording apparatus of
FIG. 14
;
FIG. 16
is a schematic view showing another example of an ink jet recording apparatus on which an ink jet recording head according to the present invention is mounted;
FIG. 17
is a schematic view showing a conventional ink jet recording head;
FIG. 18
is a schematic view showing another conventional ink jet recording head;
FIGS. 19A and 19B
are views showing growth of a bubble in the ink jet recording head of
FIG. 17
when internal temperatures are different;
FIGS. 20A
,
20
B,
20
C,
20
D and
20
E are schematic views showing a state that ink is discharged in the ink jet recording head of
FIG. 17
;
FIGS. 21A and 21B
are schematic views showing a state that a residual bubble is flown back into a nozzle in re-fill in the ink jet recording head of
FIG. 17
; and
FIGS. 22A and 22B
are schematic views showing a further conventional ink jet recording head.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be explained in connection with embodiments thereof with reference to the accompanying drawings.
First, of all, in order to explain the effect of provision of an inclined portion
107
, an ink jet recording head in which the inclined portion
107
is provided in an ink jet recording head having no bubble trapping portion
110
will be described as a reference example with reference to
FIGS. 1A
,
1
B,
2
A,
2
B,
3
and
4
.
FIGS. 1A and 1B
are schematic views showing a construction of a nozzle portion
101
of the ink jet recording head as a first reference of the present invention, where
FIG. 1A
is a sectional view and
FIG. 1B
is a plan view.
As shown in
FIGS. 1A and 1B
, the ink jet recording head is of edge shoot type having a discharge port
104
for discharging liquid (ink) in a direction substantially perpendicular to a surface on which heaters (heat generating bodies)
102
,
103
are formed. Within a nozzle (ink flow path)
101
communicating a common liquid chamber
105
for holding ink with and the discharge port
104
for discharging the ink, there are provided a small heater
102
disposed in the vicinity of the discharge port
104
and a large heater
103
disposed behind (toward the common liquid chamber
105
) of the heater
102
, which heaters are arranged side by side along a longitudinal direction of the nozzle
101
. Between a rear end of the heater
103
and a rear end
106
of each nozzle
101
, there is provided an inclined portion
107
in such a manner that a height of a ceiling (surface opposite to a surface on which the heaters
102
,
103
are located) is gradually increased toward the rear end
106
. A plurality of such nozzles
101
are arranged in parallel, and arrangement density thereof is 360 dpi. A height of the nozzle
101
at the position of the heater
103
is 30 μm and a height of the common liquid chamber
105
from an element substrate is 80 μm.
The heaters are connected to wirings (not shown) so that the heaters can be driven independently. An ink discharged amount when only the heater
102
is driven is set to about 13 pl, and an ink discharged amount when two heaters are driven is set to about 40 pl.
FIGS. 2A and 2B
are views showing a state that the ink is discharged from the ink jet recording head, where
FIG. 2A
shows a case where the discharging is effected in a condition that a temperature in the head is a room temperature (about 25° C.) and
FIG. 2B
shows a case where the discharging is effected in a condition that the temperature in the head is increased (to about 60° C.). As shown in
FIGS. 2A and 2B
, in the ink jet recording head according to the illustrated embodiment, since the ceiling of the inclined portion
107
is gradually increased toward the rearward direction, the volume in this area is increased, with the result that, even in the condition that the temperature in the head is increased, a bubble
108
generated on the heater
103
can be prevented from protruding in the common liquid chamber
105
. Thus, since the bubble
108
is not separated during extinction thereof, trapping of residual bubbles
108
in the common liquid chamber
105
can be suppressed. Further, even if the bubble is protruded in the common liquid chamber
105
, since the ink flow in the re-fill has a main flow component along the inclined surface to deviate from a direction of flow of the ink flowing-in above the bubble
108
, unlike to the above-mentioned conventional example, the eddy flow tending to separate the bubble
108
is hard to occur. In this way, in the ink jet recording head according to this reference example, since the residual bubbles
108
trapped in the common liquid chamber
105
can be reduced or eliminated, the residual bubbles
108
are prevented from flowing back into the nozzles
101
, thereby suppressing a bad influence such as poor discharging.
Further, since the ceiling of the inclined portion
107
is smoothly changed toward the rearward direction, the ink flow in the re-fill is hard to be disturbed thereby to make the ink flow smooth, and, since the cross-sectional area of the flow path at the inclined portion
107
is great to reduce the flow resistance, the re-fill time can be shortened and the ink discharging with high frequency can be achieved.
FIG. 3
shows a construction of a nozzle portion
101
of an ink jet recording head according to a second reference example of the present invention. In
FIG. 3
, the same elements as those in the first reference example are designated by the same reference numerals and explanation thereof will be omitted. Further, as comparison, the configuration of the nozzle of the ink jet recording head according to the first reference example is shown by the broken line.
The ink jet recording head according to this reference example is characterized by a restrict portion
109
disposed behind of the heater
103
and having a low ceiling to reduce a cross-sectional area of the flow path. An inclined portion
107
behind the restrict portion
109
has a cross-sectional area smoothly increased toward the rearward direction, similar to the first reference example.
This reference example serves to suppress a drawback which would occur when the ink flow in the re-fill is too fast. Namely, in the first reference example, since the cross-sectional area of the inclined portion
107
is gradually or smoothly decreased, the ink is re-filled without disturbing the ink flow to shorten the re-fill time. However, depending upon surface tension and viscosity of the ink used, resistance of the ink flow path from an ink tank to the common liquid chamber
105
, the volume of the common liquid chamber
105
and/or the number of nozzles, the ink flow in the re-fill may be too fast, with the result that, even when the meniscus is returned to the discharge port
104
, the ink is overshot due to inertia of the ink, which may lead to overflow of ink at the discharge port. In this case, the meniscus may be vibrated greatly in the vicinity of the discharge port
104
, with the result that the discharged amount may be greatly changed during the next ink discharging. That is to say, if the discharging is effected in the condition that the meniscus is protruded from the discharge port
104
, the discharged amount will be increased; whereas, when the discharging is effected in the condition that the meniscus is retarded into the discharge port, the discharged amount will be decreased. Further, if the overshoot of the ink flow in the re-fill is great, the meniscus may be broken to wet the discharge port and therearound with the ink. If the ink is discharged in such a condition that there is a wet portion around the discharge port
104
, a liquid droplet is pulled toward the wet portion, which results in a wrong discharging direction.
To avoid this, in this reference example, by providing the restrict portion
109
behind the heater
103
, it is possible to obtain the ink flow in the re-fill at a moderate speed. By designing the restrict portion
109
in such a manner that a ratio (S
1
/S
2
) between a flow path cross-sectional area S
1
of the restrict portion
109
and a flow path cross-sectional area S
1
of the rear-most end of the nozzle
101
becomes 0.5 or less, the speed of the ink flow can be reduced effectively.
In this case, similar to the first reference example, since the inclined portion
107
behind the restrict portion
109
is configured so that the cross-sectional area thereof is gradually increased toward the rearward direction, even in the condition that the temperature in the recording head is high, the growth of the bubble
108
can be remained within the nozzle thereby to reduce the residual bubbles in the common liquid chamber
105
, similar to the first reference example.
By appropriately selecting the configurations of the restrict portion
109
and the inclined portion
107
, the ink jet recording head can be constructed so that the re-fill time becomes suitable for the driving frequency.
FIG. 4
shows a construction of a nozzle of an ink jet recording head according to a third reference example of the present invention. In
FIG. 4
, the same elements as those in the first and second reference example are designated by the same reference numerals and explanation thereof will be omitted. Further, as comparison, the configuration of the nozzle of the ink jet recording head according to the first reference example is shown by the broken line.
In the ink jet recording head according to the second reference example, by providing the restrict portion
109
, when the continuous recording is effected by driving only the heater
102
, the small bubbles remained in the nozzle
101
are hard to be discharged toward the common liquid chamber
105
, and, due to the presence of such bubbles remained in the nozzle, the discharging efficiency may be reduced and, thus, the discharged amount and discharging speed may be reduced. To avoid this, when the recording (small dot recording) is effected by driving only the heaters
102
, in order to prevent the accumulation of the bubbles in the nozzle, at a certain period, ink discharge not contributing to the recording (preliminary discharge) is effected, i.e., ink discharge is effected with great discharging power by driving both heaters
102
,
103
, the bubbles remained in the nozzle
101
are discharged. However, as mentioned above, in the ink jet recording head according to the second reference example, since the bubbles are apt to be accumulated in the nozzle, the accumulated bubbles may not be discharged completely by only one preliminary discharge.
Thus, in the third reference example, the nozzle
101
is configured so that a height of the nozzle
101
is smoothly or gradually increased up to the heater portion
102
ahead of the heater
103
. With this arrangement, since the flow resistance ahead of the heater
103
is decreased and forward pressure (when the heater
103
is driven) acts on the entire cross-section of the nozzle
101
effectively, the ability for discharging the bubbles accumulated in the nozzle
101
is enhanced, thereby solving the above-mentioned problem. Further, in the nozzle structures according to the first and second reference examples, when the preliminary discharge is effected, a part of the bubbles accumulated in the nozzle
101
may be discharged in the common liquid chamber
105
. However, in the third reference example, since the effect for discharging the bubbles outside through the discharge port
104
is enhanced, when the preliminary discharge is effected, the bubbles are prevented from being discharged into the common liquid chamber
105
, with the result that the bubbles are hard to be accumulated in the common liquid chamber
105
and the number of suction recovery operations for removing the bubbles can be reduced.
Next, an embodiment of the present invention in which an inclined portion
107
is provided in an ink jet recording head having a bubble trap
110
will be explained with reference to
FIGS. 5
to
11
. This embodiment is characterized in that a bubble trap
110
is provided in each of the ink jet recording heads according to the first to third reference examples and a surface extended from an inclined surface
107
intersects with a ceiling surface of the bubble trap
110
. Now, such characteristic will be fully explained.
FIG. 5
is a sectional view of a nozzle portion
101
of an ink jet recording head according to the embodiment of the present invention. In
FIG. 5
, the same element as those in the first to third reference examples are designated by the same reference numerals and explanation thereof will be omitted.
In this embodiment, as shown in
FIG. 5
, an inclined portion
107
is provided in an ink jet recording head which includes a structure disposed between a nozzle
101
and a common liquid chamber
105
and having a height greater than a height of the nozzle
101
and smaller than a height of the common liquid chamber
105
and having a stepped portion with respect to the nozzle
101
and in which a bubble trap
110
communicating with a plurality of nozzles
101
is provided. The bubble trap
110
serves to trap residual bubbles
111
remained in the recording head therein to avoid a bad influence upon the ink discharging. That is to say, a part of bubbles
108
generated in the nozzle
101
may be remained in the nozzle as the residual bubbles
111
even after extinction of the bubbles
108
due to cooling of the bubbles by deposition of liquid solved in the ink. When the ink is discharged, such residual bubbles
111
are shifted by the ink flow (in the nozzle
101
) directing toward the common liquid chamber
105
. When the residual bubbles reach the bubble trap
110
, since the cross-sectional area of the flow path is abruptly increased at this area, the speed of the ink flow is abruptly reduced, with the residual bubbles are not further shifted and are trapped in the bubble trap.
When the inclined portion
107
is provided in the ink jet recording head having such a bubble trap
110
, as shown in
FIG. 6
, if an extension line (surface) from a ceiling of the inclined portion
107
does not intersect with a ceiling of the bubble trap
110
, during the re-fill of the ink into the nozzle
101
, a part of the ink supplied from the common liquid chamber
105
enters into the bubble trap
110
and then flows downwardly along the bubble trap. The residual bubbles
111
trapped in the bubble trap
110
is shifted by this ink flow and then may be flown back into the nozzle
101
. To avoid this, as shown in
FIG. 5
, it is desirable that the extension line from the ceiling of the inclined portion
107
intersects with the ceiling of the bubble trap
110
. With this arrangement, when the ink is re-filled into the nozzle
101
, an area where ink flow is almost not caused is created at a corner portion (left and upper portion in
FIG. 5
) constituting the stepped portion of the bubble trap
110
, thereby preventing the residual bubbles
111
from flowing back into the nozzle
101
.
If the section of the ceiling portion of the inclined portion
107
is not straight but is curved, by designing so that a tangential line (tangential plane) of the ceiling of the inclined portion
107
at the boundary between the nozzle
101
and the bubble trap
110
intersects with the ceiling of the bubble trap
110
, the same effect can be achieved.
Now, the configuration of the inclined portion
107
will be described in more detail. Hereinbelow, as shown in
FIG. 7
, it is assumed that the section of the ceiling portion of the inclined portion
107
is straight and an angle between this straight line and a bottom surface on which the heaters
102
,
103
are located is a and an angle between the bottom surface and a straight line connecting a rear end of the rear-most heater
103
in the nozzle
101
to the boundary between the ceiling of the nozzle
101
and the bubble trap
110
is β. Incidentally, if the section of the ceiling portion of the inclined portion
107
is not straight but is curved, when it is assumed that an angle between a tangential line (tangential plane) of the ceiling of the nozzle
101
at the boundary between the nozzle
101
and the bubble trap portion
110
is α, the following explanation is established, similar to the case where the section of the ceiling portion is straight.
When a is smaller than β, as mentioned above, in order to design so that the extension line from the inclined portion
107
intersects with the ceiling of the bubble trap
110
, it is required that the bubble trap
110
be lengthened. In such a case, the flow resistance during the suction recovery is increased, with the result that it is difficult to remove the bubbles in the common liquid chamber and/or the bubble trap portion completely or the recovery time is lengthened, thereby reducing the recording speed. As shown in
FIG. 8
, if a starting point of the inclined portion
107
is positioned ahead of the rear end of the heater
103
, the flow resistance behind the heater
103
is reduced considerably, with the result that the bubble
108
formed on the heater
103
is greatly shifted rearwardly. Thus, it is desirable that the value of the angle a be at least greater than the value of the angle β. As shown in
FIG. 9
, if α and β have the same value, since the direction of the ink flow in the vicinity of the ceiling of the inclined portion
107
in the re-fill and the direction of the inclination of the ceiling of the inclined portion
107
becomes substantially the same, the ceiling of the inclined portion
107
does almost not give the resistance to the ink flow, thereby achieving the smooth re-fill. When the ink flow in the re-fill is too fast for example due to low viscosity of the ink, as shown in
FIG. 7
, by selecting the angle α to be slightly greater than the angle β, the ceiling of the inclined portion
107
gives the resistance to the ink flow in the re-fill, with the result that the flow speed can be reduced to the moderate speed. However, as shown in
FIG. 10
, if the angle α is set to be too great, the area in the bubble trap
110
(left and upper portion above the broken line in
FIG. 10
) where the ink flow in the re-fill is hard to occur becomes smaller, with the result that the residual bubbles
111
cannot be remained. From the above, it is desirable to set the value of the angle α as follows:
β≦α<β+10°.
FIGS. 11A
to
11
C show a dimensional example of the ink jet recording head according to the illustrated embodiment, where
FIG. 11A
is a sectional view showing the configuration of the nozzle
101
,
FIG. 11B
is a plan view showing the arrangement of the heaters
102
,
103
in the nozzle
101
when color ink is discharged and
FIG. 11C
is a plan view showing the arrangement of the heaters
102
,
103
in the nozzle
101
when black ink is discharged.
Incidentally, in the above-mentioned reference examples and embodiment, while the ink jet recording head having two heaters was explained, the present invention can be applied to an ink jet recording head having three or more heaters or an ink jet recording head having a single heater. In any cases, the arrangement shown in the above-mentioned reference examples and embodiment may be applied to a nozzle construction from a rear end of a rear-most heater in the nozzle to a rear-most end of the nozzle.
<Ink Jet Recording Head Cartridge>
FIG. 12
is an exploded perspective view showing an example of an ink jet recording head cartridge using an ink jet recording head constructed as mentioned above.
In
FIG. 12
, an ink jet recording head unit IJU is of type in which ink is discharged by causing film boiling in the ink by generating thermal energy in response to an electrical signal. A heater board
100
is constituted by forming a plurality of electrothermal converting elements (heaters) arranged as an array and adapted to generate thermal energy and electrical wirings made of aluminum and adapted to supply electric power to the heaters on an Si-substrate by a film forming technique. A wiring substrate
200
has wirings corresponding to the wiring on the heater board
100
(respective wirings are interconnected by wire bonding, for example), and pads
201
disposed at ends of the wirings and each adapted to receive the electrical signal from a main body of the apparatus. A top plate
1300
has partition walls for defining nozzles corresponding to a plurality of discharge ports and a common liquid chamber and integrally incorporates an ink introduction port
1500
for receiving the ink supplied from an ink tank and directing the ink to the common liquid chamber, and an orifice plate
1400
in which the plurality of discharge ports are formed. The partition walls of the top plate
1300
are integrally formed with the top plate
1300
. To this end, the top plate is preferably formed from polysulfone. However, other molding resin material may be used.
The wiring substrate
200
is supported on a support
300
. The support
300
is formed from metal, for example and constitutes a constructural member of the recording head unit. An urging spring
500
has an M-shaped configuration and serves to urge a portion of the top plate
1300
corresponding to the common liquid chamber by the center of “M” and to urge a portion of the top plate
1300
corresponding to the nozzles by line contact of a front protruded portion
501
. When foot portions of the urging spring
500
inserted into holes
312
of the support
300
to be engaged with the back surface of the support, the heater board
100
and the top plate
1300
are pinched between the support
300
and the urging spring
500
, with the result that the heater board
100
and the top plate
1300
can be urged against and secured to the support
300
by biasing forces of the urging spring
500
and the front protruded portion
501
thereof. The support
300
has two positioning
312
,
1900
for receiving two positioning projections
1012
provided on the ink tank and two projections
1800
for effecting positioning and fusion holding and is also provided at its back surface with a positioning projection
2600
for positioning the head cartridge with respect to a carriage of the main body of the apparatus. In addition, the support
300
has also a hole
320
through which an ink supply tube
2200
(described later) permitting ink supply from the ink tank can be inserted. The attachment of the wiring substrate
200
to the support
300
is effected by using an adhesive and the like.
Incidentally, two recesses
2400
of the support
300
are located in the vicinity of the positioning projections
2600
, respectively. These recesses are positioned on extension of a plurality of parallel grooves
3000
,
3001
formed in three sides of the ink jet recording head unit IJU in the head cartridge assembled as shown in
FIG. 13
thereby to prevent waste matters such as dirt and ink from reaching the projections
2600
. A lid member
800
in which the parallel grooves
3000
are formed serves to cover a portion for containing the ink jet recording head unit IJU and forms a part of an outer wall of the head cartridge IJC. Further, an ink supply path member
600
in which the parallel grooves
3001
are formed serves to support an ink conduit
1600
connected to the ink supply tube
2200
to be communicated with the ink supply path in a cantilever fashion in which a connecting end of the conduit to the supply tube
2200
is fixed. Further, the member
600
has a seal pin
602
for maintaining a capillary phenomenon between the ink supply tube
2200
and the fixed portion of the ink conduit
1600
. Incidentally, a supply port portion
1200
provided on the ink tank is provided with a packing
601
and a filter
700
for effecting connection and seal between the ink tank and the supply tube
2200
. The ink supply path member
600
is formed cheaply with high positional accuracy by molding. Further, since the conduit
1600
is formed in the cantilever fashion, in the mass production, the conduit
1600
can stably be urged against the ink introduction port
1500
. In this example, in this urged condition, sealing adhesive is supplied from the ink supply path member side.
Incidentally, the securing of the ink supply path member
600
to the support
300
is simply effected by inserting pins (not shown) provided on the back surface of the ink supply path member
600
into holes
1901
,
1902
of the support
300
and by heat-fusing pin portions protruded from the back surface of the support
300
. Incidentally, since slight protruded areas on the back surface formed by the heat-fusion are housed in recesses (not shown) formed in a side wall of the attachment surface of the ink tank to the ink jet recording head unit IJU, the positioning of the ink jet recording head unit IJU is not obstructed.
The ink tank comprises a cartridge body
1000
, an ink absorbing body
900
, and a lid
1100
for sealing the ink absorbing body
900
after the ink absorbing body is inserted from a side surface opposite to the ink jet recording head unit attachment surface of the cartridge body
1000
. The ink tank is provided with the supply port
1200
for supplying the ink to the ink jet recording head unit IJU. As will be described later, this supply port is used as a pouring port for impregnating the absorbing body
900
with ink by poring the ink from the supply port
1200
in a step before the ink jet recording head unit IJU is positioned in a head arranging portion
1010
of the cartridge body
1000
.
Ribs
2300
formed on an inner surface of the body
1000
and ribs
2500
,
2501
provided on an inner surface of the lid
1100
define, within the ink tank, an air existing area contiguous to an atmosphere communicating port
1401
, thereby well maintaining ink supplying ability from the ink absorbing body. Four (only two of which are shown in
FIG. 9
) ribs
2300
are formed in parallel with a carriage shifting direction at a rear part of the cartridge body
1000
, thereby preventing the absorbing body from closely contacting with the body
1000
. Further, the ribs
2501
,
2500
are disposed on extension lines from the ribs
2300
and formed on the inner surface of the lid
1100
. However, unlike to the ribs
2300
, the ribs
2500
,
2501
have split shapes. Thus, the ribs
2500
,
2501
provide wider air existing areas than the ribs
2300
. Incidentally, the ribs
2500
,
2501
are dispersed and formed on a lower part of the right half of the lid
1100
. Due to the presence of these ribs, the ink in the corner area of the ink absorbing body
900
remotest from the supply port
1200
of the tank is more stabilized and is positively directed to the supply port
1200
by the capillary force. In order to effect good and uniform ink pouring to the absorbing body to prevent the ink from entering into the air existing area, it is desirable that the ink be poured through the ink supply port
1200
located in the vicinity of the corner area remotest from the air existing area.
An ink containing space of the ink tank has a rectangular shape in a horizontal plane, and, since the ribs
2500
,
2501
are located at ends of the longitudinal side of the rectangle, the air existing area can effectively be formed in the area where the ink is hard to be directed to the supply port
1200
. Thus, this arrangement of the ribs
2500
,
2501
is particularly effective. When the ink containing portion is elongated along the carriage shifting direction or has a cubic configuration, since the entire portion contacted with the lid
1100
constitutes the area where the ink paced apart from the supply port
1200
is hard to be directed, by providing ribs on the entire lid
1100
, the air existing area is formed on the lid portion
1100
, thereby stabilizing the ink supplying from the ink absorbing body
900
.
Within the atmospheric communication port
1401
for communicating the interior of the ink tank with the atmosphere, a liquid repelling member
1400
is provided thereby to prevent the ink from leaking from the atmospheric communication port
1401
.
The ink jet recording head unit IJU is covered, except for a lower opening, by the ink tank and the lid
800
for covering the ink jet recording head unit IJU after the ink jet recording head unit IJH is mounted to the ink tank. Further, in a condition that the ink jet recording head cartridge IJU is mounted to the carriage of the main body of the ink jet recording apparatus IJRA, since the lower opening is located closely adjacent to the carriage HC, the ink jet recording head unit IJU is substantially closed at its four sides. As a result, heat from the ink jet recording head IJH is uniformed radiated in a space around the ink jet recording head IJH four sides of which is closed, and the temperature in the space is kept uniform. However, for example, when the ink jet recording head IJH is continuously driven for a long term, the temperature in the space may be slightly increased. In consideration of this, in this example, by providing a slit
1700
having a width smaller than the space in an upper surface of the cartridge, natural radiation is promoted to prevent the temperature increase and to make distribution of temperature of the entire ink jet recording head unit IJU uniform without depending upon the environment.
As shown in
FIG. 13
, in the condition assembled as the ink jet recording head cartridge IJC, the ink is directed from the supply port
1200
of the ink tank to the conduit
1600
of the ink supply path member
600
through a hole
320
formed in the support
300
and a supply tube
2200
passing through an introduction opening formed in the center of a rear surface of the ink supply path member
600
and passes through the conduit and is supplied to the common liquid chamber of the ink jet recording head IJH through the ink introduction port
1500
of the top plate
1300
. A packing made of silicone rubber or a butyl rubber is provided at a connecting portion between the supply tube
2200
and the conduit
1600
to seal the connecting portion, thereby ensuring the sealing ability of the ink supply path.
Incidentally, in the illustrated embodiment, the top plate
1300
is formed from resin having excellent anti-ink corrosion such as polysulfone, polyether sulfone, polyphenylene oxide or polypropylene and is simultaneously molded with the orifice plate
400
by resin molding using a mold.
<Ink Jet Recording Apparatus>
FIG. 14
is a perspective view of the ink jet recording apparatus IJRA using the ink jet recording head cartridge according to the present invention. The ink jet recording head cartridge IJC integrally including the ink jet recording head IJH and the ink tank storing the ink to be supplied to the recording head is mounted on the carriage HC. A pin (not shown) of the carriage HC is engaged by a helical groove
5005
of a lead screw
5004
rotatingly driven by rotation of a drive motor
5013
through drive transmitting gears
5011
,
5009
, so that the carriage is reciprocally shifted in axial directions (shown by the arrows a, b in
FIG. 14
) in synchronous with the rotation of the lead screw
5004
.
A paper P as a recording medium is urged against a platen (not shown) by a paper urging plate
5002
so that a position of the paper P on which the recording is effected by the shifting movement of the carriage HC is correctly maintained.
A photo-coupler
5007
,
5008
as home position detecting means is disposed at an end of the shifting direction of the carriage HC. When the carriage HC is shifted to the home position at the end of the shifting direction and a lever
5006
of the carriage HC approaches the photo-coupler
5007
,
5008
, the lever is detected by the photo-coupler, and processing such as switching of rotational direction of the motor
5013
and the like is effected on the basis of a detection signal.
In an opposed relationship to the ink jet recording head IJH, there are provided a cap member
5022
supported by a cap member supporting member
5016
and adapted to cap a front surface of the ink jet recording head IJH, and suction means
5015
for sucking the interior of the cap. The cap member and the suction means effect suction recovery of the ink jet recording head IJH through an opening
5023
of the cap. Further, a cleaning blade
5017
is disposed aside the cap member and can be shifted in a front-and-rear direction by a cleaning blade shifting member
5019
. The blade and the shifting member are supported by a body support plate
5018
. As the cleaning blade
5017
, any well-known cleaning blade can be used, an well as the illustrated one. Capping, cleaning and suction recovery operations are started when the lover
5012
is shifted by a shifting movement of a cam
5020
engaged by the carriage. For such shifting movements, a driving force from the drive motor is used through well-known transmitting means such as a switching clutch. That is to say, the capping, cleaning and suction recovery means are designed so that desired processes are effected at respective positions by the action of the lead screw
5005
when the carriage HC is positioned at the home position. Such operations may be effected at well-known timings to achieve the desired processes.
In the illustrated embodiment, while the ink jet recording apparatus using the ink jet recording head cartridge IJC integrally including the ink jet recording head IJH and the ink tank was explained, the present invention may be applied to an ink jet recording apparatus in which an ink tank and an ink jet recording head IJH are provided independently and ink is supplied from the ink tank to the ink jet recording head IJH through a very fine tube.
FIG. 15
is a block diagram showing a recording operation of the ink jet recording apparatus shown in FIG.
14
.
The recording apparatus receives a signal corresponding to recording information from a host computer
4300
. This signal is temporarily stored in an input interface
4301
in the recording apparatus and at the same time is converted into data processable in the recording apparatus and then is inputted to a CPU
4302
for effecting supplying of a head drive signal and the like. The CPU
4302
serves to process the data inputted to the CPU
4302
on the basis of control program stored in a ROM
4303
by using peripheral units and to convert the data into data to be recorded (image data). Further, the CPU
4302
serves to form drive data for driving a drive motor
4306
for shifting the recording medium and the recording head in response to the image data. The image data and the motor drive data are transmitted to the head
4200
and the drive motor
4306
through a head driver
4307
and a motor driver
4305
, respectively, so that the head and the motor are driven by the timings corresponding the data, thereby forming the image.
As the recording medium which can be applied to the above-mentioned recording apparatus and on which liquid such as ink is applied, various papers, an OHP sheet, plastic material used for compact discs and decoration plates, cloth, metallic material such as aluminum or copper, leather material such as cow leather, pig leather or synthetic leather, wood material such as wood or plywood, bamboo, ceramic material such as talc, or a three-dimensional network structure such as sponge can be used.
The ink jet recording apparatus according to the illustrated embodiment may include a printer for effecting the recording on various papers or the OHP sheet, a plastic recording apparatus for effecting the recording on the plastic material such as a compact disc, a metal recording apparatus for effecting the recording on the metallic plate, a leather recording apparatus for effecting the recording on the leather, a wood recording apparatus for effecting the recording on the wood, a ceramic recording apparatus for effecting the recording on the ceramic material, a recording apparatus for effecting the recording on the three-dimensional network structure such as sponge, and a print device for effecting the recording on the cloth.
Further, as the discharging liquid (ink) used in the ink jet recording apparatus, liquid compatible with the recording medium and the recording condition may be used.
Next, another embodiment of an ink jet recording apparatus for effecting recording on the recording medium using the ink jet recording head according to the present invention will be explained.
FIG. 16
is a schematic view showing a construction of the ink jet recording apparatus using the above-mentioned ink jet recording head
5201
according to the present invention. The ink jet recording head
5201
according to the illustrated embodiment is of full-line type in which a plurality of discharge ports are arranged in an area having a length corresponding to a recording width of a recording medium
5227
at interval of 360 dpi. In this embodiment, four heads corresponding to four colors (i.e., yellow (Y), magenta (M), cyan (C) and black (Bk)) are fixedly supported by a holder
5202
in parallel with each other along a conveying direction (X direction in
FIG. 16
) of the recording medium with a predetermined interval.
A signal is supplied from a head driver
5307
as drive signal supply means corresponding to the ink jet recording heads
5201
a
to
5201
d,
and, on the basis of this signal, the corresponding ink jet recording head
5201
is driven.
Four color (Y, M, C and Bk) inks are supplied to the ink jet recording heads
5201
a
to
5201
d
as discharging liquids from respective ink tanks
5204
a
to
5204
d.
A bubbling liquid container
5204
e
for storing bubbling liquid is disposed in alignment with the ink tanks
5204
a
to
5204
d,
and the bubbling liquid is supplied to the recording heads from the bubbling liquid container
5204
e.
Further, below the ink jet recording heads
5201
a
to
5201
d,
there are disposed head caps
5203
a
to
5203
d
each including an ink absorbing member such as sponge, which head caps serve to maintenance of the heads by covering the heads when the recording operation is not performed.
The recording medium
5227
is located on a conveying belt
5206
mounted on a plurality of rollers along a predetermined path and is conveyed by driving a drive roller
5214
connected to a motor driver
5305
. The conveying belt
5206
and the drive roller
5214
constitute conveying means for the recording medium
5227
.
In the ink jet recording apparatus according to the illustrated embodiment, a pre-processing device
5251
and a post-processing device
5252
for effecting various processes with respect to the recording medium
5227
before and after the recording are arranged at an upstream side and a downstream side of a recording area in a conveying path of the recording medium
5227
.
The pre-process and the post-process have different contents in accordance with the kind of the recording medium
5227
to be recorded and the kind of the ink used.
As the pre-process, for example, regarding the recording medium such as metal, plastic or ceramic, ultraviolet ray and ozone are illuminated on the recording medium to make the surface thereof active, thereby enhancing the ink adhering ability. Further, regarding the recording medium on which electrostatic electricity is apt to be generated, due to the presence of the electrostatic electricity, dirt may easily be adhered to the surface of the recording medium, and good recording may be obstructed by such dirt. Thus, as the pre-process, by removing the electrostatic electricity on the recording medium by using an ionizer device, the dirt is removed from the recording medium. Further, when the cloth is used as the recording medium, in order to prevent the sweating and to enhance the adhering ability, a process for applying substance selected among alkaline substance, water-soluble substance, synthetic polymer, water-soluble metal salt, urea and thiourea to the cloth as the pre-process. The pre-process is not limited to the above-mentioned ones but may be a process for adjust the temperature of the recording medium to a temperature suitable for the recording.
On the other hand, the post-process may include a fixing process for promoting the fixing of the ink applied to the recording medium
5227
and a process for cleaning residual processing agent applied in the pre-process and remained in a non-reaction state.
Incidentally, in the illustrated embodiment, while the ink jet recording apparatus using the full-line head as the ink jet recording head was explained, the present invention is not limited to such an apparatus but may be applied to a recording apparatus in which the recording is effected by shifting the above-mentioned compact head in a direction of the conveying direction of the recording medium
5227
.
Claims
- 1. An ink jet recording head comprising:a plurality of discharge ports for discharging ink droplets; a plurality of ink flow paths communicated with the respective discharge ports; a common liquid chamber communicated with said ink flow paths and adapted to hold ink to be introduced into said ink flow paths; electrothermal converting portions disposed in said ink flow paths and adapted to generate heat for bubbling the ink; and bubble trapping portions disposed at communicating portion between said ink flow paths and said common liquid chamber and including stepped structures each having a cross-sectional area smaller than a main cross-sectional area of said common liquid chamber and greater than a cross-sectional area of the corresponding ink flow path in a direction perpendicular to an ink introducing direction; and wherein each of said ink flow paths is provided with an inclined portion located between an upstream end of said electrothermal converting portion and the communicating portion of said ink flow path with said common liquid chamber in the ink introducing direction and having a cross-sectional area, in the direction perpendicular to the ink introducing direction, gradually increasing toward the upstream bubble trapping portion, and a surface extended from said inclined portion intersects with a ceiling surface of said bubble trapping portion.
- 2. An ink jet recording head according to claim 1, wherein said electrothermal converting portion comprises a plurality of electrothermal converting elements arranged side by side in the ink introducing direction.
- 3. An ink jet recording head according to claim 1, wherein said inclined portion has a restrict portion disposed at an upstream side of the upstream end of said electrothermal converting portion and at a downstream side of said inclined portion and having a narrower cross-sectional area in the direction perpendicular to the ink introducing direction.
- 4. An ink jet recording head according to claim 3, wherein a relationship between a cross-sectional area S1 of said ink flow path in the direction perpendicular to the ink introducing direction and a cross-sectional area S2 of the upstream end of said ink flow path in the direction perpendicular to the ink introducing direction satisfies S1/S2≦0.5.
- 5. An ink jet recording head comprising:a plurality of discharge ports for discharging ink droplets; a plurality of ink flow paths communicating with the respective discharge ports; a common liquid chamber communicating with said ink flow paths and adapted to hold ink to be introduced into said ink flow paths; electrothermal converting portions disposed in said ink flow paths and adapted to generate heat for bubbling the ink; and bubble trapping portions disposed at a communicating portion between said ink flow paths and said common liquid chamber and including stepped structures each having a cross-sectional area smaller than a main cross-sectional area of said common liquid chamber and greater than a cross-sectional area of the corresponding ink flow path in a direction perpendicular to an ink introducing direction, wherein each of said ink flow paths is provided with an inclined portion located between an upstream end of said electro thermal converting portion and the communicating portion of said ink flow path with said common liquid chamber in the ink introducing direction and having a cross-sectional area, in the direction perpendicular to the ink introducing direction, gradually increasing toward the upstream bubble trapping portion, and a surface extended from said inclined portion intersects with a ceiling surface of said bubble trapping portion, and wherein a relationship between an angle α between said inclined portion and a surface on which said electro thermal converting portion is located and an angle β between a surface connecting the upstream end of said electro thermal converting portion to an upper end of said communication portion of said ink flow path and the surface on which said electro thermal converting portion is located satisfies β<α<β+10°.
- 6. An ink jet recording head cartridge comprising:a plurality of discharge ports for discharging ink droplets; a plurality of ink flow paths communicating with the respective discharge ports; a common liquid chamber communicating with said ink flow paths and adapted to hold ink to be introduced into said ink flow paths; electrothermal converting portions disposed in said ink flow paths and adapted to generate heat for bubbling the ink, bubble trapping portions disposed at a communicating portion between said ink flow paths and said common liquid chamber and including stepped structures each having a cross-sectional area smaller than a main cross-sectional area of said common liquid chamber and greater than a cross-sectional area of the corresponding ink flow path in a direction perpendicular to an ink introducing direction; and wherein each of said ink flow paths is provided with an inclined portion located between an upstream end of said electro thermal converting portion and the communicating portion of said ink flow path with said common liquid chamber in the ink introducing direction and having a cross-sectional area, in the direction perpendicular to the ink introducing direction, gradually increasing toward the upstream bubble trapping portion, and a surface extended from said inclined portion intersects with a ceiling surface of said bubble trapping portion, and an ink container for holding ink to be supplied to said ink jet recording head.
- 7. An ink jet recording head according to claim 6, wherein said electro thermal converting portion comprises a plurality of electro thermal converting elements arranged side by side in the ink introducing direction.
- 8. An ink jet recording head according to claim 6, wherein said inclined portion has a restrict portion disposed at an upstream side of the upstream end of said electro thermal converting portion and at a downstream side of said inclined portion and having a narrower cross-sectional area in the direction perpendicular to the ink introducing direction.
- 9. An ink jet recording head according to claim 8, wherein a relationship between a cross-sectional area S1 of said ink flow path in the direction perpendicular to the ink introducing direction and a cross-sectional area S2 of the upstream end of said ink flow path in the direction perpendicular to the ink introducing direction satisfies S1/S2≦0.5.
- 10. An ink jet recording head according to claim 6, wherein a relationship between an angle α between said inclined portion and a surface on which said electro thermal converting portion is located and an angle β between a surface connecting the upstream end of said electro thermal converting portion to an upper end of said communication portion of said ink flow path and the surface on which said electro thermal converting portion is located satisfies β≦α<β+10°.
- 11. An ink jet recording apparatus having an ink jet recording head comprising:a plurality of discharge ports for discharging ink droplets; a plurality of ink flow paths communicating with the respective discharge ports; a common liquid chamber communicating with said ink flow paths and adapted to hold ink to be introduced into said ink flow paths; electrothermal converting portions disposed in said ink flow paths and adapted to generate heat for bubbling the ink; and bubble trapping portions disposed at a communicating portion between said ink flow paths and said common liquid chamber and including stepped structures each having a cross-sectional area smaller than a main cross-sectional area of said common liquid chamber and greater than a cross-sectional area of the corresponding ink flow path in a direction perpendicular to an ink introducing direction, wherein each of said ink flow paths is provided with an inclined portion located between an upstream end of said electro thermal converting portion and the communicating portion of said ink flow path with said common liquid chamber in the ink introducing direction and having a cross-sectional area, in the direction perpendicular to the ink introducing direction, gradually increasing toward the upstream bubble trapping portion, and a surface extended from said inclined portion intersects with a ceiling surface of said bubble trapping portion.
- 12. An ink jet recording head according to claim 11, wherein said electro thermal converting portion comprises a plurality of electro thermal converting elements arranged side by side in the ink introducing direction.
- 13. An ink jet recording head according to claim 11, wherein said inclined portion has a restrict portion disposed at an upstream side of the upstream end of said electro thermal converting portion and at a downstream side of said inclined portion and having a narrower cross-sectional area in the direction perpendicular to the ink introducing direction.
- 14. An ink jet recording head according to claim 13, wherein a relationship between a cross-sectional area S1 of said ink flow path in the direction perpendicular to the ink introducing direction and a cross-sectional area S2 of the upstream end of said ink flow path in the direction perpendicular to the ink introducing direction satisfies S1/S2≦0.5.
- 15. An ink jet recording head according to claim 11, wherein a relationship between an angle α between said inclined portion and a surface on which said electro thermal converting portion is located and an angle β between a surface connecting the upstream end of said electro thermal converting portion to an upper end of said communication portion of said ink flow path and the surface on which said electro thermal converting portion is located satisfies β≦α<β+10°.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-235756 |
Aug 1999 |
JP |
|
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