Title: Ink jet head unit
Abstract: In the ink jet head unit of the present invention, an ink jet head for emitting ink in a formof droplets from nozzles formed in a nozzle face and a driving circuit for driving the ink jet head are mounted on the same surface side of the base board. A groove section is formed in the surface, extending from the nozzle face of the ink jet head to the driving circuit. In the ink jet head, a temperature measuring section is positioned in the groove section. Furthermore, there is provided a sealing member in the groove section, to prevent the flow of ink emitted from the nozzles, into the driving circuit. The sealing member is partly formed of an elastic body. Therefore, since the elastic body can restrain a change in the volume of the sealing member likely to be caused by a temperature change, it is possible to prevent the temperature change from impairing the ink jet head, consequently realizing ink projection stability.
Patent Number: 6,880,911 Issued on 04/19/2005 to Suzuki, et al.
| Inventors:
|
Suzuki; Isao (Shizuoka, JP);
Nishida; Hideaki (Shizuoka, JP)
|
| Assignee:
|
Toshiba Tec Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
620908 |
| Filed:
|
July 15, 2003 |
| Current U.S. Class: |
347/20; 347/17 |
| Intern'l Class: |
B41J 029//39.3 |
| Field of Search: |
347/17,20,44,50,59
|
References Cited [Referenced By]
U.S. Patent Documents
| 4364059 | Dec., 1982 | Nagayama.
| |
| 4504845 | Mar., 1985 | Kattner et al.
| |
| 4901091 | Feb., 1990 | Kasamoto | 347/84.
|
| 4980702 | Dec., 1990 | Kneezel et al. | 347/17.
|
| 6802585 | Oct., 2004 | Wratchford.
| |
| 2003/0052932 | Mar., 2003 | Karita et al.
| |
| Foreign Patent Documents |
| 0 928 691 | Jul., 1999 | EP.
| |
| 3-240553 | Oct., 1991 | JP.
| |
| 10-044420 | Feb., 1998 | JP.
| |
| WO 01/17779 | Mar., 2001 | WO.
| |
Primary Examiner: Nguyen; Lamson
Assistant Examiner: Mouttet; Blaise
Attorney, Agent or Firm: Frishauf, Holtz, Goodman & Chick, P.C.
Claims
What is claimed is:
1. An ink jet head unit, comprising:
a base board;
an ink jet head mounted on the base board, for emitting ink in a form of
droplets from nozzles formed in a nozzle face;
a driving circuit for driving the ink jet head, mounted on the base board,
on the same surface side as the ink jet head;
a groove section provided in the base board, on the same surface side as
the ink jet head, and extending from the nozzle face of the ink jet head
to the driving circuit;
a temperature measuring section mounted on the ink jet head, positioned in
the groove section, for measuring temperatures of the ink jet head; and
a sealing member installed in the groove section to prevent ink emitted
from the nozzles, from flowing into the driving circuit,
wherein the sealing member is partly an elastic body.
2. An ink jet head unit according to claim 1, wherein the elastic body
partly appears from the sealing member.
3. An ink jet head unit according to claim 2, wherein the elastic body
appearing from the sealing member is partly positioned oppositely to the
side where the sealing member comes into contact with ink.
4. An ink jet head unit according to claim 2, wherein the elastic body has
a resistance to ink.
5. An ink jet head unit, comprising:
a base board;
an ink jet head mounted on the base board, for emitting ink in a form of
droplets from nozzles formed in a nozzle face;
a driving circuit for driving the ink jet head, mounted on the base board,
on the same surface side as the ink jet head;
a groove section provided in the base board, on the same surface side as
the ink jet head, and extending from the nozzle face of the ink jet head
to the driving circuit;
a temperature measuring section mounted on the ink jet head, positioned in
the groove section, for measuring temperatures of the ink jet head; and
a sealing member installed in the groove section to prevent ink emitted
from the nozzles, from flowing into the driving circuit,
wherein the sealing member is partly a foamed body.
6. An ink jet head unit according to claim 5, wherein the foamed body
appears partly from the sealing member.
7. An ink jet head unit according to claim 6, wherein the foamed body
appearing from the sealing member is partly positioned oppositely to the
side where the sealing member comes into contact with ink.
8. An ink jet head unit according to claim 6, wherein the foamed body has a
resistance to ink, and is a closed-cell foamed body.
9. An ink jet head unit, comprising:
a base board;
an ink jet head mounted on the base board, for emitting ink in a form of
droplets from nozzles formed in a nozzle face;
a driving circuit for driving the ink jet head, mounted on the base board,
on the same surface side as the ink jet head;
a groove section provided in the base board, on the same surface side as
the ink jet head, and extending from the nozzle face of the ink jet head
to the driving circuit;
a temperature measuring section mounted on the ink jet head, positioned in
the groove section, for measuring temperatures of the ink jet head; and
a sealing member installed in the groove section to prevent ink emitted
from the nozzles, from flowing into the driving circuit,
wherein the sealing member is a closed-cell foamed body.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet head unit provided with an ink
jet head which projects ink in a form of droplets.
2. Discussion of the Background
As an ink jet head, there is an ink jet head mounted in an ink jet printer,
for example. The ink jet head is basically comprised of a pressure chamber
which is supplied with ink, a nozzle located in the pressure chamber for
emitting the ink, and a driving means for emitting droplets of ink out
from the pressure chamber.
The ink jet head mentioned above has been unitized by bonding to a base
board the ink jet head together with a driving circuit board having the
driving circuit for driving to control the ink jet head. The ink jet head
unit thus unitized has a groove section formed in the base board on the
same surface side as the ink jet head, and a temperature sensor mounted in
the groove section in the ink jet head.
The groove section extends from the nozzle face of the ink jet head to the
driving circuit board. On the nozzle face a plurality of nozzles (ink
outlets) are formed nearly in a straight line. The temperature sensor
functions as a sensor for measuring the temperature of the ink jet head in
order to maintain the ink in the ink jet head at a stabilized emission
viscosity. The temperature sensor is electrically connected to the driving
circuit board. An electric wire for electrical connection of the
temperature sensor with the driving circuit board is routed through in the
groove section.
In the groove section a sealing member is installed to prevent the flow of
ink projected from the nozzle, into the driving circuit board through the
groove section. It is therefore possible to prevent a trouble likely to be
caused by the ink in the driving circuit on the driving circuit board. As
the sealing member, which is demanded to have an ink resistance, an epoxy
adhesive is used.
However, when only the epoxy adhesive is used as a sealing member, the
volume of the sealing member changes with the expansion and shrinkage of
the sealing member resulting from temperature changes. Thus an external
force is applied to the ink jet head, which will be subjected to cracking.
Therefore there will arise such a problem that the ink jet head will be
impaired by a change in the volume of the sealing member caused by
temperature changes, resulting in a failure of ink emission in a form of
droplets.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to realize stabilized
ink emission by preventing temperature changes from giving damage to the
ink jet head.
The object of the present invention can be accomplished by the ink jet head
unit of the present invention.
A new ink jet head unit of the present invention is comprised of a base
board; an ink jet head mounted on the base board to project ink in a form
of droplets from a nozzle formed in a nozzle face; a driving circuit for
driving the ink jet head, mounted on the base board on the same surface
side as the ink jet head; a groove section provided in the base board, on
the same surface side as the ink jet head, and extending from the nozzle
face of the ink jet head to the driving circuit; a temperature measuring
section located in the groove section, in the ink jet head, for measuring
the temperature of the ink jet head; and a sealing member provided in the
groove section, to thereby prevent the flow of ink emitted from the
nozzle, into the driving circuit. The sealing member is partly an elastic
member.
Therefore, a new ink jet head unit of the present invention is comprised of
a base board; an ink jet head mounted on the base board to project ink in
a form of droplets from a nozzle formed in a nozzle face; a driving
circuit for driving the inkjet head, mounted on the baseboard on the same
surface side as the ink jet head; a groove section provided in the base
board, on the same surface side as the ink jet head, and extending from
the nozzle face of the ink jet head to the driving circuit; a temperature
measuring section located in the groove section, in the ink jet head, for
measuring the temperature of the ink jet head; and a sealing member
provided in the groove section, to thereby prevent the flow of ink emitted
from the nozzle, into the driving circuit. The sealing member is partly a
foamed member.
Therefore, a new ink jet head unit of the present invention is comprised of
a base board; an ink jet head mounted on the base board to project ink in
a form of droplets from a nozzle formed in a nozzle face; a driving
circuit for driving the ink jet head, mounted on the base board on the
same surface side as the ink jet head; a groove section provided in the
base board, on the same surface side as the ink jet head, and extending
from the nozzle face of the ink jet head to the driving circuit; a
temperature measuring section located in the groove section, in the ink
jet head, for measuring the temperature of the ink jet head; and a sealing
member provided in the groove section, to thereby prevent the flow of ink
emitted from the nozzle, into the driving circuit. The sealing member is
partly a closed-cell foamed member.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the present invention and many of the
attendant advantages thereof will be readily obtained as the same becomes
better understood by reference to the following detailed description when
considered in connection with the accompanying drawings, wherein:
FIG. 1 is a longitudinal side view schematically showing an ink jet head;
FIG. 2 is a sectional view of the ink jet head taken substantially along
line A--A;
FIG. 3 is an external perspective view schematically showing the ink jet
head unit of one embodiment of the present invention;
FIG. 4 is an external perspective view schematically showing a base board
of the ink jet head unit;
FIG. 5 is an enlarged sectional view schematically showing the ink jet head
unit taken substantially along line B--B;
FIG. 6 is an enlarged sectional view schematically showing the ink jet head
unit taken substantially along line C--C;
FIG. 7 is an enlarged sectional view schematically showing an ink jet head
unit of a modification 1 of the one embodiment of the present invention
taken substantially along line B--B;
FIG. 8 is an enlarged sectional view schematically showing an ink jet head
unit of a modification 2 of one embodiment of the present invention taken
substantially along line B--B;
FIG. 9 is an enlarged sectional view schematically showing an ink jet head
unit of a modification 3 according to one embodiment of the present
invention; and
FIG. 10 is an enlarged sectional view schematically showing an ink jet head
unit of a modification 4 according to one embodiment of the present
invention taken substantially along line C--C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
One embodiment of an ink jet head unit according to the present invention
will be described with reference to the accompanying drawings. FIG. 1 is a
schematic longitudinal side view of an ink jet head 1. FIG. 2 is a
sectional view thereof taken along line A--A.
The ink jet head 1 has a nozzle plate 3 in which a plurality of nozzles 2
are formed, and a plurality of pressure chambers 4 for holding ink which
are located in positions opposite to the plurality of nozzles 2
respectively. The plural pressure chambers 4 are constructed such that the
ink is supplied from a common ink chamber 5. A surface forming a part of
the pressure chamber 4 is formed of a diaphragm 6. On the diaphragm 6, a
plurality of piezoelectric members 7 are secured correspondingly to each
of the pressure chambers 4. The diaphragm 6 and the piezoelectric member 7
comprise an actuator; the piezoelectric member 7 being electrically
connected to the output terminal of a driving signal generating circuit 8.
It should be understood that a piezoelectric element is employed as the
piezoelectric member 7, but is not to be limited thereto.
In the common ink chamber 5 an ink supply port 9 connected to an ink tank
(not shown) holding the ink through an ink supply line (not shown) is
formed. The ink contained in the ink tank, therefore, is supplied to the
common ink chamber 5 from the ink supply port 9 through the ink supply
line. In a nozzle face 10 of the nozzle plate 3, nozzles (ink outlets) 11
of the plurality of nozzles 2 are formed nearly in a straight line.
For the ink, various kinds of inks such as water-based ink, oil-based ink,
solvent ink, and UV ink (ultraviolet-curing ink) are used. The UV ink is
made of, for instance, a pigment, a monomer, an oligomer, a
photopolymerization initiator, a dispersant, and other additives (e.g., a
surface tension adjuster).
In the ink jet head 1 stated above, a driving signal is fed to the
piezoelectric member 7 from the driving signal generating circuit 8, to
thereby deflect the piezoelectric member 7 to oscillate the diaphragm 6.
With the oscillation of the diaphragm 6, the volume of the pressure
chamber 4 varies. In the process that the volume of the pressure chamber 4
increases, the ink in the common ink chamber 5 is drawn into the pressure
chamber 4. Reversely in the process that the volume of the pressure
chamber 4 decreases, the ink in the pressure chamber 4 is emitted as
droplets out from the nozzle 2.
In the present embodiment, the piezoelectric member 7 is used as an
actuator; however, it will be understood that the present invention is not
to be limited thereto. For example, a heating element may be used as the
actuator to thereby boil and emit the ink in a form of droplets from the
nozzle 2.
FIG. 3 is an external perspective view schematically showing an ink jet
head unit 20. FIG. 4 is an external perspective view schematically showing
a base board 21 of the ink jet head unit 20. FIG. 5 is an enlarged
sectional view schematically showing the ink jet head unit 20 taken along
line B--B. And FIG. 6 is an enlarged sectional view schematically showing
the ink jet head unit 20 taken along line C--C.
The ink jet head unit 20 is comprised of the base board 21 for holding
various kinds of members; the ink jet head 1 mounted on the base board 21
for emitting the ink in a form of droplets from the nozzles 11 formed in
the nozzle face 10; a driving circuit board 23 mounted on the base board
21, on the same surface side as the ink jet head, and having a driving IC
(integrated circuit) 22 which is a driving circuit for driving the ink jet
head 1; a groove section 24 provided on the same surface side as the ink
jet head 1 on the base board 21, extending from the nozzle face 10 of the
ink jet head 1 to the driving circuit board 23 (see FIG. 4); a temperature
sensor 25 mounted on the ink jet head 1, located in the groove section 24,
for measuring temperatures of the ink jet head 1 (see FIGS. 5 and 6); and
a sealing member 26 located in the groove section 24, for preventing the
flow of the ink emitted from the nozzle 11, into the driving circuit board
23 (see FIGS. 5 and 6).
The ink jet head 1 is bonded with an epoxy adhesive on the base board 21,
and electrically connected to the driving IC 22 through a wiring pattern
27. The driving IC 22 is provided with the driving signal generating
circuit 8. In the present embodiment, the driving IC 22 is mounted on the
driving circuit board 23, but is not to be limited thereto. For example,
the driving IC 22 may be mounted directly on the base board 21. The base
board 21 has a step on the surface (see FIG. 4). The surface in which the
groove section 24 is formed and on which the ink jet head 1 is mounted is
located in a lower position than the surface on which the driving circuit
board 23 is mounted.
The temperature sensor 25 is located in a position opposite to the pressure
chamber 4 of the ink jet head 1, in the vicinity of the nozzle face 10 of
the ink jet head 1. The temperature sensor 25 is electrically connected to
the driving circuit board 23, and an electric wire (not shown) for
electrical connection between the temperature sensor 25 and the driving
circuit board 23 is routed, passing through the groove section 24. The
temperature sensor 25 has a resistance to ink, but is not to be limited
thereto. The groove section 24 is formed straight from the nozzle face 10
side to the driving circuit board 23 side, but is not to be limited
thereto.
The sealing member 26 is formed of for instance an epoxy resin which is an
ink-resisting resin, and partly of an elastic body 28. That is, the
sealing member 26 is constructed of the epoxy resin including the elastic
body 28. As shown in FIGS. 5 and 6, the elastic body 28 is mounted so as
to cover the temperature sensor 25 and not to appear out of the sealing
member 26.
For the elastic body 28, various kinds of rubber materials such as silicone
rubber are used. In the present embodiment, the elastic body 28 having ink
resistance is adopted, but is not to be limited thereto. For example, a
rubber material having no ink resistance will become usable as the elastic
body 28 by adopting the construction that the elastic body 28 is covered
with an ink-resisting epoxy resin. Here, the sealing member 26 is
installed in the groove section 24 when the ink jet head 1 and the base
board 21 are bonded.
In the present embodiment described above, the sealing member 26 is partly
formed of the elastic body 28, thus enabling the elastic body 28 to
restrain (alleviate) a change in the volume of the sealing member 26 even
when the volume of the sealing member 26 is changed with a temperature
change and accordingly preventing giving damage to the ink jet head 1 in
case of the temperature change to thereby realize stabilized ink emission.
In the present embodiment, as shown in FIG. 5, the elastic body 28 is
mounted so as to cover the temperature sensor 25, but is not to be limited
thereto. FIG. 7 is an enlarged sectional view schematically showing an ink
jet head unit 20A of a modification 1 according to one embodiment of the
present invention taken along line B--B. FIG. 8 is also an enlarged
sectional view schematically showing an ink jet head unit 20B of a
modification 2 according to one embodiment of the present invention taken
along line B--B. For instance, as shown in FIG. 7, the elastic body 28 may
be located on either side of the temperature sensor 25 in such a manner
that the height of the elastic body 28 above the surface of the ink jet
head 1 will be higher than the surface of the temperature sensor 25. Also
as shown in FIG. 8 the elastic body 28 may be positioned between the
temperature sensor 25 and the base board 21.
Furthermore, in the present embodiment, the elastic body 28 is mounted so
as not to appear out of the sealing member 26 as shown in FIG. 6, but is
not to be limited thereto. FIG. 9 is an enlarged sectional view
schematically showing an ink jet head unit 20C of a modification 3
according to one embodiment of the present invention taken along line
C--C. For instance, as shown in FIG. 9, the elastic body 28 may be mounted
in such a manner that a part thereof will appear out of the sealing member
26. Thus the elastic body 28 appearing from the sealing member 26 can
partly easily deflect without interference by the sealing member 26.
Furthermore, because of a large amount of deflection of the elastic body
28, a change in the volume of the sealing member 26 can be restrained.
Furthermore, the elastic body 28, having an ink resistance, can appear out
from both ends of the sealing member 26. Consequently, the elastic body 28
can largely deflect as compared with the case of the elastic body 28 which
appears only from one end of the sealing member 26, thereby fully
restraining a change in the volume of the sealing member 26.
When the elastic body 28 has no ink resistance, a part of the elastic body
28 appearing from the sealing member 26 is located on the opposite side
where the sealing member 26 comes into contact with the ink. It is
therefore possible to expose one part of the elastic body 28 even when the
elastic body 28 has no ink resistance.
Furthermore, in the present embodiment, the temperature sensor 25 is
mounted in such a position where it will not appear out of the sealing
member 26, but is not to be limited thereto as shown in FIG. 6. FIG. 10 is
a schematic sectional view of an ink jet head unit 20D of a modification 4
according to one embodiment of the present invention taken along line
C--C. For instance, the sealing member 26 may be mounted in such a manner
that the whole part of the temperature sensor 25 will appear from the
sealing member 26 as shown in FIG. 10. Furthermore, the sealing member 26
may be mounted in such a manner that the temperature sensor 25 will partly
appear from the sealing member 26.
Furthermore, in the present embodiment, the elastic body 28 is used in a
part of the sealing member 26, but is not to be limited thereto. For
instance, a foamed body may be used in place of the elastic body 28. As
the foamed body, a foamed polyurethane type or a closed-cell foamed body,
for example, is used. As the closed-cell foamed body, fluororubber sponge
is used.
Furthermore, when the closed-cell foamed body having an ink resistance is
used, the closed-cell foamed body can appear from both ends of the sealing
member 26. Consequently, since the foamed body largely deflects as
compared with the case of the foamed body appearing only from one end of
the sealing member 26, a change in the volume of the sealing member 26 can
be substantially restrained.
Furthermore, in the present embodiment, the sealing member 26 is formed of
epoxy resin and the elastic body 28, but is not to be limited thereto. For
instance, the whole part of the sealing member 26 may be formed of the
closed-cell foamed body. The adoption of the whole body of the sealing
member 26 thus formed of the closed-cell foamed body can restrain
(alleviate) the change in the volume of the sealing member 26 even in case
of a change in the volume of the sealing member 26 caused by temperature
changes. It is, therefore, possible to prevent temperature changes from
impairing the ink jet head 1, thereby realizing stabilized ink projection.
Obviously, numerous modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims, the invention may
be practiced otherwise than as specifically described herein.
*
